Experimental and numerical investigation on the mechanism of ground collapse induced by underground drainage pipe leakage

Ground collapse is a common urban geological disaster mainly triggered by the leakage of underground drainage pipe. To reproduce the process of underground cavity formation and development and investigate the formation mechanism of ground collapse, physical model tests and CFD–DEM-coupled numerical simulations are conducted in this study. Based on the monitored data of the vertical displacement of the ground surface and the soil pressure variation near the leakage point, the process of ground collapse can be divided into three stages: initial stabilization stage, slow subsidence stage, and the collapse stage. It is observed that the plane shapes of the collapse pits are almost semicircle, and their sizes are closely related to groundwater level, defect size and buried depth of pipe. This study reproduces the process of ground collapse experimentally and numerically, and basically reveals the mechanism of ground collapse induced by underground drainage pipe leakage.