易失稳瓦斯抽采钻孔加固技术数值模拟研究

Numerical simulation on reinforcement technique of instability borehole in gas extraction

针对松软煤层瓦斯抽采钻孔稳定性差、钻孔形变较大、钻孔及周围煤体漏风严重等造成钻孔密封难的技术难题,提出了预先采用加固技术来提高松软煤层瓦斯抽采钻孔的稳定性,合理的解决钻孔高效密封的现实难题。首先,阐述了易失稳瓦斯抽采钻孔加固技术的基本原理。其次,利用FLAC3D模拟软件对比分析了松软煤层、硬质煤层在不同固孔材料固化后钻孔周围位移场变化。研究表明:采取固孔措施后的钻孔相比措施前等值线分布稀疏,梯度较小,不同位置处的煤体的位移量差别较小。钻孔形成后,顶部位移量均大于底部位移量,左右两帮的位移量基本相同,有效的降低钻孔周边煤体的位移变化量,增强钻孔稳定性,为钻孔的高效密封提供了保障。

Aiming at the technical problems of difficult borehole sealing caused by the poor stability of borehole, the larger deformation of borehole and the serious air leakage at borehole and surrounding coal in gas extraction of soft coal seam, it was put forward that the reinforcement technique should be applied in advance to improve the stability of borehole, so as to solve the practical problem of efficient sealing for borehole. The basic principle of reinforcement technique for instability borehole in gas extraction was illustrated, and the change of displacement field around the borebole after solidification by different solidified material in soft coal seam and hard coal seam was compared and analyzed by using the simulation software of FLAC3D. The results showed that compared with the borehole without the measure, the borehole adopting the reinforcement measure has a contour with sparse distribution and a small gradient, and the amount of displacement for the coal in different positions has a small difference. After the formation of borehole, the amount of displacement at the top is larger than that at the bottom, and the amount of displacement at both sides is same basically. The use of reinforcement technology can effectively reduce the amount of displacement in surrounding coal of borehole and enhance the stability of borehole, and it provides a guarantee for efficient sealing of borehole.