采动过程金属矿山空区覆岩材料细观破裂特征

Meso-cracking Characteristic of Overburden Strata Material over Metal Mine Goaf under Mining Process

采空区覆岩材料的破裂与其应力变化关系密切,采用仿真试验方法,研究了在开采过程中金属矿山采空区覆岩材料在拉应力和剪应力作用下细观破裂特征。声发射是覆岩材料受外力作用发生破裂时释放的能量,其出现的位置和能量的大小间接反映了覆岩材料发生破裂的位置和严重程度。岩石材料发生破裂的主要原因是拉应力和剪应力,剪应力主要集中在采空区四周边角区域,拉应力主要集中在采空区顶板区域。剪应力和拉应力对覆岩材料的细观破裂都造成影响;最大剪应力值为11.4 MPa远比最大拉应力值7.77 MPa大,但拉应力的破坏效果更显著。剪应力是造成覆岩塑性破坏的重要因素,拉应力是覆岩垮落的主导因素。研究结果可为金属矿山安全开采提供一定参考依据。

Cracking characteristics of overburden strata material over metal mine goaf has close relationship with the changes of stress. By using simulation methods,this paper studies the meso-cracking characteristics of overburden strata material over mining goaf under tensile and shear stress during the process of metal mining. Acoustic emission（ AE） is the energy released by the overburden strata material burst under the external force,and its location and size are used to predict the location and extent of overburden strata material fracture. The tensile stress and shear stress are the main reasons for rock fracture. Shear stress appears mainly in the area around the edges and corners of goaf,while tensile stress mainly concentrates at the goaf roof. Both shear stress and tensile stress have significant impact on meso-cracking of overburden strata material. Although the value of shear stress is 11.4 MPa much larger than 7.77 MPa of tensile stress,the destruction of the tension effect is more significant. Shear stress is one of the important factors,while tensile stress is the dominant factor in the collapse of overburden strata. The results of this research could provide reference for the safety in metal mining.