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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。
Under the conditions of rainfall infiltration, the unsaturated seepage and expansive effect of the expansive soil will reduce the stability of the tunnel. It is necessary to study the influence of the two on the deformation and the structural stress of the surrounding rock. Based on finite difference software FLAC ~ (3D), the seepage and temperature field modules are respectively used to simulate the unsaturated seepage process and the humidification expansion process of expansive soil under rainfall. Through the preparation of the relevant FISH language program, the influence of matrix suction change, soil softening and expansion effect on the unsaturated seepage of expansive soil tunnels was considered. Taking a shallow expansive soil tunnel as an engineering background, the effects of infiltration time, infiltration and expansion coefficient on the deformation of surrounding rock and the supporting force of expansive soil tunnel are analyzed. The results show that during the process of rainfall infiltration, the horizontal stress of surrounding rock increases obviously while the vertical stress changes little, and the supporting structure gradually changes from vertical extrusion deformation to horizontal extrusion deformation. The soil infiltration and expansion The coefficient has a great influence on the bearing force of the supporting structure. When the infiltration and expansion coefficients increase to a certain value, the lining moment increases obviously and the safety and stability of the tunnel are greatly reduced.