土木工程专业英语原文及翻译

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完整版土木工程专业英语课文原文及对照翻译

完整版土木工程专业英语课文原文及对照翻译

Civil EngineeringCivil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities.土木工程学作为最老的工程技术学科,是指规划,设计,施工及对建筑环境的管理。

此处的环境包括建筑吻合科学规范的所有结构,从灌溉和排水系统到火箭发射设施。

Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities.土木工程师建筑道路,桥梁,管道,大坝,海港,发电厂,给排水系统,医院,学校,公共交通和其他现代社会和大量人口集中地区的基础公共设施。

土木工程专业英语(带翻译)

土木工程专业英语(带翻译)

State-of-the-art report of bridge health monitoring AbstractThe damage diagnosis and healthmonitoring of bridge structures are active areas of research in recent years. Comparing with the aerospace engineering and mechanical engineering, civil engineering has the specialities of its own in practice. For example, because bridges, as well as most civil engineering structures, are large in size, and have quite lownatural frequencies and vibration levels, at low amplitudes, the dynamic responses of bridge structure are substantially affected by the nonstructural components, unforeseen environmental conditions, and changes in these components can easily to be confused with structural damage.All these give the damage assessment of complex structures such as bridges a still challenging task for bridge engineers. This paper firstly presents the definition of structural healthmonitoring system and its components. Then, the focus of the discussion is placed on the following sections:①the laboratory and field testing research on the damage assessment;②analytical developments of damage detectionmethods, including (a) signature analysis and pattern recognition approaches, (b) model updating and system identification approaches, (c) neural networks approaches; and③sensors and their optimum placements. The predominance and shortcomings of each method are compared and analyzed. Recent examples of implementation of structural health monitoring and damage identification are summarized in this paper. The key problem of bridge healthmonitoring is damage automatic detection and diagnosis, and it is the most difficult problem. Lastly, research and development needs are addressed.1 IntroductionDue to a wide variety of unforeseen conditions and circumstance, it will never be possible or practical to design and build a structure that has a zero percent probability of failure. Structural aging, environmental conditions, and reuse are examples of circumstances that could affect the reliability and thelife of a structure. There are needs of periodic inspections to detect deterioration resulting from normal operation and environmental attack or inspections following extreme events, such as strong-motion earthquakes or hurricanes. To quantify these system performance measures requires some means to monitor and evaluate the integrity of civil structureswhile in service. Since the Aloha Boeing 737 accident that occurred on April 28, 1988, such interest has fostered research in the areas of structural health monitoring and non-destructive damage detection in recent years.According to Housner, et al. (1997), structural healthmonitoring is defined as“the use ofin-situ,non-destructive sensing and analysis of structural characteristics, including the structural response, for detecting changes that may indicate damage or degradation”[1]. This definition also identifies the weakness. While researchers have attempted the integration of NDEwith healthmonitoring, the focus has been on data collection, not evaluation. What is needed is an efficient method to collect data from a structure in-service and process the data to evaluate key performance measures, such as serviceability, reliability, and durability. So, the definition byHousner, et al.(1997)should be modified and the structural health monitoring may be defined as“the use ofin-situ,nondestructive sensing and analysis of structural characteristics, including the structural response, for the purpose of identifying if damage has occurred, determining the location of damage, estimatingthe severityof damage and evaluatingthe consequences of damage on the structures”(Fig.1). In general, a structural health monitoring system has the potential to provide both damage detection and condition assessment of a structure.Assessing the structural conditionwithout removingthe individual structural components is known as nondestructive evaluation (NDE) or nondestructive inspection. NDE techniques include those involving acoustics, dye penetrating,eddy current, emission spectroscopy, fiber-optic sensors, fiber-scope, hardness testing, isotope, leak testing, optics, magnetic particles, magnetic perturbation, X-ray, noise measurements, pattern recognition, pulse-echo, ra-diography, and visual inspection, etc. Mostof thesetechniques have been used successfullyto detect location of certain elements, cracks orweld defects, corrosion/erosion, and so on. The FederalHighwayAdministration(FHWA, USA)was sponsoring a large program of research and development in new technologies for the nondestructive evaluation of highway bridges. One of the two main objectives of the program is to develop newtools and techniques to solve specific problems. The other is to develop technologies for the quantitative assessment of the condition of bridges in support of bridge management and to investigate howbest to incorporate quantitative condition information into bridge management systems. They hoped to develop technologies to quickly, efficiently, and quantitatively measure global bridge parameters, such as flexibility and load-carrying capacity. Obviously, a combination of several NDE techniques may be used to help assess the condition of the system. They are very important to obtain the data-base for the bridge evaluation.But it is beyond the scope of this review report to get into details of local NDE.Health monitoring techniques may be classified as global and local. Global attempts to simultaneously assess the condition of the whole structure whereas local methods focus NDE tools on specific structural components. Clearly, two approaches are complementaryto eachother. All such available informationmaybe combined and analyzed by experts to assess the damage or safety state of the structure.Structural health monitoring research can be categorized into the following four levels: (I) detecting the existence of damage, (II) findingthe location of damage, (III) estimatingthe extentof damage, and (IV) predictingthe remaining fatigue life. The performance of tasks of Level (III) requires refined structural models and analyses, local physical examination, and/or traditional NDE techniques. To performtasks ofLevel (IV) requires material constitutive information on a local level, materials aging studies, damage mechanics, and high-performance computing. With improved instrumentation and understanding of dynamics of complex structures, health monitoring and damage assessment of civil engineering structures has become more practical in systematic inspection andevaluation of these structures during the past two decades.Most structural health monitoringmethods under current investigation focus on using dynamic responses to detect and locate damage because they are global methods that can provide rapid inspection of large structural systems.These dynamics-based methods can be divided into fourgroups:①spatial-domain methods,②modal-domain methods,③time-domain methods, and④frequency- domain methods. Spatial-domain methods use changes of mass, damping, and stiffness matrices to detect and locate damage. Modal-domain methods use changes of natural frequencies, modal damping ratios, andmode shapesto detect damage. In the frequency domain method, modal quantities such as natural frequencies, damping ratio, and model shapes are identified.The reverse dynamic systemof spectral analysis and the generalized frequency response function estimated fromthe nonlinear auto-regressive moving average (NARMA) model were applied in nonlinear system identification. In time domainmethod, systemparameterswere determined fromthe observational data sampled in time. It is necessaryto identifythe time variation of systemdynamic characteristics fromtime domain approach if the properties of structural system changewith time under the external loading condition. Moreover, one can use model-independent methods or model-referenced methods to perform damage detection using dynamic responses presented in any of the four domains. Literature shows that model independent methods can detect the existence of damage without much computational efforts, butthey are not accurate in locating damage. On the otherhand, model-referencedmethods are generally more accurate in locating damage and require fewer sensors than model-independent techniques, but they require appropriate structural models and significant computational efforts. Although time-domain methods use original time-domain datameasured using conventional vibrationmeasurement equipment, theyrequire certain structural information and massive computation and are case sensitive. Furthermore, frequency- and modal-domain methods use transformed data,which contain errors and noise due totransformation.Moreover, themodeling and updatingofmass and stiffnessmatrices in spatial-domain methods are problematic and difficult to be accurate. There are strong developmenttrends that two or three methods are combined together to detect and assess structural damages.For example, several researchers combined data of static and modal tests to assess damages. The combination could remove the weakness of each method and check each other. It suits the complexity of damage detection.Structural health monitoring is also an active area of research in aerospace engineering, but there are significant differences among the aerospace engineering, mechanical engineering, and civil engineering in practice. For example,because bridges, as well as most civil engineering structures, are large in size, and have quite lownatural frequencies and vibration levels, at lowamplitudes, the dynamic responses of bridge structure are substantially affected by the non-structural components, and changes in these components can easily to be confused with structural damage. Moreover,the level of modeling uncertainties in reinforced concrete bridges can be much greater than the single beam or a space truss. All these give the damage assessment of complex structures such as bridges a still challenging task for bridge engineers. Recent examples of research and implementation of structural health monitoring and damage assessment are summarized in the following sections.2 Laboratory and field testing researchIn general, there are two kinds of bridge testing methods, static testing and dynamic testing. The dynamic testing includes ambient vibration testing and forced vibration testing. In ambient vibration testing, the input excitation is not under the control. The loading could be either micro-tremors, wind, waves, vehicle or pedestrian traffic or any other service loading. The increasing popularity of this method is probably due to the convenience of measuring the vibrationresponse while the bridge is under in-service and also due to the increasing availability of robust data acquisition and storage systems. Since the input is unknown, certain assumptions have to be made. Forced vibration testing involves application of input excitation of known force level at known frequencies. The excitation manners include electro-hydraulic vibrators, forcehammers, vehicle impact, etc. The static testing in the laboratory may be conducted by actuators, and by standard vehicles in the field-testing.we can distinguish that①the models in the laboratory are mainly beams, columns, truss and/or frame structures, and the location and severity of damage in the models are determined in advance;②the testing has demonstrated lots of performances of damage structures;③the field-testing and damage assessmentof real bridges are more complicated than the models in the laboratory;④the correlation between the damage indicator and damage type,location, and extentwill still be improved.3 Analytical developmentThe bridge damage diagnosis and health monitoring are both concerned with two fundamental criteria of the bridges, namely, the physical condition and the structural function. In terms of mechanics or dynamics, these fundamental criteria can be treated as mathematical models, such as response models, modal models and physical models.Instead of taking measurements directly to assess bridge condition, the bridge damage diagnosis and monitoring systemevaluate these conditions indirectly by using mathematical models. The damage diagnosis and health monitoring are active areas of research in recentyears. For example, numerous papers on these topics appear in the proceedings of Inter-national Modal Analysis Conferences (IMAC) each year, in the proceedings of International Workshop on Structural HealthMonitoring (once of two year, at Standford University), in the proceedings of European Conference on Smart materials and Structures and European Conference on Structural Damage AssessmentUsing Advanced Signal Processing Procedures, in the proceedings ofWorld Conferences of Earthquake Engineering, and in the proceedings of International Workshop on Structural Control, etc.. There are several review papers to be referenced, for examples,Housner, et al. (1997)provided an extensive summary of the state of the art in control and health monitoring of civil engineering structures[1].Salawu (1997)discussed and reviewed the use of natural frequency as a diagnostic parameter in structural assessment procedures using vibrationmonitoring.Doebling, Farrar, et al. (1998)presented a through review of the damage detection methods by examining changes in dynamic properties.Zou, TongandSteven (2000)summarized the methods of vibration-based damage and health monitoring for composite structures, especially in delamination modeling techniques and delamination detection.4 Sensors and optimum placementOne of the problems facing structural health monitoring is that very little is known about the actual stress and strains in a structure under external excitations. For example, the standard earthquake recordings are made ofmotions of the floors of the structure and no recordings are made of the actual stresses and strains in structural members. There is a need for special sensors to determine the actual performance of structural members. Structural health monitoring requires integrated sensor functionality to measure changes in external environmental conditions, signal processing functionality to acquire, process, and combine multi-sensor and multi-measured information. Individual sensors and instrumented sensor systems are then required to provide such multiplexed information.FuandMoosa (2000)proposed probabilistic advancing cross-diagnosis method to diagnosis-decision making for structural health monitoring. It was experimented in the laboratory respectively using a coherent laser radar system and a CCD high-resolution camera. Results showed that this method was promising for field application. Another new idea is thatneural networktechniques are used to place sensors. For example,WordenandBurrows (2001)used the neural network and methods of combinatorial optimization to locate and classify faults.The static and dynamic data are collected from all kinds of sensorswhich are installed on the measured structures.And these datawill be processed and usable informationwill be extracted. So the sensitivity, accuracy, and locations,etc. of sensors are very important for the damage detections. The more information are obtained, the damage identification will be conducted more easily, but the price should be considered. That’s why the sensors are determinedin an optimal ornearoptimal distribution. In aword, the theory and validation ofoptimumsensor locationswill still being developed.5 Examples of health monitoring implementationIn order for the technology to advance sufficiently to become an operational system for the maintenance and safety of civil structures, it is of paramount importance that new analytical developments are ultimately verified with appropriate data obtained frommonitoring systems, which have been implemented on civil structures, such as bridges.Mufti (2001)summarized the applications of SHM of Canadian bridge engineering, including fibre-reinforced polymers sensors, remote monitoring, intelligent processing, practical applications in bridge engineering, and technology utilization. Further study and applications are still being conducted now.FujinoandAbe(2001)introduced the research and development of SHMsystems at the Bridge and Structural Lab of the University of Tokyo. They also presented the ambient vibration based approaches forLaser DopplerVibrometer (LDV) and the applications in the long-span suspension bridges.The extraction of the measured data is very hard work because it is hard to separate changes in vibration signature duo to damage form changes, normal usage, changes in boundary conditions, or the release of the connection joints.Newbridges offer opportunities for developing complete structural health monitoring systems for bridge inspection and condition evaluation from“cradle to grave”of the bridges. Existing bridges provide challenges for applying state-of-the-art in structural health monitoring technologies to determine the current conditions of the structural element,connections and systems, to formulate model for estimating the rate of degradation, and to predict the existing and the future capacities of the structural components and systems. Advanced health monitoring systems may lead to better understanding of structural behavior and significant improvements of design, as well as the reduction of the structural inspection requirements. Great benefits due to the introduction of SHM are being accepted by owners, managers, bridge engineers,etc..6 Research and development needsMost damage detection theories and practices are formulated based on the following assumption: that failure or deterioration would primarily affect the stiffness and therefore affect the modal characteristics of the dynamic response of the structure. This is seldom true in practice, because①Traditional modal parameters (natural frequency, damping ratio and mode shapes, etc.) are not sensitive enough to identify and locate damage. The estimation methods usually assume that structures are linear and proportional damping systems.②Most currently used damage indices depend on the severity of the damage, which is impractical in the field. Most civil engineering structures, such as highway bridges, have redundancy in design and large in size with low natural frequencies. Any damage index should consider these factors.③Scaledmodelingtechniques are used in currentbridge damage detection. Asingle beam/girder models cannot simulate the true behavior of a real bridge. Similitude laws for dynamic simulation and testing should be considered.④Manymethods usually use the undamaged structural modal parameters as the baseline comparedwith the damaged information. This will result in the need of a large data storage capacity for complex structures. But in practice,there are majority of existing structures for which baseline modal responses are not available. Only one developed method(StubbsandKim (1996)), which tried to quantify damagewithout using a baseline, may be a solution to this difficulty. There is a lot of researchwork to do in this direction.⑤Seldommethods have the ability to distinguish the type of damages on bridge structures. To establish the direct relationship between the various damage patterns and the changes of vibrational signatures is not a simple work.Health monitoring requires clearly defined performance criteria, a set of corresponding condition indicators and global and local damage and deterioration indices, which should help diagnose reasons for changes in condition indicators. It is implausible to expect that damage can be reliably detected or tracked byusing a single damage index. We note that many additional localized damage indiceswhich relate to highly localized properties ofmaterials or the circumstances may indicate a susceptibility of deterioration such as the presence of corrosive environments around reinforcing steel in concrete, should be also integrated into the health monitoring systems.There is now a considerable research and development effort in academia, industry, and management department regarding global healthmonitoring for civil engineering structures. Several commercial structural monitoring systems currently exist, but further development is needed in commercialization of the technology. We must realize that damage detection and health monitoring for bridge structures by means of vibration signature analysis is a very difficult task. Itcontains several necessary steps, including defining indicators on variations of structural physical condition, dynamic testing to extract such indication parameters, defining the type of damages and remaining capacity or life of the structure, relating the parameters to the defined damage/aging. Unfortunately, to date, no one has accomplished the above steps. There is a lot of work to do in future.桥梁健康监测应用与研究现状摘要桥梁损伤诊断与健康监测是近年来国际上的研究热点,在实践方面,土木工程和航空航天工程、机械工程有明显的差别,比如桥梁结构以及其他大多数土木结构,尺寸大、质量重,具有较低的自然频率和振动水平,桥梁结构的动力响应极容易受到不可预见的环境状态、非结构构件等的影响,这些变化往往被误解为结构的损伤,这使得桥梁这类复杂结构的损伤评估具有极大的挑战性.本文首先给出了结构健康监测系统的定义和基本构成,然后集中回顾和分析了如下几个方面的问题:①损伤评估的室内实验和现场测试;②损伤检测方法的发展,包括:(a)动力指纹分析和模式识别方法, (b)模型修正和系统识别方法, (c)神经网络方法;③传感器及其优化布置等,并比较和分析了各自方法的优点和不足.文中还总结了健康监测和损伤识别在桥梁工程中的应用,指出桥梁健康监测的关键问题在于损伤的自动检测和诊断,这也是困难的问题;最后展望了桥梁健康监测系统的研究和发展方向.关键词:健康监测系统;损伤检测;状态评估;模型修正;系统识别;传感器优化布置;神经网络方法;桥梁结构1概述由于不可预见的各种条件和情况下,设计和建造一个结构将永远不可能或无实践操作性,它有一个失败的概率百分之零。

