开挖对露天矿山软弱夹层边坡稳定性的影响分析-以南芬铁矿为例

以露天矿高边坡为背景,对分步开挖条件下含有软弱夹层边坡的稳定性问题进行了研究,采用三维有限差分程序,对比分析了不含软弱夹层和含有软弱夹层两种不同边坡计算模型受开挖效应的影响情况。水平位移云图和位移矢量图表明,开挖条件下,不含软弱夹层边坡水平方向位移变化不大;含有软弱夹层边坡水平方向位移增大明显,位移变化区域受夹层控制显著。对比剪应变增量云图表明,剪应变较大值最先出现在滑体下部弱层区,随着分步开挖进行,剪应变增量较大区域逐渐向上部弱层扩展,呈现出逐渐贯通趋势,说明含有软弱岩层边坡对工程开挖十分敏感。

Influence of Excavation on Stability of Slope with Weak Interlayer in Open Pit Mine

Based on the high slope of open pit mine, the stability of slope with weak interlayer under the condition of step excavation was studied. By using three-dimensional finite difference program, the influence of excavation effect on two different calculation models of slope without weak interlayer and with weak interlayer was compared and analyzed. The results of horizontal displacement nephogram and displacement vector graph show that the horizontal displacement of slope without weak interlayer changes little under excavation conditions. The horizontal displacement of slope with weak interlayer increases obviously, and the displacement change area is controlled by interlayer. Comparing with the incremental shear strain nephogram, it is shown that the larger shear strain first appears in the weak layer area at the lower part of the sliding body. With the step-by-step excavation, the area with large increment of shear strain gradually expands to the upper weak layer, showing a gradually penetrating trend. It shows that the slope with weak rock stratum is very sensitive to engineering excavation.