倾向煤柱边界超前失稳对工作面出煤柱动载矿压的影响

Influence of leading instability in the upper dip coal pillar boundary to the strong strata behaviors during the working face out of the pillar

针对近距离煤层工作面出上覆倾向煤柱时的动载矿压问题,采用理论分析、数值模拟以及工程验证的方法,从煤柱边界超前工作面失稳的角度阐述了其对动载矿压灾害的抑制机理,并就煤柱埋深、煤层间有无关键层以及煤柱边界有无空巷等因素对煤柱边界超前失稳的影响规律进行了研究。结果表明:工作面临近推出上覆倾向煤柱时,煤柱边界的超前失稳会造成上部关键块体提前发生反向回转,从而能在工作面出煤柱时削弱关键块体结构回转运动对煤层间岩层作用的能量,最终减弱动载矿压灾害发生的几率和强度。上覆倾向煤柱埋深大、煤层间无关键层以及煤柱边界存在空巷均易导致煤柱边界发生超前失稳,从而可对动载矿压灾害的发生发挥明显的抑制作用。对于煤层埋深较浅或煤层间仅存在一层关键层等动载矿压灾害易发生的开采条件,可在处于下煤层工作面出煤柱一侧边界内开掘空巷,或对此区域实施人工预爆破,促使煤柱边界在工作面临近出煤柱时发生超前失稳,从而达到防治动载矿压灾害的目的。研究结果得到了神东矿区活鸡兔井和补连塔煤矿4个工作面出煤柱开采工程实例的验证。

Aiming at the problem of the strong strata behaviors during the working face out of the upper dip coal pillar in contiguous seams, adopted theoretical analysis, numerical simulation and engineering verification from the view of the instability in the upper coal pillar boundary occurring ahead of the face described the inhibitory mechanism that re- sults in strong strata behavior disasters, and studied the influence law of the leading instability in coal pillar boundary that affected by buried depth of coal pillar, with or without key strata between coal seams, with or without abandoned roadway in coal pillar boundary and others. The results show that when the working face closes to push-out of the upper dip coal pillar, the reverted turning in upper key blocks will take place in advance, which caused by the instability of coal pillar boundary in advance, so weakening the energy generated when key block structure make turning motion on strata between the seams and eventually weakening the possibility and intensity of strong strata behavior disasters. Great depth of the upper dip coal pillar, without key strata between coal seams and abandoned roadway existed in the dip coal pillar boundary are easily led to instability in coal pillar boundary occurring ahead, thus which will play a sig- nificant inhibition on the occurrence of strong strata behavior disasters. For the mining conditions of the shallow burieddepth of coal seams or only one key strata existing in coal seams which easy to lead the strong strata behavior disas- ters, we can dig abandoned roadways within the boundary of the coal pillar which is corresponding to the side of the under working face out of the pillar or carry out artificial pre-blasting in this area, which cause the coal pillar boundary occurring instability in advance at the time of working face close to out of the pillar and so as to get the purpose of con- trolling mine disasters of strong strata behavior. The results are verified with mining engineering projects in four work- ing faces of Huojitu ＆ Bulianta Coal Mine in Shendong mining area.