土木工程专业英语(苏小卒版)翻译

土木工程专业英语(苏小卒版)翻译
古埃及人用最简单的机械原理和装置建造了许多至今仍矗立的庙宇和金字 塔,包括吉萨大金字塔和在卡纳克的 Amon-Ra 的寺庙。这个大金字塔,481 英 尺(146.6 米)高,由 2250000 个石块组成,石块的平均重量超过 1.5 吨(1.4 吨)。 建造如此的纪念性建筑使用了大量的人力。埃及人也作了一些重达 1000 吨(900 吨)的石头的大块切割的方尖塔。硬青铜的切削刀具在其中使用到了。
The Egyptians built causeways and roads for transporting stone from the quarries to the Nile. The large blocks of stone that were erected by the Egyptians were moved by using levers, inclined planes, rollers, and sledges.
埃及人主要对如何建造感兴趣;他们对为什么这么使用没有什么太多的兴 趣。相反,在公元前六世纪到公元前三世纪希腊人取得了巨大的进步于工程理 论的推广。他们发展了线、角度、面,和实体的抽象的知识,而不是与特定的 对象产生联系。 希腊建筑施工的几何基础包括数字如正方形、矩形和三角形。
The Greek architekton was usually the designer, as well as the builder, of architectural and engineering masterpieces. He was an architect and engineer. Craftsmen, masons, and sculptors worked under his supervision. In the classical period of Greece all important buildings were built of limestone or marble; the Parthenon, for example, was built of marble.

土木工程专业英语课文 翻译 考试必备

土木工程专业英语课文 翻译 考试必备

土木工程专业英语课文翻译The principal construction materials of earlier times were wood and masonry brick, stone, or tile, and similar materials. The courses or layers were bound together with mortar or bitumen, a tar like substance, or some other binding agent. The Greeks and Romans sometimes used iron rods or claps to strengthen their building. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rusted away. The Romans also used a natural cement called puzzling, made from volcanic ash, that became as hard as stone under water.早期时代的主要施工材料,木材和砌体砖,石,或瓷砖,和类似的材料。

这些课程或层密切联系在一起,用砂浆或沥青,焦油一个样物质,或其他一些有约束力的代理人。

希腊人和罗马人有时用铁棍或拍手以加强其建设。

在雅典的帕台农神庙列,例如,在他们的铁钻的酒吧现在已经生锈了孔。

罗马人还使用了天然水泥称为令人费解的,由火山灰制成,变得像石头一样坚硬在水中。

Both steel and cement, the two most important construction materials of modern times, were introduced in the nineteenth century. Steel, basically an alloy of iron and a small amount of carbon had been made up to that time by a laborious process that restricted it to such special uses as sword blades. After the invention of the Bessemer process in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile force which, as we have seen, tends to pull apart many materials. New alloys have further, which is a tendency for it to weaken as a result of continual changes in stress.钢铁和水泥,两个最重要的现代建筑材料,介绍了在十九世纪。

土木工程专业英语原文及翻译

土木工程专业英语原文及翻译

成绩徐州工程学院08 级土木(1) 班课程考试试卷考试科目专业英语考试时间学生姓名所在院系土木学院任课教师徐州工程学院印制Stability of Slopes9.1 IntroductionTranslational slips tend to occur where the adjacent stratum is at a relatively shallow depth below the surface of the slope:the failure surface tends to be plane and roughly parallel to the pound slips usually occur where the adjacent stratum is at greater depth,the failure surface consisting of curved and plane sections.In practice, limiting equilibrium methods are used in the analysis of slope stability. It is considered that failure is on the point of occurring along an assumed or a known failure surface.The shear strength required to maintain a condition of limiting equilibrium is compared with the available shear strength of the soil,giving the average factor of safety along the failure surface.The problem is considered in two dimensions,conditions of plane strain being assumed.It has been shown that a two-dimensional analysis gives a conservative result for a failure on a three-dimensional(dish-shaped) surface.9.2 Analysis for the Case of φu =0This analysis, in terms of total stress,covers the case of a fully saturated clay under undrained conditions, i.e. For the condition immediately after construction.Only moment equilibrium is considered in the analysis.In section, the potential failure surface is assumed to be a circular arc. A trial failure surface(centre O,radius r and length L awhere F is the factor of safety with respect to shear strength.Equating moments about O:Therefore(9.1)The moments of any additional forces must be taken into account.In the event of a tension crackdeveloping ,as shown in Fig.9.2,the arc length L a is shortened and a hydrostatic force will act normal to the crack if the crack fills with water.It is necessary to analyze the slope for a number of trial failure surfaces in order that the minimum factor of safety can be determined.Based on the principle of geometric similarity,Taylor[9.9]published stability coefficients for the analysis of homogeneous slopes in terms of total stress.For a slope of height H the stability coefficient (N s) for the failure surface along which the factor of safety is a minimum is(9.2)For the case ofφu =0,values of N ss depends on the slope angleβand the depth factor D,where DH is the depth to a firm stratum.Gibson and Morgenstern [9.3] published stability coefficients for slopes in normally consolidated clays in which the undrained strength c u(φu =0) varies linearly with depth.Example 9.1A 45°slope is excavated to a depth of 8 m in a deep layer of saturated clay of unit weight 19 kN/m3:the relevant shear strength parameters are c u =65 kN/m2 andφuIn Fig.9.4, the cross-sectional area ABCD is 70 m2.Weight of soil mass=70×19=1330kN/mThe centroid of ABCD is 4.5 m from O.The angle AOC is 89.5°and radius OC is 12.1 m.The arc length ABC is calculated as 18.9m.The factor of safety is given by:This is the factor of safety for the trial failure surface selected and is not necessarily the minimum factor of safety.The minimum factor of safety can be estimated by using Equation 9.2.From Fig.9.3,β=45°and assuming that D is large,the value of N s9.3 The Method of Slicesαand the height, measured on the centre-1ine,is h. The factor of safety is defined as the ratio of the available shear strength(τf)to the shear strength(τm) which must be mobilized to maintain a condition of limiting equilibrium, i.e.The factor of safety is taken to be the same for each slice,implying that there must be mutual support between slices,i.e. forces must act between the slices.The forces (per unit dimension normal to the section) acting on a slice are:1.The total weight of the slice,W=γb h (γsat where appropriate).2.The total normal force on the base,N (equal to σl).In general thisforce has two components,the effective normal force N'(equal toσ'l ) and the boundary water force U(equal to ul ),where u is the pore water pressure at the centre of the base and l is the length of the base.3.The shear force on the base,T=τm l.4.The total normal forces on the sides, E1 and E2.5.The shear forces on the sides,X1 and X2.Any external forces must also be included in the analysis.The problem is statically indeterminate and in order to obtain a solution assumptions must be made regarding the interslice forces E and X:the resulting solution for factor of safety is not exact.Considering moments about O,the sum of the moments of the shear forces T on the failure arc AC must equal the moment of the weight of the soil mass ABCD.For any slice the lever arm of W is rsinα,therefore∑Tr=∑Wr sinαNow,For an analysis in terms of effective stress,Or(9.3)where L a is the arc length AC.Equation 9.3 is exact but approximations are introduced in determining the forces N'.For a given failure arc the value of F will depend on the way in which the forces N' areestimated.The Fellenius SolutionIn this solution it is assumed that for each slice the resultant of the interslice forces is zero.The solution involves resolving the forces on each slice normal to the base,i.e.N'=WCOSα-ulHence the factor of safety in terms of effective stress (Equation 9.3) is given by(9.4)The components WCOSαand Wsinαcan be determined graphically for each slice.Alternatively,the value of αcan be measured or calculated.Again,a series of trial failure surfaces must be chosen in order to obtain the minimum factor of safety.This solution underestimates the factor of safety:the error,compared with more accurate methods of analysis,is usually within the range 5-2%.For an analysis in terms of total stress the parameters C u andφu are used and the value of u in Equation 9.4 is zero.If φu=0 ,the factor of safety is given by(9.5)As N’ does not appear in Equation 9.5 an exact value of F is obtained.The Bishop Simplified SolutionIn this solution it is assumed that the resultant forces on the sides of theslices are horizontal,i.e.X l-X2=0For equilibrium the shear force on the base of any slice isResolving forces in the vertical direction:(9.6)It is convenient to substitutel=b secαFrom Equation 9.3,after some rearrangement,(9.7)The pore water pressure can be related to the total ‘fill pressure’ at anypoint by means of the dimensionless pore pressure ratio,defined as(9.8)(γsat where appropriate).For any slice,Hence Equation 9.7 can be written:(9.9)As the factor of safety occurs on both sides of Equation 9.9,a process of successive approximation must be used to obtain a solution but convergence is rapid.Due to the repetitive nature of the calculations and the need to select an adequate number of trial failure surfaces,the method of slices is particularly suitable for solution by computer.More complex slope geometry and different soil strata can be introduced.In most problems the value of the pore pressure ratio r u is not constant over the whole failure surface but,unless there are isolated regions of high pore pressure,an average value(weighted on an area basis) is normally used in design.Again,the factor of safety determined by this method is an underestimate but the error is unlikely to exceed 7%and in most cases is less than 2%.Spencer [9.8] proposed a method of analysis in which the resultant Interslice forces are parallel and in which both force and moment equilibrium are satisfied.Spencer showed that the accuracy of the Bishop simplified method,in which only moment equilibrium is satisfied, is due to the insensitivity of the moment equation to the slope of the interslice forces.Dimensionless stability coefficients for homogeneous slopes,based on Equation 9.9,have been published by Bishop and Morgenstern [9.2].It can be shown that for a given slope angle and given soil properties th e factor of safety varies linearly with γu and can thus be expressed asF=m-nγu(9.10)where,m and n are the stability coefficients.The coefficients,m and n arefunctions ofβ,φ’,the dimensionless number c'/γand the depth factor D.Example 9.2Using the Fellenius method of slices,determine the factor of safety,in terms of effective stress,of the slope shown in Fig.9.6 for the given failure surface.The unit weight of the soil,both above and below the water table,is 20 kN/m 3 and the relevant shear strength parameters are c’=10 kN/m2andφ’=29°. W) of each slice is given byW=γbh=20×1.5×h=30h kN/mThe height h for each slice is set off below the centre of the base and thenormal and tangential components hcosαand hsinαWcosα=30h cosαW sinα=30h sinαThe pore water pressure at the centre of the base of each slice is taken to beγw z w,where z w is the vertical distance of the centre point below the water table (as shown in figure).This procedure slightly overestimates t he pore water pressure which strictly should be) γw z e,where z e is the vertical distance below the point of intersection of the water table and the equipotential through the centre of the slice base.The error involved is on the safe side.The arc length (L a) is calculated as 14.35 mm.The results are given inTable 9.1∑Wcosα=30×17.50=525kN/m∑W sinα=30×8.45=254kN/m∑(wcos α-ul)=525—132=393kN/m9.4 Analysis of a Plane Translational SlipIt is assumed that the potential failure surface is parallel to the surface of the slope and is at a depth that is small compared with the length of the slope. The slope can then be considered as being of infinite length,with end effects being ignored.The slope is inclined at angle βmz (0<m<1)above the failure plane.Steady seepage is assumed to be taking place in a direction parallel to the slope.The forces on the sides of any vertical slice are equal and opposite and the stress conditions are the same at every point on the failure plane.In terms of effective stress,the shear strength of the soil along the failure plane isand the factor of safety isThe expressions forσ,τandμare:The following special cases are of interest.If c’=0 and m=0 (i.e. the soilbetween the surface and the failure plane is not fully saturated),then(9.11)If c’=0 and m=1(i.e. the water table coincides with the surface of the slope),then:(9.12)It should be noted that when c’=0 the factor of safety is independent ofthe depth z.If c’ is greater than zero,the factor of safety is a function of z, and βmay exceedφ’ provided z is less than a critical value.For a total stress analysis the shear strength parameters c u andφu are used with a zero value of u. Example 9.3A long natural slope in a fissured overconsolidated clay is inclined at 12°to the horizontal.The water table is at the surface and seepage is roughly parallel to the slope.A slip has developed on a plane parallel to the surface at a depth of 5 m.The saturated unit weight of the clay is 20 kN/m3.The peak strength parameters are c’=10 kN/m2andφ’=26°;the residual strength parameters are c r’=0 andφr’=18°.Determine the factor of safety alo ng the slip plane(a)in terms of the peak strength parameters (b)in terms of the residual strength parameters.With the water table at the surface(m=1),at any point on the slip plane,Using the peak strength parameters,Then the factor of safety is given byUsing the residual strength parameters,the factor of safety can beobtained from Equation 9.12:9.5 General Methods of AnalysisMorgenstern and Price[9.4]developed a general analysis in which all boundary and equilibrium conditions are satisfied and in which the failure surface may be any shape,circular,non-circular or compound.The soil mass above the failure plane is divided into sections by a number of vertical planes and the problem is rendered statically determinate by assuming a relationship between the forces E and X on the vertical boundaries between each section.This assumption is of the formX=λf(x)E (9.13)where f(x)is an arbitrary function describing the pattern in which the ratio X/E varies across the soil mas s andλis a scale factor.The value ofλis obtained as part of the solution along with the factor of safety F.The values of the forces E and X and the point of application of E can be determined at each vertical boundary.For any assumed function f(x) it is necessary to examine the solution in detail to ensure that it is physically reasonable (i.e. no shear failure or tension must be implied within the soil mass above the failure surface). The choice of the function f(x) does not appear to influence the computed value of F by more than about 5% and f(x)=l is a common assumption.The analysis involves a complex process of iteration for the values ofλ and F,described byMorgenstern and Price[9.5],and the use of a computer is essential.Bell [9.1] proposed a method of analysis in which all the conditions of equilibrium are satisfied and the assumed failure surface may be of any shape.The soil mass is divided into a number of vertical slices and statical determinacy is obtained by means of an assumed distribution of normal stress along the failure surface.Sarma [9.6] developed a method,based on the method of slices,in which the critical earthquake acceleration required to produce a condition of limiting equilibrium is determined.An assumed distribution of vertical interslice forces is used in the analysis.Again,all the conditions of equilibrium are satisfied and the assumed failure surface may be of any shape.The static factor of safety is the factor by which the shear strength of the soil must be reduced such that the critical acceleration is zero.The use of a computer is also essential for the Bell and Sarma methods and all solutions must be checked to ensure that they are physically acceptable.References[9.1]Bell,J,M.(1968):’General Slope Stability Analysis’, Journal ASCE,V01.94,No.SM6.:‘Stability Coefficients for Earth Slopes Geotechnique,.’,Vo1.1 5,No.1.‘A Numerical Method for Solving the Equations of Stability of General Slip Surfaces’Computer Journal,Voi.9,P.388.[9.6]Sarma,S.K. (1973):’Stability Analysis of Embankments and Slopes’,Geotechnique,Vo1.23,No.2.[9.7]Skempton,A.W.(1970):’First-Time Slides in Overconsolidated Clays’(Technical Note),[9.8]Spencer,E.(1 967):‘A Method of Analysis of the Stability of Embankments Assuming Parallel Inter-SliceForces’,Geotechnique,.[9.9]Taylor,D.W.(1937):’Stability of Earth Slopes’,Journal of the Boston Society of Civil Engineers,Vo1.24,No.3边坡稳定9.1 引言重力和渗透力易引起天然边坡、开挖形成的边坡、堤防边坡和土坝的不稳定性。

