降雨作用下的土质边坡变形破坏颗粒流仿真模拟

Simulation Study on Soil Slope Deformation Destroys Particle Flow under the rainfall

为研究持续降雨作用下土质边坡的变形破坏模式及机理,以四川省古蔺县竹林沟滑坡为例,结合离散元PFC^2D虚拟双轴压缩试验对坡体微观力学参数进行标定,随后建立1∶1数值计算模型进行稳定性计算,并记录坡体运动过程中应力及位移变化的情况。研究结果表明:该滑坡在持续降雨作用下至坡内土体饱和的过程中,坡脚应力不断积累,导致坡脚发生破坏,之后向上逐级牵引,致使坡前基岩较陡区域土体优先发生滑动。中-后缘土体因前部失稳产生临空条件,随即出现二级滑动,整体表现为典型的蠕滑-拉裂破坏模式。坡体前缘破坏后应力得到部分释放,但位移不断增长;坡内应力和位移整体上从前缘到后缘均呈递减趋势。应用颗粒流PFC^2D以竹林沟滑坡为例对土质滑坡在持续降雨作用下的变形发展过程进行模拟研究,揭示了滑坡的发展及破坏模式,为该类滑坡的防治提供参考。

In order to study the deformation damage mode of soil slope and its mechanism under the continuous rainfall situation,the 1∶1 numerical calculation model was established for stability calculation.Taking the landslide of Zhulin ditch in Gulin County,Sichuan Province as an example,the discrete element PFC^2D virtual biaxial compression test to calibrate the micro mechanical parameters was used then.Meanwhile,the changes of the stress and displacement during the slope movement were recorded.The results indicate that the stress of the slope accumulates continuously,which leads to the damage of the slope.And then it causes the step-by-step upward traction,which results in soil sliding in the bedrock of the steep region before the slope in the process of the continuous rainfall to the saturation of soil.Due to the instability of the front part,the soil mass in the middle and back edge shows a free condition,and then there is a secondary sliding,which shows a typical creep-tension failure mode.The stress is partly released after the failure of the front edge of the slope,but the displacement is increasing.The stress and displacement in the slope decrease from the leading edge to the trailing edge as a whole.Taking Zhulingou landslide as an example,by using PFC^2D this paper simulates the deformation and development process of soil landslide under continuous rainfall,reveals the development and failure mode of landslide,and provides reference for the prevention and cure of this kind of landslide.