MPM Coseismic Slope Runout Prediction Using the Intergranular Strain Anisotropy Hypoplastic Model

The material point method (MPM) is an advanced particle-based numerical tool capable of modeling large deformations. However, its abilities to predict seismic site response, ground failure initiation, and post-failure consequences, including undrained conditions, have not been fully realized. This research aims to use recent MPM developments to simulate earthquake-triggered slope failures. As a novelty, an advanced constitutive model such as the intergranular strain anisotropy hypoplastic model is implemented in an effective-stress undrained MPM framework to simulate the hydromechanical response of dense and loose sand. First, an MPM simulation of a level-ground sand column is used to understand the system-level undrained response under simple sinusoidal excitation. Loose sand tends to liquefy under an increase in pore pressure, while dense sand exhibits a decrease in pore pressure. Second, a small-scale slope geometry is adopted whereby the runout investigation is conducted using void ratios ranging from 0.45 to 0.95. The framework shows promising system-level results, needing further validation using centrifuge experiments.