土木工程专业英语课文翻译

土木工程专业英语课文翻译

土木工程专业英语课文翻译土木工程专业英语课文翻译土木工程专业,是大学的一种自然学科。

专门培养掌握各类土木工程学科的基本理论和基本知识,能在房屋建筑、地下建筑、道路、隧道、桥梁建筑、水电站、港口及近海结构与设施。

以下是小编整理土木工程专业英语课文翻译的资料,欢迎阅读参考。

weight of the project. Environmental specialists study the project’s impact on the local area: the potential for air and groundwater pollution, the project’s impact on local animal and plant life, and how the project can be designed to meet government requirements aimed at protecting the environment. Transportation specialists determine what kind of facilities are needed to ease the burden on local roads and other transportation networks that will result from the completed project. Meanwhile, structural specialists use preliminary data to make detailed designs, plans, and specifications for the project. Supervising and coordinating the work of these civil engineer specialists, from beginning to end of the project, are the construction management specialists. Based on information supplies by the other specialists, construction management civil engineers estimate quantities and costs of materials and labor, schedule all work, order materials and equipment for the job, hire contractors and subcontractors, and perform other supervisory work to ensure the project is completed on time and as specified.领域。

土木工程英文文献及翻译

土木工程英文文献及翻译

Civil engineeringCivil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like bridges, roads, canals, dams, and buildings.[1][2][3] Civil engineering is the oldest engineering discipline after military engineering,[4] and it was defined to distinguish non-military engineering from military engineering.[5] It is traditionally broken into several sub-disciplines including environmental engineering, geotechnical engineering, structural engineering, transportation engineering, municipal or urban engineering, water resources engineering, materials engineering, coastal engineering,[4] surveying, and construction engineering.[6] Civil engineering takes place on all levels: in the public sector from municipal through to national governments, and in the private sector from individual homeowners through to international companies.History of the civil engineering professionSee also: History of structural engineeringEngineering has been an aspect of life since the beginnings of human existence. The earliest practices of Civil engineering may have commenced between 4000 and 2000 BC in Ancient Egypt and Mesopotamia (Ancient Iraq) when humans started to abandon a nomadic existence, thus causing a need for the construction of shelter. During this time, transportation became increasingly important leading to the development of the wheel and sailing.Until modern times there was no clear distinction between civil engineering and architecture, and the term engineer and architect were mainly geographical variations referring to the same person, often used interchangeably.[7]The construction of Pyramids in Egypt (circa 2700-2500 BC) might be considered the first instances of large structure constructions. Other ancient historic civil engineering constructions include the Parthenon by Iktinos in Ancient Greece (447-438 BC), theAppian Way by Roman engineers (c. 312 BC), the Great Wall of China by General Meng T'ien under orders from Ch'in Emperor Shih Huang Ti (c. 220 BC)[6] and the stupas constructed in ancient Sri Lanka like the Jetavanaramaya and the extensive irrigation works in Anuradhapura. The Romans developed civil structures throughout their empire, including especially aqueducts, insulae, harbours, bridges, dams and roads.In the 18th century, the term civil engineering was coined to incorporate all things civilian as opposed to military engineering.[5]The first self-proclaimed civil engineer was John Smeaton who constructed the Eddystone Lighthouse.[4][6]In 1771 Smeaton and some of his colleagues formed the Smeatonian Society of Civil Engineers, a group of leaders of the profession who met informally over dinner. Though there was evidence of some technical meetings, it was little more than a social society.In 1818 the Institution of Civil Engineers was founded in London, and in 1820 the eminent engineer Thomas Telford became its first president. The institution received a Royal Charter in 1828, formally recognising civil engineering as a profession. Its charter defined civil engineering as:the art of directing the great sources of power in nature for the use and convenience of man, as the means of production and of traffic in states, both for external and internal trade, as applied in the construction of roads, bridges, aqueducts, canals, river navigation and docks for internal intercourse and exchange, and in the construction of ports, harbours, moles, breakwaters and lighthouses, and in the art of navigation by artificial power for the purposes of commerce, and in the construction and application of machinery, and in the drainage of cities and towns.[8] The first private college to teach Civil Engineering in the United States was Norwich University founded in 1819 by Captain Alden Partridge.[9] The first degree in Civil Engineering in the United States was awarded by Rensselaer Polytechnic Institute in 1835.[10] The first such degree to be awarded to a woman was granted by Cornell University to Nora Stanton Blatchin 1905.History of civil engineeringCivil engineering is the application of physical and scientific principles, and its history is intricately linked to advances in understanding of physics and mathematics throughout history. Because civil engineering is a wide ranging profession, including several separate specialized sub-disciplines, its history is linked to knowledge of structures, materials science, geography, geology, soils, hydrology, environment, mechanics and other fields.Throughout ancient and medieval history most architectural design and construction was carried out by artisans, such as stone masons and carpenters, rising to the role of master builder. Knowledge was retained in guilds and seldom supplanted by advances. Structures, roads and infrastructure that existed were repetitive, and increases in scale were incremental.[12]One of the earliest examples of a scientific approach to physical and mathematical problems applicable to civil engineering is the work of Archimedes in the 3rd century BC, including Archimedes Principle, which underpins our understanding of buoyancy, and practical solutions such as Archimedes' screw. Brahmagupta, an Indian mathematician, used arithmetic in the 7th century AD, based on Hindu-Arabic numerals, for excavation (volume) computations.[13]Civil engineers typically possess an academic degree with a major in civil engineering. The length of study for such a degree is usually three to five years and the completed degree is usually designated as a Bachelor of Engineering, though some universities designate the degree as a Bachelor of Science. The degree generally includes units covering physics, mathematics, project management, design and specific topics in civil engineering. Initially such topics cover most, if not all, of thesub-disciplines of civil engineering. Students then choose to specialize in one or more sub-disciplines towards the end of the degree.[14]While anUndergraduate (BEng/BSc) Degree will normally provide successful students with industry accredited qualification, some universities offer postgraduate engineering awards (MEng/MSc) which allow students to further specialize in their particular area of interest within engineering.[15]In most countries, a Bachelor's degree in engineering represents the first step towards professional certification and the degree program itself is certified by a professional body. After completing a certified degree program the engineer must satisfy a range of requirements (including work experience and exam requirements) before being certified. Once certified, the engineer is designated the title of Professional Engineer (in the United States, Canada and South Africa), Chartered Engineer (in most Commonwealth countries), Chartered Professional Engineer (in Australia and New Zealand), or European Engineer (in much of the European Union). There are international engineering agreements between relevant professional bodies which are designed to allow engineers to practice across international borders.The advantages of certification vary depending upon location. For example, in the United States and Canada "only a licensed engineer may prepare, sign and seal, and submit engineering plans and drawings to a public authority for approval, or seal engineering work for public and private clients.".[16]This requirement is enforced by state and provincial legislation such as Quebec's Engineers Act.[17]In other countries, no such legislation exists. In Australia, state licensing of engineers is limited to the state of Queensland. Practically all certifying bodies maintain a code of ethics that they expect all members to abide by or risk expulsion.[18] In this way, these organizations play an important role in maintaining ethical standards for the profession. Even in jurisdictions where certification has little or no legal bearing on work, engineers are subject to contract law. In cases where an engineer's work fails he or she may be subject to the tort of negligence and, in extreme cases, thecharge of criminal negligence.[citation needed] An engineer's work must also comply with numerous other rules and regulations such as building codes and legislation pertaining to environmental law.CareersThere is no one typical career path for civil engineers. Most people who graduate with civil engineering degrees start with jobs that require a low level of responsibility, and as the new engineers prove their competence, they are trusted with tasks that have larger consequences and require a higher level of responsibility. However, within each branch of civil engineering career path options vary. In some fields and firms, entry-level engineers are put to work primarily monitoring construction in the field, serving as the "eyes and ears" of senior design engineers; while in other areas, entry-level engineers perform the more routine tasks of analysis or design and interpretation. Experienced engineers generally do more complex analysis or design work, or management of more complex design projects, or management of other engineers, or into specialized consulting, including forensic engineering.In general, civil engineering is concerned with the overall interface of human created fixed projects with the greater world. General civil engineers work closely with surveyors and specialized civil engineers to fit and serve fixed projects within their given site, community and terrain by designing grading, drainage, pavement, water supply, sewer service, electric and communications supply, and land divisions. General engineers spend much of their time visiting project sites, developing community consensus, and preparing construction plans. General civil engineering is also referred to as site engineering, a branch of civil engineering that primarily focuses on converting a tract of land from one usage to another. Civil engineers typically apply the principles of geotechnical engineering, structural engineering, environmental engineering, transportation engineering and construction engineering toresidential, commercial, industrial and public works projects of all sizes and levels of construction翻译:土木工程土木工程是一个专业的工程学科,包括设计,施工和维护与环境的改造,涉及了像桥梁,道路,河渠,堤坝和建筑物工程交易土木工程是最古老的军事工程后,工程学科,它被定义为区分军事工程非军事工程的学科它传统分解成若干子学科包括环境工程,岩土工程,结构工程,交通工程,市或城市工程,水资源工程,材料工程,海岸工程,勘测和施工工程等土木工程的范围涉及所有层次:从市政府到国家,从私人部门到国际公司。

土木工程类专业英文文献及翻译

土木工程类专业英文文献及翻译

PA VEMENT PROBLEMS CAUSEDBY COLLAPSIBLE SUBGRADESBy Sandra L. Houston,1 Associate Member, ASCE(Reviewed by the Highway Division)ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used.INTRODUCTIONWhen a soil is given free access to water, it may decrease in volume,increase in volume, or do nothing. A soil that increases in volume is calleda swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on thesoil type and structure, the initial soil density, the imposed stress state, andthe degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollarsin roadway repairs. The prediction of the volume changes that may occur inthe field is the first step in making an economic decision for dealing withthese problem subgrade materials.Each project will have different design considerations, economic con-straints, and risk factors that will have to be taken into account. However,with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, anda much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatmentswith substances such as lime, cement, or fly-ash; (2) seepage barriers and/or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to makethe most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniquesare available for any roadway problem.The emphasis here will be placed on presenting economical and simplemethods for: (1) Determining whether the subgrade materials are collapsible;and (2) estimating the amount of volume change that is likely to occur in the'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287.Note. Discussion open until April 1, 1989. To extend the closing date one month,a written request must be filed with the ASCE Manager of Journals. The manuscript for this paper was submitted for review and possible publication on February 3, 1988. This paper is part of the Journal of Transportation.Engineering, V ol. 114, No. 6, November, 1988. ASCE, ISSN 0733-947X/88/0006-0673/$1.00 + $.15 per page. Paper No. 22902.673field for the collapsible soils. Then this information will place the engineerin a position to make a rational design decision. Collapsible soils are fre-quently encountered in an arid climate. The depositional process and for-mation of these soils, and methods for identification and evaluation of theamount of volume change that may occur, will be discussed in the following sections.COLLAPSIBLE SOILSFormation of Collapsible SoilsCollapsible soils have high void ratios and low densities and are typically cohesionless or only slightly cohesive. In an arid climate, evaporation greatly exceeds rainfall. Consequently, only the near-surface soils become wettedfrom normal rainfall. It is the combination of the depositional process andthe climate conditions that leads to the formation of the collapsible soil.Although collapsible soils exist in nondesert regions, the dry environment inwhich evaporation exceeds precipitation is very favorable for the formationof the collapsible structure.As the soil dries by evaporation, capillary tension causes the remainingwater to withdraw into the soil grain interfaces, bringing with it soluble salts,clay, and silt particles. As the soil continues to dry, these salts, clays, andsilts come out of solution, and "tack-weld" the larger grains together. Thisleads to a soil structure that has high apparent strength at its low, naturalwater content. However, collapse of the "cemented" structure may occurupon wetting because the bonding material weakens and softens, and the soilis unstable at any stress level that exceeds that at which the soil had been previously wetted. Thus, if the amount of water made available to the soilis increased above that which naturally exists, collapse can occur at fairlylow levels of stress, equivalent only to overburden soil pressure. Additionalloads, such as traffic loading or the presence of a bridge structure, add tothe collapse, especially of shallow collapsible soil. The triggering mechanismfor collapse, however, is the addition of water.Highway Problems Resulting from Collapsible SoilsNonuniform collapse can result from either a nonhomogeneous subgradedeposit in which differing degrees of collapse potential exist and/or from nonuniform wetting of subgrade materials. When differential collapse ofsubgrade soils occurs, the result is a rough, wavy surface, and potentiallymany miles of extensively damaged highway. There have been several re-ported cases for which differential collapse has been cited as the cause of roadway or highway bridge distress. A few of these in the Arizona and New Mexico region include sections of 1-10 near Benson, Arizona, and sectionsof 1-25 in the vicinity of Algadonas, New Mexico (Lovelace et al. 1982; Russman 1987). In addition to the excessive waviness of the roadway sur- face, bridge foundations failures, such as the Steins Pass Highway bridge,1-10, in Arizona, have frequently been identified with collapse of foundation soils.Identification of Collapsible SoilsThere have been many techniques proposed for identifying a collapsiblesoil problem. These methods range from qualitative index tests conducted on674disturbed samples, to response to wetting tests conducted on relatively un- disturbed samples, to in situ meausrement techniques. In all cases, the en- gineer must first know if the soils may become wetted to a water content above their natural moisture state, and if so, what the extent of the potential wetted zone will be. Most methods for identifying collapsible soils are only qualitative in nature, providing no information on the magnitude of the col- lapse strain potential. These qualitative methods are based on various func- tions of dry density, moisture content, void ratio, specific gravity, and At- terberg limits.In situ measurement methods appear promising in some cases, in that many researchers feel that sample disturbance is greatly reduced, and that a more nearly quantitative measure of collapse potential is obtainable. However,in situ test methods for collapsible soils typically suffer from the deficien-cy of an unknown extent and degree of wetting during the field test. This makes a quantitative measurement difficult because the zone of material being influenced is not well-known, and, therefore, the actual strains, in- duced by the addition of stress and water, are not well-known. In addition, the degree of saturation achieved in the field test is variable and usually unknown.Based on recently conducted research, it appears that the most reliable method for identifying a collapsible soil problem is to obtain the best quality undisturbed sample possible and to subject this sample to a response to wet- ting test in the laboratory. The results of a simple oedometer test will indicate whether the soil is collapsible and, at the same time, give a direct measureof the amount of collapse strain potential that may occur in the field. Potential problems associated with the direct sampling method include sample distur- bance and the possibility that the degree of saturation achieved in the field will be less than that achieved in the laboratory test.The quality of an undisturbed sample is related most strongly to the arearatio of the tube that is used for sample collection. The area ratio is a measure of the ratio of the cross-sectional area of the sample collected to the cross- sectional area of the sample tube. A thin-walled tube sampler by definition has an area ratio of about 10-15%. Although undisturbed samples are best obtained through the use of thin-walled tube samplers, it frequently occurs that these stiff, cemented collapsible soils, especially those containing gravel, cannot be sampled unless a tube with a much thicker wall is used. Samplers having an area ratio as great as 56% are commonly used for Arizona col- lapsible soils. Further, it may take considerable hammering of the tube to drive the sample. The result is, of course, some degree of sample distur- bance, broken.bonds, densification, and a correspondingly reduced collapse measured upon laboratory testing. However, for collapsible soils, which are compressive by definition, the insertion of the sample tube leads to local shear failure at the base of the cutting edge, and, therefore, there is less sample disturbance than would be expected for soils that exhibit general shear failure (i.e., saturated clays or dilative soils). Results of an ongoing studyof sample disturbance for collapsible soils indicate that block samples some- times exhibit somewhat higher collapse strains compared to thick-walled tube samples. Block samples are usually assumed to be the very best obtainable undisturbed samples, although they are frequently difficult-to-impossible to obtain, especially at substantial depths. The overall effect of sample distur- bance is a slight underestimate of the collapse potential for the soil.675译文:湿陷性地基引起的路面问题作者:...摘要:在干旱环境中,湿陷性土壤组成的路基材料是很常见的,干旱环境中的气候条件、沉积以及风化作用都有利于湿陷性土的形成。

