顺层边坡的稳定性影响因素及失稳判据分析

Analysis of influential factors on bedding slope stability and failure criterion

针对含软弱夹层顺层边坡的破坏特征,利用极限平衡法建立了边坡稳定性的计算模型,分析了在各种因素作用下边坡的稳定性系数变化特征以及边坡失稳的判据。结果表明:1稳定性系数与抗剪强度呈线性正相关关系,凝聚力和内摩擦角对边坡稳定性的影响大小取决于其值的组合形式;2每一个坡角θ,对应存在一个最不利的岩层倾角α,α∈[25°,50°]时边坡稳定性相对较差,并且可以得出,α∈[θ/2+5°,θ/2+10°];3坡角越接近岩层倾角,稳定性系数越大,反之则越小;4稳定性系数K随着剪出高度H的增大而减小,H∈[1,10]时,减小得相对较快,H∈[10,50]时,减小得相对较慢;5水对边坡的稳定性系数影响显著,主要体现在降低了软弱夹层的抗剪强度,静水压力降低了边坡的稳定性。边坡发生失稳时后缘裂隙必须满足一定的裂隙深度,裂隙深度越大所需的充水高度越小,反之则越大。总结得出顺倾向边坡两种破坏判据,一种只是重力作用下的边坡,当H>H_(max)时边坡发生滑移失稳;一种是边坡后缘存在一定深度裂隙的边坡,当Z_w>Z_(wmax)时发生水力推动型滑移失稳。研究结果可对边坡的防护和治理具有一定的指导意义。

In order to study the failure characteristics of bedding slopes with weak interlayer,the limit equilibrium method was used to establish the calculation model of slope stability,and the variation of stability coefficient and the criterion of slope failure under various factors were analyzed. The results show that： 1 The stability coefficient and shear strength increase linearly and proportionally,and the influence of cohesion and internal friction angle on the slope stability coefficient is determined by their combination; 2 There is a most unfavorable strata dip for every slope angle,when α ∈[25°,50°],the slope stability is relatively poor and α ∈[θ /2 ＋ 5°,θ /2 ＋ 10°]can be obtained based on the experience. 3 The closer the slope angle is to the dip angle of the rock strata,the greater the stability coefficient is,otherwise the smaller the stability coefficient is. 4 The stability coefficient K decreases as the cut out height H increases,when H ∈[1,10],the reduction speed is relatively high,when H ∈[10,50],the reduction speed is relatively slow. 5 The influence of water on the stability coefficient is obvious,which is mainly reflected in the decrease of the shear strength of the weak interlayer and the decrease of slope stability caused by hydrostatic pressure. When the slope fails,the trailing edge crack must reach a certain crack depth,the deeper the crack is,the lower the water filling height is,otherwise the higher the water filling height is. Two failure criteria of bedding slope are summarized： for a slope under the single action of gravity,when H Hmax,the slip failure will occur; for a slope with certain deep cracks in the trailing edge,when ZwZ（wmax）,the hydraulic sliding instability will occur. The research results can provide some guidance for the protection and control of the slope.