反倾层状岩质边坡失稳的断裂力学分析

反倾层状岩质边坡的高危地质灾害承载体在自然界中普遍存在,为研究其失稳破坏机制,将反倾边坡岩层简化为一个带裂缝的悬臂梁,建立了由一组结构面控制边坡稳定性的断裂力学模型,推导了各岩层结构面等效应力强度因子和岩层及边坡稳定性判据。分析了岩层倾角、层厚、结构面长度、内摩擦角和粘聚力5个因素对边坡的稳定性影响。结果表明,随着岩层倾角和结构面长度的增加,边坡不稳定区域增加,坡脚处的抗滑稳定性减小;随着内摩擦角和粘聚力的增大,边坡不稳定区域减小,坡脚处的抗滑稳定性增大;随着岩层厚度的增大,不稳定岩层的范围基本保持不变,但是岩层的抗滑稳定区域随着厚度增加逐渐向坡脚移动,厚度越大,坡脚处的抗滑稳定性越大。实例分析验证了本文理论的合理与可行性,研究结论对工程实践具有一定指导意义。

Instability mechanism of counter-tilt layered rock slope by fracture mechanics analysis

The high risk geological hazard bearing body of an anti-dip layered rock slope exists universally in nature,in order to study the mechanism of instability and failure,in this paper,the anti-dip slope rock is simplified to a cantilever beam with cracks,a fracture mechanics model of slope stability controlled by a set of structural planes is established.A method of the equivalent stress intensity factors for rock blocks and the relevant stability criteria are derived.Secondly,the influences of 5factors on slope stability are analyzed,which are slope angle,thickness,length of structural plane,internal friction angle and cohesion.The results show that:①With the increase of the dip angle and the length of the structural plane,the unstable area of the slope increases,and the stability of the slope at the foot is lower.②With the increase of internal friction angle and cohesion,the unstable area of the slope decreases,and the stability of the slope at the foot is higher.③With the increase of rock thickness,the scope of unstable rock strata is basically unchanged.However,as the thickness of the rock increases,the anti-sliding stability of the strata will gradually move to the slope toe.The greater the thickness of the rock layer is,the greater the stability of the slope will have.Finally,the rationality and feasibility of the theory are verified through case studies.The research results have certain guiding significance for engineering practice.