Particle breakage limits packing density effect on pile resistance in crushable soils

Abstract

This study conducted numerical simulations of pile-bearing capacity using a finite element framework that incorporates a model for crushable soils, considering the effects of packing density. Simulations were performed for both crushable and non-crushable soils to assess how packing density affects stress–strain behavior and particle breakage during pile penetration. Results indicated that in non-crushable soils, pile resistance was significantly increased in denser soils. However, when particle breakage was included, the bearing resistance showed minimal difference between dense and loose soils. This phenomenon, consistent with experimental findings of cone penetration in pumice sand, a crushable soil. The simulations captured variation in stress–strain behavior and particle breakage around the pile tip, which are challenging to observe experimentally. In non-crushable soils, especially in dense conditions, increased dilatancy during shearing raised mobilized stresses, leading to higher shear resistance and bearing capacity. In contrast, in crushable soils, early particle breakage reduced dilatancy and mobilized stresses, minimizing the difference in bearing resistance between dense and loose soils. Additionally, particle breakage extended about 2D (D is pile diameter) below the pile tip, regardless of soil density. These findings suggest that conventional methods for calculating pile-bearing capacity can be extended to predict behavior in crushable soils by considering reduced mobilized stresses and shear resistance due to particle breakage. The study enhances the understanding of pile behavior in crushable soils and highlights the impact of soil density on pile resistance.