Numerical Simulation of Ground Collapse Caused by Pipeline Leakage in Shanghai

The main cause of the ground collapse in Shanghai city road is the leakage of underground drainage pipeline in the shallow sand layer distribution area,which leads to quicksand and the loss of underground soil,resulting in the decrease of surface hard shell bearing capacity.Numerical simulation of underground cavities induced by leakage of underground pipelines in consideration of different leakage positions,forms and the influence on adjacent pipeline and surrounding soil by coupling between finite element and discrete element.The results show that the local leakage at the top of the pipe surface causes the maximum soil loss,but the influence range caused by the bottom leakage is small.The ground subsidence caused by the pipe fracture leakage is much larger than that of the local leakage of the pipeline,but the depth is smaller than the local leakage at the top of the pipe.The larger the buried depth of the pipelineis,the larger the loss of soil will cause the greater the influence area of the collapse,and the smaller the buried depth,the greater its impact on the adjacent leaking pipeline.Meanwhile,when monitoring and preventing the ground subsidence,we should not only pay attention to the surface settlement and deformation,but also pay attention to the deformation of the surrounding soil around the pipeline,which is a more timely and effective method.