Model Test of Surface Collapse Induced by Seepage under Topographic Bias

In view of the lack of research on the development and impact mechanism of surface collapse induced by seepage under terrain bias, in this paper, a self-designed model was used to carry out a control test with slope angle as the master variable and several variables including fill height, relative density and water content. Through the analysis of the test results, the law of subsidence development process and the influence mechanism of the surface subsidence under the action of different factors are obtained. The test results show that the collapse process of well-graded sand can be divided into slow erosion stage, accelerated erosion stage and collapse stage; the center position of the settlement tank moves to the deeply buried side with the increase of the slope angle, and the expansion rate of cavity area increases with the increase of the angle. The water content affects the suction of the matrix and the shear strength of the soil, so that the expansion rate of cavity area is inversely proportional to the water content, the offset angle of the center position of settlement tank increases with the increase of water content, and the shape of the collapse pit is significantly different with the change of water content. With the increase of relative density, the collapse range has a decreasing trend.