关键词: 膨胀土, 隧道, 热力耦合, 降雨增湿, 膨胀力

Abstract: 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.

Key words: expansive soil, tunnel, thermal-mechanical coupling, rainfall infiltration, swelling force