基于颗粒流的土质边坡失稳机理

Instability Mechanism of Soil Slope Based on Particle Flow

为研究降雨工况下诱发土质边坡失稳过程及破坏机理,以泸州市古蔺县竹林沟滑坡为依托,通过PFC2D双轴压缩试验对滑坡体饱和状态下的强度参数进行标定,确定滑坡细观参数与宏观参数的内在联系,并引入接触黏结模型,对其破坏过程特征进行模拟研究,并对滑坡关键位置处的速度、孔隙率以及位移进行实时监测。计算结果表明:滑坡破坏的过程为:初期整体蠕滑变形,随着变形的发展,滑坡体向坡前临空方向发生剪切蠕变,后缘产生由坡面向深部发展的张拉裂缝,随着潜在滑面贯通,滑坡失稳破坏;通过监测不同位置的速度发现,0~10 s为加速阶段,坡体最大速度达到约14 m/s,最大颗粒速度达到约20 m/s,15~25 s坡体速度开始下降,滑坡最大位移约600 m,整体位移约450 m,并于25 s左右坡体停止滑动。通过对竹林沟滑坡的数值模拟,采用离散元颗粒流的方法去研究滑坡的运动过程有较好的应用性,也能为同类型滑坡的防灾减灾提供较好的参考意义。

In order to study the instability process and failure mechanism of soil slope induced by rainfall,based on the Zhulingou landslide in Gulin County,Luzhou City,the strength parameters of landslide in saturated state were calibrated by PFC2D biaxial compression test,and the internal connection between the landslide meso-parameters and macro-parameters was determined.In addition,the contact bonding model was introduced to simulate the failure process characteristics,and the velocity,porosity and displacement at key positions of landslide were monitored in real time.The results show that the failure process of landslide is as follows:the entire creep deformation in the initial stage.With the development of deformation,the landslide body underwent shear creep towards the front of the slope,and the trailing edge produced tension cracks developing from the slope surface to the deep part.With the penetration of the potential slip surface,the landslide is unstable and destroyed.By monitoring the velocities at different positions,it is found that 0~10 s is the acceleration stage,the maximum velocity of the slope reach about 14 m/s,the maximum particle velocity reaches about 20 m/s,the velocity of the slope begin to decrease in 15~25 s,the maximum displacement of the landslide is about 600 m,the overall displacement is about 450 m,and the slope stops sliding in about 25 s.Through the numerical simulation of Zhulingou landslide,the discrete element particle flow method is applied to study the movement process of landslide,which can also provide a good reference for disaster prevention and mitigation of the same type of landslide.