双系煤层孤岛结构对工作面矿压显现影响研究

Influence of the Structure of Reverse Ladder Overburden Island on Strata Behaviors during System Coal Mining

为了确定大同矿区侏罗系煤层群开采形成的孤岛覆岩结构对石炭二叠系工作面开采矿压显现的影响,以同忻矿8104、8106工作面为研究对象,通过理论分析确定侏罗系煤层群开采孤岛覆岩结构的形成条件,构建FLAC^(3D)数值模型,分析孤岛覆岩结构对石炭系煤层应力控制及矿压显现特征,并结合微震监测数据进行了合理验证。研究表明:当侏罗系煤层遗留煤柱宽度≥22.3 m时可形成孤岛覆岩结构,煤柱宽度为80 m时,孤岛覆岩结构对石炭系煤层工作面影响达到峰值;数值模拟说明8106工作面及5105巷道受到孤岛覆岩结构影响,其矿压显现强度及范围明显增大,围岩应力最大增至40 MPa;微震监测显示8104工作面推进孤岛覆岩结构过程中,个别微震事件能量级别达到了106J,具备了诱发冲击地压发生能量条件。

In order to confirm the influence on carboniferous coal seam mining strata behaviors caused in structure of reverse ladder overburden island,FLAC3 D numerical calculation model was built based on 8104 and8106 mining face. Combined with microseismic monitoring data,the characteristics of stress control and strata behavior of carboniferous coal seam which caused by structure of reverse ladder overburden island were analyzed. The results show that the structure of reverse ladder overburden island was formed when the width of Jurassic system coal seam legacy pillar exceeded 22.3 m,the peak value of the effects of structure of reverse ladder overburden island on carboniferous coal seam appeared at the width of 80 m. Numerical Simulation indicates that strata behaviors intensity and range were increased obviously due to 8106 mining face and 5105 roadway have been affected by structure of reverse ladder overburden island,a maximum of surrounding rock stress enlarged to 40 MPa. Microseismic monitoring shows that the distribution of the high level of microseismic events on overlying strata increased gradually in the process of 8104 mining face advancing structure of reverse ladder overburden island. Individual energy classification reached 10^6 J,which that may induced rock burst.