反倾层状岩质边坡倾倒变形机理与影响因素的离散元模拟

Discrete Element Simulation of Toppling Mechanism and Influencing Factors of Anti-Dip Layered Rock Slope

为进一步研究层状反倾边坡的弯曲倾倒变形机制,以离心试验为原型,通过离散元数值模拟,研究了层状岩质反倾边坡的变形机理与影响因素。通过预置层内随机裂隙,实现了破裂面的形成和贯通。研究结果表明:模拟结果与试验吻合较好,边坡变形可分为起始蠕变、稳态变形和失稳破坏3个阶段;边坡破裂面在达到破坏荷载(G_(f))后瞬间贯通,呈直线型,产状受岩层倾角控制,G_(f)值与坡角幂函数相关;反倾边坡的破坏需满足倾角和坡角启动条件,且变形破坏与岩层所受弯矩关系密切,当倾角为70°~80°、坡角大于60°时,最易破坏;典型破坏模式有倾倒—折断—块体式、倾倒—弯曲—折断式、倾倒—反折式3种,其受倾角、坡角组合控制;对材料参数的正交试验表明,各参数对G_(f)的敏感性从大到小依次为密度、层面内摩擦角、层厚、密度比、层面黏聚力,且G_(f)与层厚、层面内摩擦角及密度比具有良好的线性相关性;层面内摩擦角可影响破裂面产状,从而控制变形体规模,其他参数仅影响G_(f)的大小。

In order to further study the mechanism and influcing factors of the toppling of layered anti-dip slopes, the discrete element simulation based on centrifugal model test was adopted. The formation of rupture surface was realized by presetting random cracks in the rock layers. The simulation results are in good agreement with the physical test. Slope deformation can be divided into three stages: Initial creep, steady-state deformation, and instability failure. The results show that: The rupture surface is straight-line after the failure load(G_(f)) is reached, and the occurrence is controlled by the dip angle of the rock layer;The G_(f)value is related to the power function of the slope angle;The failure of the anaclinal slope needs to satisfy the initial conditions, and the deformation is closely related to the bending moment of the rock layer, when the dip angle is 70°-80° and the slope angle is larger than 60°, it is the most vulnerable state. There are three typical failure modes: Toppling-rupture-block detachment type, toppling-bend-rupture type, and toppling-reversal type, which are controlled by the combination of dip and slope angle. The orthogonal simulations on material parameters show that the sensitivity of each parameter to G_(f)from large to small is density, friction angle of beddings, layer thickness, density ratio, and cohesion of beddings;The value of friction angle of beddings can affect the occurrence of the rupture surface, thus controlling the size of the deformation area, while other parameters only affect the value of G_(f).