Integrated prevention and control technology of unloading pressure from boreholes and high-efficiency extraction for compound power disasters

ZHANG Xingrun; PAN Bojie; ZHANG Yongbin; HAO Fuchang; GAO Baobin; XI Zhiqi

doi:10.12438/cst.2024-0941

Abstract：Addressing the technical challenges posed by the compound disaster of intense mining pressure and high gas concentration,this study developed a novel viscous sealing material based on cellulose ether.Experimental analyses were conducted to evaluate the expan-sion,water retention,and penetration capabilities of the sealing material.An integrated system for drilling pressure relief and efficient gas extraction prevention and control technology was established.The spacing of pressure relief sections and the effective extraction radius were determined under various conditions,optimizing technical parameters for integrated boreholes.The effectiveness of the technology in pressure relief and extraction was assessed,achieving multipurpose use of boreholes and simultaneous management of mining pressure and gas.Results indicate that the new viscous sealing material exhibits a 14.2%expansion coefficient,with only a 5%water loss rate over 30 days and a penetration radius up to 1.0 m,demonstrating superior expansion,water retention,and penetration performance.By combining pressure relief and extraction holes and strategically placing viscous sealing sections in stress concentration areas,the technology utilizes principles such as"solid sealing fluid,liquid sealing fluid"to ensure effective pressure sealing without compromising drilling efficacy.The spacing of pressure relief sections correlates inversely with mining pressure hazard levels and directly with borehole diameter,determined by drilling cuttings and borehole conditions.Extraction timings for different boreholes were determined using a differential pressure meth-od,considering varying extraction radii and pressure relief effects.Evaluation of borehole pressure relief through surface displacement ob-servations and drill cutting indicators confirms the technology effectively reduces mining pressure hazards and controls tunnel deforma-tion.Integrating the new viscous sealing material in boreholes increased average gas extraction concentrations from 32.9%to 64.87%,nearly doubling the average pure gas flow rate,highlighting the effectiveness of the integrated drilling pressure relief and high-efficiency extraction technology in preventing and controlling complex dynamic disasters involving intense mining pressure and high gas levels.These findings provide crucial technical support for safe and efficient mining operations facing compound disasters.