土木工程专业英语Lesson 1 Civil Engineering

土木工程专业英语Lesson  1 Civil Engineering
This environment includes all structures built according to scientific principles,from irrigation and drainage systems to rocket-launching facilities.
[dʒi:əu'teknikəl]
Geotechnical specialists perform soil experiments to determine if the earth can bear the weight of the project.
岩土工程专家要做土工试验以确定该土是否 能承受这项工程的重量。
对于任何给定的工程,土木工程师都能广泛地利用计算机。
Computers are used to design the project’s various elements (computer-aided design,or CAD) and to manage it.
计算机被用来设计工程的各个部分并进行管理。
Depending on the type of project,the skills of many kinds of civil engineer specialists may be needed.
根据工程的类型,就需要土木工程师专家的各种 技能。
Scope
When a project begins,the site is surveyed and mapped by civil engineers who locate utility placement-water,sewer,and power lines. 当一项工程开始时,土木工程师要勘测现场并绘图, 他们还要确定水管、污水管道和电线的实用布置。

土木工程专业英语课文译文

土木工程专业英语课文译文

参考译文第一单元第一部分钢筋混凝土混凝土混凝土由水,砂,石子和水泥构成。

这些不同的,分散的材料混合在一起就构成了一种坚硬的大块状物体(形状各异),有着良好的性能。

混凝土被用作建筑材料已有150年的历史。

它的普遍应用主要由于以下几点:(1)恶劣环境下的耐久性(包括耐水)(2)极易被浇铸成不同的形状和尺寸(3)相对经济实惠,极易获得(4)有极强的抗压能力但众所周知,与其较强的抗压强度相比,混凝土抗拉和抗弯强度较低。

因此,每当荷载,限制收缩或是温度发生变化,产生的拉应力超过混凝土的拉伸强度时,就会有裂缝出现。

在结构应用方面,通常的做法是利用钢筋来抵抗拉力或者是给混凝土施加压力来抵消这些拉力。

预应力混凝土对混凝土构件加载之前,对其进行压缩的方法称为预应力。

把钢筋和混凝土使用很强的力结合在一起就被称为预应力混凝土。

预应力混凝土的优点如下:1.在预应力操作过程中,混凝土和钢筋经过严格测试,较低的安全系数也是正当的。

2.混凝土中可容许的工作压力通常是抗压强度的三分之一,从而使保证金来弥补劣质混凝土在临界区发生的风险。

3.预应力减少风险,是由于混凝土在预应力操作期间产生的应力可能是其抗压强度的50%到75%。

今天,预应力混凝土被应用于建筑物,地下结构,电视塔,浮动储藏器和海上结构,电站,核反应堆容器和包括拱形桥和斜拉桥在内的各种桥梁系统当中。

这说明了预应力概念的多方面适应性以及对它的广泛应用。

所有这些结构的发展和建造的成功都是由于材料技术的进步,尤其是预应力钢和在估计预应力长期和短期损失方面积累的知识。

钢筋钢筋是一种极好的建筑材料。

与其他材料相比,钢筋有着较高的抗拉强度。

尽管在体积上是木材的十倍以上。

钢筋有着较高的弹性模量,因此在荷载下容易发生小的变形。

到目前为止所描述的钢筋的特性只适用于温度保持在70F上下的情况,大约从30F到110F。

这个温度区间覆盖了大多数结构的运行状况,但搞清楚当温度远远超出正常水平时所发生的情况仍然非常重要。

土木工程专业英语课文原文及对照翻译

土木工程专业英语课文原文及对照翻译

土木工程专业英语课文原文及对照翻译土木工程师建造道路、桥梁、隧道、水坝、港口、发电厂、水和污水系统、医院、学校、大众交通和其他对现代社会和大量人口集中地区至关重要的公共设施。

他们还建造私人拥有的设施,如机场、铁路、管道、摩天大楼和其他为工业、商业或住宅使用而设计的大型结构。

此外,土木工程师规划、设计和建造完整的城市和城镇,最近还在规划和设计太空平台,以容纳自给自足的社区。

___ passes the planning。

design。

n。

and management of the built ___ scientific principles。

from ___ are essential to modern society。

such as roads。

bridges。

___。

dams。

and hospitals.___ public facilities。

civil engineers also design and build privately-owned structures。

including airports。

railroads。

pipelines。

skyscrapers。

and other ___。

and ___.Overall。

___ civil engineers。

our modern infrastructure and public facilities would not exist.___。

n。

and maintenance of public and private infrastructure。

This includes roads。

bridges。

pipelines。

dams。

ports。

power plants。

water supply and sewage systems。

hospitals。

schools。

___。

and other structures that are essential to modern ___ as airports。

土木工程英语文献原文及中文翻译

土木工程英语文献原文及中文翻译

Civil engineering introduction papers[英语原文]Abstract: the civil engineering is a huge discipline, but the main one is building, building whether in China or abroad, has a long history, long-term development process. The world is changing every day, but the building also along with the progress of science and development. Mechanics findings, material of update, ever more scientific technology into the building. But before a room with a tile to cover the top of the house, now for comfort, different ideas, different scientific, promoted the development of civil engineering, making it more perfect.[key words] : civil engineering; Architecture; Mechanics, Materials.Civil engineering is build various projects collectively. It was meant to be and "military project" corresponding. In English the history of Civil Engineering, mechanical Engineering, electrical Engineering, chemical Engineering belong to to Engineering, because they all have MinYongXing. Later, as the project development of science and technology, mechanical, electrical, chemical has gradually formed independent scientific, to Engineering became Civil Engineering of specialized nouns. So far, in English, to Engineering include water conservancy project, port Engineering, While in our country, water conservancy projects and port projects also become very close and civil engineering relatively independent branch. Civil engineering construction of object, both refers to that built on the ground, underground water engineering facilities, also refers to applied materials equipment and conduct of the investigation, design and construction, maintenance, repair and other professional technology.Civil engineering is a kind of with people's food, clothing, shelter and transportation has close relation of the project. Among them with "live" relationship is directly. Because, to solve the "live" problem must build various types of buildings. To solve the "line, food and clothes" problem both direct side, but also a indirect side. "Line", must build railways, roads, Bridges, "Feed", must be well drilling water, water conservancy, farm irrigation, drainage water supply for the city, that is direct relation. Indirectly relationship is no matter what you do, manufacturing cars, ships, or spinning and weaving, clothing, or even production steel, launch satellites, conducting scientific research activities are inseparable from build various buildings, structures and build all kinds of project facilities.Civil engineering with the progress of human society and development, yet has evolved into large-scale comprehensive discipline, it has out many branch, such as: architectural engineering, the railway engineering, road engineering, bridge engineering, special engineering structure, waterand wastewater engineering, port engineering, hydraulic engineering, environment engineering disciplines. [1]Civil engineering as an important basic disciplines, and has its important attributes of: integrated, sociality, practicality, unity. Civil engineering for the development of national economy and the improvement of people's life provides an important material and technical basis, for many industrial invigoration played a role in promoting, engineering construction is the formation of a fixed asset basic production process, therefore, construction and real estate become in many countries and regions, economic powerhouses.Construction project is housing planning, survey, design, construction of the floorboard. Purpose is for human life and production provide places.Houses will be like a man, it's like a man's life planning environment is responsible by the planners, Its layout and artistic processing, corresponding to the body shape looks and temperament, is responsible by the architect, Its structure is like a person's bones and life expectancy, the structural engineer is responsible, Its water, heating ventilation and electrical facilities such as the human organ and the nerve, is by the equipment engineer is responsible for. Also like nature intact shaped like people, in the city I district planning based on build houses, and is the construction unit, reconnaissance unit, design unit of various design engineers and construction units comprehensive coordination and cooperation process.After all, but is structural stress body reaction force and the internal stress and how external force balance. Building to tackle, also must solve the problem is mechanical problems. We have to solve the problem of discipline called architectural mechanics. Architectural mechanics have can be divided into: statics, material mechanics and structural mechanics three mechanical system. Architectural mechanics is discussion and research building structure and component in load and other factors affecting the working condition of, also is the building of intensity, stiffness and stability. In load, bear load and load of structure and component can cause the surrounding objects in their function, and the object itself by the load effect and deformation, and there is the possibility of damage, but the structure itself has certain resistance to deformation and destruction of competence, and the bearing capacity of the structure size is and component of materials, cross section, and the structural properties of geometry size, working conditions and structure circumstance relevant. While these relationships can be improved by mechanics formula solved through calculation.Building materials in building and has a pivotal role. Building material is with human society productivity and science and technologyimproves gradually developed. In ancient times, the human lives, the line USES is the rocks andTrees. The 4th century BC, 12 ~ has created a tile and brick, humans are only useful synthetic materials made of housing. The 17th century had cast iron and ShouTie later, until the eighteenth century had Portland cement, just make later reinforced concrete engineering get vigorous development. Now all sorts of high-strength structural materials, new decoration materials and waterproof material development, criterion and 20th century since mid organic polymer materials in civil engineering are closely related to the widely application. In all materials, the most main and most popular is steel, concrete, lumber, masonry. In recent years, by using two kinds of material advantage, will make them together, the combination of structure was developed. Now, architecture, engineering quality fit and unfit quality usually adopted materials quality, performance and using reasonable or not have direct connection, in meet the same technical indicators and quality requirements, under the precondition of choice of different material is different, use method of engineering cost has direct impact.In construction process, building construction is and architectural mechanics, building materials also important links. Construction is to the mind of the designer, intention and idea into realistic process, from the ancient hole JuChao place to now skyscrapers, from rural to urban country road elevated road all need through "construction" means. A construction project, including many jobs such as dredging engineering, deep foundation pit bracing engineering, foundation engineering, reinforced concrete structure engineering, structural lifting project, waterproofing, decorate projects, each type of project has its own rules, all need according to different construction object and construction environment conditions using relevant construction technology, in work-site.whenever while, need and the relevant hydropower and other equipment composition of a whole, each project between reasonable organizing and coordination, better play investment benefit. Civil engineering construction in the benefit, while also issued by the state in strict accordance with the relevant construction technology standard, thus further enhance China's construction level to ensure construction quality, reduce the cost for the project.Any building built on the surface of the earth all strata, building weight eventually to stratum, have to bear. Formation Support building the rocks were referred to as foundation, and the buildings on the ground and under the upper structure of self-respect and liable to load transfer to the foundation of components or component called foundation. Foundation, and the foundation and the superstructure is a building of three inseparable part. According to the function is different, but in load, under the action of them are related to each other, is theinteraction of the whole. Foundation can be divided into natural foundation and artificial foundation, basic according to the buried depth is divided into deep foundation and shallow foundation. , foundation and foundation is the guarantee of the quality of the buildings and normal use close button, where buildings foundation in building under loads of both must maintain overall stability and if the settlement of foundation produce in building scope permitted inside, and foundation itself should have sufficient strength, stiffness and durability, also consider repair methods and the necessary foundation soil retaining retaining water and relevant measures. [3]As people living standard rise ceaselessly, the people to their place of building space has become not only from the number, and put forward higher requirement from quality are put car higher demands that the environment is beautiful, have certain comfort. This needs to decorate a building to be necessary. If architecture major engineering constitutes the skeleton of the building, then after adornment building has become the flesh-and-blood organism, final with rich, perfect appearance in people's in front, the best architecture should fully embody all sorts of adornment material related properties, with existing construction technology, the most effective gimmick, to achieve conception must express effect. Building outfit fix to consider the architectural space use requirement, protect the subject institutions from damage, give a person with beautifulenjoying, satisfy the requirements of fire evacuation, decorative materials and scheme of rationality, construction technology and economic feasibility, etc. Housing construction development and at the same time, like housing construction as affecting people life of roads, Bridges, tunnels has made great progress.In general civil engineering is one of the oldest subjects, it has made great achievements, the future of the civil engineering will occupy in people's life more important position. The environment worsening population increase, people to fight for survival, to strive for a more comfortable living environment, and will pay more attention to civil engineering. In the near future, some major projects extimated to build, insert roller skyscrapers, across the oceanBridges, more convenient traffic would not dream. The development of science and technology, and the earth is deteriorating environment will be prompted civil engineering to aerospace and Marine development, provide mankind broader space of living. In recent years, engineering materials mainly is reinforced concrete, lumber and brick materials, in the future, the traditional materials will be improved, more suitable for some new building materials market, especially the chemistry materials will promote the construction of towards a higher point. Meanwhile, design method of precision, design work of automation, information and intelligent technology of introducing, will be people have a morecomfortable living environment. The word, and the development of the theory and new materials, the emergence of the application of computer, high-tech introduction to wait to will make civil engineering have a new leap.This is a door needs calm and a great deal of patience and attentive professional. Because hundreds of thousands, even hundreds of thousands of lines to building each place structure clearly reflected. Without a gentle state of mind, do what thing just floating on the surface, to any a building structure, to be engaged in business and could not have had a clear, accurate and profound understanding of, the nature is no good. In this business, probably not burn the midnight oil of courage, not to reach the goal of spirit not to give up, will only be companies eliminated.This is a responsible and caring industry. Should have a single responsible heart - I one's life in my hand, thousands of life in my hand. Since the civil, should choose dependably shoulder the responsibility.Finally, this is a constant pursuit of perfect industry. Pyramid, spectacular now: The Great Wall, the majestic... But if no generations of the pursuit of today, we may also use the sort of the oldest way to build this same architecture. Design a building structure is numerous, but this is all experienced centuries of clarification, through continuous accumulation, keep improving, innovation obtained. And such pursuit, not confined in the past. Just think, if the design of a building can be like calculation one plus one equals two as simple and easy to grasp, that was not for what? Therefore, a civil engineer is in constant of in formation. One of the most simple structure, the least cost, the biggest function. Choose civil, choosing a steadfast diligence, innovation, pursuit of perfect path.Reference:[1] LuoFuWu editor. Civil engineering (professional). Introduction to wuhan. Wuhan university of technology press. 2007[2] WangFuChuan, palace rice expensive editor. Construction engineering materials. Beijing. Science and technology literature press. 2002[3] jiang see whales, zhiming editor. Civil engineering introduction of higher education press. Beijing.. 1992土木工程概论 [译文]摘要:土木工程是个庞大的学科,但最主要的是建筑,建筑无论是在中国还是在国外,都有着悠久的历史,长期的发展历程。

