盾构隧道施工期上浮对结构受力、接缝防水影响的分析.pdf

1、摘 要 摘 要 盾构施工法已成为我国城市地下和水下隧道建设的主要方法，壁后注浆作为盾构隧道施工中必备和关键工序，其质量的好坏不仅影响地层变形，在施工期还可能引起隧道的上浮，对结构受力、接头防水产生较大影响。施工中管片环脱出盾尾后上浮问题较为突出、管片损坏并形成贯通裂缝时有发生。隧道上浮主要发生在盾尾浆液还处于液态或流塑状态，当浆液逐渐胶结转化为固态时，隧道上浮将会停止甚至回落。分析上浮对隧道结构的影响，显然属于纵向设计问题。然而，目前的盾构隧道设计主要是针对横向断面进行的，盾构隧道纵向问题还没有引起足够的重视。本文以此为背景，针对壁后注浆产生的上浮力进行了模型试验研究，确定隧道在壁后注浆液中浮

2、力及其变化规律，并在此基础上建立了纵向分析模型，研究上浮对结构受力及接头防水的影响。主要工作和研究成果如下：（1）本文结合实际工程中常用的浆液配比关系，按正交试验方法设计了 16种具有不同工程特性的浆液，利用研制的盾构隧道模型来测定由壁后注浆对结构产生的上浮力。试验表明：处于浆液包裹中的隧道初期上浮力近似为浆液密度、重力加速度和隧道的体积的乘积；上浮力随着龄期的增长而逐渐降低，表现为前期降低快，后期降低慢，最终对隧道的上浮力为水的上浮力；上浮力的大小随着浆液密度的增大而增大，随着流动度的增大而减小。浆液类型对初期上浮力的大小及上浮力的降低速度都有影响，其中，水胶比是影响上浮力的关键因素。基于以

3、上认识，可以认为，施工期盾构隧道的上浮主要是由于壁后注浆对隧道上浮力引起的。（2）在上述试验确定了上浮力的基础上，基于等效连续化模型和弹性地基梁理论，建立了盾构隧道脱出盾尾后的纵向分析模型，通过 Ansys 软件求解，研究壁后注浆产生的上浮对结构受力、接缝防水的影响规律。结果表明：在本文确定的基本参数条件下，得到结构的最大上浮量为 65.7mm，出现在盾尾后第 10 环附近，接缝最大张开量为 3.61mm；管片环宽度、地基系数、掘进速度对结构受力、接缝防水的影响均较大，纵向连接螺栓的数量对裂缝的最大张开量影响较明显；增大管片环宽度或增加纵向连接螺栓数量，均能较大幅度地提高管片环的纵向等效抗弯刚

4、度，降低隧道施工期的上浮量。关键词关键词：盾构隧道；壁后注浆；隧道上浮；纵向刚度；接缝防水 Abstract Abstract The shield method has been very popular in building the city underground and submarine tunnel in China.As an essential process and a key factor,the quality of the back-filled grouting engineering directly affects not only the deformatio

5、n of the stratum around the tunnel but also the mechanics and waterproof ability of the structure.In practical projects,the issue of upward movement is relatively outstanding,and transfixion crack may happen occasionally after the lining rings go out from the shield machine.The upward movement of tu

6、nnel mostly occurs when the grout around the tunnel is of liquid to liquid-plastic state,and it will stop with the grout gradually hardening.It obviously belongs to the longitudinal issue to analysis the effects of upward movement.But the present designs of shield tunnel concentrate upon the horizon

7、tal analysis,and it hasnt received enough attention to study the longitudinal property.As the background,this dissertation designed a model test to determine the value and the reducing rules of the buoyancy caused by the grouting engineering.And the effects of the upward movement were studied by num

8、erical simulation method through the longitudinal analysis model built in this dissertation.The detailed contents and conclusions can be summarized as follows:(1)Combining with the practical projects,16 kinds of grouts with different grout engineering properties were designed and studied in the mode

9、l test which can simulate the working environment of the linings after they go out from the shield machine.The experimental analysis results show that the value of the buoyancy at the grouts early age approximately equals the product of the grouts density,the gravity acceleration and the volume of t

10、he tunnel.It reduces with the grouts age.The reducing speed is relatively high at the early age,and it will slow down with time.At last,the value is similar with the buoyancy caused by water.The buoyancy increases with the increase of the density while it decreases with the increase of the fluidity.

11、The value and its reducing speed vary in different grouts,and the water to binder ratio is a key factor.As a conclusion,the upward movement of shield tunnel is mainly caused by the back-filled grouting engineering.(2)Based on the conclusion obtained by the experiment,a longitudinal analysis model wh

12、ich can be used to simulate the shield tunnel after the linings go out from the shield machine wrapped by the grouts was designed according to the present 河海大学本科毕业论文 longitudinal equivalent continuous model theory and the elastic foundation theory.With the help of Ansys software,a research is conduc

13、ted on the effect of upward movement on the mechanics of the linings and the waterproofing of the joints.The analysis results show that under the basic parameters conditions,the largest deformation is 65.7mm located near the tenth lining ring and the max splaying amount of joints is 3.61mm.The width

14、 of lining rings,the foundations elastic coefficient and the driving speed have much influence on the mechanics and waterproofing.The number of longitudinal bolts directly affects the splaying amount of joints.The linings longitudinal equivalent rigidity will improve if the width of lining ring or t

15、he number of bolts rises,which is very useful to control the structures deformation.Keyword:shield tunnel;longitudinal rigidity;back-filled grouting;upward movement;waterproof of joints.目 录 目 录 第一章 绪论.1 1.1 盾构隧道简介.1 1.2 问题的提出.2 1.3 盾构隧道上浮研究现状.3 1.3.1 盾构隧道上浮机理研究.3 1.3.2 盾构隧道壁后注浆研究.6 1.3.3 盾构隧道纵向计算模型.

16、9 1.3.4 盾构隧道纵向等效参数的确定.12 1.4 研究内容和技术路线.14 1.4.1 研究内容.14 1.4.2 技术路线.15 第二章 壁后注浆引起盾构隧道上浮的试验研究.16 2.1 试验材料及设备.16 2.1.1 试验材料.16 2.1.2 试验设备.18 2.2 试验原理.20 2.3 试验的基本方案.21 2.3.1 浆液制备方案.21 2.3.2 基本性质测定方案.21 2.3.3 上浮力测定方案.23 2.4 试验成果分析.24 2.4.1 浮力重度随时间的变化.24 2.4.2 浮力重度和基本性质之间的关系.25 2.4.3 浮力重度受浆液配比的影响情况.26 2.5 本章小结.29 第三章 壁后注浆引起盾构隧道上浮对结构影响的计算分析.30 3.1 壁后注浆引起盾构隧道上浮机理.30 3.1.1 壁后注浆浆液硬化滞后.30 3.1.2 衬砌自重和盾尾约束不足以抵抗上浮力.30 3.1.3 浆液分布形式对上浮的影响.31 河海大学本科毕业论文 3.2 盾构隧道纵向设计模型的建立.32 3.2.1 弹性地基梁理论.32 3.2.2 纵向设计模型的建立.33 3