Influence of topography on the fragmentation and mobility of landslides

Abstract

This study uses discrete element method models to simulate the fragmentation and deposition of landslides with varying volumes on terrains with different slopes and heights. The slope motion process during the numerical simulations of the landslide movement can be divided into three stages based on changes in the kinetic energy. The variations in the kinetic and frictional energies throughout the mass motion are used to establish pertinent parameters to analyze the dynamics of the slider fragmentation characteristics. Building on prior research, the impact of the slope on the mobility and deposit morphology, including the apparent and equivalent friction coefficients and the ratio of the width to length as a deposit morphology model, is examined using motion models. Concurrently, the three experimental variables (the slope gradient, slope height, and sliding block volume) are analyzed and discussed in conjunction with the motion and deposit morphology models. Previous studies indicate that the quantification of landslide fragmentation is only applicable to rock landslides and has limitations. In the numerical simulations, distinct contact models for pre- and post-fragment particles are defined to enumerate the total number of intact particles. Subsequently, a dimensionless parameter is formulated to quantify the degree of slope fragmentation. The relationship of this parameter with the motion and deposition models is subsequently explored. The results show that increased fragmentation reduces the landslide mobility, indicating that fragmentation is an energy-consumptive process that hinders landslide motion. These findings provide insights into the mechanisms of long-runout landslides and contribute to the reproduction of landslide dynamics.