Effect of Particle Shape on Soil Arching in the Pile-Supported Embankment by 3D Discrete-Element Method Simulation

The particle shape plays an important role in controlling the behavior of granular material, thus needing to be considered in the formation and evolution of soil arching in the pile-supported embankment. Based on the three-dimensional discrete-element method simulation, the effect of the soil particle shape on the formation and evolution of soil arching in the pile-supported embankment is unraveled from the construction to the operation period by adopting spherical, oval, and tetrahedron particles. An additional simulation of spherical particles with the rolling resistance contact model is conducted to reveal the applicability of the indirect method to reproduce the behavior of the case with irregular particles. After sample preparation, four simulation procedures are applied for each case: differential settlement, static loading, cyclic loading, and final equilibrium. The results indicate that due to interlocking, smaller surface settlement occurs for the case with irregular particles at a given simulation state. Furthermore, the case with irregular particles tends to induce a more significant soil arching than the case with spherical particles, also showing a higher resistance to the degradation of soil arching under external load. Owing to various homogeneity and angularity, the two cases with irregular particles present different mechanical patterns under the external load. The reorientation and destruction of the contact force network are the microscale reasons for the formation and degradation of soil arching. As the rolling resistance method cannot fully reproduce the behavior of irregular particles for the soil arching, this method should be carefully validated and used in further simulation of the pile-supported embankment.