边坡稳定slopstability
基于Flac3D的某土质边坡稳定性分析
Value Engineering0引言滑坡作为一种常见的地质灾害在我国频繁发生并且分布广泛，不仅破坏基础设施，影响各工程的施工与建设，还阻碍国家的经济建设与发展进程，并对人民群众的生命财产安全造成严重的影响。
滑坡地质灾害如果处理不及时，将会造成一定的设施破坏、财产损失甚至是人员的伤亡[1-3]。
因此，研究分析滑坡地质灾害的成因和机理及滑坡的防治措施等一直是工程地质领域的热点问题。
瞬时暴雨或长期降雨等条件下诱发滑坡是土质边坡中最容易发生的类型[4]。
针对降雨条件下的边坡稳定性，众多学者主要从多个方面进行了相关的研究。
目前边坡稳定性分析评价的主要方法是极限平衡法和数值模拟法。
数值模拟分析方法包括有限单元法、有限差分法、离散单元法等。
李安润等[5]通过极限平衡法和有限元数值分析方法，对降雨条件下某堆积体边坡进行了稳定性分析，并提出了合理的防治措施。
Chang等[6]采用PFC数值模拟软件分析研究了某黄土滑坡在地表水入渗条件下边坡的失稳破坏过程。
回恒酉等[7]采用传统极限平衡理论的条分法和数值模拟的Flac3D方法进行对比分析，得出Flac3D 法分析条件更加完善，在理论上更加可靠，而条分法计算理论理想化，计算结果偏保守的结论。
李振江等[8]通过GeoStudio软件对暴雨工况下的南京某下蜀土滑坡进行了模拟分析，研究了暴雨条件下边坡的孔隙水压力和位移变化，并对应急治理措施进行了检验分析。
张树轩等[9]利用Flac3D模拟分析了甘肃天水红旗山黄土滑坡的稳定性，为潜在强震区地震滑坡的变形机理及防震减灾研究提供了可靠依据。
Flac3D数值模拟法是近年来比较流行的边坡稳定性计算分析方法，主要应用于土质滑坡，在岩质滑坡方面，相对应用较少。
本文以江苏西南部一土质边坡为研究对象，结合现场监测数据，采用Flac3D软件对边坡进行稳定性评价及变形破坏机理分析，为滑坡防治提供参考。
1工程概况1.1边坡基本特征江苏省西南部某一典型土质边坡现状如图1所示。
边坡稳定分析方法综述
边坡稳定分析方法综述工程技术SCIENCE&TECHN0L0GY匪圆边坡稳定分析方法综述沈烨(江苏省苏州市交通设计研究院有限责任公司江苏苏州215007)摘要:介绍了土坡稳定分析常用的瑞典法,毕肖普法和杨布法安全系数的定义方法,对土坡稳定分析有一定的指导意义.关键词:边坡稳定安全系数中图分类号:TU443文献标识码:A文章编号:1672--3791(2011)04(b)一0023—02 Abstract:IntroducedsomeanalysismethodsofsoilslopestabilitysuchasSweden,bishop,jan buandtheirdefinitionmethodofsafetyfactor,whichhasguidancefortheslopestabilityanalysis.KeyWords:SlopeIStability;Safetyfactor边坡工程广泛存在,土石坝,路堤,基坑开挖,渠道,堤防,山体等.由于边坡表面倾斜,在土体自重及其它外力作用下,整个土体都有从高处向低处滑动的趋势.边坡丧失其原有的稳定性,一部分土体相对于另一部分土体滑动的现象,称为滑坡.引起滑坡的根本原因在于土体内部某个面上的剪应力达到了它的抗剪强度,稳定平衡遭到破坏,使剪应力达到抗剪强度的原因有二:一是由于剪应力的增加;二是土体抗剪强度的减小.对边坡进行稳定性计算,评价当前边坡的稳定状态和可能的变化发展趋势,对不太稳定的土坡采取防治措施,是工程师们普遍面对的问题.目前应用于边坡稳定分析的方法主要有基于极限平衡的传图1瑞典条分法统方法和有限元法.极限平衡法是边坡稳定分析中最常用的方法,它是通过分析在临近破坏状况下,土体外力与内部强度所提供抗力之间的平衡,计算土体在自身和外荷作用下的土坡稳定性程度.传统的边坡稳定性分析方法中,为了便于分析计算的进行,做了许多假设…_2],如假设一个滑动面,不考虑土体内部的应力一应变关系等.在边坡稳定分析中引入有限元法始于20世纪70年代【3】,起初由于需要花费大量的机时, 且误差较大,该法很难在实践中推广应用,随着计算机技术和有限元技术的发展,该法开始在边坡分析得到较广泛地应用【Ⅱ5】, 而且逐渐从线弹性有限元发展到非线性有限元方法.采用有限元法来分析边坡的稳定性时,可分为二维分析和三维分析.由于自然界发生的滑坡,基本上呈三维形态,二维分析只是一种近似分析.1常用的边坡稳定分析方法边坡稳定分析的刚体极限平衡方法原理.刚体极限平衡方法原理的三大要点….(1)刚体条件:在分析滑坡的受力和变形过程中,忽略滑体的内部变形,认为滑体为不可变形的刚体.(2)极限强度条件:假定滑体处于极限图2毕肖普法强度状态.(3)力的平衡条件:在考虑安全系数后,滑体在所受各种力的作用下处于平衡状态.1.1瑞典条分法如图1所实示,瑞典条分法的安全系数Fs的一般计算公式表达为:F一c+cosO,tg~o,)….sin0lI,式中:w,为土条重力;e,为土条底部中点与滑弧中心连线垂直夹角;抗剪强度指标C,值是为总应力指标,也可采用有效应力指标.工程中常用的替代重度法进行计算,即公式中分子的容重在浸润线以上部分采用天然容重,以下采用浮容重;分母中浸润线以上部分采用天然容重,以下采用饱和容重,这种方法既考虑了稳定渗流对土坡稳定性的影响,又方便了计算,其精度也能较好地满足工程需要,因此在实际工程中得到广泛应用.1.2毕肖普法毕肖普(Bishop)考虑了土条两边的侧向力的不平衡,土条上的受力有重力,滑面上的法向力N.,切向抗滑力T,两侧面法向力E.和E(水平向),切向力Y和Y(竖向), 如图2所示.它们是平衡的,形成的封闭力多边形.根据竖向力平衡条件,有+△一sin口一NiCOS=0(2)式中,△=—+.,抗滑力Ti是抗剪强度f,提供的.对于有一定安全性的土坡,抗剪强度并没有全部发挥,仅仅发挥了I/F:.毕肖普定义安全系数为土的实际抗剪强度与保持平衡(指总体平衡)所须要的强度之比.即=r,/f,安全系数F是对整个土坡而言的,对各土条均取这一相同的值,意味着假定滑动体各部分强度的发挥程度是一致的.—(cr,tge—+c)4:=—Nitgrp—+clFsFs将其代入式(2)整理后求出,再将Ⅳ代入式(3)得::~((w,+AUtge一—cl~sin—a/ge+c):}m4}}imq【(下接25页)科技资讯SCIENCE&TECHNOLOGYINFORMATION23 工程技术!Q:SCIENCE&TECHNOLOGYINFORMATION建视图对象,并设置显示模式属性;oView=OBJ—NEW(.IDLgrView')oWindow=OBJ—NEW('[DLgrWindow, RETAIN=2.C0L0R—M0DEL=0)使用类IDLgrWindow创建显示窗口,并设置显示模式;使用类IDLgrView~1]建视图对象,并设置视图属性;oSufface=OBJ—NEW('IDLgrSurface',gd.STYLE=2)用类IDLgrSurface和插值后的Grid数据创建曲面对象,并设置曲面属性;oImage=OBJ—NEW('lDLgrImage, image,INTERLEA VE=0,/INTERPOLATE) oSurface->GetProperty,XRANGE:x,YRANGE=y,ZRANGE=zXS=N0RM—CO0RD(xr)xs【O】=xs【0卜O.5ys=NORM—COORD(yr)-ys[O]=ys[O]一0.5zs:NORM—C00RD(ZF)zs[O]=zs[O]-O.5OSUrface一>SetPropertY, XCOORD—CONV:XS,YCOORD—CONV:ys,ZCOORD=zs0Surface一>SetProDertY. TEXTURE—MAP=oImage,C0L0R=【255, 255,255】使用IDLgrlmage~ll遥感图像数据创建图像对象,并设置图像属性;读入的图像数据;OModel->Add,oSurfaceOView一>Add.oModelOWindOw一>Draw.oVJew在IDLgrModei对象中添加曲面对象和图2DEM和影像叠加显示(上接23页)i(十Ar,)tg~o+cb)(4)f,Fl口式中b=COSa,,为土条宽.对滑动体建立整体力矩平衡方程,各土条问的侧向力成了内力,在整体方程中不出现,法向力Ni通过圆心,又不引起力矩,故总体力矩平衡方程为∑一∑R=0将式(4)代入,整理后可得1∑_二-(Wi+at,)tg妒+cb):————(5)∑sin1.3杨布法杨布(Janbu)沿用了毕肖普关于安全系数的定义,以及土条的竖向力平衡的公式, 因此式(2)至式(4)照用.杨布补充了土条水平力的平衡方程:△=Nisina一COSa,补充了土条的力矩平衡方程,为了力矩平衡方程的简化,将土条宽度取得很小,不用b而用Ax来表示,它与土条高度相比是微量.