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MOTION SIMULATION OF RAPID LONG RUN-OUT LOESS LANDSLIDE AT DONGFENG IN JINGYANG, SHAANXI
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摘要: 陕西泾阳南塬的东风滑坡是一个典型的高速远程黄土滑坡，由于斜坡顶部的黄土台塬长期灌溉所诱发。通过野外调查，采取滑坡后缘斜坡的黄土试样，对斜坡中部的Q2黄土做天然含水率的固结不排水剪试验，对斜坡底部地下水位面附近的Q1黄土做饱和固结不排水剪试验，结果表明非饱和的Q2黄土和饱和的Q1黄土在破坏后都具有显著的应力降，但前者是由结构强度引起，而后者则是由剪切形成的超孔隙水压力引起，由此表明该斜坡一旦破坏，就会有较高的启动速度。对滑坡坡脚以外一级阶地上的砂卵层做环剪慢剪试验，测得其有效残余摩擦角，根据滑坡各部分含水状态给定孔隙水压力参数，利用Sassa. K滑坡运动模型对该滑坡运动过程进行模拟，从模拟结果反映出滑坡运动过程中的覆盖范围和速度的变化，模拟的滑坡运动距离和覆盖范围与实测比较吻合，最高速可达到37m s-1，为高速滑坡。黄土滑坡以高的初速度下滑到坡脚下一级阶地上的饱和砂卵层上，砂卵层上液化是导致其远程运动的主要原因。Abstract: The Dongfeng loess landslide on the south platform in Jing Yang is a typical type of high-speed long distant landslides, induced by the long-term irrigation at the top tableland of the slope. After field investigation, loess samples are taken in different parts of the slope. The intact samples taken in the central slope(Q2) are utilized to do the CU tests, and the ones taken in the slope bottom(Q1) are saturated and then used to conduct the CU tests. Results show that both the unsaturated loess Q2 and the saturated loess Q1 display significantly stress decrease. However, they have different reasons. For the former is caused by the decline of structure strength, while the latter is caused by the pore water pressure generated during the shearing process. All above reveal that once the slope failure occurs, there will be high initiating speed. The ring shear tests are conducted on the sand on the first terrace out of the slope toe to obtain the effective residual friction angle. Then according to the situation of water contents, pore pressure coefficients in different parts are obtained. Then the landslide movement process can be simulated by Sassas landslide motion model,which can show the speed changes and the coverage of landslide. The simulation results are in good agreement with the measures results. The highest speed can reach 37m s-1,also revealing that it is a high speed landslide. The loess landslide with high initial velocity down to the slope foot in the saturate sand layer of the first terraces and liquefaction in the sand layer is the main factor of its remote movement.
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Key words:
- Loess /
- Rapid long run-out /
- slide /
- Motion simulation
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