降雨入渗对浅埋黄土隧道稳定性的影响

为了研究降雨入渗作用下黄土力学性质劣化对浅埋黄土隧道稳定性的影响，对隧道围岩中的黄土进行了不同含水率和不同围压的剪切、等压三轴试验，结果表明，含水率对黄土力学性质和破坏形态有较大影响。根据试验结果建立了黄土不同含水率的塑性本构关系，对比了计算结果和试验结果，证明了该本构关系能较好地描述黄土的应力-应变规律。对不同降雨强度、不同深度的黄土在雨水入渗影响下的含水率分布规律进行分析，并在数值模拟软件中调用建立的不同含水率的黄土塑性本构关系，计算不同降雨强度下隧道结构的受力和变形，结果表明：考虑降雨入渗后隧道结构变形和受力增加明显，其中，拱顶沉降增幅达到46%，隧道初期支护应力增加20%~27%。将浅埋黄土隧道结构变形监测数据与数值模拟结果对比，验证了黄土本构关系的正确性，所模拟的降雨入渗对隧道结构稳定性的影响符合实际工程。

Stability analysis of shallow loess tunnel considering rainfall infiltration

In order to investigate the influence of strength reduction of loess induced by rainfall infiltration on the stability of tunnel, direct shear- and triaxial- tests were carried out on loess.The results show that the water content has significant influence on the mechanical behaviors of loess.The elastic-plastic incremental constitutive relation of undisturbed soil was established.By compared with experimental data, the constitutive model was proved to be capable of describing the stress-strain relationship of loess.The distribution characteristic of water content in different depth land under different rain intensity were analyzed.Besides, the constitutive model for loess with different water contents were established so as to calculate the stress and deformation of structure in tunnel under different rain intensities.The results show that when considering rainfall infiltration, the deformation of tunnel and the stress of preliminary support structure are significantly increased.In this situation, the settlement of the tunnel vault increases 46% and the stress of preliminary support structure increases 20%~27%.It is found the elastic-plastic incremental constitutive relation is reasonable and results of the numerical simulation is reliable with comparing the calculated and measured data of tunnel deformation.