既有地基基础加固最新版本
既有建筑鉴定与加固通用规范
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既有建筑物地基基础加固方法与探讨
既有建筑物地基基础加固方法与探讨随着建筑物的使用年限的增加，建筑物的地基基础也随之老化、变形、裂缝等问题也相应出现。
为了保障建筑物的安全使用，必须采取适当的加固措施。
下面将介绍几种既有建筑物地基基础加固方法。
一、碎石灌注加固碎石灌注是将石子脱盐后，用泵车把碎石直接打入灌注孔洞中，浇入适量的水，使石子互相摩擦密实，形成一种高强度的地基基础加固层。
碎石灌注加固方法的优点是施工简单、快速，加固效果好。
但由于硬化后的石子体积比原来要缩小，加固后的地基呈现出一定的下沉变形。
因此，碎石灌注加固不适用于强度不够的地基基础加固。
二、桩基加固桩基加固是通过钢筋混凝土桩来加固原有的地基基础。
桩基加固方法可分为灌注桩和钻孔灌注桩两种。
灌注桩施工时先钻孔，再把管道插入孔中，灌入混凝土，配合振捣，待混凝土凝固后，撤出管道，形成桩。
钻孔灌注桩是钻孔后，在孔中先加入一定厚度的灌注混凝土，再钻入钢筋，再灌入混凝土。
桩基加固具有施工难度大、费用高、但加固效果好的特点。
适用于地基土层软、承载能力不足的场合。
三、高压注浆加固高压注浆加固是指通过高压泵将类似于水泥的物质注入到地基空隙中，使地基内部形成一种类似于混凝土的坚硬层，提高地基的承载能力。
高压注浆加固方法的优点是施工简单，对地基基础的侵蚀小，加固效果显著。
适用于地基不稳定、地基土层土石混合不规则的场合。
四、加筋土墙加固加筋土墙加固是指在地基基础上开挖一段宽度为3-4米，深度为地基基础下沉深度的坑，然后在坑中的外墙上垂直钻孔，装入钢筋，再施工填筑混凝土，形成加筋土墙，并在墙与原有地基之间，浇筑一层水泥浆，加强墙与地基的粘结力。
加筋土墙加固方法的优点是施工方便，对原有地基损伤小，加固效果显著。
适用于原有地基承载能力不足，地基基础轻微下降的场合。
综上所述，不同的地基基础加固方法适用于不同的场合，具体应该根据实际情况选择。
同时，还应该注重施工质量和材料控制，以保证加固效果。
既有建筑鉴定与加固通用规范标准
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既有建筑物地基及基础常用加固方式
既有建筑物地基及基础常用加固方式字体大小：大 - 中 - 小dongdateji发表于 11-08-24 16:40 阅读(295) 评论(0)分类：技术交流类既有建筑物地基及基础常用加固方式1.基础补强注浆加固法1.1 基础补强注浆加固法适用于基础因受不均匀沉降、冻胀或其他原因引起的基础裂损时的加固。
1.2 注浆施工时，先在原基础裂损处钻孔，注浆管直径可为25mm,钻孔与水平面的倾角不应小于30°,钻孔孔径应比注浆管的直径大2-3mm,孔距可为0.5-1.0m。
1.3 浆液材料可采用水泥浆等，注浆压力可取0.1-0.3MPa。
如果浆液不下沉，则可逐渐加大压力至0.6MPa，浆液在10-15min内再不下沉则可停止注浆。
注浆的有效直径为0.6-1.2m。
1.4 对单独基础每边钻孔不应少于2个；对条形基础应沿基础纵向分段施工，每段长度可取1.5-2.0m。
2 加大基础底面积法2.1 加大基础底面积法适用于当既有建筑的地基承载力或基础底面积尺寸不满足设计要求时的加固。
可采用混凝土套或钢筋混凝土套加大基础底面积。
加大基础底面积的设计和施工应符合下列规定：1 当基础承受偏心受压时，可采用不对称加宽；当承受中心受压时，可采用对称加宽。
2 在灌注混凝土前应将原基础凿毛和刷洗干净后，铺一层高强度等级水泥浆或涂混凝土界面剂，以增加新老混凝土基础的粘结力。
3 对加宽部分，地基上应铺设厚度和材料均与原基础垫层相同的夯实垫层。
4 当采用混凝土套加固时，基础每边加宽的宽度其外形尺寸应符合国家现行标准《建筑地基基础设计规范》GBJ7中有关刚性基础台阶宽高比允许值的规定。
沿基础高度隔一定距离应设置锚固钢筋。
5 当采用钢筋混凝土套加固时，加宽部分的主筋应与原基础内主筋相焊接。
6 对条形基础加宽时，应按长度1.5-2.0m划分成单独区段，分批、分段、间隔进行施工。
2.2 当不宜采用混凝土套或钢筋混凝土套加大基础底面积时，可将原独立基础改成条形基础；将原条形基础改成十字交叉条形基础或筏形基础；将原筏形基础改成箱形基础。
既有建筑鉴定与加固通用规范标准
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既有建筑地基基础加固技术规范30881
既有建筑地基基础加固技术规范6.8 注浆加固法6.8.1注浆加固法适用于砂土、粉土、粘性土和人工填土等地基加固。
一般用于防渗堵漏、提高地基土的强度和变形模量以及控制地层沉降等。
注浆设计前宜进行室内浆液配比试验和现场注浆试验，以确定设计参数和检验施工方法及设备。
也可参考当地类似工程的经验确定设计参数。
6.8.2注浆设计应符合下列规定：1 对软弱土处理，可选用以水泥为主剂的浆液，也可选用水泥和水玻璃的双液型混合浆液。
在有地下水流动的情况下，不应采用单液水泥浆液。
2 注浆孔间距可取1.0-2.0m,并应能使被加固土体在平面和深度范围内连成一个整体。
3 浆液的初凝时间应根据地基土质条件和注浆目的确定。
在砂土地基中，浆液的初凝时间宜为5-20min；在粘性土地基中，宜为1-2h。
4 注浆量和注浆有效范围应通过现场注浆试验确定，在粘性土地基中，浆液注入率宜为15%-20%。
注浆点上的覆盖土厚度应大于2m。
5 对劈裂注浆的注浆压力，在砂土中，宜选用0.2-0.5MPa;在粘性土中,宜选用0.2-0.3MPa。
对压密注浆，当采用水泥砂浆浆液时，坍落度宜为25-75mm，注浆压力为1-7MPa。
当坍落度较小时，注浆压力可取上限值。
当采用水泥水玻璃双液快凝浆液时，注浆压力应小于1MPa。
6.8.3注浆施工应符合下列规定：1 施工场地应预先平整，并沿钻孔位置开挖沟槽和集水坑。
2 注浆施工时，宜采用自动流量和压力记录仪，并应及时对资料进行整理分析。
3 注浆孔的孔径宜为70-110mm，垂直度偏差应小于1%。
4 花管注浆法施工可按下列步骤进行：1) 钻机与注浆设备就位；2）钻孔或采用振动法将花管置入士层；3）当采用钻孔法时，应从钻杆内注入封闭泥浆，然后插入孔径为50mm的金属花管。
4）待封闭泥浆凝固后，移动花管自下向上或自上向下进行注浆。
5 压密注浆施工可按下列步骤进行：1）钻机与注浆设备就位；2）钻孔或采用振动法将金属注浆管压入土层；3）当采用钻孔法时，应从钻杆内注入封闭泥浆，然后插入孔径为50mm的金属注浆管；4）待封闭泥浆凝固后，捅去注浆管的活络堵头，然后提升注浆管自下向上或自上向下对地层注入水泥-砂浆液或水泥-水玻璃双液快凝浆液。
《英文版：既有建筑地基基础加固技术规范》JGJ123-2000
中华人民共和国行业标准Industrial Standard of the People’s Republic of ChinaJGJ 123-2000 既有建筑地基基础加固技术规范Technical Code for Improvement ofSoil and Foundation of Existing BuildingsBeijing, 2000中华人民共和国行业标准Industrial Standard of the People’s Republic of China既有建筑地基基础加固技术规范Technical Code for Improvement ofSoil and Foundation of Existing BuildingsJGJ 123-2000Mainly prepared by: Research Institute of Construction Science of the People’sRepublic of ChinaApproved by: Ministry of Construction of the People’s Republic of China Implementation date: June 1, 2000Notice on issuing the industrial standard “Technical Code for Improvement of Soil and foundation of Existing Buildings”Jian Biao [2000] No.35As per the requirement in “Notice on Issuing Compilation and Revision Project Plan for Construction Project Industrial Standards of 1993” (Jian Biao 1993 No. 285), “Technical Code for Improvement of Soil and Foundation of Existing Buildings” compiled by Research Institute of Construction Science of People’s Republic of China is hereby reviewed and approved as compulsory industrial standard, number as JGJ 123-2000, and should come into force from June 1, 2000.The subject standard will be managed and interpreted by the Research Institute of Construction Science of P. R. China which is the technical responsible unit for the Ministry of Construction. The Research Institute of Standard Quotas organized China Construction Publishing House to publish the standard.Ministry of Construction of People’s Republic of ChinaFebruary 12, 2000ForwardAs per the requirement of Jian Biao 1993 No. 285 issued by the Ministry of Construction, the code compilation team hereby compiled this code through extensive investigation and research, with many research results home and abroad and a large