考虑非饱和渗流与增湿膨胀下的膨胀土隧道稳定性分析  

Stability analysis of expansive soil tunnel considering unsaturated seepage and moistening swelling deformation

作　　者：郑俊杰[1] 郭震山 崔岚[1] 张军[2] 

机构地区：[1]华中科技大学岩土与地下工程研究所,湖北武汉430074 [2]山西省交通科学研究院黄土地区公路建设与养护技术交通行业重点实验室,山西太原030006

出　　处：《岩土力学》2017年第11期3271-3277,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51278216)~~

摘　　要：降雨入渗条件下,膨胀土的非饱和渗流与膨胀效应会降低隧道稳定性,研究两者对围岩变形与结构受力的影响非常必要。基于有限差分软件FLAC^(3D),根据其内置的渗流与温度场模块分别模拟降雨条件下的非饱和渗流过程与膨胀土增湿膨胀过程。通过编制相关FISH语言程序,考虑了膨胀土隧道非饱和渗流过程中基质吸力变化、土体软化和膨胀效应的影响。以某浅埋膨胀土隧道为工程背景,分析了降雨入渗时间、渗透与膨胀系数对膨胀土隧道围岩变形及支护结构受力的影响。结果表明:膨胀土隧道在降雨入渗过程中,围岩水平应力增大明显,而垂直应力变化不大;支护结构逐渐由竖向挤压变形转变为水平挤压变形;土体渗透和膨胀系数对支护结构受力影响很大,当渗透和膨胀系数增加到一定值后,衬砌弯矩显著增大,隧道安全性和稳定性大幅降低。The stability of tunnel is gradually undermined by the effects of unsaturated seepage and soil expansion under the condition of continuous rainfall infiltration. Hence, it is important to investigate their effects on the deformation of surrounding rock mass and stress in the supporting system. This study simulated the processes of unsaturated seepage and soil expansion with the rainfall infiltration by using the seepage module and thermal module in the finite difference software FLAC^3 D, respectively. FISH language was also adopted to investigate the impacts of changes in matrix suction, soil softening and soil expansion during the unsaturated seepage process. A shallow expansive soil tunnel was simulated as a case study. Then the effects of rainfall duration, permeability coefficient and expansion coefficient on the deformation of surrounding rock mass and stress in the supporting system were analyzed. The results showed that during the rainfall infiltration process, the horizontal stress of surrounding rock mass increased remarkably, whereas the vertical stress changed within a small range. Moreover, the supporting system transformed from initial vertical extrusion deformation to horizontal extrusion deformation. It was found that the permeability coefficient and expansion coefficient exerted great actions on the stress in the supporting system. When the permeability coefficient and expansion coefficient reached a particular value, the bending moment of the supporting system substantially increased, which greatly reduced the tunnel stability and safety.

关 键 词：降雨入渗 非饱和渗流 膨胀土 隧道 数值模拟 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]