On the Response of Polyethylene Pipes to Lateral Ground Movements: Insights from Finite-Discrete Element Analysis

Abstract

The current knowledge of the behaviour of polyethylene pipes subjected to lateral soil movement is limited and the commonly used design equations were initially developed for steel pipes. In this study, an attempt has been made to understand the soil–structure interaction using a three-dimensional finite-discrete (FE-DE) element model of a medium density polyethylene (MDPE) pipe buried in dense sand and subjected to lateral soil movement. The soil particles are modelled using discrete elements, while the pipe is modelled using finite elements and interface elements are introduced to transfer the forces between the two domains. Validation is performed using experimental data. This study shows that, when a pipe section experiences lateral movement induced by two symmetrically applied loads, the pipe will resist the imposed lateral forces by bending. Particle displacement patterns show that passive wedges develop locally close to the applied loads and the remaining pipe sections experience negligible deformation. Furthermore, it is found that the current expressions used to estimate the ultimate lateral soil force on buried pipes in granular soil, which is generally developed for rigid steel pipes, should be used with caution as they may overestimate the soil load on flexible MDPE pipes.