仿岩孔条件下顺层钻孔瓦斯压力测定技术研究

在利用煤孔测定本煤层瓦斯压力的过程中,为从根本上封堵煤层钻孔周围的裂隙,解决煤层钻孔易变形、塌孔的问题,提出了仿岩孔瓦斯压力测定方法。钻孔失稳破坏的力学分析表明,钻孔破碎带半径与围岩的岩性有关,提高围岩内摩擦角和内聚力是增大围岩强度的有效途径。通过分析煤层固化成孔的机理和数值模拟发现,高压注浆加固煤体可以增大孔壁围岩强度。现场对比试验表明:仿岩孔测压技术与岩孔测压差值为0.02 MPa,相对误差仅为3.85%,仿岩孔测压技术具有较好的可行性。

Pressure measurement technology of drilling borehole down the seam in imitative rock hole

During the measurement of gas pressure in borehole embedded in coal seam, drilling defor-mation and collapse are very difficult to avoid. In order to fundamentally seal the cracks around bore-hole in coal seam, gas pressure measurement method conducted in borehole embedded in imitative rock has been put forward in this paper. The mechanical analysis of drilling instability shows that the radius of drilling fracture zone is relevant to rock lithology. Improving the internal friction angle and the cohe-sion of surrounding rock is an effective way to enhance the strength of rock. Moreover, through mecha-nism analysis of solidified borehole in coal seam and numerical simulation, it has been found that high pressure grouting technique applied to coal seam can strengthen the intensity of borehole surface. Field comparison tests show that the difference between gas pressure measured in imitative rock borehole and rock borehole is 0.02 MPa and its relative error is only 3.85%. Consequently, gas pressure measurement method in imitative rock borehole is feasible and has a promising future.