中文摘要：

针对小河沟膨胀土隧道降雨增湿塌方现象，以围岩含水率分布变化引起膨胀应力场为主要研究内容，展开增湿对隧道支护结构的影响研究。首先，利用热传导热能量平衡方程与孔隙渗流连续方程数学描述相似性，推导出热传导膨胀模拟增湿膨胀的替代方程。然后，结合室内试验和文献资料，率定膨胀土膨胀力及渗流参数。最后，在正确考虑地质构造影响的基础上运用有限差分软件 FLAC3D热-力耦合模块进行建模计算，分别对不同膨胀力模型的增湿过程进行仿真模拟，得出支护结构受力变形随含水率分布及膨胀力大小的变化规律。分析得到了对隧道支护结构造成不良影响的关键含水率和膨胀力值。研究成果可以有效指导膨胀性黄土隧道支护设计和变形控制。

英文摘要：

In light of the collapse of an expansive soil tunnel owing to rainfall infiltration, swelling stress field caused by the change in the moisture content distribution of surrounding soil was taken into consideration to solve the problem. At first, due to the similarity of continuum heat conduction energy-balance equation and seepage continuity equation, an alternative expansive equation is derived based on the theory of heat conduction expansive to simulate water-increased expansion of expansive soil, and then determine the swelling force and seepage parameters by laboratory test and engineering simulation. Finally, considering the proper geologic factors, a numerical model of tunnel is established by means of thermal-mechanical coupling of FLAC3D. And by the simulations of tunnel with different swelling forces under water-increased state, relation curves are acquired between liner deformation and moisture content, swelling force. According to the above analysis, turning points of moisture content and swelling force to prevent liner from failure are proposed, which can effectively guide the design and deformation controlling of tunnel liner in expansive soil.