牵引式滑坡演化模式研究

该研究以甘肃黑方台为区域背景,通过离心模型试验与应力路径试验相结合的手段,研究地下水位抬升引发牵引式黄土滑坡的演化模式和力学机理。离心模型试验中,模型边坡的尺寸为0.8 m×0.4 m×0.45 m(长×宽×高),离心加速度为100g。在试验中,通过水位控制系统实现地下水位的不断抬升,利用数码摄像、孔隙水压力及激光位移传感器、侧面示踪点等仪器设备详细记录地下水位抬升过程中边坡内的孔隙水压力、边坡变形、滑动面形态及坡面裂缝的形成和发展过程。应力路径试验中,通过恒载增孔压试验和偏压固结不排水试验,模拟了滑坡酝酿启动过程和局部破坏向整体滑移的发展过程。基于以上成果,提出饱水黄土在上覆荷载下因孔隙水压力增大而失稳,在卸荷条件下使应力重分布,导致局部剪切带发展并逐渐形成贯通的破坏面,边坡表现为牵引式的破坏模式。该研究结果有助于深入认识水位抬升引发牵引式滑坡的演化模式和力学机理,为治理此类滑坡提供科学依据。

Evolution mode of retrogressive landslide

For the region of Heifangtai Plateau, in Gansu Province of China, centrifugal model tests and two sets of stress-path tests are conducted to investigate the evolution mode and the mechanism of retrogressive landslides. In the centrifugal model tests, the rising of groundwater level is controlled by a designed facility. Digital cameras, pore-water pressure transducers, laser sensors and tracking points are adopted to record the variations in the pore-water pressure, deformation, slipping surfaces and cracks during the rising of groundwater level. In the stress-path tests, the dead-load tests with increasing pore-water pressure are performed to simulate the initiation of a landslide during the rising of groundwater level. Anisotropically consolidated and undrained tests are conducted to simulate the transferring process from local failure to global one in a landslide. Based on the above results, the findings are summarized as follows: the saturated loess fails under overburden pressure due to the rising of pore-water pressure. Under unloading conditions, the re-distribution of stresses leads to the development of local shearing band into the connected global failure surface gradually, while the slope appears in a retrogressive mode. The results are helpful in understanding the evolution mode and clarifying the mechanism of retrogressive landslides, and they may provide scientific support to the landslide treatment.