NUMERICAL SIMULATION OF DYNAMIC BEHAVIOR OF DONGHEKOU ROCKSLIDE-DEBRIS AVALANCHE

The rockslide-debris avalanche is a geological disaster of great danger and always causes disastrous catastrophes because of its high velocity and unexpected long runout. Scholars in China had made a lot of forward-looking results for the high-speed rockslide-debris flows after Wenchuan Earthquake. A majority of the research results on this field have not been widely accepted due to itself complication. This paper takes the Donghekou rockslide-debris avalanche in Qingchuan County triggered by Wenchuan Earthquake as example to reveal the moving mechanism of rockslide-debris avalanches. The dynamic analysis software of DAN-W is applied to the creation of three different rheological models. They are Friction model, Voellmy model and F-V model to simulate on the motion behavior of flow slides and put an emphasis on the travel distance, speed characteristics at different intervals, distribution of the deposits. The volume and duration are estimated. The results reveal that applying different rheological models to different moving stages have reasonable results. The Friction model is better to simulate the landslide at set-out phase and short-runout phase. The Voellmy model has advantages of simulating flow debris at long run-out phase. The two-rheological model"F-V"provides the best simulation of the Donghekou rockslide-debris avalanche movement. The best fitting rheological parameters friction angle φ=18°,friction coefficient μ=0.1 and turbulence parameter ξ=400m·s-2 have been found by the back analysis.