In order to ensure the outburst prevention effect of a joint mining with a underneath protective seam and the surrounding rock with long distance and ultra thin and to reduce the outburst prevention cost and many other problems occurred from the over mining of the seam and surrounding rock,taking Zhongtai Company as an example,with the analysis on the factors of the protective seam No.1-8 seam mining with a long distance and ultra tine affected to the protective effect of No.2-1 seam,the location of No.2-1 seam in "caving zone,fracture zone,bending subsidence zone" was calculated under the deferent mining height in No.1-8 seam.The RFPA2D was applied to simulate the deformation condition of No.2-1 seam when the mining height of the lower protective seam was 0.5 m,1 m and 1.5 m.In combined with the results of the theoretical analysis and simulation,when the mining height of the protective seam was determined as 1 m,the permeability coefficient of No.2-1 seam would be increased by 106 times and the max swelling deformation value would be 0.613％.The site experiment showed that when the mining height of the coal mining face in No.1-8 seam was 1 m,the gas drainage volume from the mining seam within the protected scope of No.2-1 seam was reached at 14 m3/min,the max residual gas content of the seam would be only 1.83 m3/t and the protected seam had an excellent regional outburst prevention effect.%为保证远距离极薄下保护层与其围岩一起开采的防突效果,降低过量开采煤层围岩产生的防突费用,以中泰公司为例,通过分析开采远距离极薄下保护层一8煤层对二1煤层保护效果的影响因素,计算出一8煤层不同采高下二1煤层在“上三带”的位置;运用RFPA2D模拟下保护层采高为0.5、1.0、1.5m时二1煤层的变形情况.综合理论分析和模拟结果,确定保护层开采高度为1 m时,二1煤层透气性系数增大106倍,最大膨胀变形量达0.613％.现场试验表明,一8煤层工作面采高为1 m时,二1煤层被保护范围内本煤层瓦斯抽采量达到14 m3/min,煤层最大残存瓦斯含量仅为1.83 m3/t,被保护层取得了良好的区域防突效果.
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