特厚煤层掘进巷道两帮卸压钻孔合理参数数值模拟研究

Numerical simulation study on the optimal parameters for destressing boreholes in the two ribs of excavation roadways in extra-thick coal seam

目前钻孔卸压技术为冲击地压矿井巷道掘进期间防冲主要措施之一,钻孔布置和参数决定着卸压效果。目的为了探讨特厚煤层掘进巷道两帮卸压钻孔合理布置参数,方法基于耿村煤矿综放工作面运输巷道地质采矿条件,利用数值计算方法研究掘进巷道两帮在单排布置时孔深、孔径、孔间距,双排布置时排距等不同参数条件下,巷道围岩应力云图和两帮垂直应力分布特征。结果结果表明:(1)单排布置卸压钻孔时,随着孔深、孔径递增,巷道两帮高应力区逐渐向深部围岩转移,而巷道两帮浅部围岩处于低应力区。(2)当钻孔孔深、孔径达到一定值时,巷道两帮支承压力由“单峰型”转化为“双峰型”,浅部围岩处于临界卸压状态;随着孔深、孔径继续增加,巷道两帮处于过度卸压状态。(3)利用卸压后、无卸压时巷道两帮高应力区向深部围岩的转移量ΔL、峰值应力处距巷道表面距离的比值η表示临界卸压和过度卸压状态,确定出卸压钻孔的合理参数。在耿村煤矿13230综放工作面运输平巷进行超前钻孔卸压和锚网索+36U型可缩性金属支架二级支护后,对巷道两帮实施钻孔卸压防冲,效果显著。结论研究结果对冲击地压矿井回采巷道掘进期间的卸压防冲具有指导和借鉴意义。

At present,borehole destressing technology is one of the main measures to prevent coal bump during roadway excavation in coal mines.Objectives Borehole layout and parameters determine the destressing effect.Methods Based on the geological and mining conditions of the roadway in the fully mechanized caving face of Gengcun Coal Mine,the numerical calculation was used to study the stress cloud diagram of the surrounding rock of the roadway and the vertical stress distribution characteristics of the two ribs of the roadway,while the destressing boreholes were arranged with different borehole depths,diameters and row spacings in singlerow and with different double row spacings in double-row.Results The results are as follows.(1)While the destressing boreholes are arranged in a single row,with the increase of borehole depth and diameter,the higher stress area of the two ribs of the roadway gradually shifts to the deep surrounding rocks,but the shallow surrounding rock of the two ribs of the roadway is in the lower stress area.(2)When the depth and diameter of the boreholes reach a certain value,the abutment pressure curve of the two ribs of roadway is changed from single peak to double peak one,and the shallow surrounding rock of the two ribs is in a critical destressing state.As the borehole depth and diameter continue to increase,the two ribs of roadway are in a state of excessive destressing.(3)By using the transfer amountΔL of the high stress zone of the two ribs of the roadway to the deep surrounding rock and the ratioηof the distances between the peak stress and the surface of the roadway after its destressing and without destressing boreholes,the two quantitative indexes are used to represent the critical destressing and excessive destressing states,and the reasonable parameters of the destressing boreholes are determined.It is the advanced destressing boreholes and secondary supporting with bolting and cable anchor plus 36U type retractable metal support,that was implemented in the roadway of longwall caving face 13230 in Gengcun Coal Mine,the implementation effect of deep borehole destressing and anti-impact on the two ribs of the roadway is remarkable.Conclusions The conclusions have reference and guiding significance for the prevention of coal bumps during the excavation of roadway in coal mine.