Abstract: To address the issues of poor borehole sealing quality and rapid attenuation of extraction rates in coal seam mining,this study integrates the stress-seepage coupling theory with borehole sealing techniques.By modifying inorganic silicate materials with nano-oxides and surfactants,a novel inorganic nano-flexible sealing material was developed.Industrial-scale tri als were conducted in the No.3 coal seam of Changping Mine,where the developed material was applied to gas drainage opera tions and the existing process was optimized in conjunction with the "three-blocking and two-grouting" sealing technique.The results indicate that the experimental group employing the nano-diffusion expanding agent exhibited overall superior average gas drainage concentrations compared to the control group using ordinary sealing cement.The average net gas drainage rate in the experimental group reached 0.13 m3 /min,whereas that of the control group was only 0.06 m3 /min.Following secondary grou ting,the average drainage concentrations of the two representative boreholes increased by 21.3% and 69.0%,respectively.The findings demonstrate that the developed inorganic nano-flexible sealing material and the associated sealing process can effec tively improve borehole sealing integrity,which is also of great significance for mitigating mining-related risks.

Key words: drilling and sealing technology,sealing material,inorganic nanoparticles,seepage characteristics,slurry re plenishment