Experimental investigation of breaching process of moraine dam with different breach-notch shapes due to surge wave of glacier avlanches

To investigate the impact of breach-notch shape on the failure process of moraine dams triggered by glacier avalanche surge waves, flume experiments on dam failure were conducted based on the characteristic parameters of the Jialongcuo glacial lake. Three conditions were selected: trapezoidal, triangular, and composite notches. The experiments analyzed the variations in peak discharge and the development of lateral and vertical erosion of the moraine dam body during dam-breaching process. The results indicate that after the glacier avalanche enters the water, the waves propagate in a shape resembling solitary waves. They repeatedly scour the downstream of the dam until a complete spillway channel is formed. After this, it becomes difficult to observe significant waves in front of the dam, and the subsequent failure development resembles a rising water overflow breach, with vertical deepening and lateral widening of the breach occurring. Under the three conditions, the influence of breach-notch shape on peak discharge and cross-sectional erosion rate does not exceed 3.05% and 18.50%, respectively. The research findings help in understanding the mechanisms of wave-induced dam failure and the erosion development and breach expansion processes of the moraine dam body.