这样对土条底面中心取力矩平衡,并略去高阶微量,可得A:Ei留aI+=hi(6)杨布假定土条侧向力作用位置在土条高的l/3处,将条土条侧向力作点连成一线,叫推力线.上式中h.为推力线与滑面线之间的竖向距离,口,为推力线在各土条的仰角,它不同于滑面仰角,与毕肖普法的所不同的是,杨布法不是建立总体力矩平衡方程,而是建立总体水平向力的平衡方程,∑△=0.由式(6)得Z(Nsina一COSa)=0(7)由式(2),将N,用T+表示,代人式(7),再将式(4)代入可得∑——一((+△)留9+c△)F:一!…～∑(+△)tga图像对象,同时在IDIgrView对象中,添加IDLgrModel图像对象;XOBJV【EW,OMOdel,/BLOCK, SCALE:1OBJDESTR0Y,【oView,olmage]End使用XObjView交互显示贴图,或使用IDLgrWindow对象的Draw方法.XObjView 显示结果如图2所示.为了增强地形三维可视化效果,IDL还提供了灯光对象IDLgrLight,可以建立光源增加光照渲染.由上可知,IDL程序设计可以完全使用面向对象技术,读入的数据均封装在对象中,操作起来十分方便.3结语LiDAR技术是新的获取数据的方法,它具有普通航空摄影测量无法比拟的优势.随着计算机技术的飞速发展,LiDAR理论的逐步完善,现在已经由以前的理论阶段进入了实际应用生产阶段.LiDAR技术必定有更广阔的发展前景.IDL作为一种交互式的,跨平台的,面向对象的数据可视化语言,具有较强的数据分析和可视化功能,在IDL语言中往往只需要几个简单语句就能实现大量的,复杂的数据处理或者二一维,三维图形的绘制,且其语法简单,内嵌各种丰富的算法库,具有对三维体数据的支持能力,因而是一种进行地形三维建模及可视化的理想开发语占.参考文献[1】何全军.基于IDL的三维地形可视化系统开发【J】.测绘信启,与工程,2006(1). 【2】杨朝辉,陈映鹰.IDL在三维地层可视化中的应用研究【J].工程勘察,2008(6).由于没有用整体力矩平衡方程,因此滑动面不须要假定为圆弧面,可以是任意形状的面,这也是与前两种方法不同的.当土层软硬变化使滑动面不成圆弧状时,这种方法显现其优越性.2结语本文简要介绍了几种边坡稳定分析的方法,及各种方法的适用性.参考文献[1]冯守中.公路软基处理新技术[M】.北京:人民交通出版社,2008.【2】徐泽中.公路软土地基路堤设计与施工关键技术[M】.北京:人民交通出版社,2008.科技资讯SCIENCE&TECHNOL0GYINFORMATION25。
岩石边坡稳定性分析方法
岩石边坡稳定性分析方法作者：蔡伟刘秋强来源：《价值工程》2014年第17期摘要：在进行岩石边坡稳定性的分析过程中，相关人员应该根据勘探地点的实际情况，采用有效的勘探方法，才能够进一步提高勘探的准确性，促进勘探工作的顺利开展。
因此，本文针对于岩石边坡稳定性分析方法进行了具体的分析和研究，希望本文的分析能够进一步促进地质勘探工作的顺利进行。
Abstract： In the analysis process of rock slope stability， relevant personnel should based on the actual situation of exploration sites to use effective exploration methods， then will further improve the accuracy of exploration， and promote the smooth conduction of exploration work. Therefore， this paper analyzes and researches the analysis method of rock slope rock slope， hopes to further promote the smooth conduction of geological exploration work.关键词：岩石边坡；稳定性；分析方法Key words： rock slope；stability；analysis method中图分类号：TU457 文献标识码：A 文章编号：1006-4311（2014）17-0085-021 岩石边坡稳定性分析中的注意事项在岩石边坡稳定性分析中，不能单纯的使用一种分析法，这样会导致岩石边坡稳定性分析不够全面，如极限平衡法，虽然简单易行，但是将滑动体看作刚体的话，是使得边界的条件都相应简化，会使分析结果不准确，因此在对岩石边坡稳定性进行分析时，要同时采用两种或两种以上的分析方法，这样才能保证对岩石边坡稳定性的全面分析。
应用矢量图解法分析岩质边坡的稳定性
应用矢量图解法分析岩质边坡的稳定性李明连（广东核力工程勘察院广州 510800）摘要：矢量图解法是基于岩土体结构面、内摩擦角（含等效内摩擦角）和坡面关系分析的一种边坡稳定性评价方法。
在运用该方法对岩质边坡进行稳定性分析时，除了要考虑岩体中的外倾结构面（含隐性的）之外，还应注意岩体受侧向岩压力可能产生的破裂面。
文章按无外倾结构面、有外倾硬性结构面和有外倾软弱结构面三种情况对岩质边坡进行了稳定性分析，试图向读者推荐一种简单适用的评价岩质边坡稳定性的新方法。
关键词：矢量图结构面坡面等效内摩擦角破裂角An Evaluation of A Slope Stability in The Vectorgraph MethodLI Minglian SU Wencong LONG Xichun（Guangdong heli Institute of Engineering Exploration, guangzhou 510800）Abstract The Vectorgraph Method is a method for evaluation the stability of a slope based on the relationship between structural planes, angles of internal friction of the rock or structural planes and the plane of the slope. Besides the structural plane ( blind structural plane), the fracture structural plane caused by lateral stress should be considered in the evaluation with the vectorgraph method. This paper recommended a new simply method to evaluate the slope stability by discussing three different conditions.Key words vectorgraph, structural plane, slope plane, equivalent angle of internal friction, fractural plane引言2004年，笔者曾撰文〔1〕论述适用于边坡稳定性评价的“矢量图解法”的原理、方法和应用实例。
基础工程-边坡稳定分析电子教案
T>T
单元体 稳定
T
T N
W
稳定条件：T>T
TWsin NWcos
砂土的内 摩擦角
T' Ntan
T' Wcosta n
抗滑力与滑 动力的比值
T Wcostan tan FsT Wsin tan
土体完全浸润在水 安全系数 中而无渗流时？
二、有渗流作用时的无粘性土土坡分析
T
JT N
W
稳定条件：T>T+J
1：2 26.57 25
35
1：5 18.43 25
37
例题
O
9.55m
30
70
土层1
W 3.9m 土层2
土层1：cu20kPa,u0
土层2： cu25kPa,u0
容重均为19KN/m3， 滑坡体总面积为 46.9m2，计算该滑动 面的稳定安全系数。
O
9.55m
土层1
W 3.9m 土层2
Fs
Homework1
1.无粘性土坡的坡角＝20，土的内摩 擦角＝32 ，浮容重’＝10KN/m3，若渗 流逸出段内水流的方向平行于地面，求 土坡的稳定安全系数。
Pi
hi X i
H i H i1 H i
例题
瑞典条分法
Bishop法
边坡稳定分析图解法
土坡的稳定性相关因素：
抗剪强度指标c和、 重度 、
土坡的尺寸坡角
坡高H
稳定数：N c H
根据不同的 绘出 与N 的关系曲线
泰勒（Taylor,D.W， 1937）用图表表达影 响因素的相互关系
假定条间力的作用方向或规定Pi和Hi的比 值。
假定条间力的作用位置，即规定hi的大小 （Janbu法）。
