无黏性土滑坡型泥石流形成机理的离心机模型试验研究

采用自主研发的可视化试验装置,参照某泥石流现场试验进行了离心机模型试验,研究典型滑坡型泥石流形成的宏细观机理。根据现场试验的颗粒级配和重力比,用粉砂和细砂按比例配制土样进行20g加速度下的离心机试验。利用高清数码成像设备和细观结构分析软件Geodip分别从宏观和细观角度分析了滑坡型泥石流的形成模式和水土作用机理。研究结果表明：离心机模型试验较好地重现了现场试验现象,滑坡型泥石流的形成模式为自坡脚逐渐向上分块坍塌的倒退式块体滑动。滑坡型泥石流形成的原因是坡体中细颗粒随孔隙水迁移,引起孔隙水压力升高并形成底部渗流,造成坡体发生抗剪强度破坏形成泥石流。

Centrifugal model tests on formation mechanism of landslide-type debris flows of cohesiveless soils

Using the self-developed visualization test apparatus, centrifuge model tests are carried out to study the macro-mesoscopic formation mechanism of typical landslide-type debris flows according to field tests on a debris flow. Based on the grain-size gradation of field tests and gravity ratio, the centrifugal model tests are carried out under 20g. The soil samples are made up by silt sands and fine sands. The formation mode and soil-water action mechanism of landslide-type debris flows are analyzed from the macroscopic and mesoscopic points of view respectively by using the HD digital imaging equipment and the mesoscopic structure analysis software Geodip. The test results indicate that the centrifugal model tests can reproduce the phenomenon of the field tests approximatively. The formation mode of landslide-type debris flows is gradually collapsed in form of retrogradation to sliding. The reason of the formation of landslide-type debris flows is the shear strength failure of the slope caused by the rise of the pore water pressure and the seepage on the floor resulted from the motion of the fine particles with migratation of pore water in the slope.