杨军平 赵卫洁 赵文兰

摘 要：为了探究膨胀围岩隧道在不同含水率条件下隧道开挖过程中膨胀围岩的受力情况。文章以广西某高速公路膨胀围岩隧道项目为依托工程，结合本课题组相似模型试验，利用大型有限元软件ANSYS的温度应力场模块和结构分析模块的耦合作用来模拟含水率变化的条件下，膨胀岩隧道开挖的力学性态。数值分析结果显示：不同含水率条件下，随着含水率的增大，围岩位移，围岩应力增大，随着含水率越接近饱和含水率，围岩位移、应力增大的梯度越大；由围岩位移、应力云图可知拱顶、两侧拱腰拱底两侧的位移和应力变化最大，出现应力集中，为设计施工中薄弱点，要重点监测。

关键词：膨胀围岩；耦合作用；含水率变化；围岩位移；围岩应力

中图分类号：U451 文献标志码：A 文章编号：2095-2945（2018）10-0001-05

Abstract： In order to investigate the stress of expansive surrounding rock in the process of tunnel excavation under different moisture contents， the stress of the expansive surrounding rock tunnel is studied. Based on the project of expansive surrounding rock tunnel of a highway in Guangxi， this paper combines the similar model test of our group in research. The mechanical behavior of expansive rock tunnel excavation is simulated by the coupling of the thermal stress field module and the structure analysis module of the large-scale finite element software ANSYS. The numerical results show that with the increase of moisture content， the displacement of surrounding rock and the stress of surrounding rock increase with the increase of moisture content， and the gradient of displacement and stress of surrounding rock increases with the moisture content approaching saturated water content. According to the displacement and stress cloud map of surrounding rock， the displacement and stress change of arch roof and arch bottom of both sides of arch waist are the biggest， and the stress concentration appears， which are the weak points in design and construction and it is necessary to focus on monitoring.

Keywords： swelling surrounding rock； coupling action； moisture content variation； surrounding rock displacement； surrounding rock stress

引言

膨脹性岩土是一类在水的作用下发生物理化学变化，产生体积膨胀和物性软化的一类特殊地质体。这类围岩强度低，岩土中黏土矿物含量很高，围岩与水作用强烈，吸水能力强，且具有很大塑性，围岩分级属于软岩类。在我国膨胀岩土的矿物成分主要是蒙脱石，伊利石居其次。由于膨胀性岩土特殊的力学机制，在工程建设中常常带来严重的灾害，例如：地基塌陷、地下硐室开裂、隧道坍塌等。因此，研究在不同含水率条件下膨胀围岩隧道施工性态具有重大的现实意义。

近年来，研究膨胀性围岩在遇水条件下的力学形态取得了一定的成果，但是这些成果都建立在施工实时监测数据分析和室内特定的相似模型实验基础上。……