土木工程专业英语翻译(含中英)

土木工程专业英语翻译(含中英)

Structural behavior of low- and normal-strength interface mortar of masonryThomas Zimmermann1 , Alfred Strauss1 and Konrad Bergmeister1(1) Institute for Structural Engineering, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, 1190 Vienna, AustriaThomasZimmermann(Correspondingauthor)Email:Zimmermann.Thomas@boku.ac.atAlfredStraussEmail:Alfred.Strauss@boku.ac.atKonradBergmeisterEmail:Konrad.Bergmeister@boku.ac.atReceived:12 April 2011 Accepted:29 August 2011 Published online:8 November 2011 Abstract Building with masonry is based on the experience of many centuries. Although this design is used worldwide, knowledge about the material behaviour of masonry is still subject to uncertainties. The determination of safety of these structures against earthquakes is a complex challenge. For instance it depends on the resistance of the structure, the seismic action and on many uncertain structural details. One of the key parameters regarding the resistance is the shear strength of the masonry. A series of tests on mortar prisms according to EN 1015-11 was performed in which the mortar properties were varied in order to measure bending and compressive strength. In a second test program, the shear strength of the masonry was tested according to EN 1052-3. Shear triplets were made to establish the shear strength variation due to deliberate variation of the mortar properties. In addition, for both tests on mortar prisms and tests on shear triplets, descriptive statistical parameters were calculated and an attempt was made to describe the datasets with probabilistic distributions for further dimensioning and stochastic assessments. Keywords Shear strength – Coefficient of friction – Old masonry1IntroductionMasonry is a typical construction material which can withstand compression, but has low shear and bending resistance. This makes unreinforced masonry buildings highly interesting: (a) to gather mechanical properties and their wide scatter, which is characteristic for old masonry, and, (b) to obtain appropriate tools for assessment, analysis and retrofit methods.General rules and design aspects are stated in specific Eurocodes (EC). For masonry structures, rules and design aspects are regulated in EC 6 [1]. The ultimate limit state distinguishes between three major conditions: (a) masonry under vertical loading, (b) masonry under shear, and, (c) masonry under bending. The most critical loading conditions are cases (b) and (c), especially in the case of unreinforced masonry. Thereby the inappropriate horizontal loading situation is caused by wind loads or by seismic actions.Regarding the material behaviour under horizontal loading, two types of material parameters could be distinguished. The first type directly affects the stress side e.g. energy dissipation and behaviour factor. The second type directly affects the resistant side e.g. shear resistance, tensile strength and shear modulus. According to EC 6, the design value of shear strength depends on initial shear strength and the coefficient of friction as well as on geometrical parameters. With a testing program according to EN 1052-3 [2] it is possible to characterize these two material parameters for masonry. Further it is possible to define the shear resistance if sliding shear failure takes place. Therefore an extensive study can be found in Tomazevic [3], but it is focused on new brick material and mortar respectively.The procedure described in EN 1052-3 is the state of the art testing method to evaluate masonry shear strength without distinguishing between old and new masonry. Thereby two specimen layouts can be used. The smallest practical specimen consists of two brick units and one mortar layer while the second layout consists of three brick units and two mortar layers. In the case of testing old masonry the second specimen layout is more appropriate because the normative requirements can be easier achieved and further a symmetric loading situation occurs.The testing program presented in this paper is focused on old masonry and was carried out with different mortar properties. The results of this testing program, as well as a stochastic approach to describe the material strength in combination with an extensive literature review, are presented in this paper.2Material properties2.1BricksThe shear specimens were made with only one type of old, solid masonry bricks, see Fig. 1. This type of brick is typical for houses from the nineteenth century in Vienna. The mean dimensions of bricks were L/B/H = 29.12/14.13/7.05 cm. The dimensions were measured according to EN 772-16 [4]. Based on the obtained minimum dimensions in length and width, the bricks were cut to provide a consistent interface between the bricks and the mortar layer. The final dimensions of bricks were L = 25 cm and B = 12 cm. The height of bricks remained unchanged. The mean value of the dry density of bricks was ρ = 1,467 kg/m3.Fig. 1 Old, solid bricks used for shear testsThe compressive strength f b was obtained according to EN 772-1 [5] whereby the mean value of compressive strength resulted in f b = 19.28 MPa.2.2MortarTo determine the initial and shear strength between brick and mortar, a mortar mixture was chosen which was of low strength and a simple composition. Two mortar compositions out of four mixtures were chosen such that (a) the mortar had almost the same characteristics as the mortar for shear tests on masonry walls to provide comparability and (b) it was a very low strength mortar. These shear tests on masonry walls have already been carried out and are documented in [6]. In a testing program, consisting of four different mixtures, mortar prisms with dimensions of 40 × 40 × 160 mm were tested to obtain the compressive strength, f m and flexural strength, f m,fl. Table 1 shows the composition of all four mortar mixtures.Table 1 Investigated mortar mixtures, units in gramMix. I Mix. II Mix. III Mix. IVCEM 32.5 1,000 1,500 2,000 0Lime 400 400 400 400Rock flour 1,200 1,200 1,200 0Fine sand 0–1 4,650 4,650 4,650 4,650Course sand 0–4 12,445 12,445 12,445 12,445Water 3,500 3,500 3,500 3,250Compressive strength and flexural strength were obtained according to EN 1015-11 [7] after a curing time of 28 days. Table 2 shows the results of the testing program.Table 2 Material parameters of investigated mortar mixtures, units in MPaMix. I Mix. II Mix. III Mix. IVFlexural strength 0.58 1.02 1.39 –Compressive strength 1.50 3.58 4.06 0.22Based on these results mortar mixture II was chosen for a first triplet shear test groupbecause its characteristics are closest to the mortar characteristics of the mortar which was used in the shear tests on masonry walls. Mortar mixture IV was chosen for a second triplet shear test group.2.3Masonry specimensSpecimens for the triplet shear tests were built which consisted of three brick units with two mortar joints. The cut bricks provide a smooth surface for the bearings as well as for the load application area. The upper and lower surfaces of the specimens were confined with a cement mortar. After the specimens were built, each one was loaded with a compression load of about 3.0 × 10−3 MPa until testing. Simultaneously, while building the specimens for the triplet shear tests, additional mortar specimens of both mixtures were built for further mortar tests.3Testing methodsThe general problem in testing the shear behaviour along mortar joints and brick units is in applying a uniform distribution of both shear stress and normal stress. To avoid additional moments, the shear load should be applied as close as possible to the mortar joints, see [8]. There should also be no tensile stresses along the joint because these stresses could affect the failure load. However, some stress concentrations occur around the load introduction area and also some moment is introduced at the joint, which means that it is nearly impossible to introduce a pure shear stress distribution. The shear strength of masonry is dependent on the shear bond properties of the mortar joints, the vertical compression level and the friction angle. To obtain these properties different types of specimens can be used. Figure 2 shows a variety of different testing methods.Fig. 2 Various test arrangements for shear tests, a triplet test according to EN 1052-3, b Hoffmann and Stoeckl [9], c Riddington et al. [10], d Van der Pluijm [11], e Hamid et al. [12], f Abdou et al. [13] and g Popal and Lissel [14]These test methods consist of either two, three or four bricks. A review can be found in Jukes et al. [15] and additional experimental investigations are presented by Abdou et al. [13]. Further, several test arrangements have been investigated via FEM. Results are proposed by Stoeckl et al. [16]. Hence, it could be shown that peaks of both shear and normal stresses occur in all arrangements. There are also some approaches to combine the advantages of different test methods, e.g. [14].However, all the mentioned methods have it in common that they require very complex equipment and they are not a standard test method, expect triplet shear tests according to EN 1052-3.4Investigation of the shear behaviorPreviously mentioned test methods are designed so that the bricks only partially overlap. It does not matter with new bricks with more or less even surfaces. In the case of old bricks, a complete overlap is more advantageous because possible influences from uneven surfaces and imprints are taken into account. Thus the triplet test method according to EN 1052-3 was used for the investigations presented in this paper.According to EN 1052-3, two different test procedures are possible. In procedure (a) specimens have to be tested under at least three different normal stress levels with at least three specimens for each level. Procedure (b) is performed without any pre-compression with at least six specimens. In order to avoid normal tensile stresses along the mortar bed joints, procedure (a) was chosen. This normal stress is undesirable since the results for the shear strength can be affected by the tensile strength of the mortar bed joints.Two groups of specimens were tested. Table 3shows the properties of shear specimens. The bricks for both groups are the same, but the mortar mixtures differ. Mortar mixture II was used for group A while mortar mixture IV was used for group B.Table 3 Characteristics of masonry specimens, units in MPaCompressive strength ofBricks f b Mortar f m Masonry f kGroup A 19.28 3.58 5.65Group B 19.28 0.22 2.81Based on the compressive strengths of both bricks f b, and mortar f m, the compressive strength of masonry f k was calculated according to EC 6, National Annex B 1996-1-1 [17].(1)Shear strength was measured using the set up shown in Fig. 3. The brick in the middle is sheared and the upper and lower bricks are supported. The horizontal shear load was applied with a hydraulic jack. The varying pre-compression load was applied perpendicular to the shear surface.Fig. 3 Triplet shear test set upIn the case of group A, five vertical stress levels (3, 7, 15, 25 and 40% of f k) were applied and five tests were performed at each level for statistical evaluation. This resulted in a total number of 25 specimens for group A. In the case of group B, three vertical stress levels (13, 28 and 48% of f k) were applied. Hence, three tests were performed at each level. This resulted in a total number of nine specimens for group B.Each test took about 5 min until shear failure occurred. When the specimen cracks and pure shearing starts, the pre-compression load fluctuates. This was adjusted manually in order to keep it constant. During testing, the shear load and the applied pre-compression load were measured simultaneously.The evaluation of shear tests was based on the maximum horizontal force H max obtained during testing. Since the middle brick was loaded, the horizontal force had to be divided by two times the corresponding shear area (250 × 120 mm = 30,000 mm2). Hence, i the shear strength for each specimen f v,i could be calculated as:(2)The applied normal stress level σd was calculated with the applied pre-compressionforce with respect to the corresponding shear area of the specimen i.(3)The shear strength of masonry depends on the applicable friction forces in the horizontal joints, the tensile strength of the bricks, the compressive strength of masonry and the bond strength between bricks and mortar. The shear strength is essentially determined by the normal stress level. According to EC 6 it can be calculated as:(4)where f vko is the initial shear strength without any vertical stresses; σd the normal stress level perpendicular to the shear force and μk the coefficient of friction (both characteristic values).The evaluation of the shear test results was done (a) based on mean values, (b) based on a statistical approach using 5% fractiles of a Lognormal distribution and (c) according to EN 1052-3. Finally both evaluations were compared to each other, see Table 4.Table 4 Mean values of initial shear strenght and coefficient of friction and comparison of characteristic valuesInitial shear strength (MPa) Coefficient of friction (–)Mean EC 6 5% fractile EN 1052-3 Mean EC 6 5% fractil EN 1052-3f vo f vko f vko,5%f vkoμμkμk,5%μkGroup A 0.210 0.200 0.174 0.168a0.709 0.400 0.624 0.566 Group B 0.027 0.100 0.014 0.010b0.643 0.400 0.623 0.514a Calculated from mean value by multiplying with 0.8;b smallest single value of testdata4.1Failure modesGenerally, four failure modes during shear tests can appear. Mode (a) is a fracture plane localised at one brick mortar interface. Mode (b) is a fracture plane at each brick mortar interface combined with a vertical crack in the mortar layer. Mode (c) is a pure shear failure in the mortar layer and mode (d) is a fracture plane through both mortar and bricks, see Fig. 4. For the shear tests presented in this paper, only the failure modes (a) and (b) were observed during testing.Fig. 4 Failure modes of masonry specimens during shear testing4.2Results group AFigure 5shows the shear strength with respect to the corresponding normal stress level for the tested specimens of group A. For each stress level the mean value, the 5% fractile based on a Lognormal distribution and characteristic value according toEN 1052-3 were calculated. Linear best fits through (a) and (b) values were carried out using the least square method. Thereby, for case (a) a Mohr–Coulomb relationship was obtained as:(5)and for case (b) as:(6)Fig. 5 Shear strength with respect to vertical stress, group ACase (c), the determination of characteristic value according to EN 1052-3, can be directly calculated from mean values by multiplying with 0.8 or it corresponds to the smallest single value of the testdata. The smaller value is decisive:(7)Further, the normative relationship (norm) is plotted in Fig. 5. Due to the mortar properties, the corresponding mortar class, according to EC 6, is M2.5–M9. Hence the initial shear strength f vko norm= 0.20 MPa and the coefficient of friction μk norm = 0.4. Table 5 summarizes the test results and descriptive statistical parameters.Table 5 Test results of shear strength f v, i (MPa) with respect to normal stress levelSymbol Normal force level (kN)5.0 11.0 24.0 40.5 65.0Group AMean 0.3040.47960.8104 1.15001.7436Standard deviation s0.04890.04920.0634 0.0890 0.1413Coefficient of variation cov0.16090.10250.0783 0.0774 0.08105% fractile x50.11250.39910.7057 1.0036 1.5116Group BMean –0.2610.5440 0.8933 –Standard deviation s–0.01250.0092 0.0302 –Coefficient of variation cov–0.04760.0169 0.0338 –5% fractile x5–0.2410.5291 0.8445 –4.3Results group BFigure 6shows the shear strength with respect to the corresponding normal stress level for the tested specimens of group B. Again, linear best fits through (a) the mean values and (b) the fractile values were carried out using the least square method.Fig. 6 Shear strength with respect to vertical stress, group BThereby for case (a), a Mohr–Coulomb relationship was obtained as:(8)and for case (c) as:(9)Again, case (c), the determination of characteristic value according to EN 1052-3, can be directly calculated from mean values by multiplying with 0.8 or it corresponds to the smallest single value of the testdata. The smaller value is decisive:(10)Also the normative relationship (norm) is plotted in Fig. 6. Due to the mortar properties, the corresponding mortar class according to EC 6 is M1 – M2. Hence theinitial shear strength f vko norm= 0.10 MPa and the coefficient of friction μk norm = 0.4. Table 5 summarizes the test results and descriptive statistical parameters.5Probabilistic modelsThis section provides an overview of the investigated probabilistic models which were considered here to describe test results and literature data of the coefficient of friction of masonry. Depending on the distribution function, different procedures were used for estimating the unknown parameters e.g. Method of Moments and Method of Maximum Likelihood. Detailed studies regarding parameter estimation can be found in [18–20] and other sources. The functions of the investigated distributions relate to the two and three parameter function respectively.The investigated probabilistic models are the usual distribution functions like Normal and Lognormal, and also common distribution functions to describe material strength, such as Gamma and Weibull. Different methods have been used for choosing the best fit model to a given data set. These methods are the Kolmogrorv Smirnov (KS), the χ2 and the Anderson Darling (AD) test. The last method was chosen for this study as it is more sensitive to the tail behaviour. The sensitivity to the tail behaviour is particularly useful in structural engineering applications, where the tail is important in computing the structural reliability.The KS procedure involves the comparison between the assumed hypothetical and the empirical cumulative distribution function. For computing models, it is natural to choose a particular model for a given sample whereby the discrepancy is low. Otherwise, if the discrepancy is large with respect to what is normally expected from a given sample, the hypothetical model is rejected.The χ2-test is used to determine if a sample comes from a population with a specificdistribution. It compares the observed frequencies in k intervals of thevariate with the corresponding frequencies from an assumed hypothetical distribution.Finally, the AD-procedure is a general test to compare the fit of an empirical cumulative distribution function to a hypothetical cumulative distribution function. This test gives more weight to the tails than the KS-test.The various probabilistic models were applied to a data set consisting of values from an extensive literature review as well as of values from laboratory tests, as described in Sect. 4. A total number of n = 2,028 values were used. Table 6 shows the mean and characteristic values of the coefficient of friction from literature.Table 6 Mean and characteristic values of coefficient of friction, form literatureName Ref. Coef. of frictionμkAbdou et al. [13] 0.886 0.709Amadio and Rajgelj [21] 0.700 0.560Benjamin and Williams [22] 1.100 0.880Chin [23] 0.750 0.600Ghazali and Riddington [24] 0.778 0.622Hegemioer et al. [25] 0.941 0.753Jukes [26] 0.797 0.638Khalaf [27] 0.793 0.635Page [28] 0.700 0.560Sinha and Hendry [29] 0.700 0.560Van der Pluijm [11, 30, 31] 0.850 0.680Vermeltfoort [32, 33] 0.747 0.598Min 0.700 0.560Max 1.100 0.880Figure 7shows proportion–proportion plots (PP-plots) for some investigated distribution functions. The empirical cumulative proportion is plotted against the hypothetical cumulative proportion. The straight line is added as a reference line. The further the points vary from this line, the greater the indication of departures from the designated distribution. Table 7shows the results of the goodness of fit tests for different distribution functions.Fig. 7 PP-plots of different distribution functionsTable 7 KS-distances, AD-values and χ2-values for different distribution functionsPDF KS AD χ2Normal 0.05884 1.6669 16.827Lognormal 0.07429 2.3188 26.802Gamma 0.06551 1.8732 22.899Weibull 0.07256 4.4672 10.128Gumbel max 0.11476 6.147 39.993All probabilistic models can represent the lower and upper tail behaviour of the observed data, except Weibull where the points of lower tail are above the reference line. This indicates shorter than Weibull tails, i.e. less variance than expected. Further, a comparison between the median area and the remaining distributions shows that the slightest deviations arise for Normal and Lognormal distributions. This is in correlation with the applied goodness of fit tests.6ConclusionsAs a part of the SEISMID research project, several tests on masonry were carried out. In this case, the focus was on testing the shear behaviour of masonry triplets under different conditions according to EN 1052-3. Additional tests on bricks and mortar were carried out to determine the basic material properties.To estimate possible influences on the shear behaviour of masonry, two different groups of shear triplets were built and tested under different normal stress levels. The two groups (A and B) differed in terms of compressive strength of mortar (f m,A = 3.58 MPa and f m,B= 0.22 MPa). The evaluation of the test results show that the shear behaviour can be described by the Mohr–Coulomb friction law. Hence, the initial shear strength f vko and the coefficient of friction μk were determined. When compared to the values according to EC 6, some agreement can be seen, but also some values which are not in agreement.In the case of specimen group A, the mean value of the initial shear strength from testing (0.210 MPa) is very consistent with the suggested normative value (0.200 MPa). In case of group B, there is no consistency between the values from testing (0.027 MPa) and EC 6 (0.100 MPa). This inconsistency is mainly due to the mortar mixture in that the mortar of group B contains no cement and just a small amount of lime (compare Table 1). Hence, no significant initial shear strength between mortar joints and bricks can be developed.The evaluation of the characteristic value of initial shear strength according to EN 1052-3 results in f vko= 0.168 MPa for mortar group A and f vko= 0.010 MPa for mortar group B. If the evaluation is based on 5% fractiles of a Lognormal distribution the values results in f vko = 0.174 MPa for mortar group A and f vko = 0.014 MPa for mortar group B. As can be seen there are no significant differences of the calculated values. This indicates that both evaluation procedures are suitable to derive characteristic values from experimental test results.The comparison of the coefficient of friction shows a gap between the test results andthe value according to EC 6. The normative value for the coefficient of friction is suggested to be 0.400. The experimental data show that the percentage of normal stress on the shear strength amounts μ = 0.709 in case of group A and μ = 0.643 in case of group B, based on mean values. The evaluation of the characteristic value of coefficient of friction according to EN 1052-3 results in μk = 0.566 for mortar group A and μk= 0.514 for mortar group B. If the evaluation is based on 5% fractiles of a Lognormal distribution the values results in μk= 0.624 for mortar group A and μk = 0.623 for mortar group B. As can be seen there are differences of the calculated values. This indicates that the evaluation procedure according to EN 1052-3 procedure is more conservative because mean values are multiplied by the factor 0.8 to derive characteristic values but any additional information of test results are neglected. These additional information are accounted by the statistical approach. In addition, the literature review shows that the normative value for the coefficient of friction is too low.The choice of a probabilistic model plays an important role for a probabilistic based design approach and reliability assessment. In this work different statistical distribution functions were considered in order to critically analyze the coefficient of friction of masonry. Hence, two- and three-parameter distributions were used. The data set for the statistical distribution fitting was collected from both literature and laboratory tests.Based on the set of strength data and using several statistical criteria, like KS-test, χ2-test and AD-procedure, the Normal and Lognormal distributions appear to be more appropriate than the others. A further result is that all distributions, except Weibull, show an accurate tail behaviour in the lower as well as the upper bound. It is also reflected in the PP-plots. This is important since the sensitivity to the tail behaviour is particularly useful in structural engineering approaches and reliability.The overall conclusion from these investigations it is that the friction property of bricks should be characterized using a Lognormal distribution. Since the coefficient of friction is a low value (close to 0), the Lognormal distribution should be preferred over the Normal because its domain is limited to zero or a certain bound (γ > 0) wh ile the domain of a Normal distribution is between andThe assessment of existing structures is becoming more and more important for social and economical reasons, while most codes deal explicitly only with design situations of new structures. The assessment of an existing structure may, however, differ much from the design of a new one. In general, the safety assessment of an existing structure differs from that of a new one in a number of aspects, see Diamantidis [34] and Vrouwenvelder [35]. The main differences are: (1) Increasing safety levels usually involves more costs for an existing structure than for structures that are still in the design phase. The safety provisions embodied in safety standards have also to be set off against the cost of providing them, and on this basis improvements are more difficult to justify for existing structures. For this reason and under certain circumstances, a lower safety level is acceptable. (2) The remaining lifetime of an existing building is often less than the standard reference period of 50 or 100 yearsthat applies to new structures. The reduction of the reference period may lead to reductions in the values of representative loads as for instance indicated in the Eurocode for Actions.Therefore the safety philosophy for existing structures must be discussed with respect to the reliability levels in terms of the β-values for (a) new structures, and (b) for existing structures and with respect to monitoring and inverse analysis concepts [36, 37].Required β-values must be derived for masonry structures and anchored in code specifications such as ISO 13822 ―Assessment of existing structures‖ [38] or EC 8 part 3 ―Assessment and retrofitting of buildings‖ [39].Acknowledgments Research results discussed in this paper were carried out within the European research project SEISMID, supported and financed in cooperation with the Centre for Innovation and Technology (ZIT). We also wish to thank Mr. Walter Brusatti (Brusatti GmbH) for providing bricks and further Mr. Johann Lang from the College of Civil Engineering (HTBL Krems) Austria, for his efficient help during testing in the laboratory.References1. EN-1996-1-1 (2006) Eurocode 6: Design of masonry structures—part 1-1: common rules for reinforced and unreinforced masonry structures2. EN-1052-3 (2007) Methods of test for masonry—part 3: determination of initial shear strength3. Tomazevic M (2008) Shear resistance of masonry walls and eurocode 6: shear versus tensile strength of masonry. Mater Struct 42:889–9074. EN-772-16 (2005) Methods of test for masonry units—part 1: determination of dimensions5. EN-772-1 (2000) Methods of test for masonry units—part 1: determination of compressive strength6. Zimmermann T, Strauss A, Bergmeister K (2010) Numerical investigations of historic masonry walls under normal and shear load. Constr Build Mater 24:1385–13917. EN-1015-11 (2007) Methods of test for mortar for masonry—part 11: determination of flexural and compressive strength of hardened mortar8. Edgell G (2005) Testing of ceramics in construction. Whittles Publishing Ltd.,。