Chapter 7 Slope Stability Part 1 [边坡稳定
Chapter 7 Slope Stability Part 1 [边坡稳定]7.1 Types of slope failure [滑坡的类型]The most common types of slope failure [滑坡] are illustrated in Fig.7.1. Translational slide tends to occur where an adjacent weak zone [软弱层] of soil is at a relatively shallow depth below the surface of the slope. The failure surface tends to be plane and roughly parallel to the slope. [滑动面为平面与坡面平行]Rotational slide is common for cohesive soil [粘性土] (e.g. clays) slope. The shape of the failure surface in section may be a circular arc or a non-circular curve. In general circular slides are associated with homogeneous soil conditions and non-circular slides are associated with non-homogeneous soil conditions. [滑动面为一曲面]7.2 Methods of slope stability analysis [边坡稳定分析方法]The stability of a slope can be analysed using one or more of the following methods:– Limit equilibrium method (equilibrium of forces) [极限平衡法]– Limit analysis based on plasticity (equilibrium of stresses) [极限应力分析法]– Finite difference method [有限差分法]– Finite element method [有限元法]Although a finite element or a finite difference method is more flexible and general, in practice, the limit equilibrium method(LEM)is used in the slope stability analysis.In LEM, the soil is considered to be on the verge of failure along an assumed or a known sliding surface. [在某一假设滑动面,整个块体处于极限平衡状态] In general, the sliding surface is assumed to be a circular arc for clays or a logarithmic spiral for sands and gravels. 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 sliding surface [安全糸数定义为抗剪力与下滑力之比]. The problem is normally considered in two dimensions. [土坡的稳定分析可简化为平面问题] For the slope stability analysis using the LEM, two analyses are considered for each slope:–Effective Stress Analysis [有效应力分析] (ESA) which represents drained or long-term behaviour of the slope. Cohesion (c’) and angle of internal friction (φ’) are used in the analysis.–Total Stress Analysis [总应力分析] (TSA) which represents undrained or short-term behaviour of the slope. Undrained shear strength (c u) is used in the analysis.7.3 Analysis of a plane translational slideIt 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. [假设滑动面与坡面平行, 滑动块体深度远小于边坡长度, 边坡为无限长]The slope is inclined at angle α to the horizontal and the depth of the failure plane is z, as shown in Fig.7.2. Consider a slice of soil element of width b. [坡角为α, 滑动面深度z, 土条宽度为b] Assume the side forces on the soil element can be neglected in the stability analysis, ground water table is below the failure plane and the soil is cohesionless. [假设不考虑土条两边的合力,地下水位低于滑动面,无粘性土] The forces acting on the element are shown in Fig.7.2. W is weight of soil element [土条重量], T is shear force on the failure plane [平行于滑动面的下滑剪切力] and N is normal force on the failure plane [滑动面法线方向的分力]. Consider equilibrium of forces parallel to the slope surface, [边坡平行方向的静力平衡] α⋅=sin W T(7.1) Consider equilibrium of forces normal to the slope surface, [边坡法线方向的静力平衡] α⋅=cos W N(7.2) The available shear strength (T f ) along the failure surface is [滑动面上的抗剪力] φ⋅α⋅=φ⋅=tan cos W tan N T f(7.3)where φ is the angle of internal friction. Factor of safety (F S ) is defined as the ratio of T f and T. [安全糸数定义为抗剪力与下滑力之比]αφ=α⋅φ⋅α⋅==tan tan sin W tan cos W T T F f s (7.4)If water table coincides with the slope surface, the forces acting on the element are shown inFig.7.3. [地下水位于坡面] An additional hydrostatic force (U) is acting on the failure plane normal to the slope surface [边坡法线方向的静水力]. The equilibrium of forces parallel to the slope surface is also represented by equation (7.1). Consider equilibrium of forces normal to the slope surface,U 'N cos W +=α⋅ (7.5) The available shear strength (T f ) along the slip surface is φ⋅-α⋅=φ⋅=tan )U cos W (tan 'N T f(7.6)Then, factor of safety (F S ) is expressed as:α⋅φ⋅-α⋅==sin W