为了对混合开采孤岛面冲击矿压进行预报和控制,采用离散元数值计算程序UDEC4.0,对混合开采孤岛面围岩的应力分布、变形规律以及顶分层煤柱的稳定性进行了模拟研究,并结合现场观测分析了混合开采孤岛面的矿压显现特征。研究表明:1)孤岛煤柱开采过程中,上覆岩层引起的应力通过15 m煤柱向下传递至工作面,煤柱两侧6~8 m范围形成高应力区。2)下分层孤岛工作面两侧开采结束,煤层上方10.08 m处和147.3 m处测点的最大下沉量分别达到7.84 m和3.6 m,分别是采高的83.4%和38.3%。3)顶分层、孤岛面两侧煤层采后,15 m煤柱垂向压缩量分别为原始高度的38.8%和59.4%,15 m煤柱基本被压酥,己经失去支撑能力。4)现场实测孤岛面初次来压步距为23.2 m和周期来压步距为11.78 m,与数值模拟得到的规律基本一致。
In order to forecast prevention and control the rock burst of insular face of mixed mining,the discrete element numerical calculation program UDEC4.0 were applied to simulate and analyze the stress distributions and deformation law of the surrounding rocks on insular face of mixed mining and the stability of the coal pillar of top slice,this paper also analyzes the characteristics of strata behavior on insular face of mixed mining combined with field test data.The result shows that 1)during mining periods of coal pillar,the stress casued by overlying strata was transferred downward to working face,and high stress area formation on both sides of coal pillar 6~8 m.2) after caving both sides of island face in lower layered,the maximum value of sinkage of measuring points which located at the top of coal seam 10.08m and 147.3m respectively reach 7.48m and 3.6m,which are 83.4% and 38.3% of mining height,respectively.3) after exploiting the coal seam of top slice and both sides of island working face,the vertical compressive deformation of 15m coal pillar respectively reach 38.8% and 59.4% of original high of pillar,the pillar basically been crushed and lost supporting ability,and 4) the field measurement result shows that the first weighting interval is 23.2m and periodic weighting length is 11.78m,which were basically identical with the numerical simulation result.