Cooperative Control Of Gas Disaster During Mining Of Thin And Short Distance Upper Protective Coal Seam In Deep Coal Mine

This paper aimed at gas control in the condition of deep(depth≥1000m) close (8 ~ 12m), low mining height (1.2m), and high gas in 12th mine Pingdingshan Coalmine Group on the protective layer and the problem of the blank caused by coal pillar made by the roadway of protective layer. By the use of elastic mechanics, rock mechanics, damage mechanics, fluid mechanics, and other related theories, and by the use of theoretical analysis, physical modeling, numerical Simulation, field test and other methods, technology of Cooperative Control of Gas Disaster during Mining of Thin and Short Distance Upper Protective Coal Seam in Deep Coal Mine was given. The major creative achievements were presented as follows:Aiming at gas content over-limitation at the corner of the protective layer and the problem of pressure unrelief in local areas with the mining of thin and Short Distance Upper Protective Coal Seam in Deep Coal Mine, ideas were put forward which is gas disaster control cooperating the technology of progressive and large diameter buried drainage pipe by wearing layers and directional hydraulic fracturing technology. This idea achieved fast and safe mining of the protective layer and Outburst Control region-wide of the protectived layer and provided management ideas for other similar coal.By the use of experimental and numerical simulation, the pressure relief in the underlying coal with thin and short distance upper protective coal Seam was first researched in the conditions of different height, different spacing and different rock layers. By the research,it was found that the higher of the working face in protective layer , the greater pressure relief in the protected layer, with increase of the interlayer distance, the worse pressure relief, and that as the hard rock layer control, its presence is not conducive to reducing the stress below the coal and rock, curbing the expansion deformation of the rock below, and increasing permeability of the under protected layer.The technology of progressive and large diameter buried drainage pipe by wearing layers was put forward for the first time, not only to overcome the great construction and maintenance difficulties caused by the traditional measures such as gob-side entry retaining, but also to avoid the problem of limited roadway space caused by the drainage pipe in the current seam. Without affecting the mining of the protective laye, the problem, frequent gas content over-limitation at the corner of the thin and short distance upper protective coal seam, was solved creatively.Practice shows that the effect of this technology was significant. The pure gas drainage reached 29.1 ~ 35.3m3/min, drainage gas concentration was 13.7% on average, and gas concentration in the corner remained 0.51%.Aiming at characteristics of short distance between the protective and the protected layer, the existence of the local-area-unrelief in the protected layer and the area with stress concentration relative, directional hydraulic fracturing technology was put forward to release the danger of outburst in local unprotected areas. By using the guiding role making guiding function, it could be avoided that stress concentration caused by single hydraulic fracturing hole, resulting in high pressure storage.After taking the technology, the value of q and S was significantly lower (q reduced to 1.0 L / min and S decreased to 2.0 kg/m or so), the over standard of danger of outburst greatly reduced and amplitude decreased, and gas drainage density increased by 70% while drainage quantity increased by 382%.This dissertation provides theoretical and practical basis for cooperative control of gas disaster during mining of thin and short distance upper protective coal seam in deep coal mine. During the research, the authors published 7 papers, in which 2 were Search by EI; won 6 items of the prize of the ministerial-level scientific or other researches.There are 105 figures, 10 tables and 109 references in this dissertation.