amount of construction practice experiences summarized, and through opinions broadly solicited.The technical contents of this code many consist of general rules, symbols, basic stipulation, verification of soil and foundation, foundation calculation, improvement methods of soil and foundation, remedy and prevention of soil and foundation incident or accident, improvement through added layers, reinforcement to rectify incline or replacement, and etc.The code is managed and interpreted by the Research Institute of Construction Science of P. R. China which is the technical responsible unit for the Ministry of Construction.The code is mainly compiled by the Research Institute of Construction Science of P. R. China (Address: 30 East Third North Ring Road, Beijing; Postcode 100013)The code is jointly compiled by Tongji University, Nothern Communication University, Research Institute of Construction Science of Fujian province.The code is mainly compiled by following personnel: Zhang Yongjun, Ye Shuqi, Tang Yeqing, and Hou Weisheng.Table of Content1 General Rules (5)2 Symbols (5)3 Basic stipulation (6)4 Verification of Soil and Foundation (7)5 Foundation Calculation (9)6 Methods for Improvement of Soil and Foundation (11)7 Remedy and Prevention of Soil and Foundation Incident (27)8 Modification to Add Stories (32)1 General Rules1.0.1In order to execute the technical and economical policy of the country during the design and construction of the improvement of soil and foundation, the code is compiled so that “advanced technology, reasonable economy, safety and adequacy, ensured quality and protected environment” can be achieved.1.0.2This code is applicable to design and construction of any improvement to soil and foundation caused by inadequate soil investigation, design, construction, or operations, by increased load, incline, displacement, reconstruction or protection of ancient buildings, or by nearby new buildings, excavation of deep foundation pits, new underground services, or natural disaster.1.0.3 The design and construction of improvement of soil and foundation of existing buildings, besides meeting the requirements of this code, should meet the requirement of relevant national compulsory standards which is in force.2 SymbolsA – Bottom area of foundationd – Pile diameterd’ – Diameter of lime pile after expansionEp – Compression modulus of pile bodyEs – Compression modulus of soil between pilesEsp – Compression modulus of compound soil layerF – Design value of the vertical force on the top surface of foundation from upper structure after reinforcement of foundation or load increased.f – Design value of foundation bearing capacityfs,k – Standard value of bearing capacity of soil between piles after improvementfp,k – Standard value of bearing capacity of pile unit sectionfsp,k – Standard value of bearing capacity of compound foundationG – Design value of foundation weight and weight of soil on top of foundationl1 – Line distance of pilesl2 – Row distance of pilesM – Design value of moment applied to the bottom of foundation after improvement or increased loadm – Replacement ratio of areaNa – Design value of bearing load for uplifting pointN – Number of uplifting pointsp – Design value of average pressure on the bottom of foundation after improvement or increased loadpmax – Design value of maximum pressure along the side of the bottom of foundation after improvement or increased loadpmin – Design value of minimum pressure along the side of the bottom of foundation after improvement or increased loadQ – Design value of total load for buildingq – Lime volume for each meter of lime piles – Final settlement of foundations0 – Settlement achieved before improvement or increased loads1 – Settlement achieved after improvement or increased loads2 – Settlement to be achieved under original building loadW – Sectional modulus at the bottom of foundation after improvement or increased loadηc – Expansion factor3 Basic stipulation3.0.1 Before improvement of soil and foundation of existing buildings, soil and foundation should be examined to enable design and construction. The examination of soil and foundation, and design and construction of improvement should be carried out by companies with relevant certifications and by professional personnel with experiences.3.0.2 Design of improvement of soil and foundation of existing buildings should be carried out according to the following steps:1 When selecting method for improvement, objective of improvement, joint function of upper structure, foundation and soil should be considered to decide initially whether soil, foundation, stiffness of upper structure or combination of soil and foundation should