tan )U cos W (T T F f s (7.7)The weight W is expressed as: sat b z W γ⋅⋅=(7.8)where γsat is saturated unit weight of soil. The hydrostatic force U is expressed asα⋅γ⋅⋅=α⋅γ⋅α⋅=α⋅=cos b z cos bcos z cos b u U w w 2 (7.9)where u is pore-water pressure at failure plane and γw is unit weight of water. Substitute equations (7.8) and (7.9) into equation (7.7) ()α⋅γφ⋅γ=α⋅γ⋅⋅φ⋅α⋅γ⋅⋅-α⋅γ⋅⋅⋅=α⋅φ⋅-α⋅==tan tan 'sin b z tan cos b z cos b z sin W tan )U cos W (T T F s s w s f s(7.10)Comparing Equations (7.4) and (7.10), the factor of safety is reduced by a factor γ’/γs if the water tablerises to the slope surface.7.4 Total stress analysis (φu = 0) [总应力分析]This total stress analysis covers the case of a fully saturated clay under undrained condition, or for the condition immediately after construction. [总应力分析合适用于饱和粘土在不排水条件下或短期的稳定分析] Only moment equilibrium is considered in the analysis. [满足力矩平衡条件] In section, the potential failure surface is assumed to be a circular arc [滑动面为弧形]. A trial failure surface (center O, radius r and length L [圆心为O,半径为r,弧长为L]) is shown in Fig.7.4. The failure of slope is mainly due self-weight (W) of the soil. Consider the moment at point O, the disturbing moment of W is expressed asd W M d ⋅=(7.11)where d is the moment arm of W from point O [d 是W 对滑弧圆心的力臂]. The forces resisting the rotation of the sliding soil mass are the shear forces (T f ) mobilised along the circular sliding surface. The resisting moment of T f at point O is expressed as r L c r T M u f r ⋅⋅=⋅=(7.12)where c u is undrained shear strength of the soil, L is length of the circular arc and r is radius of thecircular arc. Then factor of safety (F s ) is given bydW r L c M MF u d r s ⋅⋅⋅==(7.13)It is necessary to analyse the slope for a number of trial failure surfaces in order that the minimum factor of safety can be determined. If tension crack exists at the crest of the slope, the arc length L will be shortened. [当裂缝在坡顶出现,滑弧长度便会减小] The depth of the tension crack can be evaluated from the method presented in 土力学 p.196. [计算裂缝深度可参考土力学 p.196] If the crack is filled with water, a hydrostatic force will act normal to the crack. The additional moment of this hydrostatic force must be added to equation (7.11) for calculating the factor of safety of the slope. [当裂缝积水,计算安全糸数时公式(7.11)中必需考虑静水压力对滑弧圆心O 的力矩]Fig.7.1a Types of slope failures – translational slideFig.7.1b Types of slope failures – rotational slideDetached landslide deposit(滑动面)Sliding mass (滑体)Fig.7.2 Plane Translational slide with no water tableFig.7.3 Plane Translational slide with water tableFig.7.4 Total stress analysiszb WN T zb WN’ T Ud O。
几种常用边坡稳定性分析方法的比较
几种常用边坡稳定性分析方法的比较祝方才;刘佳鹏;刘增杰【摘要】基于仿真软件Geo-Slop,应用Morgenstern-Price法、Spencer法、Janbu法和Bishop法,分别对深圳外环高速公路某路堑边坡在天然状态和饱和状态下进行稳定性分析,计算得到最危险滑裂面以及相应的边坡安全系数.同时,根据现场调查,基于不平衡推力法分析出边坡最可能的滑裂面,并计算得到沿该滑裂面的安全稳定系数.通过数值分析和现场调查结果对比,得出以下结论:坡体在天然状态的安全系数大于1.0,接近1.2,边坡是稳定的,而在饱和状态下其安全系数小于1.0,坡体不稳定;数值计算分析得到的滑裂面位置与现场调查分析得出的滑裂面的位置一致,证明了结果的可靠性;最后,考虑到该地区雨水多发,坡体在饱和状态下安全系数小于1.0,建议及时对坡体进行支护,防止边坡失稳.【期刊名称】《湖南工业大学学报》【年(卷),期】2019(033)002【总页数】5页(P1-5)【关键词】Morgenstern-Price法;Spencer法;Janbu法;Bishop法;不平衡推力法;边坡稳定性【作者】祝方才;刘佳鹏;刘增杰【作者单位】湖南工业大学土木工程学院,湖南株洲 412007;湖南工业大学土木工程学院,湖南株洲 412007;湖南工业大学土木工程学院,湖南株洲 412007【正文语种】中文【中图分类】TU4570 引言随着我国国民经济的迅猛发展，基础设施建设大力推进，建设过程中形成了大量边坡，边坡稳定性分析成为岩土工程中的一项重要研究课题。
边坡稳定分析的方法有很多，主要包括强度折减法和极限平衡分析法。
极限平衡分析法主要包括Spencer 法、Janbu法、Bishop法及不平衡推力法，该方法计算简单，经过工程检验，因而至今仍然是应用最广的一种方法；强度折减法不用事先假定滑裂面的位置便能得出边坡的变形、安全系数及滑裂面等工程所需参数值，然而其缺少统一的边坡极限破坏判断标准，因而该方法在实际工程中应用较少[1]。
基于ABAQUS的边坡稳定性分析
