南芬露天铁矿边坡开挖稳定性实验研究

以南芬露天铁矿“298~370滑坡”为例, 基于相似理论构建地质力学模型实验和FLAC^3D数值模拟, 研究不同开挖阶段边坡滑体和锚索的变化特征, 对比分析不同开挖方式对边坡稳定性的影响。地质力学模型实验结果表明, 开挖过程中锚索发生变形弯曲, 滑体破坏前与水平岩体有明显位移差。数值模拟结果表明, 露天矿开采后, X方向产生最大位移17.06 cm, Y方向产生最大沉降10.31 cm, 锚索明显约束滑体竖向位移; 锚索处发生应力集中和位移突变, 与地质力学模型实验结果一致。在实际工程中, 位移突变可作为边坡失稳的监测依据; 分台阶开挖时, 位移和应力变化均小于无台阶开挖, 边坡稳定性更好。

Slope Stability During Excavation of Nanfen Open-Pit Iron Mine

The landslide at level of 298~370 in Nanfen open-pit iron mine was taken as an example in the study. A geomechanical model constructed for it based on the similar theory was taken in an experiment and FLAC^3D numerical simulation. The variation characteristics of slope landslide and anchor cable at different excavation stages were investigated, and impact of different excavation methods on slope stability was also analyzed based on comparison. The experimental results of the geomechanical model show that the anchor cable deforms and bends during the excavation, and there is a significant difference in the displacement between the sliding body and the horizontal rock mass before the sliding body fails. The numerical simulation results show that after open-pit mining, the maximum displacement in the X direction is 17.06 cm, and the maximum subsidence in the Y direction is 10.31 cm. The anchor cable obviously restricts the vertical displacement of the sliding body, and stress concentration and displacement mutation can be found in the anchor cable. It is found that the numerical simulation results are consistent with the experimental results of the geomechanical model. In actual engineering, the sudden change of displacement can be taken as the basis for monitoring slope instability. Compared to the excavation without benching, a benched excavation can bring in smaller displacement and stress variations, thus leading to high slope stability.