be improved.2 After the initial schemes are selected, they should be compared through expected achievement, difficulty of construction, material availability and delivery conditions, safe constructability, impact to adjacent building or environment, conditions of construction equipment, construction period and cost, so that a optimum scheme can be selected.3.0.3 The construction people should understand the objective of improvement, theory, technical requirement and quality standard for the improvement project undertaken.Dedicated personnel are required for quality control through strict monitoring. Whenever an abnormal condition is observed, meeting should be held with designers and relevant department to analyze the problem and find solutions.3.0.4 A dedicated organization is required to supervise quality during construction. When the construction is complete, quality inspection and acceptance should be conducted.3.0.5 Settlement observation is required during construction of improved to soil and foundation. For buildings of importance or of strict restriction of settlement, settlement observation should be continued after the improvement until it becomes stable. Adjacent buildings and underground services should be monitored at the same time.4 Verification of Soil and Foundation4.1 Verification of Soil4.1.1The following steps should be observed when examining soil of existing buildings,1 Collect geotechnical investigation information, design documents and drawings of foundations for existing buildings and upper structure, construction recorded of concealed parts, and as-built drawings.2 The following things should be analyzed when studying the original geotechnical investigation information.1)Distribution and evenness of subsoil, weak underlying layer, special soil, gullies,ditches, rivers, tombs, caves, and holes.2)Physical and mechanical properties of subsoil.3)Water level and corrosivity of groundwater4)Liquefaction characteristic of silt or sand, and earthquake characteristic of soft soil5)Stability of site3 Investigate the current condition of the building, actual working load, settlement, and settlement stability, differential settlement, distortion, incline and crack etc, and find causes.4 Investigate adjacent buildings, underground services, and pipeline.5 Work out inspection method to verify the soil based on the objective of improved, together with information collected and analyses of information.4.1.2 The following methods can be adopted for inspection of soil according to improvement requirement and site condition.1 Drilling, pit exploration, channel exploration, or earth physical method can be adopted.2 Indoor physical mechanical property test can be carried out on undisturbed soil.3 In-situ tests like load test, cone penetration test, standard penetration test, dynamic penetration test, cross-board shear test or side pressure test can be adopted.4.1.3Inspection of soil of existing buildings should comply the following requirements.1 According to the importance fo the building and original geotechnical investigation information, supplementary borehole or in-situ test hole should be provided to find out subsoil distribution and soil physical and mechanical properties. Holes should be close to foundation.2 For important buildings that require adding stories or increase load, it is suitable to take undisturbed soil and carry out indoor physical mechanical property test or load test under the foundation.4.1.4 When evaluating soil of existing building, the following requirements should be met.1 According to the inspection result, together with local experience, a compressive evaluation of the soil should be prepared.2 Decide whether it is necessary to improve soil and provide recommendations of improvement method based on the soil condition and upper structure.4.2 Verification of foundation4.2.1Inspection of foundation of existing building should be carried out according to the following steps.1 Collect design and construction documents for foundation, upper structure, and pipeline, and as-built drawings. Understand the actual load on different parts of the building.2 Site proof is required. Exploration channel may be required to verify foundation type, material, dimension, and embedded depth. Examine crack in the foundation, corrosiveness, degree of damage, strength and grade of foundation materials. If the building inclines, then degree of incline and distortion should be investigated as well. For piled foundations, pile depth, bearing layer and pile quality should also be investigated.4.2.2The following methods can be adopted for the inspection of foundation of existing building.1 Visual check of foundation2 