高位钻孔不同封孔方法质量检测及其优选

为优选出高位钻孔最佳的封孔方式，通过理论分析给出钻孔漏气6种表现形式，并推导出钻孔漏气量及漏风率的计算公式，进而基于不同钻孔深度瓦斯浓度及抽采负压的变化率确立钻孔漏气位置、漏气量、漏气率等封孔质量定量判定指标体系。结合封孔质量探测结果、操作难易程度及经济成本建立封孔方法优劣的多因素评价方法，并对聚氨酯式常压封孔（方法1）、囊袋式注浆带压封孔（方法2）、钻屑回填式注浆带压封孔（方法3）3种方法进行综合评价分析。研究结果表明:方法1～3的封孔段平均瓦斯浓度分别为5.6%，3.2%及8%，方法1对应的瓦斯浓度与抽采负压均出现突降，方法2对应的抽采负压在8～14 m出现突降，方法3则较稳定。故判定三者封孔质量为钻屑回填式＞囊袋式＞聚氨酯式，结合成本分析和操作难易综合分析确定高位钻孔的最优封孔方式为钻屑回填式注浆带压封孔。

Quality inspection and optimization of different sealing methods for high level borehole

In order to optimize the best sealing method for the high level borehole,six expression forms of borehole leakage were given through the theoretical analysis,and the calculation formulas of borehole leakage volume and air leakage rate were derived,then a quantitative evaluation index system of sealing quality such as the leakage position,leakage volume,and leakage rate of the borehole was established based on the change rates of gas concentration and drainage negative pressure under different borehole depths.A multi factor evaluation method for the advantages and disadvantages of the sealing method was established by combining with the detection results of sealing quality,difficulty level of operation,and economic cost,and the comprehensive evaluation analysis was conducted on three types of method including the polyurethane atmospheric pressure sealing (method 1),the capsular grouting with pressure sealing (method 2),and the drill cuttings backfill grouting with pressure sealing (method 3).The results showed that the average gas concentrations in the sealing sections by the methods 1-3 were 5.6%,3.2%,and 8%,respectively.Both the gas concentration and drainage negative pressure corresponding to the method 1 had the sudden drop,and the drainage negative pressure corresponding to the method 2 presented the sudden drop from 8 to 14 m,while the method 3 was more stable.Therefore,it was determined that the sealing quality of the three was method 3>method 2>method 1,and the optimal sealing method for high level borehole was the drilling cuttings backfill grouting with pressure sealing combined with the comprehensive analysis of cost analysis and operational difficulty.