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发生在西藏波密县易贡藏布扎木弄沟的易贡滑坡可称为国内规模最大的超高速远程滑坡,引起广大学者的广泛关注。针对易贡滑坡的高速、长距离运动等特点,通过不同剪切速率下的环剪试验以及排水和不排水条件下的对比环剪试验分析易贡高速滑坡的形成原因。结果表明,高速剪切使孔隙水压力不能及时消散,剪切过程引发孔隙水向剪切面运移,剪切面土体含水率和细粒含量明显高于剪切面上下层土体,出现剪切面液化现象。不排水剪切条件下的有效内摩擦角比排水剪切大幅降低,初步揭示了剪切速度越高,土体强度越低,两者交互作用的滑坡加速促进原因。
The Yigong landslide, which occurred in the Yungong Buzamuonggou of Biling County, Tibet, can be regarded as the largest ultra-high-speed remote landslide in China and has aroused widespread concern of many scholars. According to the characteristics of high speed and long distance movement of Yigong landslide, the reasons for the formation of Yigong high speed landslide are analyzed by the ring shear tests under different shear rates and the comparative ring shear tests under drained and undrained conditions. The results show that the pore water pressure can not be dissipated in time by high-speed shearing, and the shearing process leads to the migration of pore water to the shearing surface. The soil moisture content and fine-grained content in the shearing surface are obviously higher than those in the upper and lower shear layers Shear liquefaction phenomenon. Under the condition of undrained shear, the effective internal friction angle is significantly lower than that of drainage shear, and the reasons for accelerating the acceleration of landslide interaction are revealed when the shear rate is higher and the soil strength is lower.