基于ABAQUS的边坡稳定性分析刘一鸣;崔丽娅【摘要】High slop has a large proportion in mountain highway construction. The success of subgrade slope stability control is not only a key factor in the success of mountain highway construction, but also an important part of project safety and lower costs. By establishing ABAQUS three -dimensional numerical simulation model, and using strength reduction method to reduce the strength parameters of slope, this paper derived the law of deformation of the slope in the near destruction, and evaluated the effect of reinforcement.%高边坡在山区公路建设中所占的比例很大,路基边坡稳定性控制成功与否既是山区公路建设成败的关键因素,也是工程安全和降低费用的重要环节。
文章通过建立ABAQUS三维数值仿真模型,运用强度折减法对边坡的强度参数进行折减,得出边坡在临近破坏时的变形规律,并评价其加固效果。
【期刊名称】《内蒙古公路与运输》【年(卷),期】2012(000)002【总页数】3页(P1-3)【关键词】强度折减;边坡稳定性;加固【作者】刘一鸣;崔丽娅【作者单位】唐山市交通运输局,河北唐山063000;唐山天昱市政工程有限公司【正文语种】中文【中图分类】U416.141 研究目的和意义随着我国路网建设的不断完善，公路建设的重点正在逐步转移到丘陵地区和山区，而在这些地形崎岖的地段修建道路难免会出现高填深挖路基现象，随之而来的边坡稳定性问题也引起了人们的普遍关注，特别是高路堑边坡的治理，其成败直接影响工程的投资经费、安全运营和人身财产安全。
边坡的稳定性英语作文
边坡的稳定性英语作文1. Slope stability is a crucial factor in engineering and construction projects. It refers to the ability of a slope to resist failure and maintain its original shape. Without proper stability, slopes can collapse, leading to disastrous consequences.2. There are several factors that can affect slope stability. One of the key factors is the angle of the slope. Steeper slopes are generally more prone to failure as the gravitational forces acting on them are stronger. In addition, the type of soil or rock present in the slopealso plays a significant role. Loose or weak soils are more likely to give way compared to compacted or cohesive soils.3. Another factor that can impact slope stability isthe presence of water. Water adds weight to the slope, increasing the gravitational forces acting on it. Moreover, it can infiltrate the soil or rock, reducing their strength and cohesion. This is particularly true in areas with highrainfall or near bodies of water.4. Human activities can also contribute to slope instability. Excavations, construction, or even vegetation removal can alter the natural balance of forces within a slope. This can weaken the slope and make it more susceptible to failure. Therefore, it is important to carefully plan and execute any activities near slopes to minimize the risk of instability.5. Slope stability can be assessed through various methods. Geotechnical engineers often conduct site investigations to analyze the soil or rock properties, as well as the presence of water. They may also use slope stability analysis software to simulate different scenarios and assess the potential for failure. This allows them to design appropriate measures to enhance slope stability, such as installing retaining walls, drainage systems, or slope reinforcement techniques.6. It is crucial to regularly monitor slopes for signs of instability. This can include observing cracks, bulges,or changes in vegetation patterns. Any unusual or sudden changes should be investigated promptly to preventpotential disasters. Slope stability maintenance should be an ongoing process to ensure the safety of nearbystructures and the environment.7. In conclusion, slope stability is a critical aspect of engineering and construction projects. Understanding the factors that influence slope stability and implementing appropriate measures to enhance it are essential for ensuring the safety and success of such projects. Regular monitoring and maintenance are necessary to prevent and mitigate the risks associated with slope instability.。
平面滑动边坡稳定性的解析计算
ANALYTICAL CALCULATION ON STABILITY OF SLOPE WITH PLANAR FAILURE SURFACE
Jiang Binsong1，2，Cai Meifeng2，Du Hao1
(1 College of Civil Engineering and Architecture，Shandong University of Science and Technology， Taian 271019 China) (2 School of Civil and Environmental Engineering，University of Science and Technology Beijing， Beijing 100083 China)
(13)
W sinα + V cosα
βα
图 4 具有张裂缝和静水压力的边坡 Fig.4 Slope with tension joint and water pressure
式中：W = γ [(H 2 − z2 ) cotα − H 2 cot β ]/ 2 ，A = (H −
z) cscα
，U
数。取 f = tan ϕ ， a = 2c /(γ H ) ，并令 dF / dα = 0 ，
