Analysis of run-up of granular avalanches against steep, adverse slopes and protective barriers

Abstract

The purpose of this study was to determine whether run-up of rapid landslides or avalanches against protective dykes or walls placed perpendicular to the path can be predicted using a dynamic model based on shallow-flow assumptions. A series of laboratory experiments were carried out involving rapid flow of dry sand in a flume, arrested by a steep adverse slope. The barrier slope was varied and included a perpendicular wall. A curved transition of varying radius separated the path from the barrier. The dynamic internal and basal friction angles of the sand were determined by independent testing. The results were analysed using a Savage–Hutter type model. A shock wave was observed as the flow approached the barrier toe and the model had to be improved by an original velocity-smoothing algorithm to prevent numerical instability. The new model is capable of simulating the entire process of run-up of the leading edge against the barrier face, deposition of the sand behind the barrier, and backward migration of the shock wave. Comparisons between experiment and analysis results are presented. The model tends to overpredict the vertical run-up in cases where the barrier slope is steep. The results of traditional run-up formulas are also compared.