高边坡开挖卸荷过程强度折减法分析

针对露天矿开采过程中边坡变形破坏严重影响露天矿安全生产的问题，采用数值模拟的方法，应用MidasGTS NX软件建立重钢太和露天铁矿黄家山高边坡三维模型，进行开挖卸荷过程中的应力应变、位移及安全系数变化的数值模拟分析。结果表明：边坡岩体开挖卸荷过程中，随着采场的延深，边坡角的增大,塑性应力带的逐渐向边坡岩体内部扩大，风化破碎层及上部冰碛土层之间产生塑性应变贯通区，破坏面形成。开挖完成后整体边坡坡脚处发生剪切破坏，坡顶后缘形成张拉破坏区，边坡上部冰碛土层形成 “坐落—滑移”式滑动。边坡安全系数随向下开挖过程逐级降低，最终达到1.15稍显偏低。后期开采过程中，需对边坡中上部风化破碎岩层及冰碛土进行加固措施。

Analysis of Strength Reduction Method in Unloading Process of High Slope Excavation

In view of the problem that the deformation and damage of the slope seriously affect the safety production of the open pit mine in the process of open pit mining,a three dimensional model of the high slope of huangjiashan mountain in Taihe Open pit Iron Mine of Chongqing Iron and Steel Group Co.,Ltd.is established by using the numerical simulation method and MidasGTS NX software,and the numerical simulation analysis of the stress strain,displacement and the change of the safety coefficient in the process of excavation and unloading is carried out.The results show that in the process of excavation and unloading of slope rock mass,with the deepening of stope and the increase of slope angle,the plastic stress zone gradually expands to the inside of slope rock mass,and the plastic strain breakthrough area is formed between the weathered broken layer and the upper moraine soil layer,and the failure surface is formed.After the excavation,shear failure occurs at the foot of the whole slope,tensile failure area is formed at the back edge of the slope top,and the moraine soil layer at the upper part of the slope forms "seat slip" sliding.The safety factor of slope decreases gradually with the downward excavation process,and finally reaches 1.15,which is slightly lower.In the later mining process,it is necessary to reinforce the weathered broken rock and moraine soil in the middle and upper part of the slope.