非贯通节理岩体边坡稳定性及破坏规律的数值分析

非贯通节理普遍存在于岩体边坡中,并对边坡的稳定性产生较大影响。利用数值分析软件Optum G2建立2类含非贯通节理岩体边坡的稳定性分析模型,采用shear joint单元模拟非贯通节理,基于有限元强度折减法得到不同节理(组)倾角、节理长度和岩桥长度下边坡的稳定系数F及破坏规律。研究结果表明,第一类模型中,随节理倾角α的增大,F先减小,再增大,最后基本保持不变。节理倾角等于边坡倾角时(α=60°),F有最小值,且节理长度越大,最小值越小,此时破坏面为由非贯通节理向坡脚发育的近圆弧状破坏面,而在其它倾角方向则影响较小;第二类模型中,随节理组倾角θ的增大,F先急剧减小(θ=30°时为最小值),再缓慢增大,最后缓慢降低。岩桥长度越小,F越小,在θ=30°时最为显著。此时破坏面呈不规则状,节理裂隙扩展路径由重力作用从上往下发展,并由一非贯通节理端部向相邻节理端部直线发展,当岩桥长度较小时,节理裂隙扩展路径更为复杂和密集。

NUMERICAL ANALYSIS FOR STABILITY AND FAILURE CHARACTERISTIC OF INTERMITTENT JOINTED ROCK SLOPE

Intermittent joints are generally found in rock slope,which have a great influence on the stability of rock slope.Two kinds of the stability analysis models were built for the intermittent jointed rock slopes by the numerical analysis software OptumG2.The shear joint element was used to simulate the intermittent joint in rock slope.Based on the strength reduction method of FEM,the safety factor F and the failure characteristic of rock slope were obtained with different dip and length of joint (set) and length of the rock bridge.The resuhs show that,in the first models,with the increase of the joint inclination angle,F decreases first,then increases,and finally remains the same.When α =60°,the safety factor reaches the minimum value.The larger the length of intermittent joint,the smaller the minimum value.And the failure surface is close to the slipping arc which is developed from the intermittent joint to the slope foot.In other cases,the impact is not obvious.For the second model,the slope safety factor F decrease sharply (F reaches the minimum value,when θ =30°),increase and then decrease slowly with the increase of θ.The shorter the length of rock bridge,the smaller the F.And when θ =30°,the im pact is the most obvious.The failure surface is irregular,and the cracks propagation path which are linear between adjacent crack-tips develop downward under the influence of gravity.When the length of rock bridge is shorter,the cracks propagation path is more complex and dense.