Initial check with hand hammer to find out foundation quality. Find out strength or grade of foundation material using non-destructive method or core-taking method.3 Check rebar diameter, number of piles, location, and corrosiveness.4 Observe settlement of pile foundation.4.2.3When evaluating foundation of existing building, the following requirements should be met.1 Evaluate completeness of the foundation based on cracks, corrosiveness, degree of damage and grade of materials.2 Calculate bearing capacity and deformation based on the actual load and deformation characteristics. Decide whether it is necessary to improve, and recommend method of improvement.5 Foundation Calculation5.1 Calculation of bearing capacity5.1.1When the foundation of existing building need to be improved or the load is to be increased, the bearing capacity of soil should be calculated in accordance with following requirements.When the axial load worksp<=f (5.1.1-1)Where,p – design value of average pressure at the bottom of foundation after improved or increased load.f – Design value of soil bearing capacity, which should be determined based on the standard value determined through this code in accordance with current national standard “Code for building foundation design” (GBJ 7). For foundation that requires improvement, the standard value of soil bearing capacity should be determined through examination after the improvement. For soil with increased load, standard value of soil bearing capacity should be determined through examination before load is increased. For buildings with stabilized settlement, when adding stories, article 8.2 of this code may be referred to determine standard value of soil bearing capacity.When the eccentric load works, besides meeting the requirement of formula 5.1.1-1, the following formula should be met as well.pmax<=1.2f (5.1.1-2)Where,pmax – design value of maximum pressure along the bottom of foundation after improvement or increased load.5.1.2Pressure at the bottom of foundation after improvement or increased load may be determined through the following formulaWhen the axial load works,p=(F+G)/A (5.1.2-1)Where,F – design value of vertical force on the top of foundation from upper structure after improvement or increased loadG – design value of foundation weight and soil weight on top of foundation. If below water level, floating force should be deducted.A – foundation bottom areaWhen the eccentric load works,pmax = (F+G)/A + M/W (5.1.2-2)pmin = (F+G)/A - M/W (5.1.2-3)Where,M – design value of moment applied to the bottom of foundation after improvement or increased loadW – sectional modulus of foundation bottom after improvement or increased load.pmin – design value of minimum pressure along foundation bottom after improvement or increased load.5.1.3 When there is weak underlying layer within the bearing layers of foundation, the bearing capacity of weak underlying layer should be calculated.5.1.4 For existing buildings on a slope or adjacent to deep foundation pit, soil stability should be calculated as well.5.2 Calculation of Soil Deformation5.2.1The calculated value of soil deformation after improvement or inreased load should not exceed the allowable value in the current national standard “Code for Building Foundation Design” (GBJ 7).5.2.2 The final settlement of foundation for existing building after soil and foundationimprovement or increased load shall be determined through the following formula.s=s0+s1+s2 (5.2.2)Where,s – final settlement of foundations0 – settlement achieved before improvement or increased load, which can be determined through settlement observation information or estimated according to local experience.s1 – settlement achieved after improvement or increased load. If soil and foundation are improved, the value can be calculated with the compression modulus after improvement. If the load is increased, the value can be calculated with the compression modulus before increased load.s2 - settlement to be achieved under original building load. The value can be estimated based on the settlement observation information or local experience. If the foundation settlement under original building load is stabilized, then the value should be zero.5.2.3Calculation of foundation settlement may be referred to the current national standard “Code for Building Foundation Design” (GBJ 7).6 Methods for Improvement of Soil and Foundation6.1 Mortar Filling Method6.1.1 The method is applicable when cracks are found in foundations due to uneven settlement, frost heaving or other reasons.6.1.2When the method is applies, first drill a hole at the crack. The filling tube can be 25mm in diameter. Angle between the hole and