土木工程专业英语(苏小卒版)翻译.

土木工程专业英语(苏小卒版)翻译.

第一单元Fundamentally, engineering is an end-product-oriented discipline that is innovative, cost-conscious and mindful of human factors. It is concerned with the creation of new entities, devices or methods of solution: a new process, a new material, an improved power source, a more efficient arrangement of tasks to accomplish a desired goal or a new structure. Engineering is also more often than not concerned with obtaining economical solutions. And, finally, human safety is always a key consideration.从根本上,工程是一个以最终产品为导向的行业,它具有创新、成本意识,同时也注意到人为因素。

它与创建新的实体、设备或解决方案有关:新工艺、新材料、一个改进的动力来源、任务的一项更有效地安排,用以完成所需的目标或创建一个新的结构。

工程是也不仅仅关心获得经济的解决方案。

最终,人类安全才是一个最重要的考虑因素。

Engineering is concerned with the use of abstract scientific ways of thinking and of defining real world problems. The use of idealizations and development of procedures for establishing bounds within which behavior can be ascertained are part of the process.工程关心的是,使用抽象的科学方法思考和定义现实世界的问题。

土木工程专业英语完整版本

土木工程专业英语完整版本
他们还要确定合适的材料组合,包括钢材、混凝土、塑料、石头、 沥青、砖、铝及其它建筑材
Most structural engineer work for apartment or public construction and factory constructions.
大多数结构工程师从事公寓建筑、公共建筑和厂房建筑工作。
这些工程师要分析支撑结构和影响结构性能的土壤及岩石的性能。 They evaluate and work to minimize the potential settlement of buildings and other structures, which stems from the pressure of their weight on the earth. 他们评估并采取措施使建筑物和其他结构的重量对地面的压力引 起的潜在的沉降最小化。
工程师们设计并维护港口、水电坝、河流设施,控制水流量,控 制并治理不同的水资源,他们建造坝、水库并把水渠分布到耕地。
Contents
Those engaged in environmental engineering design systems to sanitize water and air, they provide safety drinking water for people and control pollution of water supplies, they help to build water and wastewater treatment plants, dump sites to eliminate hazardous or toxic wastes and prevent pollution of surrounding land.

