A debris-flow brake is an erosion control facility designed to stop debris flows. However, the mechanism of the debris-flow brake has not been explained. This study discusses the change in pore-water pressure near the deck of a debris flow brake which controls solid friction between the debris flow and the deck. A dynamic model that describes the behavior of debris flows at the debris-flow brake was built It incorporates not only the change in sediment concentration of the debris flow due to water draining through the debris-flow brake but also the resulting change in pore-water pressure. Numerical simulations and experiments examined the behavior of debris flows at a debris-flow brake. The simulation and experimental results agreed. The simulation results show that the change in pore-water pressure plays an important role in how a debris-flow brake stops debris flows.
A debris flow is a phenomenon in which large quantities of water, mud, and gravel flow down a stream at ahigh velocity. Because debris flows have such high density and velocity, they can be highly destructive andcan have severe and tragic results such as destruction of homes, bridges, and infrastructures, as well as loss oflife. Numerical simulations are important to ensure that countermeasures such as sabo dams will be efficientbefore construction. This paper presents one-dimensional numerical simulations of a debris flow usingKanako, a user-friendly GUI-equipped debris flow simulator that allows good visualization and easyexplanation. Kanako (Ver. 1.40) was applied to a case study at Cipanas, Guntur Volcanoes, West Java,Indonesia. Simulations tested various conditions including cases without any sabo dams, with various typesof sabo dams either alone or in a series, and with full sabo dams.