“12·20”深圳滑坡动态模拟

将深圳滑坡堆填渣土近似视为饱和土,考虑快速填筑效应,假定填筑高度在填筑过程中随时间线性增大,由一维固结理论推导出由于快速加载引起的土体内超静孔隙水压力分布,同时根据修正剑桥模型考虑填土剪缩效应对超静孔隙水压力的影响。总孔隙水压力为静水压力、快速加载和剪缩引起的超静孔隙水压力三部分之和,从而由总应力得到余泥渣土失稳时的有效应力,进而由有效内摩擦角得到其剪切强度。再将快速滑出过程看作不排水条件下的破坏,利用推导出的填土不排水强度,采用可以有效模拟超大变形问题的物质点法对深圳滑坡的全过程进行了动态模拟,并研究了滑坡体对建筑物的破坏作用。模拟结果表明该模型能较好解释深圳滑坡中滑动土体高速远程输送特征。

Dynamic simulation of“12·20”Shenzhen landslide

The filled soil of Shenzhen landslide is treated as saturated porous media. The excess pore pressure due to fast filling process is derived using the classical one-dimensional consolidation theory by assuming the thickness of the filled soil to increase linearly. Meanwhile, another part of the excess pore pressure induced by the soil contraction under shear deformation is derived by using the modified Cam-clay model. Then the effective stress is obtained by subtracting the pore pressure, i.e., the static pore pressure and the two parts of the excess pore pressure, from the total stress. The undrained shear strength can be expressed by the effective friction angle and the effective stress. Finally, the landslide is simulated using the material point method by assuming an undrained run-out process in which the soil strength keeps constant. The destructive effect of the sliding soil on the buildings is also analyzed. The proposed theory can be used to explain the extraordinary flow ability of the soil satisfactorily.