Experimental analysis on breaching mechanism of earth-rock dam induced by landslide generated waves

Abstract

High earth-rock dams and large reservoirs have been widely constructed in mountainous river valleys. These areas contain a significant number of potential landslide areas, which can be triggered by external factors, such as earthquakes, heavy rainfall, or water level fluctuations. The impact of landslide-generated waves can lead to the breaching and failure of earth-rock dams. To investigate the breaching mechanisms of earth-rock dams and the erosion patterns caused by landslide-generated waves, a series of integrated physical experiments was conducted to simulate the process of wave-dam breach scenarios. The wave climbing process in front of a dam and the erosion characteristics of different types of waves were analysed. Critical criteria for wave-induced dam erosion and breaches were also proposed. The breaching process was examined under the influence of various factors. The results indicate that the dam breach can be divided into three stages under the impact of landslide-generated waves: surge run-up overtopping stage, surge impact erosion stage, and conventional overtopping erosion stage. When a wave climbing height in front of the dam is higher than the dam height (R_i^⁎ > (h_d)_i-1), the dam crest is continuously eroded; when the average water level in front of the dam is greater than the height of the dam after erosion (h_i > (h_d)_i), the earth-rock dam breaks. The erosion of the dam body induced by waves was more severe under identical hydraulic conditions than dam breaches under natural overtopping. This results in faster breach development, earlier breach initiation, higher peak discharge, longer breach duration, and greater overall risk.