金属矿山复杂采空区围岩破坏及岩层移动机制研究

Mechanism of surrounding rock failure and strata movement in complex goaf of metal mines

以武钢资源集团金山店铁矿东区为依托工程,厘清矿区工程地质条件和矿体开采情况;通过地压显现调查和微震破裂监测开展复杂采空区围岩破坏空间特征分析;结合三维数值模拟、围岩破裂监测和巷道破坏调查结果阐明矿区上下盘围岩破坏机制,提出基于岩体塑性破坏的围岩破坏角不连续变形分析指标,并与陷落角指标进行对比验证,揭示金属矿山复杂采空区引起的平面和剖面方向上岩层移动规律。研究结果表明:围岩破坏和巷道地压显现围绕采空区分布,在平面上半月形采空区凸出形状对两翼围岩破坏具有放大效应,在剖面上分段运输巷道破坏具有高程滞后发生的特点;采空区围岩破坏最初以顶部岩体垮塌冒落为主,随着采矿推进发展为断层滑移控制的筒状冒落破坏,最后扩展成为岩体结构控制的贯通滑移破坏,上盘围岩呈现倾倒-滑移破坏特征,下盘围岩呈现追踪断层和结构面的剪切-滑移破坏特征;不同勘探线剖面的上盘和下盘围岩破坏角和陷落角的数值及变化规律较为一致,均随采矿进程近似呈现先减小后趋于稳定的变化规律;上盘采空区(FeI)为条带状展布,趋于稳定的破坏角在不同勘探线位置近似一致,且主控优势结构面倾角越大,其稳定破坏角越小;下盘采空区(FeII)呈半月形平面形状展布,半月形中间凸出位置的稳定破坏角较大,两翼位置角度较小,且距离中间位置越远其角度越小。研究结果对指导矿山安全生产和保障周边居民正常生活具有重要意义。

Taking the east area of Jinshandian iron mine of Wuhan Iron and Steel(Group)Company as a relying project,the engineering geological condition of the mine area and the mining process of the ore body were clarified.The spatial characteristics of surrounding rock failure in complex goaf were analyzed by ground pressure behavior investigation and microseismic fracture monitoring.Combining with the results of three-dimensional numerical simulation,surrounding rock fracture monitoring and roadway failure survey,the failure mechanisms of surrounding rocks in hanging wall and footwall of the mining area were elucidated,and the analysis index of discontinuous deformation of surrounding rock failure(i.e.,failure angle)was proposed based on the plastic failure of rock mass,which was verified by comparing it with the collapse angle index.Furthermore,the strata movement laws in both the plane and profile directions caused by the complex goaf in metal mine were revealed.The results show that the failure of surrounding rock and the ground pressure behavior of roadway are distributed around the goaf.On the plane,the convex shape of the half-moon goaf has a magnifying effect on the failure of the surrounding rocks of its two wings.On the profile,the failure of the haulage roadways in the sublevels has the characteristics of elevation lag.Initially,the failure of the surrounding rock in the goaf is mainly caused by the collapse and caving of the rock mass at its top position.As mining progressed,it develops into the fault-slip-controlled chimney caving failure,and finally expands into the through-slip failure controlled by the rock mass structure.The surrounding rock failure of hanging wall presents the characteristics of toppling-slip failure,while that failure of footwall presents the characteristics of the shear-slip failure tracking the faults and structural surfaces.Moreover,the values and variations of the failure and collapse angles of the surrounding rocks of the hanging wall and the footwall are relatively consistent for various exploration line profiles,and these two angles are approximate to show the first decrease after the tendency to stabilize with the mining process.In addition,the hanging wall goaf(FeI)spreads like a strip,and the failure angles that tends to be stable are approximately the same at different exploration lines,and the larger the inclination angle of the main dominant structural surface,the smaller the stable failure angle.Whereas,the footwall goaf(FeII)is distributed in a half-moon plane shape.The stable failure angle in the middle position of the half-moon is larger compared to its two wings,and this angle decreases with increasing the distance between its location and the middle position.The research results are of great significance for guiding the safety production of the mine and ensuring the normal life of the neighboring residents.