采动覆岩高位离层演化特征及涌( 突) 水前兆信息研究

采用理论分析、物理模拟和数值模拟相结合的方法,重点研究了招贤煤矿工作面的高位离层的时空演化,并将开采期间水位变化、微震监测数据作为高位离层涌(突)水前兆信息,揭示了特厚煤层综放开采覆岩主控裂隙(纵向主导水裂隙和横向离层裂隙)演化特征及离层水害机理。以永陇矿区招贤煤矿为研究对象,黄陇侏罗系煤田永陇矿区煤层覆岩具有弱胶结、泥质含量高和单层厚度大等特点,侏罗系覆岩之上为巨厚高水压白垩系含水层,厚及特厚煤层开采时易在侏罗-白垩系交界上下形成高位离层积水;当导水裂隙与高位离层积水沟通时,形成离层水害。离层水害具有瞬时性、大流量并伴随强烈矿山压力显现等特点。研究结果表明:当工作面达到充分开采时,采空区两帮离层裂隙较为发育,中部处于压实区,最大横向高位离层位于梯形破坏区顶部;工作面上覆亚关键层的周期性破断造成工作面周期性来压、高位离层空间周期性扩张、闭合,导致宜君组水位周期性异常下降;工作面经长时间停采,恢复开采后,重复扰动覆岩诱发覆岩岩体结构失稳,导水裂缝带沟通离层空间,造成离层涌(突)水;水位突降、水位下降速率突增、微震大能量事件可作为1304工作面突水前兆信息;关键层的破断会引起微震能量事件,伴随关键层的快速回转、下沉扩大离层空间,造成宜君组水位异常下降;工作面多次复采造成覆岩自稳能力逐渐劣化严重,加快离层涌(突)水通道形成,离层涌(突)水通道逐步增大;随着出水次数增加,水位提前下降时间减少,微震能量事件能量降低,涌水量增大;采动过程中离层涌(突)水的前兆信息-白垩系含水层的水位变化以及矿井微震监测数据验证了模拟结果是可信的。

Study on evolution features of high level overburden separation layer and precursor information of water inrush during coal mining

This paper focuses on the space-time evolution of high-level separation strata in Zhaoxian coal mine by using the methods of theoretical analysis,physical simulation and numerical simulation.Taking the water level change and microseismic monitoring data during the mining period as the precursor information of water inrush from high-level separated strata,the evolution characteristics of main con?trolling fractures(longitudinal dominant fractures and transverse separated fractures)in overlying strata and the mechanism of water disas?ter from separated strata in fully-mechanized top coal caving mining of extra thick coal seam are revealed.The coal seam overburden in Yonglong mining area of Huanglong Jurassic coalfield has the characteristics of weak cementation,high argillaceous content and large single layer thickness.The Jurassic overburden is a Cretaceous aquifer with huge thickness and high water pressure.When mining thick and extra thick coal seams,it is easy to form high-level separated layer water above and below the Jurassic Cretaceous boundary.When the water flowing crack communicates with the high-level separated layer water,the separated layer water disaster is formed.Separated layer water disaster has the characteristics of instantaneity,large discharge and strong mine pressure behavior.The research results show that:when the working face reaches full mining,the two sides of the goaf separation fractures are relatively developed,the middle part is in the com?paction area,and the maximum horizontal high separation layer is at the top of the trapezoidal failure area.The periodic breaking of the sub key strata on the working face results in the periodic weighting of the working face,the periodic expansion and closure of the high separa?tion layer space,and the periodic abnormal decline of the water level of the Yijun formation.After stoping for a long time and resuming mining,the overburden rock mass structure instability is induced by repeatedly disturbing the overburden rock mass,and the water flowing fracture zone connects with the separated layer space,resulting in the separated layer gushing(water inrush).The sudden drop of water level,the sudden increase of water level drop rate and the microseismic large energy events can be used as the precursory information of water inrush in No.1304 working face.The breaking of the key layer will cause microseismic energy events.With the rapid rotation and sinking of the key layer,the space of separated layer will be expanded,resulting in the abnormal decline of water level in Yijun formation.The repeated mining of working face results in the gradual deterioration of overburden self stability ability,accelerates the formation of sep?arated layer water inrush channel,and gradually increases the separated layer water inrush channel.With the increase of outflow times,the time of water level falling ahead of time decreases,the energy of microseismic energy event decreases,the water inflow increases.The pre?cursory information of water inrush from separated strata during mining the water level change of Cretaceous aquifer and the monitoring data of mine microseism verify that the simulation results are reliable.