Study on estimation method of debris flow load using a channel flume with a movable bed and pre-deposited gravel

Abstract

 Bouldery debris flows exert large impact forces, causing sighnificant damage to open Sabo dams and residential areas. Observations of damage to these dams suggest that the forces acting on the dams vary locally depending on the riverbed morphology and the sediment and boulders already trapped. This study analytically examines debris flow loads in conditions involving a movable bed and pre-deposited gravel using Distinct Element Method. The results reveal that pre-deposited gravel significantly affects the maximum load exerted on the entire dam, with particularly large loads occurring at the points where the front of debris flow impacts each step height of the dam. Additionally, using contact force diagram and velocity vector diagrams, the causes of the reduction in debris flow load due to the influence of pre-deposited gravel were analyzed from the flow process to the point of impact.