深部强采动工作面卸压瓦斯全生命周期分阶段精准治理方法OA

Under deep high-intensity mining conditions,the spatiotemporal evolution pattern of pressure-relief gas emission in the fully mechanized top-coal caving working face is unclear,while traditional high-level drainage roadway construction is costly and exhibits low gas extraction efficiency.At present,research on staged precise gas control over the full time scale from the opening cut to mining termination(i.e.,the full lifecycle),based on the coupling relationship between the dynamic evolution of mining-induced overburden and gas emission stages,remains insufficient.To address these issues,taking the 307 working face of Wangjialing Mine as the engineering case,the feasibility of replacing high-level drainage roadways with high-level directional long boreholes at different strata for pressure-relief gas extraction was evaluated,and a"staged and differentiated"precise control method was proposed.① A permeability distribution model of the deep mining-induced fracture field with three zones of"penetrating-vertical-horizontal"was established,which clarified that the horizontal storage-transport zone was the dominant migration and enrichment area for pressure-relief gas.② The concept of the"full lifecycle"of mining-induced pressure-relief gas emission was proposed,and based on the dynamic coupling relationship between roof weighting characteristics and gas emission,the process was divided into four stages:occurrence stage,bursting stage,fluctuation stage,and stable stage.The gas source composition,emission characteristics,and proportion of each stage were clarified,providing a theoretical basis for staged precise gas control.③ For the initial mining stage(occurrence stage and bursting stage),a"bow-shaped"directional borehole trajectory was designed to achieve precise interception of gas buoyant migration paths;for the normal mining stage(fluctuation stage),a"high-middle-low"multi-layer horizontal directional borehole optimized layout was constructed to comprehensively cover the pressure-relief gas storage and transport zones within the mining-induced overburden space.Field test results showed that this method increased the extracted gas volume fraction of the working face to over 8％,stably controlled the gas volume fraction in the return airflow below 0.4％,effectively solved the problem of gas exceeding the limit in the return air corner,and achieved precise and controllable gas extraction.