层状饱和软土中盾构隧道渗漏水诱发邻近管线非线性变形的时效机理研究

Previous researches for the interaction mechanism between adjacent pipelines and disturbed soils induced by tunneling in soft strata are usually assumed that the boundary condition for tunnel liners is totally sealing and impermeable status. Then the deforamtion influences for adjacent pipelines are not conducted in the theoretical predictions considering the relative permeability between tunnel liners and surrounding soils, and the partial seepage uniformity for liners. Furthermore, the undrained foundation model is usually adopted to simulate the interaction mechanism. Little attention is given to the the long-term influence behavior of soft soil consolidation on the boundary of tunnel liner leakage. Few investigations are conducted on the time-dependent evolution rules for the interface behavior of adjacent pipeline. Based on the layered saturated strata model, the time-domain solution for the pipeline deformation induced by the permeable tunneling is proposed firstly by introducing the partial sealing boundary condition. After obtaining the solution of liner elastic interface interaction, Combing the centrifuge model tests, the advanced mechanisms such as the three-dimensional constraint influences of lateral soils beside the pipelines, and the nonlinear whole-circle interface behavior for slipping and gapping, have been introduced into this analysis. The influences of tunnel liner leakage on the nonlinear time-dependent interface mechanism are investigated in detail. Finally, the displacement controlled standards, which are proper to evaluate the time-dependent deforamtion of pipelines induced by tunnel liner leakage in soft soils, are proposed in the analyses based on the time-dependent rules for the whole-circle interface behavior of pipeline considering the influences of tunnel partial sealing boundary. The research achievements can effectively overcome the time-domain analyses limitations for the interaction between structures and tunnels in soft soils. It may provide certain theoretical basis to control the underground environmental hazards influenced by the tunnel liner permeability.

目前针对软土隧道与邻近管线相互作用的理论研究，隧道边界一般假定为全封闭不透水，较少考虑衬砌与土体的相对渗透性以及局部不均匀渗漏水给管线时效变形带来的影响；同时，一般基于不排水地基模型来模拟相互影响机制，忽略了隧道渗漏水边界下软土固结的长期影响形态，无从考虑邻近管线界面接触性状的全过程演化规律。本项目引入隧道半封闭边界条件，基于层状饱和地基模型，提出盾构隧道渗漏水扰动诱发既有管线变形的时域解。在线弹性界面接触解答基础上，结合离心物理模型试验，进一步考虑管侧扰动土体的三维约束效应以及管土界面全周接触的滑脱性状，重点研究隧道渗漏水给非线性时效接触机制带来的影响。最终基于隧道半封闭边界下管线全周界面接触性状的时程规律，建立适用于评价隧道渗漏水诱发管线时效变形的位移控制标准。本研究成果将有效避免目前软土隧道与结构物相互作用的时域分析方法缺陷，为控制因隧道衬砌渗漏水诱发的地下工程灾害提供理论依据。

目前针对软土隧道与邻近管线相互作用的理论研究，隧道边界一般假定为全封闭不透水，较少考虑衬砌与土体的相对渗透性以及局部不均匀渗漏水给管线时效变形带来的影响；同时，一般基于不排水地基模型来模拟相互影响机制，忽略了隧道渗漏水边界下软土固结的长期影响形态，无从考虑邻近管线界面接触性状的全过程演化规律。本项目引入隧道半封闭边界条件，基于层状饱和地基模型，提出盾构隧道渗漏水扰动诱发既有管线变形的时域解。在线弹性界面接触解答基础上，结合物理模型试验，重点研究隧道渗漏水给非线性时效接触机制带来的影响。最终基于隧道半封闭边界下管线全周界面接触性状的时程规律，建立适用于评价隧道渗漏水诱发管线时效变形的位移控制标准。本研究成果将有效避免目前软土隧道与结构物相互作用的时域分析方法缺陷，为控制因隧道衬砌渗漏水诱发的地下工程灾害提供理论依据。.本项目主要理论研究成果包括以下几方面：.（1）基于Terzaghi-Rendulic固结理论，采用保角映射和分离变量法，提出了隧道衬砌半封闭渗透漏水边界条件下，盾构施工扰动引起的隧道周围土体超孔隙水压力消散解和地表土体固结沉降时域解。.（2）基于类矩形盾构隧道开挖面收敛位移变形模式，首先采用镜像法提出了类矩形盾构隧道施工诱发周围土体自由场位移的分析方法；其次，基于Winkler地基模型，考虑管侧扰动土体的三维约束效应，提出了类矩形盾构隧道施工诱发邻近管线非线性变形的简化计算方法。.（3）基于体现土体剪切特性的Pasternak地基模型，首先计算了既有隧道渗漏水影响下盾构开挖在既有隧道轴线处产生的附加荷载；在此基础上，通过能量变分法建立由抗拉弹簧及剪切弹簧共同连接相邻管片环的既有隧道变形模型，提出了考虑渗漏水影响的盾构下穿既有隧道结构错台变形计算方法。.（4）基于临界漏缝宽度，针对不同漏缝位置、不同覆土深度、不同上覆水位高度，进行隧道渗漏影响下砂层沉降及管线变形时效规律影响因素的模型试验分析，并设计一套渗流示踪装置探究渗流场的分布情况及其流线轨迹变化规律。