Parametric study of earth dam failure simulation using material point method

Aging and heavy rainfall can cause earth dams to undergo failure, which involves large displacements. Due to mesh distortion, however, the finite element method (FEM) is unsuitable for analyzing such large displacements. As an alternative, the material point method (MPM) ensures accurate simulation of large displacements, without the need for remeshing. This study uses MPM to investigate the post-failure behaviors of earth dams with various geometries and under different rainfall intensities. The MPM results are validated by comparing the MPM-derived pore water pressure with FEM-derived values for the same model, and a close alignment is confirmed. Different failure patterns are observed depending on the geometry and rainfall intensity. Under high water levels and rainfall conditions, the distributions and evolutions of the displacements and deviatoric strain are initially concentrated at the dam toe and gradually propagated from the downstream slope toe to the dam crest. Conversely, the distribution of pore water pressure remains relatively constant under high water levels, while rapid changes are observed under rainfall conditions. The runout distance, crest settlement, and sliding volume increase with increasing dam height, decreasing slope ratio, and increasing rainfall intensity. Therefore, MPM can be used as a promising tool for evaluating the entire failure mechanisms and post-failure behaviors of unsaturated earth dams.