the horizon should be no less than 30 degrees. The diameter of the hole should be 2-3mm greater than the diameter of the filling tube. The distance between holes may be 0.5 to 1.0 meter.6.1.3 Cement Mortar can be used as filling material. Filling pressure can be 0.1 to 0.3 Mpa. If the mortar is not going inside, the pressure maybe increased to 0.6 Mpa slowly. If the filling material is not going inside for 10 to 15 minutes, filling can be stopped. The effective diameter of filling is 0.6 to 1.2 meters.6.1.4For single foundations, holes on each side of the foundation should be no less than two. For strip foundations, construction should be carried out by sections, with each section between 1.5 to 2.0 meters.6.2 Foundation Bottom Enlargement Method6.2.1When the bearing capacity of the foundation or the size of the foundation for the existing building can not meeting design requirement, foundation bottom enlargement method can be adopted. Concrete or reinforced concrete may be used to make the bottom of foundation bigger. The design and construction should meet the following requirements when making the bottom of foundation bigger.1. If the foundation is under eccentric load, asymmetrical enlargement can be adopted while if the foundation is under central load, symmetrical enlargement.2. The surface of original foundation should be made rough and washed clean, and a layer of high-strength cement mortar or concrete agent to increase the adhesive force of old concrete foundation and new concrete foundations.3. For the enlarged area, a compacted blinding layer of the same thickness and materiel as the original blinding should be used.4. When using concrete to improve the foundation, the dimension of added concrete should meeting the allowable height and width ration for stiff foundation stipulated in the current national standard “Code for Building Foundation Design” (GBJ 7). Anchor re-bar should be placed at certain distance along the height of the foundation.5. When using reinforced concrete to improve the foundation, the main re-bars in the added part should be welded to the main re-bars in the original foundation.6. For the improvement to strip foundation, sections of 1.5 to 2.0 meters should be planned, and construction should be carried by batches and sections at different times.6.2.2 When concrete or reinforced concrete is not suitable for making the bottom of foundation bigger, single foundation may be changed into strip foundation, original strip foundation to cross strip foundation or raft foundation, or original raft foundation to box foundation.6.3 Foundation Deepen Method6.3.1The method is applicable when good subsoil layer exists near grade, which can be used as bearing layer, and with low water table. Make the original foundation deeper, so that it sits on a better bearing layer to meet the bearing and deformation requirements of the design. When the water table is high, dewater or draining measures should be carried out.6.3.2The following steps should be observed when making foundation deeper.1. Excavate a 1.2 meter long, 0.9 meter wide vertical pit along the foundation of existing buildings by sections or batches. If the pit wall can not be upright due to sand soil or soft soil, then supports are required for the walls. The bottom of the pit may be 1.5 meters lower than the existing foundation.2. Excavate a foundation pit under the original foundation, the width of which should be the same as the original foundation, and the excavation depth should reach the bearing layer required by the design.3. Concrete should be poured at the site under the existing foundation. The pour should be stopped when it is 80mm from the bottom of original foundation. After one day of curing, thick cement mortar with expansion agent and quick cure agent should be inserted into the gap under the existing foundation. Hammer the wood pieces to make the mortar tight.6.4 Anchor Rod Static Load Pile Method6.4.1The subject method is applicable for mud, muddy soil, clay, silt and manual backfill.6.4.2 The design of the Anchor rod static load pile should meet the following requirements.1. The vertical bearing capacity of the subject pile should be determined through single pile load test. When there is not test information, the current national standard “Code for Building Foundation Design” (GBJ 7) can be referred to estimate the bearing capacity.2. The pile should located next to the wall body or columns. Number of piles should be determined through the load of upper structure and single pile vertical bearing capacity. Static load on the pile should be controlled as not to exceed the sold weight of the structure to be improved. The hole for driving