土木工程外文文献及翻译

土木工程外文文献及翻译

本科毕业设计外文文献及译文文献、资料题目:Designing Against Fire Of Building 文献、资料来源:国道数据库文献、资料发表(出版)日期:2008.3.25院(部):土木工程学院专业:土木工程班级:土木辅修091姓名:xxxx外文文献:Designing Against Fire Of BulidingxxxABSTRACT:This paper considers the design of buildings for fire safety. It is found that fire and the associ- ated effects on buildings is significantly different to other forms of loading such as gravity live loads, wind and earthquakes and their respective effects on the building structure. Fire events are derived from the human activities within buildings or from the malfunction of mechanical and electrical equipment provided within buildings to achieve a serviceable environment. It is therefore possible to directly influence the rate of fire starts within buildings by changing human behaviour, improved maintenance and improved design of mechanical and electrical systems. Furthermore, should a fire develops, it is possible to directly influence the resulting fire severity by the incorporation of fire safety systems such as sprinklers and to provide measures within the building to enable safer egress from the building. The ability to influence the rate of fire starts and the resulting fire severity is unique to the consideration of fire within buildings since other loads such as wind and earthquakes are directly a function of nature. The possible approaches for designing a building for fire safety are presented using an example of a multi-storey building constructed over a railway line. The design of both the transfer structure supporting the building over the railway and the levels above the transfer structure are considered in the context of current regulatory requirements. The principles and assumptions associ- ated with various approaches are discussed.1 INTRODUCTIONOther papers presented in this series consider the design of buildings for gravity loads, wind and earthquakes.The design of buildings against such load effects is to a large extent covered by engineering based standards referenced by the building regulations. This is not the case, to nearly the same extent, in the case of fire. Rather, it is building regulations such as the Building Code of Australia (BCA) that directly specify most of the requirements for fire safety of buildings with reference being made to Standards such as AS3600 or AS4100 for methods for determining the fire resistance of structural elements.The purpose of this paper is to consider the design of buildings for fire safety from an engineering perspective (as is currently done for other loads such as wind or earthquakes), whilst at the same time,putting such approaches in the context of the current regulatory requirements.At the outset,it needs to be noted that designing a building for fire safety is far morethan simply considering the building structure and whether it has sufficient structural adequacy.This is because fires can have a direct influence on occupants via smoke and heat and can grow in size and severity unlike other effects imposed on the building. Notwithstanding these comments, the focus of this paper will be largely on design issues associated with the building structure.Two situations associated with a building are used for the purpose of discussion. The multi-storey office building shown in Figure 1 is supported by a transfer structure that spans over a set of railway tracks. It is assumed that a wide range of rail traffic utilises these tracks including freight and diesel locomotives. The first situation to be considered from a fire safety perspective is the transfer structure.This is termed Situation 1 and the key questions are: what level of fire resistance is required for this transfer structure and how can this be determined? This situation has been chosen since it clearly falls outside the normal regulatory scope of most build- ing regulations. An engineering solution, rather than a prescriptive one is required. The second fire situation (termed Situation 2) corresponds to a fire within the office levels of the building and is covered by building regulations. This situation is chosen because it will enable a discussion of engineering approaches and how these interface with the building regulations–since both engineering and prescriptive solutions are possible.2 UNIQUENESS OF FIRE2.1 IntroductionWind and earthquakes can be considered to b e “natural” phenomena over which designers have no control except perhaps to choose the location of buildings more carefully on the basis of historical records and to design building to resist sufficiently high loads or accelerations for the particular location. Dead and live loads in buildings are the result of gravity. All of these loads are variable and it is possible (although generally unlikely) that the loads may exceed the resistance of the critical structural members resulting in structural failure.The nature and influence of fires in buildings are quite different to those associated with other“loads” to which a building may be subjected to. The essential differences are described in the following sections.2.2 Origin of FireIn most situations (ignoring bush fires), fire originates from human activities within the building or the malfunction of equipment placed within the building to provide a serviceable environment. It follows therefore that it is possible to influence the rate of fire starts by influencing human behaviour, limiting and monitoring human behaviour and improving thedesign of equipment and its maintenance. This is not the case for the usual loads applied to a building.2.3 Ability to InfluenceSince wind and earthquake are directly functions of nature, it is not possible to influence such events to any extent. One has to anticipate them and design accordingly. It may be possible to influence the level of live load in a building by conducting audits and placing restrictions on contents. However, in the case of a fire start, there are many factors that can be brought to bear to influence the ultimate size of the fire and its effect within the building. It is known that occupants within a building will often detect a fire and deal with it before it reaches a sig- nificant size. It is estimated that less than one fire in five (Favre, 1996) results in a call to the fire brigade and for fires reported to the fire brigade, the majority will be limited to the room of fire origin. In oc- cupied spaces, olfactory cues (smell) provide powerful evidence of the presence of even a small fire. The addition of a functional smoke detection system will further improve the likelihood of detection and of action being taken by the occupants.Fire fighting equipment, such as extinguishers and hose reels, is generally provided within buildings for the use of occupants and many organisations provide training for staff in respect of the use of such equipment.The growth of a fire can also be limited by automatic extinguishing systems such as sprinklers, which can be designed to have high levels of effectiveness.Fires can also be limited by the fire brigade depending on the size and location of the fire at the time of arrival. 2.4 Effects of FireThe structural elements in the vicinity of the fire will experience the effects of heat. The temperatures within the structural elements will increase with time of exposure to the fire, the rate of temperature rise being dictated by the thermal resistance of the structural element and the severity of the fire. The increase in temperatures within a member will result in both thermal expansion and,eventually,a reduction in the structural resistance of the member. Differential thermal expansion will lead to bowing of a member. Significant axial expansion will be accommodated in steel members by either overall or local buckling or yielding of local- ised regions. These effects will be detrimental for columns but for beams forming part of a floor system may assist in the development of other load resisting mechanisms (see Section 4.3.5).With the exception of the development of forces due to restraint of thermal expansion, fire does not impose loads on the structure but rather reduces stiffness and strength. Such effects are not instantaneous but are a function of time and this is different to the effects of loads such as earthquake and wind that are more or less instantaneous.Heating effects associated with a fire will not be significant or the rate of loss of capacity will be slowed if:(a) the fire is extinguished (e.g. an effective sprinkler system)(b) the fire is of insufficient severity – insufficient fuel, and/or(c)the structural elements have sufficient thermal mass and/or insulation to slow the rise in internal temperatureFire protection measures such as providing sufficient axis distance and dimensions for concrete elements, and sufficient insulation thickness for steel elements are examples of (c). These are illustrated in Figure 2.The two situations described in the introduction are now considered.3 FIRE WITHIN BUILDINGS3.1 Fire Safety ConsiderationsThe implications of fire within the occupied parts of the office building (Figure 1) (Situation 2) are now considered. Fire statistics for office buildings show that about one fatality is expected in an office building for every 1000 fires reported to the fire brigade. This is an order of magnitude less than the fatality rate associated with apartment buildings. More than two thirds of fires occur during occupied hours and this is due to the greater human activity and the greater use of services within the building. It is twice as likely that a fire that commences out of normal working hours will extend beyond the enclosure of fire origin.A relatively small fire can generate large quantities of smoke within the floor of fire origin. If the floor is of open-plan construction with few partitions, the presence of a fire during normal occupied hours is almost certain to be detected through the observation of smoke on the floor. The presence of full height partitions across the floor will slow the spread of smoke and possibly also the speed at which the occupants detect the fire. Any measures aimed at improving housekeeping, fire awareness and fire response will be beneficial in reducing thelikelihood of major fires during occupied hours.For multi-storey buildings, smoke detection systems and alarms are often provided to give “automatic” detection and warning to the occupants. An alarm signal is also transmitted to the fire brigade.Should the fire not be able to be controlled by the occupants on the fire floor, they will need to leave the floor of fire origin via the stairs. Stair enclosures may be designed to be fire-resistant but this may not be sufficient to keep the smoke out of the stairs. Many buildings incorporate stair pressurisation systems whereby positive airflow is introduced into the stairs upon detection of smoke within the building. However, this increases the forces required to open the stair doors and makes it increasingly difficult to access the stairs. It is quite likely that excessive door opening forces will exist(Fazio et al,2006)From a fire perspective, it is common to consider that a building consists of enclosures formed by the presence of walls and floors.An enclosure that has sufficiently fire-resistant boundaries (i.e. walls and floors) is considered to constitute a fire compartment and to be capable of limiting the spread of fire to an adjacent compartment. However, the ability of such boundaries to restrict the spread of fire can be severely limited by the need to provide natural lighting (windows)and access openings between the adjacent compartments (doors and stairs). Fire spread via the external openings (windows) is a distinct possibility given a fully developed fire. Limit- ing the window sizes and geometry can reduce but not eliminate the possibility of vertical fire spread.By far the most effective measure in limiting fire spread, other than the presence of occupants, is an effective sprinkler system that delivers water to a growing fire rapidly reducing the heat being generated and virtually extinguishing it.3.2 Estimating Fire SeverityIn the absence of measures to extinguish developing fires, or should such systems fail; severe fires can develop within buildings.In fire en gineering literature, the term “fire load” refers to the quantity of combustibles within an enclosure and not the loads (forces) applied to the structure during a fire. Similarly, fire load density refers to the quantity of fuel per unit area. It is normally expressed in terms of MJ/m2 or kg/m2 of wood equivalent. Surveys of combustibles for various occupancies (i.e offices, retail, hospitals, warehouses, etc)have been undertaken and a good summary of the available data is given in FCRC (1999). As would be expected, the fire load density is highly variable. Publications such as the International Fire Engineering Guidelines (2005) give fire load data in terms of the mean and 80th percentile.The latter level of fire load density is sometimes taken asthe characteristic fire load density and is sometimes taken as being distributed according to a Gumbel distribution (Schleich et al, 1999).The rate at which heat is released within an enclosure is termed the heat release rate (HRR) and normally expressed in megawatts (MW). The application of sufficient heat to a combustible material results in the generation of gases some of which are combustible. This process is called pyrolisation.Upon coming into contact with sufficient oxygen these gases ignite generating heat. The rate of burning(and therefore of heat generation) is therefore dependent on the flow of air to the gases generated by the pyrolising fuel.This flow is influenced by the shape of the enclosure (aspect ratio), and the position and size of any potential openings. It is found from experiments with single openings in approximately cubic enclosures that the rate of burning is directly proportional to A h where A is the area of the opening and h is the opening height. It is known that for deep enclosures with single openings that burning will occur initially closest to the opening moving back into the enclosure once the fuel closest to the opening is consumed (Thomas et al, 2005). Significant temperature variations throughout such enclosures can be expected.The use of the word ‘opening’ in relation to real building enclosures refers to any openings present around the walls including doors that are left open and any windows containing non fire-resistant glass.It is presumed that such glass breaks in the event of development of a significant fire. If the windows could be prevented from breaking and other sources of air to the enclosure limited, then the fire would be prevented from becoming a severe fire.Various methods have been developed for determining the potential severity of a fire within an enclosure.These are described in SFPE (2004). The predictions of these methods are variable and are mostly based on estimating a representative heat release rate (HRR) and the proportion of total fuel ςlikely to be consumed during the primary burning stage (Figure 4). Further studies of enclosure fires are required to assist with the development of improved models, as the behaviour is very complex.3.3 Role of the Building StructureIf the design objectives are to provide an adequate level of safety for the occupants and protection of adjacent properties from damage, then the structural adequacy of the building in fire need only be sufficient to allow the occupants to exit the building and for the building to ultimately deform in a way that does not lead to damage or fire spread to a building located on an adjacent site.These objectives are those associated with most building regulations includingthe Building Code of Australia (BCA). There could be other objectives including protection of the building against significant damage. In considering these various objectives, the following should be taken into account when considering the fire resistance of the building structure.3.3.1 Non-Structural ConsequencesSince fire can produce smoke and flame, it is important to ask whether these outcomes will threaten life safety within other parts of the building before the building is compromised by a loss of structural adequacy? Is search and rescue by the fire brigade not feasible given the likely extent of smoke? Will the loss of use of the building due to a severe fire result in major property and income loss? If the answer to these questions is in the affirmative, then it may be necessary to minimise the occurrence of a significant fire rather than simply assuming that the building structure needs to be designed for high levels of fire resistance. A low-rise shopping centre with levels interconnected by large voids is an example of such a situation.3.3.2 Other Fire Safety SystemsThe presence of other systems (e.g. sprinklers) within the building to minimise the occurrence of a serious fire can greatly reduce the need for the structural elements to have high levels of fire resistance. In this regard, the uncertainties of all fire-safety systems need to be considered. Irrespective of whether the fire safety system is the sprinkler system, stair pressurisation, compartmentation or the system giving the structure a fire-resistance level (e.g. concrete cover), there is an uncertainty of performance. Uncertainty data is available for sprinkler systems(because it is relatively easy to collect) but is not readily available for the other fire safety systems. This sometimes results in the designers and building regulators considering that only sprinkler systems are subject to uncertainty. In reality, it would appear that sprinklers systems have a high level of performance and can be designed to have very high levels of reliability.3.3.3 Height of BuildingIt takes longer for a tall building to be evacuated than a short building and therefore the structure of a tall building may need to have a higher level of fire resistance. The implications of collapse of tall buildings on adjacent properties are also greater than for buildings of only several storeys.3.3.4 Limited Extent of BurningIf the likely extent of burning is small in comparison with the plan area of the building, then the fire cannot have a significant impact on the overall stability of the building structure. Examples of situations where this is the case are open-deck carparks and very large area building such as shopping complexes where the fire-effected part is likely to be small in relation to area of the building floor plan.3.3.5 Behaviour of Floor ElementsThe effect of real fires on composite and concrete floors continues to be a subject of much research.Experimental testing at Cardington demonstrated that when parts of a composite floor are subject to heating, large displacement behaviour can develop that greatly assists the load carrying capacity of the floor beyond that which would predicted by considering only the behaviour of the beams and slabs in isolation.These situations have been analysed by both yield line methods that take into account the effects of membrane forces (Bailey, 2004) and finite element techniques. In essence, the methods illustrate that it is not necessary to insulate all structural steel elements in a composite floor to achieve high levels of fire resistance.This work also demonstrated that exposure of a composite floor having unprotected steel beams, to a localised fire, will not result in failure of the floor.A similar real fire test on a multistory reinforced concrete building demonstrated that the real structural behaviour in fire was significantly different to that expected using small displacement theory as for normal tempera- ture design (Bailey, 2002) with the performance being superior than that predicted by considering isolated member behaviour.3.4 Prescriptive Approach to DesignThe building regulations of most countries provide prescriptive requirements for the design of buildings for fire.These requirements are generally not subject to interpretation and compliance with them makes for simpler design approval–although not necessarily the most cost-effective designs.These provisions are often termed deemed-to-satisfy (DTS) provisions. All aspects of designing buildings for fire safety are covered–the provision of emergency exits, spacings between buildings, occupant fire fighting measures, detection and alarms, measures for automatic fire suppression, air and smoke handling requirements and last, but not least, requirements for compartmentation and fire resistance levels for structural members. However, there is little evidence that the requirements have been developed from a systematic evaluation of fire safety. Rather it would appear that many of the requirements have been added one to another to deal with another fire incident or to incorporate a new form of technology. There does not appear to have been any real attempt to determine which provision have the most significant influence on fire safety and whether some of the former provisions could be modified.The FRL requirements specified in the DTS provisions are traditionally considered to result in member resistances that will only rarely experience failure in the event of a fire.This is why it is acceptable to use the above arbitrary point in time load combination for assessing members in fire. There have been attempts to evaluate the various deemed-to-satisfy provisions (particularly the fire- resistance requirements)from a fire-engineering perspective taking intoaccount the possible variations in enclosure geometry, opening sizes and fire load (see FCRC, 1999).One of the outcomes of this evaluation was the recognition that deemed-to- satisfy provisions necessarily cover the broad range of buildings and thus must, on average, be quite onerous because of the magnitude of the above variations.It should be noted that the DTS provisions assume that compartmentation works and that fire is limited to a single compartment. This means that fire is normally only considered to exist at one level. Thus floors are assumed to be heated from below and columns only over one storey height.3.5 Performance-Based DesignAn approach that offers substantial benefits for individual buildings is the move towards performance-based regulations. This is permitted by regulations such as the BCA which state that a designer must demonstrate that the particular building will achieve the relevant performance requirements. The prescriptive provisions (i.e. the DTS provisions) are presumed to achieve these requirements. It is necessary to show that any building that does not conform to the DTS provisions will achieve the performance requirements.But what are the performance requirements? Most often the specified performance is simply a set of performance statements (such as with the Building Code of Australia)with no quantitative level given. Therefore, although these statements remind the designer of the key elements of design, they do not, in themselves, provide any measure against which to determine whether the design is adequately safe.Possible acceptance criteria are now considered.3.5.1 Acceptance CriteriaSome guidance as to the basis for acceptable designs is given in regulations such as the BCA. These and other possible bases are now considered in principle.(i)compare the levels of safety (with respect to achieving each of the design objectives) of the proposed alternative solution with those asso- ciated with a corresponding DTS solution for the building.This comparison may be done on either a qualitative or qualitative risk basis or perhaps a combination. In this case, the basis for comparison is an acceptable DTS solution. Such an approach requires a “holistic” approach to safety whereby all aspects relevant to safety, including the structure, are considered. This is, by far, the most common basis for acceptance.(ii)undertake a probabilistic risk assessment and show that the risk associated with the proposed design is less than that associated with common societal activities such as using pub lic transport. Undertaking a full probabilistic risk assessment can be very difficult for all but the simplest situations.Assuming that such an assessment is undertaken it will be necessary for the stakeholders to accept the nominated level of acceptable risk. Again, this requires a “holistic”approach to fire safety.(iii) a design is presented where it is demonstrated that all reasonable measures have been adopted to manage the risks and that any possible measures that have not been adopted will have negligible effect on the risk of not achieving the design objectives.(iv) as far as the building structure is concerned,benchmark the acceptable probability of failure in fire against that for normal temperature design. This is similar to the approach used when considering Building Situation 1 but only considers the building structure and not the effects of flame or smoke spread. It is not a holistic approach to fire safety.Finally, the questions of arson and terrorism must be considered. Deliberate acts of fire initiation range from relatively minor incidents to acts of mass destruction.Acts of arson are well within the accepted range of fire events experienced by build- ings(e.g. 8% of fire starts in offices are deemed "suspicious"). The simplest act is to use a small heat source to start a fire. The resulting fire will develop slowly in one location within the building and will most probably be controlled by the various fire- safety systems within the building. The outcome is likely to be the same even if an accelerant is used to assist fire spread.An important illustration of this occurred during the race riots in Los Angeles in 1992 (Hart 1992) when fires were started in many buildings often at multiple locations. In the case of buildings with sprinkler systems,the damage was limited and the fires significantly controlled.Although the intent was to destroy the buildings,the fire-safety systems were able to limit the resulting fires. Security measures are provided with systems such as sprinkler systems and include:- locking of valves- anti-tamper monitoring- location of valves in secure locationsFurthermore, access to significant buildings is often restricted by security measures.The very fact that the above steps have been taken demonstrates that acts of destruction within buildings are considered although most acts of arson do not involve any attempt to disable the fire-safety systems.At the one end of the spectrum is "simple" arson and at the other end, extremely rare acts where attempts are made to destroy the fire-safety systems along with substantial parts of the building.This can be only achieved through massive impact or the use of explosives. The latter may be achieved through explosives being introduced into the building or from outside by missile attack.The former could result from missile attack or from the collision of a large aircraft. The greater the destructiveness of the act,the greater the means and knowledge required. Conversely, the more extreme the act, the less confidence there can be in designing against suchan act. This is because the more extreme the event, the harder it is to predict precisely and the less understood will be its effects. The important point to recognise is that if sufficient means can be assembled, then it will always be possible to overcome a particular building design.Thus these acts are completely different to the other loadings to which a building is subjected such as wind,earthquake and gravity loading. This is because such acts of destruction are the work of intelligent beings and take into account the characteristics of the target.Should high-rise buildings be designed for given terrorist activities,then terrorists will simply use greater means to achieve the end result.For example, if buildings were designed to resist the impact effects from a certain size aircraft, then the use of a larger aircraft or more than one aircraft could still achieve destruction of the building. An appropriate strategy is therefore to minimise the likelihood of means of mass destruction getting into the hands of persons intent on such acts. This is not an engineering solution associated with the building structure.It should not be assumed that structural solutions are always the most appropriate, or indeed, possible.In the same way, aircrafts are not designed to survive a major fire or a crash landing but steps are taken to minimise the likelihood of either occurrence.The mobilization of large quantities of fire load (the normal combustibles on the floors) simultaneously on numerous levels throughout a building is well outside fire situations envisaged by current fire test standards and prescriptive regulations. Risk management measures to avoid such a possibility must be considered.4 CONCLUSIONSFire differs significantly from other “loads” such as wind, live load and earthquakes i n respect of its origin and its effects.Due to the fact that fire originates from human activities or equipment installed within buildings, it is possible to directly influence the potential effects on the building by reducing the rate of fire starts and providing measures to directly limit fire severity.The design of buildings for fire safety is mostly achieved by following the prescriptive requirements of building codes such as the BCA. For situations that fall outside of the scope of such regulations, or where proposed designs are not in accordance with the prescriptive requirements, it is possible to undertake performance-based fire engineering designs.However, there are no design codes or standards or detailed methodologies available for undertaking such designs.Building regulations require that such alternative designs satisfy performance requirements and give some guidance as to the basis for acceptance of these designs (i.e. acceptance criteria).This paper presents a number of possible acceptance criteria, all of which use the measure of risk level as the basis for comparison.Strictly, when considering the risks。

