Group Effects for Pile Rows under Passive Lateral Loading-Paper

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The study examines how pile spacing affects lateral loads on pile rows when soft cohesive soil moves passively against them. Predicting this interaction is difficult because soil response is nonlinear and large ground movements can distort conventional Lagrangian finite-element meshes, producing inaccurate or non-convergent results.<br /><br />The authors use the Convected Particle Domain Interpolation (CPDI) method, a large-deformation variant of the Material Point Method. It represents soil with moving material points and uses a computational grid for calculations, avoiding persistent mesh distortion. A penalty-based contact formulation models interaction between soil and piles. The numerical approach is checked against an analytical strip-footing solution and applied to small-scale tests of piles in kaolin clay using a Mohr–Coulomb soil model.<br /><br />Simulations of two-pile rows show that spacing strongly influences soil displacement fields and group effects. At close spacing, the soil displacement zones around the piles overlap, indicating mutual interaction. As spacing increases, this interaction diminishes; at about 10 pile diameters, the group’s response approaches that of an isolated pile. For transverse two-pile rows, CPDI predictions of normalized force–displacement behavior generally agree well with experimental results, although the results diverge at larger pile displacements.<br /><br />The authors conclude that CPDI can reproduce soil movement and pile-group behavior under large deformation, offering a useful alternative to conventional finite-element methods for assessing passive lateral loading.

Keywords

pile spacing

lateral loads

passive soil movement

soft cohesive soil

CPDI method

Material Point Method

pile group interaction

kaolin clay

Mohr-Coulomb model

large deformation