piles should be a square pyramid with small top and large bottom. The side of hole should be 50 to 100 mm greater than the dimension of the pile.3. When the bearing capacity of the foundation for existing building can not meet static load requirement, foundation should be improved, or newly-poured reinforced concrete beam can be used as a platform for driving piles.4. Manufacture of pile should meet the following requirements1)Reinforced concrete or steel should be used as pile material;2)For reinforced concrete pile, square section is recommended with 200 to 300 mmsection dimension.3)Length of each section of pile should be determined based on the net constructionspace (height) and conditions of the construction machinery, which is recommended for 1.0 to 2.5 meters;4)Main re-bar in the pile should be determined through calculation. When the sectionis 200mm, re-bar should be no less than 4ф10; when the section is 250 mm, re-bar no less than 4ф12ф; section 300mm, re-bar no less than 4ф16.5)Concrete grade for pile should be no less than C30.6)When the pile is under tensile force, welded connection should be adopted. In othercases, sulfur glue may be used as connection material. When sulfur glue is used for connection, re-bar mesh for welding should be put on both ends of the pile, one end with embedded re-bar, and the other end with reserved holes for re-bar and holes for lifting. When welding connection is used, embedded connection iron pieces should be put on both ends of the pile.5. Besides meeting the requirement for bearing capacity, the following requirements should be observed for original foundation.1)The net distance between side of the base and side pile is not suitable to be less than200 mm,2)The thickness of the base should be no less than 350mm.3)The length of pile tip into the base should be between 50 to 100mm. When the pilebears tensile forces or there is any special requirement, anchor re-bar should be places at four corners of pile top. The length of anchor into the base should meeting anchor requirement of re-bar.4)The hole for driving pile should be filled and compacted with C30 slight expansiveconcrete;5)When the thickness of original foundation is less than 350 mm, hole for seal pileshould have 2ф16 re-bar cross welded onto the anchor bar. When pouring concrete to the hole for driving piles, pile cap should be poured on top of the hole, with the thickness no less than 150mm.6. Straight bolts or welded bolts maybe used as anchor rod. At the same time, the following requirements should be met.1)When the static load for driving pile is less than 400kN, M24 anchor bar may beused; and when the load is between 400 to 500 kN, M27 anchor bar may be used.2)The embedded depth of anchor bolt may be 10 to 12 times of bolt diameter, andshould be no less than 300 mm. Anchor rod above the base should meet the requirement of piling rig, which normally should be no less than 120mm.3)Epoxy mortar or sulfur glue may be used in the anchor rod hole as the adhesiveagent for anchor bolts.4)The distances between anchor rod and hole for driving piles, or adjacent structure orside of base should be no less than 200mm.6.4.3During construction of anchor rod static load pile, the following stipulations should be observed.1. The following preparation should be carried out prior to construction1)Clean the construction faces for hole for driving piles and anchor hole.2)Preparation for manufacture of anchor bolts and pile sections.3)Excavate hole for driving piles, make the hole rough, and then make it clean. Cut there-bar of the original foundation and bend it, ready to be welded after pile driven.4)Excavate anchor hole, make sure the hole is clean and dry before put the anchor rod,and then seal the hole with adhesive.2. The following stipulations should be observed during construction.1)Piling rig should be kept vertical during driving. The nut and anchor should bebalanced and tightened. Tighten loosed nuts during pile driving.2)Pile sections placed should be kept vertical. Make sure the jack, pile section, anddriving hole are aligned at the same axial. No eccentric pressure is allowed for driving piles. Steel plate or plastic bag should be used as cushion material, and steel cap should be in place before driving piles. Plan difference of the pile location should not exceed ±20mm. The verticality of pile should not exceed 1% of the total pile length.3)A pile should be driven to the design elevation at one attempt. If driving needs to besuspended, pile tip should be left in a soft soil layer, and driving should be resumed in no more than 24 hours.4)Driving should be carried out symmetrically. It is not suitable using several rigsworking