基于露天矿岩质边坡的稳定性分析及边坡角优化的需要,提出采用有限元折减强度法与极限平衡法相结合的方法对露天岩质边坡进行稳定分析,并对算例中的最终边坡角进行了优化。该方法首先利用有限元折减强度法计算出边坡内部塑性区,并假定塑性区为边坡潜在的滑动面,从而能够确定滑动面的倾角范围。此后再以此滑动面倾角范围为分析起点,结合极限平衡理论计算出在不同边坡角下的边坡安全系数。通过绘制安全系数随边坡角的变化曲线,即可找出满足安全阈值的最优边坡角。最后,采用该方法对兰伯特角铁矿中部矿区上盘边坡角进行了优化,证明了该方法的可行性。

A hybrid methodology combining strength reduction of Finite Element Method(FEM) with limit equilibrium theory is presented to evaluate rock slope stability by considering the demand for slope stability analysis and slope angle optimization of an open-pit, and it is applied to a case study for optimizing slope angle. The methodology uses the strength reduction of FEM to identify the plastic area in slope preliminary, which is supposed to be the most likely sliding surface. Thus the range of sliding surface inclination could be regularized. And then by taking this sliding surface as a start point of analysis, the limit equilibrium theory is used to calculate safety factors under different slope angles. By plotting the curve of safety factors with respect to different slope angles, the optimal inclination of a slope which is met to safety threshold could be determined. Finally, the upper slope located in the central part of open-pit iron mine, Cape of Lambert is presented to demonstrate this methodology. Results show that this approach is effective to deal with the analysis of rock slope stability.