急倾斜巨厚煤层开采深度影响的覆岩能量演化规律研究

Study on the evolution law of overburden energy of steeply inclined extra-thick coal seam influenced by mining depth

针对急倾斜巨厚煤层开采深度影响下的能量变化及传递问题,采用物理模拟实验方法,运用微震监测设备,对开采深度影响的能量分布及其变化特征加以分析,由微震事件聚类分析理清开采深度影响的能量迁移路径,结合数值模拟实验得到开采深度对急倾斜煤岩体弹性能与水平应力的影响规律,掌握向深开采诱使动力灾害发生的能量动态响应特征,形成急倾斜巨厚煤层动力灾害防治理念与策略。研究结果表明:伴随着急倾斜巨厚煤层开采深度的增加,集中区域内峰值能量大小及集中程度明显增加,微震能量、频次、大能量事件的数量与占比明显增大;煤岩弯曲加载蓄能源头主要位于综放面开采水平及其上方2个开采阶段的夹持岩柱范围内,能量主要沿夹持岩柱作为优势路径进行能量传导,且向深开采过程中的震源中心存在由岩柱中部向两端逐渐偏移的变化趋势。急倾斜煤岩体能量密度峰值、高能量积聚区的面积均随开采深度的增加而增大,当工作面采至+400水平时较+475水平的峰值应力增加约30.14%,增速约为0.11 MPa/m。开采深度增加使得工作面单次推进的最大水平应力变化量明显增加,即工作面单次推进下的加载速率增大。通过模拟实验与现场微震实测的综合分析,揭示了急倾斜巨厚煤层向深开采过程中动力灾害发生“靶向源头-优势传导路径-释放终端”机制,并提出了“弱化源头-转移路径-加强终端”的急倾斜巨厚煤层向深开采的动力灾害防治理念。研究结果为急倾斜巨厚煤层的安全开采提供了科学依据。

Aiming at the problem of energy change and transmission under the influence of the mining depth in steeply inclined extra-thick coal seam,the physical simulation experiment method and microseismic monitoring equipment were used to analyze the energy distribution and its change characteristics.By cluster analysis of microseismic events,the energy migration path affected by the mining depth is clarified,and the influence law of the mining depth on the elastic energy and the horizontal stress of steeply inclined coal and rock mass is obtained by numerical simulation experiment.The dynamic response characteristics of energy induced by the deep mining are mastered,and the concept and strategy of power disaster prevention and control in steeply inclined extra-thick coal seam are formed.The results show that with the increase of the mining depth of steeply inclined extra-thick coal seam,the peak energy and concentration degree in concentrated areas obviously increase,and the number and proportion of microseismic energy,frequency and large energy events obviously increase.The bent loaded energy storage head of coal and rock is mainly located in the range of the clamping rock pillar in the mining level of fully mechanized top-coal caving face and the two mining stages above it.The energy is mainly conducted along the clamping rock pillar as the dominant path.And in the process of deep mining,the focal center gradually shifts from the middle of the rock pillar to both ends.The peak energy density of steep coal rock mass and the area of high energy accumulation area all increase with the increase of mining depth.When the mining face reaches+400 level,the peak stress increases by about 30.14%compared with+475 level,and the growth rate is about 0.11 MPa/m.With the increase of mining depth,the maximum horizontal stress variation of the single advance of the working face obviously increases,that is,the loading rate of the working face increases under the single advance.Through the comprehensive analysis of simulation experiment and field microseismic measurement,this paper reveals the mechanism of“Target source-predominant conduction path-release terminal”of dynamic disasters in deep mining of steeply inclined extra-thick coal seam,and puts forward the concept of dynamic disaster prevention and control of deep mining in steeply inclined extra-thick coal seam with“Weaken the source-transfer the path-and strengthen the terminal”.The research results provide a scientific basis for the safe mining of steeply inclined extra-thick coal seam.