以求 F 为最小时的滑面倾角α 0 ，得[10]
cot α 0 = cot β + csc β a /(a + f )
(3)
将式(3)代入式(2)，得最小安全系数为
Fmin = (2a + f ) cot β + 2 csc β a(a + f ) (4)
应小于或等于滑动面的抗滑阻力，根据刚体极限平
论述边坡工程稳定性与治理措施
论述边坡工程稳定性与治理措施摘要:本文阐述了边坡工程稳定性与治理措施，边坡工程稳定性的一些常用方法，提出了边坡工程治理措施。
关键词:稳定性分析；边坡工程；治理措施Abstract: in the paper, the stability of slope engineering and management measures, the stability of the slope engineering some commonly used method, puts forward the slope engineering management measures.Key words: stability analysis; The slope engineering; Management measures1边坡工程稳定性分析1.1 边坡稳定性的影响因素(1) 地质构造。
地质构造因素主要是指边坡地段的褶皱形态、岩层产状、断层和节理裂隙的发育程度以及新构造运动的特点等。
通常在区域构造复杂、褶皱强烈、断层众多、岩体裂隙发育、新构造运动比较活跃的地区，往往岩体破碎、沟谷深切，较大规模的崩塌、滑坡极易发生。
(2) 岩体结构。
不同结构的岩体物理力学性质差别很大，边坡变形破坏的性质也不同。
(3) 风化作用。
边坡岩体长期暴露在地表，受到水文、气象变化的影响，逐渐产生物理和化学风化作用，出现各种不良现象。
当边坡岩体遭受风化作用后，边坡的稳定性大大降低。
(4) 地下水。
处于水下的透水边坡将承受水的浮托力的作用，使坡体的有效重力减轻; 水流冲刷岩坡，可使坡脚出现临空面，上部岩体失去支撑，导致边坡失稳。
(5)边坡形态。
边坡形态通常指边坡的高度、坡度、平面形状及周边的临空条件等。
一般来说，坡高越大，坡度越陡，对稳定性越不利。
(6) 其他作用。
此外，人类的工程作用、气象条件、植被生长状况等因素也会影响边坡的稳定性。
1.2 边坡工程稳定性分析方法(1) 边坡极限平衡法。
边坡的稳定性英语作文
边坡的稳定性英语作文英文回答：Slope stability is a critical aspect of geotechnical engineering, as it ensures the safety and stability of slopes in various construction projects. Several factors can affect slope stability, including the slope angle, soil properties, water content, and external forces such as earthquakes.To assess slope stability, engineers conduct detailed geotechnical investigations to analyze the soil conditions and identify potential failure mechanisms. Common methods include field investigations (e.g., soil sampling, boreholes) and laboratory testing (e.g., shear strength tests). These tests provide valuable data on soil parameters such as cohesion, friction angle, and permeability.Once the soil properties are determined, engineers canperform slope stability analysis using various methods, such as the limit equilibrium method or finite element analysis. These analyses help evaluate the factor of safety (FOS), which indicates the slope's resistance to failure compared to the destabilizing forces acting on it. A FOS greater than 1.5 is generally considered acceptable for most slopes.To enhance slope stability, engineers employ a range of techniques, including:Slope flattening: Reducing the slope angle increases the stability by decreasing the gravitational forces acting on the slope.Soil reinforcement: Installing geosynthetics or soil nails within the slope improves its shear strength and resistance to failure.Drainage systems: Installing drainage systems, such as perforated pipes or trenches, helps control water seepage and reduce pore water pressure within the slope.Retaining walls: Constructing retaining walls at the base of the slope provides lateral support and prevents the slope from collapsing.In summary, maintaining slope stability is crucial for ensuring the safety and integrity of slopes in construction projects. Through detailed geotechnical investigations, thorough analysis, and effective mitigation measures, engineers can design and implement slopes that can withstand various external forces and environmental conditions.中文回答：边坡稳定性是岩土工程的一项关键内容，它确保了边坡在各种建设项目中的安全和稳定。
Stability of Slopes(边坡稳定)
CHAPTER 9Stability of Slopes9.1 IntroductionGravitational and seepage forces tend to cause instability in natural slopes, in slopes formed by excavation and in the slopes of embankments and earth dams. The most important types of slope failure are illustrated in Fig.9.1.In rotational slips the shape of the failure surface in section may be a circular arc or a non-circular curve．In general，circular slips are associated with homogeneous soil conditions and non-circular slips with non-homogeneous conditions．Translational and compound slips occur where the form of the failure surface is influenced by the presence of an adjacent stratum of significantlydifferent strength．