FIELD EXPERIMENT ON PROGRESSIVE FAILURE OF A LANDSLIDE DAM

Processes leading to landslide dam outburst are classified into the following three types: erosion due to overtopping, instantaneous slip failure, and progressive failure. There have been many indoor channel experiments and field experiments focusing on the overtopping failure of a landslide dam. Experimental research focusing on progressive failure has been limited to indoor channel experiments on a small scale. Hence, we carried out large-scale experiments on progressive failure of a landslide dam in a mountainous streambed of the Ashiarai Basin. The aim of these experiments was to observe processes of dam deformation and flood runoff. We obtained data on the dam deformation process, reservoir water level, water level inside the dam and outflow discharge. The results show that the water volume of a dam is the main factor affecting the peak discharge rate.