Experimental study of landslide dam failure by headcutting erosion

The stream embankment failure and serious massive landslides always caused by earthquake and excessive rainfall which some times blocked the rivers into natural lakes. For example, there are over 10 landslide dams cause by 921 earthquake in Taiwan, China. These landslide dams are natural phenomena and thus are not subject to engineering design (although engineering methods can be utilized to alter their geometries or to add physical control measures), they are vulnerable to catastrophic failure by flow overtopping and erosion. Most landslide dams are remarkably short-lived. In the past flow overtopping was the most frequent cause of landslide-dam failure. Therefore, prediction of the rate of overtopping headcutting movement and erosion are criteria to assess the risk of a hydraulic engineering structure. In this study, dam type and discharge have been designed in order to establish the headcutting model. From analysis it is seen that the step type headcutting process is in parallel retreat with the constant speed in first stage and rotating type headcutting process in the second stage. In this paper we particularly provide the basic theory of landslide dams and discuss the headcutting formation of flood overtopping and headcutting type on landslide dams break.