特厚煤层充分采动覆岩下沉规律研究

Research on subsidence law of overlying strata in full mining of extra-thick coal seam

  • 摘要: 大同矿区特厚煤层临空工作面开采过程中强矿压显现问题较开采首采工作面时严重。为研究特厚煤层充分采动条件下的覆岩运移规律,采用采动覆岩内部岩移无线远程监测系统、钻孔电视窥视技术,对同忻煤矿8202工作面覆岩下沉位移变化进行了监测与分析,结果表明:特厚煤层大空间开采早期,覆岩会超前工作面出现自上而下的岩层变形破坏现象,之后才发生自下而上正常的层组破断下沉运移;采场覆岩变形破坏呈现阶段性台阶跃升的变化特征,与关键层所处位置具有一致的对应关系,表明关键层在岩层运动中起主控作用;充分采动条件下覆岩运动出现联动下沉现象。通过物理模拟试验进一步研究了充分采动时覆岩全地层联动下沉的本质,结果表明在主关键层初次破断前,各关键层的分组分层运动趋势较明显,当主关键层初次破断后,受各关键层周期破断长度及上下岩层复合破断规律的影响,覆岩下沉运移更易呈现全地层联动现象。

     

    Abstract: The problem of strong mine pressure during the mining of the near goaf working face in Datong coalfield is more serious than that of the first mining face. In order to study the overlying strata movement law under the full mining conditions of extra-thick coal seam, the overlying strata movement of 8202 working face in Tongxin Coal Mine is monitored and analyzed by using a wireless remote monitoring system for internal strata movement of overlying strata under mining condition and borehole TV observing technology. The results show that in the early stage of large space mining of extra-thick coal seam, the overlying strata will be deformed and damaged from top to bottom in the advance working face, and then the layer group will break down and move normally from bottom to top. The overlying strata deformation and destruction in the mining site shows the change characteristics of stage step-up jump, which has a consistent correspondence with the location of the key strata, indicating that the key strata play the main control role in the strata movement. Under the condition of full mining, the overlying strata movement appears linkage subsidence phenomenon. Through physical simulation experiments, this paper further studies the nature of the whole-strata linkage subsidence of the overlying strata during full mining. The results show that before the initial breaking of the main key stratum, the grouped layered movement trend of each key layer is more obvious. After the main key stratum breaks for the first time, affected by the periodic breaking length of each key stratum and the compound breaking law of the upper and lower rock layers, the overlying strata subsidence and movement is more likely to show the whole-stratum linkage phenomenon.

     

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