边坡深层抗滑稳定动力分析

Dynamic analysis of side slope stability against deep sliding

岩体结构面在循环加载条件下的力学特性直接关系到上部结构的稳定安全。本文结合边坡动力抗滑稳定工程算例,采用有限元接触分析方法,对岩休结构面的理想弹塑性模型、简化非线性模型、考虑剪胀和磨损等现象的复杂非线性模型的计算结果进行了对比分析。接触面的理想弹塑性模型低估了接触面的变形能力,计算出的位移偏小,屈服区范围偏大,安全系数偏小。简化非线性模型的刚度随变形的增加而减少,增强了接触面的变形能力,计算出的位移增大,屈服区范围偏小,安全系数偏大。天然岩体结构面具有峰值剪切和剪胀特性,在循环加载条件下,峰值摩擦角、剪胀角会逐步磨损,考虑这些复杂特性后,模型计算结果处于理想弹塑性模型和简化非线性模型之间,更准确地模拟了接触面的受力变形特性。

Mechanical characteristics of rock joints and interfaces under cyclic loading are important to stability safety of upper structure. For an example, three kinds of models are compared in dynamic stability analysis against sliding. Finite element method is used and rock structural surfaces are simulated with contact elements. The sliding security is evaluated by displacements, yield region of contact surface and point safety coefficient. Elastic-perfect plastic model underestimate the deformation capability of contact surface, relative displacement obtained is less than real value, yield region is on the high side, and safety coefficient is on the low side. In simplified nonlinear model, contact stiffness decreases when shear relative displacement increases, deformation capability and safety coefficient are overestimated. In complex nonlinear model, the characters of peak friction and dilation wear under cyclic load of natural rock joints are considered, and the numerical analysis result lies between last two models.