Modeling pipe-soil interaction under surface loading using material point method

Considering the increasing demand for urban land resources, the construction of new structures in areas with buried pipelines poses novel challenges to both pipeline structural integrity and foundation design. Based on numerical modeling using the material point method (MPM), this paper investigates the pipe–soil interactions when the pipeline system is subjected to surface loading caused by construction activities, focusing on the failure mechanisms and earth pressure distribution around a buried pipe. The accuracy of the numerical model is verified through comparison with results from laboratory model tests as reported in the literature. The influence of both the embedment ratio and the horizontal distance ratio on the failure mechanisms is analyzed in detail. The results show that as the embedment ratio and horizontal distance ratio increase, the bearing capacity of pipe-soil systems increases significantly. The effect of buried pipes on the bearing capacity becomes negligible when the horizontal distance ratio exceeds 3 or when the embedment ratio reaches 4. The failure modes of pipe-soil systems change from Prandtl-type foundation failures to asymmetric failures as the horizontal distance increases. Both external loads and the burial position of pipes affect the earth pressure distribution around the pipe. The pipe-soil interface can provide a potential sliding surface for foundation failure, which may exhibit a suction effect on the shear band. Finally, an understanding of the failure modes of pipe-soil systems is proposed for use in the design of underground pipelines and foundation systems.