Finite element modeling of lateral pipeline-soil interactions in dense sand

Finite element (FE) analyses of pipeline-soil interaction for pipelines buried in dense sand subjected to lateral ground displacements are presented in this paper. Analysis is performed - using the Arbitrary Lagrangian-Eulerian (ALE) method available in Abaqus/Explicit FE software - in the plane strain condition using the Mohr-Coulomb (MC) and modified Mohr-Coulomb (MMC) models. The MMC model considers a number of important features and properties of stress-strain and volume change behaviour of dense sand including the nonlinear pre- and post-peak behaviour with a smooth transition and the variation of the angle of internal friction and dilation angle with plastic shear strain, loading conditions (triaxial or plane strain), density, and mean effective stress. Comparing FE and experimental results, it is shown that the MMC model can better simulate the force-displacement response for a wide range of lateral displacements of the pipe for different burial depths, although the peak force on the pipe could be matched using the MC model. Examining the progressive development of zones of large inelastic shear deformation (shear bands), it is shown that the mobilized angle of internal friction and dilation angle vary along the length of the shear band; however, constant values are used in the MC model. A comprehensive parametric study is also performed to investigate the effects of pipeline diameter, burial depth, and soil properties. Many important aspects in the force-displacement curves and failure mechanisms are explained using the present FE analyses.