NUMERICAL SIMULATION OF LAKE WATER DOWNSTREAM FLOODING DUE TO SUDDEN BREAKAGE OF YIGONG LANDSLIDE DAM IN TIBET

The dam of the landslide debris barrier lake mainly consists of boulder and stony soil and it is more vulnerable to instability as the result of a rise in water level. The dambreak may cause huge economic property and life loss. Therefore the study of dambreak problem has important academic significance and application value. A highspeed giant landslide occurred in Yigong River in the Bomi,Tibet,on April 9, 2〖CS％0,0,0,0〗〖CS〗000.A landslide dam was formed suddenly with 2500 m long, 2500 m wide and 60 m high, 280～300 million m3 in volume. A debris barrier lake was formed. Taking the dambreak of Yigong barrier lake as an example,according to the continuity equation and NavierStokes equation,combining with standard turbulence model,and tracking the freesurface with VOF method,via computational fluid dynamics software Fluent,this paper analyzes the dambreak flood evolution in downstream river course and the velocity changes at different sites. The simulation results are consistent with the observed data. At the same time,it shows that the model can simply simulate the flood evolution in the river bend with complex terrain after dambreak. The study can provide the prevention of dambreak disaster in terms of downstream flooding.