反倾岩质边坡弯曲倾倒-剪切滑移破坏分析方法研究

Analytical Method for Flexural Toppling-Shear Sliding Failure of Counter-tilted Rock Slopes

目前反倾岩质边坡弯曲倾倒破坏分析方法仍以基于极限平衡理论的悬臂梁模型为主,但大多未考虑坡脚岩层的剪切破坏。为准确评价该类边坡的稳定性,建立考虑坡脚岩层剪切破坏的分析计算方法。首先,根据岩层变形破坏特征,将边坡分为后缘稳定区、中部弯曲倾倒区和前缘剪切区3个区域;其次,建立弯曲倾倒-剪切滑移破坏模式的稳定性分析方法;最后,通过工程实例验证,并进行参数分析。研究结果表明:提出的分析方法与工程实际符合性较好;边坡在倾角较陡、坡角较大时稳定性最差,坡角对边坡稳定性影响大于岩层倾角的影响;岩层厚度及层面内摩擦角增加有利于边坡稳定性,且会扩大坡脚剪切区范围。研究成果对反倾岩质边坡破坏的防治具有实践指导意义。

At present,the cantilever beam model based on the limit equilibrium theory is still the main method to analyze the flexural toppling failure of counter-tilted rock slopes,but most do not consider the shear failure of the rock layer at the toe of the slope.According to the deformation and failure characteristics of rock layer,we divided the slope into three zones:stable zone in the back edge,flexural toppling zone in the middle,and shear zone in the front edge.In subsequence,we established the analytical method for flexural toppling-shear sliding failure mode and verified the analytical method through application in an engineering example and analyzed the model parameters.Results manifest that the result obtained by the proposed analytical method is in good agreement with actual engineering.The slope stability is at the worst in the presence of large dip angle of rock layer and slope angle.The influence of slope angle on slope stability is greater than that of dip angle of rock layer.The increment in the thickness and internal friction angle of rock layer is conducive to slope stability and will widen the scope of the shear zone at slope toe.