Modeling Pipe-Soil Interaction under Lateral Movement Using Material Point Method

Excessive lateral movements of buried pipes in geohazard-prone areas frequently jeopardize the structural integrity and serviceability of pipelines, as well as the safety of the surrounding geoenvironments. Based on the material point method (MPM), this paper investigates the pipe-soil interactions under lateral pipe movements, with a focus on the failure mechanisms of the surrounding soil during postfailure stages. The accuracy of the numerical model is validated by comparison with the results of large-scale model tests in the literature. There is a strong correlation between the experimental and numerical results in terms of force-displacement relationships and soil failure patterns. The impacts of burial depths, pipe diameters, and soil densities on the failure mechanism are analyzed in detail. The results showed that general shear failure tends to occur in shallow pipe conditions, resulting in significant ground heave. As the pipe burial depth increases, the peak soil resistance increases accordingly, and a transition from general shear failure to a localized flow-around mechanism gradually evolves. Furthermore, the softening effect after the peak resistance is reduced under the smaller pipe diameter and greater buried depth conditions. Comparisons of failure patterns illustrate that the embedment ratio is the main determinant of pipe-soil interaction modes as compared with the soil density. Transition failure often occurs when the embedment ratio ranges from 4.5 to 9.5, with slight influences from pipe diameters and soil properties. Finally, the prediction of the soil peak lateral resistance is explored to assist in underground pipeline design.