近距离煤层煤柱下开采应力分布特征研究

Study on stress distribution characteristics of mining under coal pillar in close distance coal seams

以内蒙古某矿近距离煤层开采条件为研究背景,采用理论分析与数值模拟的方法,研究了6-1_(上)煤层煤柱内压力分布特征和煤柱底板下应力传递规律。理论分析结果表明,6-1_(上)煤层单侧超前支承压力影响距离34.7 m,煤柱两侧支承压力叠加使得应力集中增大,煤柱内应力集中系数7.3,煤柱影响垂直深度32.7 m,影响水平范围41.2 m,6-1煤层的应力集中系数5.1。数值模拟6-1煤层应力集中系数4.8,确定6-1煤层工作面巷道布置距离煤柱5 m。煤柱承载状态稳定,对6-1煤层工作面开采将产生显著影响。为保证下煤层工作面的安全开采,对上煤层煤柱采取钻孔卸压措施,钻孔布置2排三花眼排距500 mm、孔距800 mm,回风巷超前支承应力峰值由12.2 MPa降低至7.8 MPa,取得了良好效果。研究结果可为近距离煤层矿井安全高效开采提供理论依据。

The research background was based on the mining conditions of close range coal seams in a certain mine in Inner Mongolia,the pressure distribution characteristics inside the coal pillar of the 6-1 upper coal seam and the stress transfer law under the floor of the coal pillar were studied by theoretical analysis and numerical simulation.The theoretical analysis results showed that the influence distance of single side advance supporting pressure of 6-1_(upper)coal seam was 34.7 m,the superposition of pressure on both sides of coal pillar increases the stress concentration,the stress concentration coefficient inside the coal pillar was 7.3,the vertical depth affected by the coal pillar was 32.7 m,the horizontal range affected was 41.2 m,and the stress concentration coefficient of the 6-1 coal seam was 5.1.Numerical simulation shows that the stress concentration coefficient of the 6-1 coal seam was 4.8,it was determined that the roadway layout of 6-1 coal seam working face was 5 m away from the coal pillar.The stable bearing state of coal pillar would have significant influence on the mining of 6-1 coal seam working face.In order to ensure the safe mining of the lower coal seam working face,drilling and pressure relief measures were taken for the upper coal seam coal pillar.The drilling holes were arranged in two rows and row spacing was 500 mm,hole spacing was 800 mm,and the peak value of advance supporting pressure of the return airway was reduced from 12.2 MPa to 7.8 MPa,and good results were achieved.The research results can provide theoretical basis for safe and efficient mining of close coal seam.