| China's coal resources are rich,"with coal as base and diversified development"is China's long-term energy development strategy, however, coal mine gas accident affects the sustainable development of our country's coal industry at present. In the process of controling gas, the gas drainage is one of the important means. Sealing of the drainage drilling hole which will affect gas drainage efficiency is the key link during the gas drainage. In recent years, polyurethane sealing process has gotten very good promotion and application in coal mine, the sealing process is still in the researching and improving stage. Reasonable choice its sealing way and adopting effective sealing length are the problem which need to be researched and solved recently.This paper starting from drilling hole sealing principle mainly analyzed drilling hole peripheral gas leakage and sealing material gas penetration. Main factors which affected the sealing effect were sealing material viscosity and sealing length, which should be mainly researched in the research of polyurethane sealing process sealing effect.According to polyurethane production "one-step" principle, the rigid polyurethane foam material was made up in the laboratory, and the material'bonding with drilling hole peripheral was tested. Coal samples were selected from Ping Ding Shan mine, Tang Shan mine, Zhao Ge Zhuang mine, Xin Long Hongling mine and Huai Bei Luling mine. The final average bonding strength of different coal samples was 427.25 KPa, and the final average bonding strength of same coal samples was 387.95 KPa. The determination conclusion showed that the material'bonding strength was good, it would be made a good bonding with drilling hole peripheral. According to the principle of gas drainage, the gas drainage process was simulated in the laboratory. The comparative study which aimed at the sealing effect of injecting method and coiling method sealing process was made,which was from macroscopic, permeability and compression performance. The conclusion of injecting method's sealing effect was better than coiling method was drawn after the study. Thus it provided the basis for mine choosing polyurethane sealing process. From the polyurethane sealing materials'bonding and permeability, sealing length of polyurethane injecting method was researched and different diameter drilling hole's sealing length were calculated. And the effective sealing length of 75mm diameter drilling hole was tested by the experimental method, the reasonable sealing length should be between 95cm~100cm. The conclusion was close to the theoretical calculation conclusion, it had the certain reference value and made very good significance for coal mine gas drainage reasonable hole sealing. |
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