考虑裂隙水流拖曳力效应的平推式滑坡稳定性

Stability of horizontal-push landslide considering drag force of fissure water flow

为研究滑面裂隙水流拖曳力对平推式滑坡稳定性的影响,建立平推式滑坡渗流–径流耦合模型。该模型采用Navier–Stokes方程描述滑面裂隙径流,用Brinkman-extended Darcy方程描述软弱层多孔介质渗流。径流区和渗流区的流体运动均满足连续性方程,且在交界面处的流体满足流速相等和切应力连续双边界条件。根据上述条件推求出径流区和渗流区的流速分布,并引入Newton内摩擦定律求出滑动面裂隙径流拖曳力。利用刚体极限平衡理论对径流状态下平推式斜坡的稳定性进行分析,得出修正后的平推式斜坡抗滑稳定安全系数和后缘裂隙临界水深之间的关系。并结合工程实例讨论后缘水深、滑面倾角和滑面裂隙宽度对安全系数的影响。结果表明,考虑底部裂隙流体拖曳力效应时,滑坡安全系数下降了5.90%。因此,在进行平推式滑坡稳定性分析与计算中,应考虑滑动面裂隙水流拖曳力作用。

In order to study the influences of the drag force of slide fissure flow on the stability of the horizontal-push landslide, a seepage-runoff coupled model of horizontal-push landslide is established. The Navier-Stokes equation is used to describe slip surface runoff, and the Brinkman-extended Darcy equation to describe the seepage of porous media in weak layers. The fluid flow in the runoff and seepage areas all satisfy the continuity equation, and the fluid at the interface satisfies the condition of equal flow velocity and continuous shear stress. According to the above conditions, the distribution of flow velocity in runoff and seepage areas is deduced, and Newton’s internal friction law is introduced to obtain the drag force on the sliding surface. Based on the rigid body limit equilibrium theory, the stability of run-flat slopes under runoff condition is analyzed, and the relation between the corrected safety factor of anti-slide stability and the critical depth of trailing edge fissures is obtained. Combined with the engineering examples, the influences of the water depth at the trailing edge, dip of the slip surface and width of the slip surface crack on the safety factor are discussed. The results show that the safety factor of landslide decreases by 5.90% when considering the drag effect of bottom fissure fluid. Therefore, in the analysis and calculation of the stability of the horizontal-push landslide, the drag force of the fissured water flow in the sliding surface should be considered.