Translational 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 a)is shown in Fig.9.2. Potential instability is due to the total weight of the soil mass(W per unit Length) above the failure surface．For equilibrium the shear strength which must be mobilized along the failure surface is expressed aswhere 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 crack developing ，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 ofυu=0，values of N s can be obtained from Fig.9.3.The coefficient N s 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(υu=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 ofunit weight 19 kN／m3:the relevant shear strength parameters are c u =65 kN／m2 andυu =0．Determine the factor of safety for the trial failure surface specified in Fig.9.4.In 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 s is 0.18.Then9.3The Method of SlicesIn this method the potential failure surface，in section，is again assumed to be a circular arc with centre O and radius r．The soil mass (ABCD) above a trial failure surface (AC) is divided by vertical planes into a series of slices of width b, as shown in Fig.9.5.The base of each slice is assumed to be a straight line．For any slice the inclination of the base to the horizontal isαand 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 solutionassumptions 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' 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，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 andυu are used and the value of u in Equation 9.4 is zero．If υu=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 particularlysuitable 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 the 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 are functions ofβ,υ’，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/m2 andυ’=29°.The factor of safety is given by Equation 9.4.The soil mass is divided into slices l.5 m wide. The weight (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 hsinαrespectively are determined graphically，as shown in Fig.9.6.ThenWcosα=30h cosαW sinα=30h sinαThe pore water pressure at the centre of the base of each slice is taken to beγz w，where z w is the vertical distance of the centre point below the water table (as wshown in figure)．This procedure slightly overestimates the 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 βto the horizontal and the depth of the failure plane is z．as shown in section in Fig.9.7.The water table is taken to be parallel to the slope at a height of mz (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 anyvertical 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 soil between 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 exceedυ’provided z is less than a critical value．For a total stress analysis the shear strength parameters c u andυu 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 strengthparameters are c’=10 kN/m2 andυ’=26°；the residual strength parameters are c r’=0 andυr’=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 9.12:9.5General 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 mass 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 ofλand F，described by Morgenstern 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.[9.2]Bishop,A.W.and Morgenstern,N.R.(1960)：‘Stability Coefficients for Earth SlopesGeotechnique，Vo1.10.No.4．[9.3]Gibson,R.E.and Morgenstern,N.R.(1962):’A Note on the Stability of Cuttings inNormally Consolidated Clays’.Geotechnique,Vo1.12.No.3[9.4]Morgenstern,N.R.and Price,V.E.(1965):’The Analysis of the Stability of GeneralSlip Surfaces’,Geotechnique，Vo1.1 5,No.1.[9.5]Morgenstern,N.R.and Price,V.E.(1967): ‘A Numerical Method for Solving theEquations 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]Skemp ton,A.W.(1970):’First-Time Slides in Overconsolidated Clays’(TechnicalNote)，Geotechnique,Vo1.20.No.3[9.8]Spencer，E．(1 967)：‘A Method of Analysis of the Stability of EmbankmentsAssuming Parallel Inter-Slice Forces’，Geotechnique，Vo1.17.No.1．[9.9]Taylor,D.W.(1937):’Stability of Earth Slopes’,Journal of the Boston Society of CivilEngineers，Vo1.24,No.3- 11 -。
