Bao Ruoyu, Zhou Fubao, Shang Hongbo, Song Shuang
Information Institute of the Ministry of Emergency Management, Beijing 100029, China.
China Academy of Safety Science and Technology, Beijing 100012, China.
Heliyon. 2024 Mar 19;10(6):e28303. doi: 10.1016/j.heliyon.2024.e28303. eCollection 2024 Mar 30.
The construction of gas extraction boreholes in soft coal seams is prone to collapse and deformation, and grouting reinforcement is one of the main methods to solve the problem of efficient sealing. However, the reasonable selection of key grouting parameters still needs further research. In response to the problem of selecting grouting sealing parameters for gas drainage drilling in soft coal seams, based on the "concentric ring" reinforcement sealing technology obtained in previous research, the key parameters and sealing technology of the "concentric ring" reinforcement were studied through theoretical calculation and numerical simulation experiments. The slurry diffusion morphology and range under different grouting pressures and grouting time slurry viscosity were obtained. Finally, in order to explore the application effect of key grouting parameters, on-site industrial tests were conducted in a soft and high gas coal seam. The research results indicate that the optimal grouting pressure for the "retaining wall rock hole ring" should not be less than 3 MPa, the reasonable grouting time should be 10-15 min, and the water material ratio of the grouting material should be greater than 1:1; The use of new reinforcement sealing and grouting technology can ensure long-term good extraction effect. Compared to the testing of drilling sealing effect using ordinary cloth bags with two plugs and one injection, The adoption of new reinforcement sealing technology can effectively prevent the deformation and collapse of the borehole before sealing, and due to two rounds of grouting and pre reinforcement of fractured coal, the sealing effect of the borehole is also relatively good. The research results have important theoretical value for guiding the drilling and sealing grouting engineering of gas extraction in soft coal seams.
软煤层瓦斯抽采钻孔施工易发生塌孔变形，注浆加固是解决高效密封问题的主要方法之一。然而，关键注浆参数的合理选择仍需进一步研究。针对软煤层瓦斯抽采钻孔注浆密封参数选择问题，基于前期研究获得的“同心环”加固密封技术，通过理论计算和数值模拟试验研究了“同心环”加固的关键参数及密封技术。得到了不同注浆压力和注浆时间浆液黏度下的浆液扩散形态及范围。最后，为探究关键注浆参数的应用效果，在松软高瓦斯煤层进行了现场工业试验。研究结果表明，“挡墙岩孔环”的最佳注浆压力不应小于3MPa，合理注浆时间应为10 - 15min，注浆材料的水灰比应大于1:1；采用新型加固密封注浆技术可确保长期良好的抽采效果。与采用普通双塞单注布袋进行钻孔密封效果检测相比，采用新型加固密封技术可有效防止封孔前钻孔变形塌孔，且由于对裂隙煤体进行了两轮注浆和预加固，钻孔的密封效果也相对较好。研究成果对指导软煤层瓦斯抽采钻孔封孔注浆工程具有重要的理论价值。