on one single foundation.5)Vertical axial of top and bottom section should be lined before welding of twosections. Full penetration is required after removal of rust on the surface of the welding face.6)When sulfur glue is used to connect two pile sections, the relevant clauses in thecurrent national standard “Code for Construction and Acceptance of Soil and Foundation Engineering” GBJ 202 should be observed.7)Pile tip should be embedded into the designed bearing layer. The driving forceshould reach 1.5 time the standard value for single pile vertical bearing capacity stipulated in the current national standard “Code for Building Foundation Design”GBJ 7, and the time should be no less than 5 minutes.8)Pile top and sides should be made rough and clean before concrete interface agent isapplied. Non-pre-stressed method or pre-stressed method can be chosen for sealing piles.When non-pre-stressed method is adopted, jack should be discharged, and pile rig removed when the pile reaches the designed driving force and the designed depth.Weld crossing re-bar for the anchor rod, removed debris, water or any slurry in the driving hole, and then pour C30 slight expansion accelerated concrete together with pile cap beam. When pre-stressed method is adopted, jack should not be discharged, and steel beam support should be used. Clean the driving hole and then immediately anchor the pile and driving hole together. When the sealing concrete reaches design strength, jack should be discharged.6.4.4The quality inspection of the pile should meet the following stipulation,1 The final driving force and depth should meet the design requirement.2 Strength of the cube for pile and cube for the sealing concrete should meet the design requirement. The strength of the sulfur glue should meet the stipulations in the current national standard “Code for Construction and Acceptance of Soil and Foundation Engineering” GBJ 202.6.5 Tree Root Pile6.5.1 The so-called tree root pile is suitable for repair or increase of stories of existing buildings, repairs of ancient buildings, or reinforcement of tunnel work on top of mud, muddy soil, clay, silt, sand, gravel or manual backfill.6.5.2The design of tree root pile should meet the following stipulations.1 The diameter of pile is recommended as 150 to 300mm. The pile length is not suitable to be more than 30m. The layout of piles can be vertical type or network inclined type.2 Vertical bearing capacity of tree root pile may be determined through single pile loading test. If there is not testing information, the capacity may be estimated according to the。
既有建筑地基基础加固技术规范
《既有建筑地基基础加固技术规范》简介时间：2008-09-17根据建设部建标[1993]285号文的要求，由中国建筑科学研究院会同同济大学、北方交通大学和福建省建筑科学研究院等单位共同编制的《既有建筑地基基础加固技术规范》，已经建设部审查、批准为强制性行业标准，编号为JGJ123-2000，自2000年6月1日起施行。
本规范包括九章和一个附录。
即总则，符号，基本规定，地基基础的鉴定，地基计算，地基基础的加固方法，地基基础事故的补救与预防，增层改造，纠倾加固和移位，基础下地基土载荷试验要点等。
本规范的适用范围较广，大致可归纳为以下几类：1、因勘察、设计、施工或使用不当等原因造成地基基础损坏，而需要对地基基础进行加固的既有建筑。
常见于建造在各种软弱地基或特殊土地基上的房屋。
2、因改变建筑的使用要求而需地基基础进行加固的既有建筑，如增层、增加荷载，改建，扩建等。
3、由于周围环境影响，而需对既有建筑地基基础进行加固。
如邻近新建建筑、深基坑开挖，新建地下工程，或遭受自然灾害等。
4、为保护古建筑而需对其地基基础进行加固。
本规范的主要内容如下：第三章基本规定1、既有建筑地基和基础加固前，应先对地基和基础进行鉴定，方可进行加固设计和施工。
2、既有建筑地基和基础的鉴定、加固设计和施工，应由有相应资质的单位和有经验的专业技术人员承担。
3、规定了既有建筑地基和基础加固设计的步骤。
4、加固施工中应有专人负责质量控制，并进行严密的监测。
5、规定了对地基基础加固的建筑，应进行沉降观测。
对邻近建筑和地下管线应同时进行监测。
第四章地基基础的鉴定1、地基的鉴定。
地基的检验步骤、方法和要求，以及地基加固必要性的评价，并提出加固方法的建议。
2、基础的鉴定。
即基础的检验步骤和方法，以及基础加固必要性的评价，并提出加固方法的建议。
第五章地基计算1、地基承载力计算。
要求既有建筑基础加固或增加荷载后基础底面处的平均压力设计值应不大于地基承载力设计值。
17 既有建筑地基基础加固解析
2、为时新旧基础牢固联结，在灌注混凝土前应将原基础凿毛并刷洗干净， 再涂 一层高标号水泥砂浆，沿基础高度每隔一定距离应设置锚固钢 筋；也可以在墙角或圈梁钻孔钢筋，再用环氧树脂填满，穿孔钢筋须与加 固筋焊牢。
3、对对于加宽部分，其地基上应铺设的垫料及其厚度，应与原基础垫层的 材料及其厚度相同。时加套后的基础与原基础的基地标高和应力扩散条件 相同且变形协调。
8
二、墩式托换的设计要点
（1）采用间断式或连续式的混坑式托换要根据被托换加固结构
的荷载和坑下地基土的承载力大小确定，在设计上优先考虑间断坑式托
换，当间断墩的底面积不能对建（构）筑物荷载提供足够支承时，则可
设置连续式基础（相当于基础加深技术），施工时应首先设置间断墩以
提供临时支承，在开挖间断墩间的土，将坑的侧板拆除，在坑内灌注混
原基础 嵌条 嵌条 嵌条 伸向基础下挖坑 横向挡板 继续向下挖坑 导坑
a）剖面图 b）平面 图 坑式静压桩施工导坑开挖示意图
15
17.5 注浆加固技术
一、 注浆加固法概念与应用
既有建筑地基基础注浆加固 方法常采用压力灌浆法和高压 喷射注浆法。
基础灌浆加固示意图
16
二、 注浆加固法的设计
注浆设计前宜进行室内浆液配比试验和现场注浆试验。 ①对软弱土处理，可选用以水泥为主剂浆液，也可选用水泥和水玻璃 双液型混合浆液。在有地下水流动的情况下，不应采用单液水泥浆液。
2
17.2 基础加宽技术
一、 采用钢筋混凝土套加大基础底面积
当既有建筑的地基承载力或基础底面积尺寸不满足设计要求时的加固。 可采用混凝土套或钢筋混凝土套加大基础底面积。
条形基础的双面加宽
3
对于单独柱基础，可沿基础底面四边扩大加宽。
既有地基基础加固最新版本课件
04 地基基础加固施工
施工准备
勘察现场
对既有建筑物的地基基 础进行详细勘察，了解 其现状和存在的问题。
制定方案
根据勘察结果，制定具 体的加固方案和施工计 划。
材料准备
准备所需的加固材料， 如混凝土、ቤተ መጻሕፍቲ ባይዱ筋等，确 保质量合格。
设备检查
对施工所需的设备进行 检查和维护，确保其正 常运行。
施工流程
基础清理
注浆加固法
总结词
通过压力注浆将浆液注入土体孔隙中，改善土体结构，提高土体强度和防渗性能 。
详细描述
注浆加固法适用于各种类型的土壤和岩层，尤其适用于既有建筑物的地基加固。 通过注浆管将浆液均匀注入地层中，浆液在压力作用下扩散、凝固，形成强度高 、抗渗性能好的结石体，从而提高地基承载力和稳定性。
树根桩法
案例二：某商业大厦地基基础加固
总结词：技术先进
详细描述：某商业大厦采用最新的地基基础加固技术，如微型桩和树根桩等，对大厦进行整体抬升和加固，确保了建筑的安 全性和稳定性。
案例三：某桥梁地基基础加固
总结词：工程量大
详细描述：某大型桥梁因河床冲刷导致基础裸露，通过大面积的桩基、护岸和防冲刷等措施，对桥梁 进行全面加固，工程量巨大，技术难度高。
