基于离散元的含软弱夹层岩质边坡滑移机理分析

Sliding failure mechanism of bedding rock slope with weak intercalated layer based on discrete element method

以苏州清明山滑坡为例,采用颗粒流软件PFC2D建立了滑坡体的二维数值模型,通过监测坡体表面不同部位的位移和应力变化情况,对边坡滑动的演化过程和破坏机理进行了详细的分析。数值试验结果显示该顺层边坡的失稳是一个渐进的过程,首先沿靠近坡面的一组软弱结构面发生滑动,下方滑床岩体在上覆滑体的挤压和摩擦作用下发生破碎,使滑动不断向深处发展。在前期形成的临空面和软弱结构面的共同影响下,滑坡后缘岩体产生一组近乎垂直的拉裂面,该竖向破裂面的存在有利于雨水入渗,进一步降低软弱夹层的抗剪强度参数,从而使边坡由小范围的崩塌破坏转为大范围的滑动破坏,属滑移-压致拉裂型滑坡。清明山滑坡滑移机理的研究对后续地质灾害治理有重要意义。

Taking the Qingming Mountain landslide in Suzhou as an example,a two-dimensional numerical model of the landslide body was established by using the particle flow code software PFC2 D. By monitoring the displacement and stress changes in different parts of the slope,the evolution process and the failure mechanism were analyzed. The numerical test results show that the maximum slip distance of the unstable block on the surface of the slope is 54. 18 m and the depth of the sliding surface is about 20 m. The sliding instability of the slope is a gradual process. Firstly,the landslide is a plane slip along the weak structural plane close to the surface of the slope,and the rock mass below it is crushed under the pressure and friction of the overlying body,the landslides develop to the deep. Under the combined effect of the free plane and the weak plane formed in the early stage,the vertical failure plane is produced in the trailing edge of the rock mass. The existence of the vertical failure plane helps to infiltrate the rainwater and further reduce the mechanical parameters of the weak structural plane,thus the small range of collapse damage changes to a wide range of sliding failure. The failure of this slope can be defined as sliding and compression cracking. The study on the sliding failure mechanism of Qingming Mountain landslide is of great significance for the subsequent geological disaster management.