某路堑边坡楔型滑动机制分析

Wedge Failure Mechanism Analysis on a Road Cutting Slope

某路堑边坡在开挖6年后发生滑动,为研究边坡的滑动机制,根据其滑动前、后野外调查和岩体物理力学试验对边坡稳定性进行分析。发现岩体破坏模式为楔型体滑动,开挖和降雨加速了边坡岩体的风化,XRD试验发现,与新鲜岩石相比,风化后岩石中粘土矿物成分增多,导致岩体强度下降。基于Barton-Bandis强度理论,确定了岩体结构面的强度参数,运用极限平衡法分析了风化结构面控制下的边坡稳定性。基于两种楔型体结构面水压力模型的稳定性计算结果表明,随着水压力的提高,边坡楔型体稳定性逐渐下降,最终导致边坡滑动。最后依据滑坡机制提出了治理建议。

This paper presents the case history of a rock slope which failed six years after the excavation.The failure mechanism was analyzed throughout the field investigation before and after the sliding,physical and mechanical test of the rock mass and the stability evaluation.It is found that the failure modes of the slope are mainly wedge sliding.The excavation and the rainfall also accelerated the weathering of the slope rock mass.The XRD test showed that,compared with the fresh rock,the clay mineral composition in the weathered rock increased,which resulted in the decrease of the rock mass strength.The shear strength parameters of the weathered joints were determined by the Barton-Bandis criterion,and the stability of the was analyzed by the limit equilibrium method.Considering the dynamic change process of the groundwater,the slope stability was evaluated based on two types of water pressure models.The results showed that the slope stability decreases gradually,with the increase of the water pressure,and eventually led to the failure.According to the failure mechanism,suggestions were proposed for the slope treatment.