牵引式滑坡的破坏机制及其加固措施探讨 ——以某高速公路牵引式滑坡为例

牵引式滑坡在山区公路滑坡中占有相当的比重，其治理工程往往耗资巨大、环境破坏严重。针对某高速公路牵引式滑坡，通过地质调查、变形迹象分析、岩土体应力-应变分析及数值模拟等方法，指出具体破坏机制为：（1）坡脚开挖致使阻滑关键块体缺失，应力集中导致剪切应变软化；（2）地表降水与地下水对岩土体物理力学性能的改造；（3）滑体变形不协调，导致拉裂缝产生，滑坡后缘得以继续向后扩展。目前监测表明，已施工的组合加固措施效果良好。最后讨论挖方引起的牵引式滑坡的工程地质特征，对牵引式滑坡进行评价应坚持安全系数分区原则，滑坡总体加固应按安全系数控制，同时对后缘加固按位移控制。

Discussion on failure mechanism of retrogressive landslide and its reinforcement measures: taking a certain expressway retrogressive landslide for example

The retrogressive landslide occupies a considerable proportion among expressway landslides in the mountain area. The reinforcement projects often cost enormously and the environment around is usually damaged severely. Taking a certain expressway retrogressive landslide for example, through approaches of geological survey, deformation investigation, stress-strain behavior analysis and numerical modeling, the failure mechanism is confirmed as follows: (1) the loss of resisting key block is caused by slope foot excavation, shear strain softening is induced by stress concentration; (2) physico-mechanical properties alternation of the rock and soil mass are remolded by the surface rainfall and groundwater; (3) tensile cracks are fromed deformation incompatibility and its expanding backward. The monitoring results show that the applied combined reinforcement measures work well. The geological characteristics of excavation-induced retrogressive landslides are discussed. A principle that “the safety factor should be calculated by section should use to evaluate retrogressive landslide; the reinforcement of the whole landslide should be controlled by the predetermined safety factor; while the reinforcement of landslide rear should be controlled by displacement.