加固的历史与发展
历史回顾
地基基础加固技术随着建筑业的发展而不断进步，早期的加固方法较为简单， 如增加支撑、填土等。随着科技的发展，现代加固技术越来越多样化、专业化 。
发展趋势
未来地基基础加固技术将朝着更加高效、环保、智能化的方向发展，如采用新 型材料、引入信息化技术等，以提高加固效果和施工效率。
02 地基基础加固方法
案例四：某隧道地基基础加固
总结词：环境复杂
住房和城乡建设部公告第1452号――关于发布行业标准《既有建筑地基基础加固技术规范》的公告
住房和城乡建设部公告第1452号――关于发布行业标准《既有建筑地基基础加固技术规范》的公告
文章属性
•【制定机关】住房和城乡建设部
•【公布日期】2012.08.23
•【文号】住房和城乡建设部公告第1452号
•【施行日期】2013.06.01
•【效力等级】部门规范性文件
•【时效性】现行有效
•【主题分类】标准定额
正文
住房和城乡建设部公告
（第1452号）
关于发布行业标准《既有建筑地基基础加固技术规范》的公告现批准《既有建筑地基基础加固技术规范》为行业标准，编号为JGJ123-2012，自2013年6月1日起实施。
其中，第3.0.2、3.0.4、3.0.8、3.0.9、
3.0.11、5.3.1条为强制性条文，必须严格执行。
原行业标准《既有建筑地基基础加固技术规范》JGJ123-2000同时废止。
本规范由我部标准定额研究所组织中国建筑工业出版社出版发行。
住房和城乡建设部
2012年8月23日。
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九、托换技术安全及工程监测
(一) 托换技术施工要点
1．根据工程实际需要，对建筑物进行加固；或对建筑物基础 全部或部分支托住，或对建筑物地基或基础进行加固。
2．当建筑物基础下有新建地下工程时，应将荷载传递到新建
的地下工程上。 3. 不论何种情况，托换工程都是在一部分被托换后，才能开 始另一部分的托换工作，否则就难以保证质量。所以，托 换范围往往由小到大，逐步扩大。
体者，亦可称为侧向托换(lateral underpinning)
按照具体脱换方式的分类
图7-1-2 预防性托换：
侧向托换（地下连 续墙）
六、托换处理的特点及其对有关工程人员的要求 1) 建筑技术难度大、费用较高，工期较长，责任性强。 2) 相关工程人员需要具备“岩土工程”与“结构工程” 的知识，是一项高度综合性技术。 3) 相关人员要有丰富的勘察、设计、施工及科研等方面 的工作经验。
③ 墙体内设置圈梁(整体性)；
④ 根据不同的预估沉降量确定相应的建筑物标高； ⑤ 优化施工顺序加速沉降； ⑥ 预压力处理做好； ⑦ 施工时避免基坑土的优动。
2、湿陷性黄土地基
处理湿陷性黄土地基事故时，首先要抓的主要矛盾是湿
陷，而黄土地基的承载力和压缩性是第二位的，这与软土地 基考虑的重点是不同的。 措施：以消除湿陷性为主要矛盾和目的， 主要处理方法有：石灰桩、灰土桩、石灰砂桩、化学加 固法，灰土井墩托换、灌注桩、墩式托换，树根桩托换，掏 土纠偏、加压或浸水纠偏。
单面加固
——基础承受偏心荷载时，或受相邻基础 条件限制
图7-1-4 条基的单面加宽
四边扩大加固 ——单独柱基
图7-1-5 柱基的加宽
2、改变浅基础形式，加大基础底面积 柔性基础——刚性基础
单独基础——条形基础
条形基础——十字交叉条形基础、片筏基础或
箱形基础
扩大基础底面积，加强基础刚度
图7-1-7 条基扩大成片 筏基础 图7-1-6 柔性基础加宽改 为刚性基础
第十五章 既有建（构）筑物 地基基础加固
15.1 概述 15.2 基础加宽托换（例题） 15.3 墩式托换技术 15.4 桩式托换技术 15.5 地基加固技术 15.6 综合加固技术
主要内容
第一节 概 述
一、定义
基础托换又叫托换技术( Underpinning) ，是指解决对原有建筑物 的地基处理和基础加固；或解决对既有建筑物基础下需要修建地 下工程，其中包括隧道要穿越 (Undercossing) 既有建筑物（地 铁），以及邻近需要建造新工程而影响到既有建筑物的安全等问 题的技术总称。
凡进行托换技术的工程总称为托换工程。
一、定义 也叫托换技术，指解决对原有建筑物的地基
基础安全问题的技术总称。
托换技术 underpining
二、加固情形 1）建（构）筑物沉降或沉降差超过有关规定， 出现裂缝、倾斜，影响正常使用；
2）既有建（构）筑物需要增层改造；或使用功 能改变－增加荷载－地基承载力和变形不能满足要 求
预期效果、施工难易程度、材料来源
运输条件、施工安全性、
对邻近建筑和环境的影响、
施工工期和工程造价
四、加固考虑因素 1）将原基础加宽，减小基底压力——
使原有地基满足地基承载力和变形要求；
2）通过地基处理改良地基土体或部分土体——
提高地基土的抗剪强度和改善压缩性，满足地基
承载力和变形要求；
四、加固考虑因素 3）在地基中设置墩基础或桩基础，通过桩土共 同作用来满足地基承载力和变形要求； 4）将上述三方面的加固措施综合应用。
二、加固情形 3）因周围环境改变而需要进行地基基础加固
（既有建构筑物或相邻地基中修建地下工程）；
4）古建构筑物加固工程，地基或基础需要补强
加固。
三、加固步骤
1）根据鉴定检验获得的测试数据——
确定地基承载力和地基变形计算参数等；
2）选择地基基础加固方案
初选加固方案
选定最佳方案
（2）选定最佳方案
考虑因素
十 托换工程实施步骤
1 对既有建筑物各个方面进行加固(如有必要时)； 2 将既有建筑物基础全部或部分支托住； 3 根据工程需要，对既有建筑物地基或基础进行加固； 4 当需要在建筑物下建造地下构筑物时 (如地铁通道、车站等)， 在基础已支托的状态下，在原基础下开挖土方进行该部分工 程施工； 5 当既有建筑物基础下有新建地下工程时，应将荷载传到新建 的地下工程上；
第二节 基础托换各方法简介
一、基础加宽托换
注意事项：
(1) 基础加大后应满足混凝土刚度要求；
(2) 应将原墙凿毛、浇水湿透便于沾接； (3) 加宽部分两边的地基土上进行与原基础同样的地基土压实处理。
(4) 为使新旧基础牢固结合，可适当设置锚杆或圈梁穿筋，化学粘合剂。二、坑式托换(墩式托换)
一些既有建筑物或改建工程中，由于基底面积不足而使
九、托换技术安全及工程监测
（二）工程监测
监测过程中要做好以下四方面工作：
1．确定托换或穿越的每个施工步骤对沉降所产生的影响;
2．对托换或穿越过程所引起的各个监测点的运动情况，整理 出沉降(或其它观测量)与时间的关系曲线，并应用外推法 预测最终沉降量；
3．根据沉降曲线预估被托换建筑物的安全度以及针对现状采
地基承载力或变形不满足要求=>还可以进行坑式托换。施工 步骤： ① 原基础前面开挖导坑(且此原基底深1.5m) ； ② 将导坑横向扩展到直接的基础下面； ③ 现浇混凝土烧筑； ④ 按上述步骤分段实施 直至完工。
(a) 开 挖 导 坑 ， 直接在基础下 挖坑，边挖坑 边建立支撑， (b)继续开挖
坑 式 托 换
图7-1-1 补救性托换
3) 预防性托换(precautionary underpinning)： 由于既有建筑物下部或邻近要修建较深的新建筑物基础， 包括深基坑的开挖和隧道穿越，因而需将既有建筑物的基础加 深、桩基托换或地基土灌浆加固等进行托换措施者，称为预防
性托换。
其中,当采用在平行于既有建筑物基础而修筑比较深的墙
五、纠偏托换
建筑物纠偏是指既有建筑物偏离垂直位置发生倾斜而影响
正常使用时所采取的托换措施。纠偏中采用的思路和手段与其 它托换加固方法类同，故纠偏是托换技术中的一个重要分枝。 造成建筑物倾斜的原因，大致有如下几方面因素： 1．软土地层不均匀。填土层厚薄和松密不一；局部地区遇有
暗浜、暗塘等。
2．设计方案不合理。如地基基础的设计及基础选型不当；建 筑物的平面(包括体型)布置、荷载重心位置及沉降缝的布置欠 妥。
3、膨胀土地基：
由于大的胀缩性(反复胀缩) ⇒⇒外纵墙裂缝；内横墙裂
缝；山墙裂缝；(地基与墙体变形不协调)。
措施：以消除大的胀缩性为主要目的时，可采用隔水
措施，改性措施，换填措施等。
主要处理方法有：各种置换法为主。
八、托换前需做的工作
1、掌握地基变形对建筑的损害程度。以建筑物裂缝宽度作为 判别损坏程度； 2、现场的工程地质及水文地质条件； 3、被托换结构物的结构、构造及受力特征； 4、结构物托换情况及原因分析； 5、托换施工期内可能的影响，(季节、挖土、排水、天气) ； 6、使用期间和周围环境的实际情况：(水位升降、地面排水条 件变迁、环境绿化、邻近建筑物修建、基坑开挖、打桩振 动等影响) 。
(c)建立支撑
三、桩式托换
有静压桩、灌注桩、打入桩、灰土桩、树根桩
1 、静压桩：采用静压方式进行沉桩，有顶承静压桩 ( 压入
桩)，自承静压桩、锚杆静压桩和预试桩。(不适于有障碍物
的地层，上部建筑物结构较差时也不适用) 2、打入桩灌注桩、灰土桩：常用于隔墙或设备不多的建筑 物。 3、树根桩：在钢套管的导向下钻进施工成桩，(有一些列入 到了土加筋范畴)
2．按工艺性质，可分为单浆液和双浆浓；
3．按主剂性质，可分为无机系和有机系。通常可按下图进 行分类：
浆液材料
粒状浆材（悬液） 不稳定粘状浆 材(水泥浆、水 泥砂浆等) 稳定粘状浆 材(粘土浆、 水泥粘土浆) 化学浆材（真溶液） 无机浆材 (硅酸盐)
有机浆材(环氧树脂类;聚 氨指类;丙烯酰胺类;木质 素;甲基丙烯酸酯类等)
取相应的措施，如增加安全支护或改变施工方法；
九、托换技术安全及工程监测
（二）工程监测
4．监测期限和测量频度的要求取决于施工过程，特别是在荷
栽转移阶段每天都要求观测，危险程度越大，则观测应越
额繁。
当直接的托换或穿越过程完成后，监测过程尚需持续到 沉降稳定为止。沉降稳定标准可采用半年沉阵量不超过2mm为 依据。
上切断墙柱体后再加千斤顶项升纠偏；在新建工程设计
中预留千斤顶的位置，以便今后顶升的顶升纠偏。
纠偏方法的分类有如下三种：
三、综合纠偏：用以上两种纠偏方法进行组合，如顶桩掏土 纠偏、浸水加压纠偏。
除了从以上三种方法纠偏入手外，有时必须辅以地基加
固，用以调整沉降尚未稳定的建筑物。
注意：纠偏工作切忌矫枉过正，一定要遵循由浅到深、
七、特殊地基土上常见的建筑物危害及处理原则
1、软土地基： 1) 沉降和差异沉降大建筑物过量沉降和偏斜，砌体开裂
建筑物沉降缝宽度 表7-1-1
2) 沉降速率大建筑物易裂、地基失稳； 3) 沉降稳定时间长建筑长期受稳定困扰；
采取的主要措施：
① 应用沉降缝将其分隔成若独立单元；
② 结构设计上采取适当措施；
五、托换技术的分类
按照目的可分三类类型
1) 补救性托换(remedial underpinning)：
凡解决对既有建筑物的地基土因不满足地基承载力和变形
要求，而需进行地基处理或基础加固者，称为补救性托换。 2) 维持性托换(maintenance underpinning)： 在新建的建筑物基础上预先设置好可顶升的措施（如设 置千斤顶以调整差异沉降），以适应事后不容许出现的地基差 异沉降值而需进行托换者，称为维持性托换。