Earth Pressure Buildup in Impacting Earth Flow behind a Barrier

Abstract

Barriers are commonly used to intercept landslide flows or debris flows. The presence of a barrier changes the flow condition and leads to a buildup of earth pressure in a zone behind the barrier. Investigating this buildup process is essential to understand the landslide–barrier interaction and the stress evolution inside the earth flow. This study used an explicit integration program to simulate earth pressure buildup in the impacting earth flow in a series of two-dimensional (2D) and three-dimensional (3D) impact cases. In the idealized 2D flow cases, the stress state of earth flow reached the active limit state after the flow started and maintained the stress state until impact. During impact, horizontal earth pressure buildup occurred and propagated backward to the continuing flow; a dead zone thus formed. When the material ceased flow, a static earth pressure distribution was achieved. Starting from the distance at which the static lateral earth pressure coefficient was close to that in the greenfield case, the coefficient increased toward the barrier due to the earth pressure buildup, approaching the passive mode in the dead zone immediately behind the barrier. The static earth pressure on the back of the barrier was not uniform, with a passive mode in the dead zone and an active mode in the run-up zone in which the earth pressure was more easily released after impact. In the 3D flow cases, the opening spaces at both sides of the barrier affected flow conditions and weakened the buildup process.