公路路基边坡稳定性及提高技术的要点
科技视界
公路路基边坡稳定性及提高技术的要点
张秀萍 渊 陇 南 公 路 管 理 局 应 急 抢 险 保 障 中 心 袁 甘 肃 陇 南 746000 冤
揖摘 要铱公路路基边坡防稳定作为公路工程基础建设的重要环节袁它对公路安全性起着决定性作用遥 本 文通过查阅文献大量资料及工作经验总结袁对公路路基边坡稳定性技术要求进行了分析袁总结了公路路基边 坡稳定设计和提高公路路基边坡稳定性技术要点袁希望能对公路工程的发展有所益处遥
2.1 植被防护 植被防护是指在边坡上种植各类矮生植物袁 以此
使边坡的表面和空气间能够形成植物屏障袁 起到缓解 径流冲刷尧 固土等作用遥 可在边坡上种植的植物主要 有以下几种院各类花草尧盘根草等藤本植物尧冬青等木 本植物袁 以及车前草等草本植物袁 选取植物类型时应 充分考虑当地气候袁 选择适宜生长的植物遥 如果边坡 所在地区的气候暖和且雨量充沛袁 则可种植矮灌木 丛袁使边坡绿化尧行道树和道路绿化形成一体袁进一步 美化公路的环境遥 在土质不适宜种植的边坡上袁 可先 铺 设 10 - 20cm 厚 种 植 土 袁 再 种 植 根 系 较 为 发 达 的 植 物袁如盘根草等袁植物生长形成盘根错结的草丛袁从而 起到保护作用遥 另外袁为避免种植土与植物被水冲走袁 需 在 和 边 坡 表 面 呈 45 毅 的 方 向 上 按 3 - 5m 的 间 隔 均 匀 铺设浆砌片石遥 在坡度较大或植物难以生长的边坡 上袁 可通过移植草皮来起到绿化和防护的作用袁 其效 果与种植相当遥 在植物生长茂盛处袁 均匀切割草皮形 成若干方块袁 然后连同表土一同铲出袁 将其铺设至边 坡的表面袁同时予以养生和保护遥 2.2 铺设预制混凝土块
揖关键词铱公路路基曰边坡稳定曰技术要点
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b
▪ Assumptions (假定):
▪ no ground water table (没有地下水)
z
▪ homogeneous cohesionless soil (均质
无粘性土)
▪ failure surface is parallel to the
surface of the slope (滑动面与坡面
▪ For the slope stability analysis using the LEM, two
analyses are considered for each slope: ▪ Effective Stress Analysis (c´ and ´) that represents
drained or long-term behaviour of the slope (有效应 力分析对应边坡长期的稳定) ▪ Total Stress Analysis (cu) that represents undrained or short-term behaviour of the slope (总应力分析对应 边坡短期的稳定)
平行)
▪ The slope is inclined at angle to the
slope (滑动面为平面与坡面平行 )
Sliding mass (滑体)
Sliding surface or weak zone (滑动面
或软弱层)
Detached landslide deposit
(ii) Rotational slides ▪ Sliding surface is an arc which is common
▪ In general, the sliding surface is assumed to be a circular arc for clays or a logarithmic spiral for sands and gravels.
▪ Factor of safety is defined as the ratio of shear strength over shear stress acting on the soil mass at the assumed slip plane in order to maintain a condition of limiting equilibrium. (安全糸数定义为在极限平衡条件下抗剪 强度与下滑力之比)
Madison (Montana)
1959
Vaiont (Italy)
1963
Aberfan (Wales)
1966
Huascaran (Peru)
1970
Nevado del Ruiz (Colombia) 1985
Casitas (Nicaragua)
1998
Venezuela
1999
Swiss/Italian Alps
7.2 Types of slope failures (滑坡的类型)
(i) Translational slides
▪ failure of a slope along a weak zone of soil (沿软弱层滑动) ▪ failure surface tends to be plane and roughly parallel to the
2. Slop in cohesionless soil 无粘土边坡
1）. General case 常规情况
▪ For an infinite slope, the depth of the
failure surface is small compared ope (滑动面深度比边坡长 度小)
1. Limit equilibrium method (极限平衡法)
▪ In the limit equilibrium method (LEM), the soil is considered to be on the verge of failure along an assumed or a known sliding surface. (在某一假设滑动面上,整个 块体处于极限平衡状态)
2000
Loess flow Rockslide Rockslide Rockslide Debris-slide Complex Debris flow Debris flow Complex Debris flow
200,000 killed ~40 killed >100 killed 2,600 killed 144 killed 25,000 killed 23,000 killed +2,000 killed +20,000 killed 38 killed
Alpine debris flow (2000)
Las Colinas landslide, El Salvador (2001)
Major slope-instability related catastrophes of the 20th century
Kansu (China)
1920
Gros Ventre (Wyoming) 1925
in cohesive soils (粘性土的滑动面为一曲面)
Sliding surface (滑动面)
7.3 Methods of slope stability analysis (边坡稳定分析方法)
▪ The stability of a slope can be analysed using one or more of the following methods: ▪ Limit equilibrium method - equilibrium of forces ( 极限平衡法) ▪ Limit analysis based on plasticity - equilibrium of stresses (极限应力分析法) ▪ Finite difference method (有限差分法) ▪ Finite element method (有限元法)