东河口高速远程滑坡-碎屑流全程动力特性模拟

NUMERICAL SIMULATION OF DYNAMIC BEHAVIOR OF DONGHEKOU ROCKSLIDE-DEBRIS AVALANCHE

高速远程滑坡-碎屑流具有速度快、滑程远、冲击破坏力强等特点,是一种危害性极大的地质灾害,往往会造成严重的生命财产损失。汶川地震后,国内学者对高速远程滑坡-碎屑流的研究取得了大量前瞻性成果,但由于此类滑坡自身的复杂性,目前为止尚未取得公认的研究成果。为了进一步揭示高速远程-碎屑流效应机理,本文以汶川地震触发的青川东河口滑坡-碎屑流为例,通过滑坡动力分析软件DAN-W分别建立了摩擦模型、Voellmy模型和F-V等3种不同的滑坡数值模型,对东河口滑坡-碎屑流的运动距离、不同时刻运动速度特性、堆积物分布规律及滑坡堆积体积进行了模拟,同时对滑坡运动时间进行了估算。模拟结果表明:根据高速远程滑坡-碎屑流不同运动阶段选择不同的流变模型分析的结果更加合理。摩擦流变模型对运动距离的模拟结果小于滑坡的实际滑程,适于模拟滑体整体性好的启程和近程运动阶段;Voellmy流变模型对滑体的运动距离模拟效果很好,但对速度的分析结果偏大,适合模拟滑坡远程碎屑流运动阶段;F-V双流变模型对滑坡运动特性模拟效果最佳,并给出了选取东河口滑坡-碎屑流数值模型的最佳流变参数,摩擦角φ=18°,摩擦系数μ=0.1,湍流系数ξ=400m.s-2。

The rockslide-debris avalanche is a geological disaster of great danger and always causes disastrous ca- tastrophes because of its high velocity and unexpected long runout. Scholars in China had made a lot of forward-loo- king 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 roekslide- debris avalanche in Qingchuan County triggered by Wenchuan Earthquake as example to reveal the moving mecha- nism of rockslide-debris avalanches. The dynamic analysis software of DAN-W is applied to the creation of threedifferent rheological models. They are Friction model, Voellmy model and F-V model to simulate on the motion be- havior of flow slides and put an emphasis on the travel distance, speed characteristics at different intervals, distri- bution 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 coefficientμ = 0. 1 and turbulence parameter ξ=400m.s-2 have been found by the back analysis.