(完整版)土木工程专业英语课文原文及对照翻译

(完整版)土木工程专业英语课文原文及对照翻译

Civil EngineeringCivil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities.土木工程学作为最老的工程技术学科,是指规划,设计,施工及对建筑环境的管理。

此处的环境包括建筑符合科学规范的所有结构,从灌溉和排水系统到火箭发射设施。

Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities.土木工程师建造道路,桥梁,管道,大坝,海港,发电厂,给排水系统,医院,学校,公共交通和其他现代社会和大量人口集中地区的基础公共设施。

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土木工程专业英语原文及翻译文档编制序号:[KKIDT-LLE0828-LLETD298-POI08]08 级土木(1) 班课程考试试卷考试科目专业英语考试时间学生姓名所在院系土木学院任课教师徐州工程学院印制Stability of SlopesIntroductionTranslational slips tend to occur where the adjacent stratum is at a relatively shallow depth below the surface of the slope:the failure surface tends to be plane and roughly parallel to the slips usually occur where the adjacent stratum is at greater depth,the failure surface consisting of curved and plane sections.In practice, limiting equilibrium methods are used in the analysis of slope stability. It is considered that failure is on the point of occurring along an assumed or a known failure surface.The shear strength required to maintain a condition of limiting equilibrium is compared with the available shear strength of the soil,giving the average factor of safety along the failure surface.The problem is considered in two dimensions,conditions of plane strain being assumed.It has been shown that a two-dimensional analysis gives a conservative result for a failure on a three-dimensional(dish-shaped) surface.Analysis for the Case of φu =0This analysis, in terms of total stress,covers the case of a fully saturated clay under undrained conditions, . For the condition immediately after construction.Only moment equilibrium is considered in the analysis.In section, the potential failure surface is assumed to be a circular arc. A trial failure surface(centre O,radius r and length L awhere F is the factor of safety with respect to shear strength.Equating moments about O:ThereforeThe moments of any additional forces must be taken into account.In the event of a tension crack developing ,as shown in ,the arc length L a is shortened and a hydrostatic force will act normal to the crack if the crack fills with water.It is necessary to analyze the slope for a number of trial failure surfaces in order that the minimum factor of safety can be determined. Based on the principle of geometric similarity,Taylor[]published stability coefficients for the analysis of homogeneous slopes in terms of total stress.For a slope of height H the stability coefficient (N s) for the failure surface along which the factor of safety is a minimum isFor the case ofφu =0,values of N ss depends on the slope angleβand the depth factor D,where DH is the depth to a firm stratum.Gibson and Morgenstern [] published stability coefficients for slopes in normally consolidated clays in which the undrained strength c u(φu =0) varies linearly with depth.ExampleA 45°slope is excavated to a depth of 8 m in a deep layer of saturated clay of unit weight 19 kN /m3:the relevant shear strength parameters are c u =65 kN/m2 andφuIn the cross-sectional area ABCD is 70 m2.Weight of soil mass=70×19=1330kN/mThe centroid of ABCD is m from O.The angle AOC is °and radius OC is m.The arc length ABC is calculated as .The factor of safety is given by:This is the factor of safety for the trial failure surface selected and is not necessarily the minimum factor of safety.The minimum factor of safety can be estimated by using Equation .From ,β=45°and assuming that D is large,the value of N s9.3 The Method of Slicesαand the height, measured on the centre-1ine,is h. The factor of safety is defined as the ratio of the available shear strength(τf)to the shear strength(τm) which must be mobilized to maintain a condition of limiting equilibrium, .The factor of safety is taken to be the same for each slice,implying that there must be mutual support between slices,. forces must act between the slices.The forces (per unit dimension normal to the section) acting on a slice are:total weight of the slice,W=γb h (γsat where appropriate).total normal force on the base,N (equal to σl).In general thisforce has two components,the effective normal force N'(equal toσ'l ) and the boundary water force U(equal to ul ),where u is the pore water pressure at the centre of the base and l is the length of the base.shear force on the base,T=τm l.total normal forces on the sides, E1 and E2.shear forces on the sides,X1 and X2.Any external forces must also be included in the analysis.The problem is statically indeterminate and in order to obtain a solution assumptions must be made regarding the interslice forces E and X:the resulting solution for factor of safety is not exact.Considering moments about O,the sum of the moments of the shear forces T on the failure arc AC must equal the moment of the weight of the soil mass ABCD.For any slice the lever arm of W is rsinα,therefore∑Tr=∑Wr sinαNow,For an analysis in terms of effective stress,Orwhere L a is the arc length AC.Equation is exact but approximations are introduced in determining the forces N'.For a given failure arc the value of F will depend on the way inwhich the forces N' are estimated.The Fellenius SolutionIn this solution it is assumed that for each slice the resultant of the interslice forces is zero.The solution involves resolving the forces on each slice normal to the base,.N'=WCOSα-ulHence the factor of safety in terms of effective stress (Equation is given byThe components WCOSαand Wsinαcan be determined graphically for each slice.Alternatively,the value of αcan be measured or calculated.Again,a series of trial failure surfaces must be chosen in order to obtain the minimum factor of safety.This solution underestimates the factor of safety:the error,compared with more accurate methods of analysis,is usually within the range 5-2%.For an analysis in terms of total stress the parameters C u andφu are used and the value of u in Equation is zero.If φu=0 ,the factor of safety is given byAs N’ does not appear in Equation an exact value of F is obtained.The Bishop Simplified SolutionIn this solution it is assumed that the resultant forces on the sides of theslices are horizontal,.X l-X2=0For equilibrium the shear force on the base of any slice isResolving forces in the vertical direction:It is convenient to substitutel=b secαFrom Equation ,after some rearrangement,The pore water pressure can be related to the total ‘fill pressure’ at anypoint by means of the dimensionless pore pressure ratio,defined as(γsat where appropriate).For any slice,Hence Equation can be written:As the factor of safety occurs on both sides of Equation ,a process of successive approximation must be used to obtain a solution but convergence is rapid.Due to the repetitive nature of the calculations and the need to select an adequate number of trial failure surfaces,the method of slices is particularly suitable for solution by computer.More complex slope geometry and different soil strata can be introduced.In most problems the value of the pore pressure ratio r u is not constant over the whole failuresurface but,unless there are isolated regions of high pore pressure,an average value(weighted on an area basis) is normally used in design.Again,the factor of safety determined by this method is an underestimate but the error is unlikely to exceed 7%and in most cases is less than 2%.Spencer [] proposed a method of analysis in which the resultant Interslice forces are parallel and in which both force and moment equilibrium are satisfied.Spencer showed that the accuracy of the Bishop simplified method,in which only moment equilibrium is satisfied, is due to the insensitivity of the moment equation to the slope of the interslice forces.Dimensionless stability coefficients for homogeneous slopes,based on Equation ,have been published by Bishop and Morgenstern [].It can be shown that for a given slope angle and given soil properties the factor of safety varies linearly with γu and can thus be expressed asF=m-nγuwhere,m and n are the stability coefficients.The coefficients,m and n arefunctions ofβ,φ’,the dimensionless number c'/γand the depth factor D.ExampleUsing the Fellenius method of slices,determine the factor of safety,in terms of effective stress,of the slope shown in for the given failure surface.The unit weight of the soil,both above and below the water table,is 20 kN/m 3 and the relevant shear strength parameters are c’=10 kN/m2andφ’=29°.W) of each slice is given byW=γbh=20××h=30h kN/mThe height h for each slice is set off below the centre of the base and thenormal and tangential components hcosαand hsinαWcosα=30h cosαW sinα=30h sinαThe pore water pressure at the centre of the base of each slice is taken to beγw z w,where z w is the vertical distance of the centre point below the water table (as shown in figure).This procedure slightly overestimates the pore water pressure which str ictly should be) γw z e,where z e is the vertical distance below the point of intersection of the water table and the equipotential through the centre of the slice base.The error involved is on the safe side.The arc length (L a) is calculated as mm.The results are given inTable∑Wcosα=30×=525kN/m∑W sinα=30×=254kN/m∑(wcos α-ul)=525—132=393kN/mAnalysis of a Plane Translational SlipIt is assumed that the potential failure surface is parallel to the surface of the slope and is at a depth that is small compared with the length of the slope. The slope can then be considered as being of infinite length,with end effects being ignored.The slope is inclined at angle βmz (0<m<1)above the failure plane.Steady seepage is assumed to be taking place in a direction parallel to the slope.The forces on the sides of any vertical slice are equal and opposite and the stress conditions are the same at every point on the failure plane.In terms of effective stress,the shear strength of the soil along the failure plane isand the factor of safety isThe expressions forσ,τandμare:The following special cases are of interest.If c’=0 and m=0 . the soilbetween the surface and the failure plane is not fully saturated),thenIf c’=0 and m=1. the water table coincides with the surface of the slope),then:It should b e noted that when c’=0 the factor of safety is independent ofthe depth z.If c’ is greater than zero,the factor of safety is a function of z, and βmay exceedφ’ provided z is less than a critical value.For a total stress analysis the shear strength parameters c u andφu are used with a zero value of u.ExampleA long natural slope in a fissured overconsolidated clay is inclined at 12°to the horizontal.The water table is at the surface and seepage is roughly parallel to the slope.A slip has developed on a plane parallel to the surface at a depth of 5 m.The saturated unit weight of the clay is 20 kN/m3.The peak strength parameters are c’=10 kN/m2andφ’=26°;the residual strength parameters are c r’=0 andφr’=18°.Determine the factor of safety along the slip plane(a)in terms of the peak strength parameters (b)in terms of the residual strength parameters.With the water table at the surface(m=1),at any point on the slip plane,Using the peak strength parameters,Then the factor of safety is given byUsing the residual strength parameters,the factor of safety can beobtained from Equation :General Methods of AnalysisMorgenstern and Price[]developed a general analysis in which all boundary and equilibrium conditions are satisfied and in which the failure surface may be any shape,circular,non-circular or compound.The soil mass above the failure plane is divided into sections by a number of vertical planes and the problem is rendered statically determinate by assuming a relationship between the forces E and X on the vertical boundaries between each section.This assumption is of the formX=λf(x)Ewhere f(x)is an arbitrary function describing the pattern in which the ratio X/E varies across the soil mass andλis a scale factor.The v alue ofλis obtained as part of the solution along with the factor of safety F.The values of the forces E and X and the point of application of E can be determined at each vertical boundary.For any assumed function f(x) it is necessary to examine the solution in detail to ensure that it is physically reasonable . no shear failure or tension must be implied within the soil mass above the failure surface). The choice of the function f(x) does not appear to influence the computed value of F by more than about 5% and f(x)=l is a common assumption.The analysis involves a complex process of iteration for the values ofλ and F,described by Morgenstern and Price[],and the use of a computer is essential.Bell [] proposed a method of analysis in which all the conditions of equilibrium are satisfied and the assumed failure surface may be of any shape.The soil mass is divided into a number of vertical slices and statical determinacy is obtained by means of an assumed distribution of normal stress along the failure surface.Sarma [] developed a method,based on the method of slices,in which the critical earthquake acceleration required to produce a condition of limiting equilibrium is determined.An assumed distribution of vertical interslice forces is used in the analysis.Again,all the conditions of equilibrium are satisfied and the assumed failure surface may be of any shape.The static factor of safety is the factor by which the shear strength of the soil must be reduced such that the critical acceleration is zero.The use of a computer is also essential for the Bell and Sarma methods and all solutions must be checked to ensure that they are physically acceptable.References[]Bell,J,M.(1968):’General Slope Stability Analysis’, Journal ASCE,,.:‘Stability Coefficients for Earth Slopes Geotechnique,.’, 5,.‘A Numerical Method for Solving the Equations of Stability of General Slip Surfaces’Computer Journal,,.[]Sarma,. (1973):’Stability Analysis of Embankments and Slopes’,Geotechnique,,. []Skempton,.(1970):’Firs t-Time Slides in Overconsolidated Clays’(Technical Note),[]Spencer,E.(1 967):‘A Method of Analysis of the Stability of Embankments Assuming Parallel Inter-Slice Forces’,Geotechnique,.[]Taylor,.(1937):’Stability of Earth Slopes’,Journal of the Boston Society of Civil Engineers,,边坡稳定引言重力和渗透力易引起天然边坡、开挖形成的边坡、堤防边坡和土坝的不稳定性。

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