| Coal the most important resource in China’s energy consumption plays a decisive role inChina’s economy development. Safe mining is the solid foundation of miners’ life, resourcesecurity and healthy economy development, at the same time it is the focus of society concernand experts and engineers research. When shallow buried coal seam excavates under thinoverlying rock and water-rich loose area, there are several sand inrush and water blastingaccidents have happened in China which has caused huge property loss and casualty. Sandinrush and water blasting has been one of the key problems of shallow buried coal mining.Sand inrush and water blasting can happen is because of the special geological andhydrological engineering condition of shallow buried, thin overlying rock and water-richloose strata. It involves geological structure, hydrogeology and engineering geology, coalseam, overburden and mining technics, etc. This paper systematically analyzed the influencefactors and obtained the mechanism of sand inrush and water blasting from this specialmining condition view. Based on the analysis results, the author set up a mechanical modeland provides a method for prevention and control of sand inrush and water blasting. Themethod was applied in a comprehensive long-wall panel at Shendong Halagou coal mine andit successfully prevented the accident. This prevention and control technics has gained goodtechnical, economic and social effects.This paper’s main research results are below:(1) Through systematically analyzing of the engineering geological and hydrologicalcondition and the mining method of22404long-wall panel of Halagou coal mine, this paper gets the influence factors and mechanism of sand inrush and water blasting. There are fourrequisites of the happening of sand inrush and water blasting which are supply (looseoverburden), motive source (high phreatic water level), passage (thin overlying rock fracture)and storage capacity (mine gobs). When the roof bedrock fractures and the water pressuregets the threshold value, sand and water will inrush into roadway and gobs through thefracture.(2) Analyze the sand inrush and water blasting condition of22404comprehensive stopeat Halagou coal mine.22404comprehensive stope is260meters wide and the coal burieddepth under Halagou ditch is about42m to45m and its mining height is4.2m. Themining-induced fracture develops directly to the surface. Therefore,22404stope belongs tothe special condition of shallow buried and thin overlying bedrock and water-rich loose sandlayer. So, sand inrush and water blasting may happen when mining under Halagou ditch.(3) Theoretically calculate and measurement analyze the roof behavior of22040comprehensive stope at Halagou coal mine. The calculated first weighting interval of the mainroof is50m to60m while the monitoring data is66m. The calculated periodic weightinginterval is21m to28m while the monitoring data is16m to19m.(4) Theoretically calculate and analyze the sand inrush and water blasting water pressurecondition of22404stope of Halagou coal mine. This paper provides a feasible calculationmethod of threshold hydraulic gradient and water level and calculated the hydraulic gradientof22404stope. The calculated result shows sand inrush and water blasting may happen.(5) Provide an integrated technics of prevention and control of sand inrush and waterblasting. This paper suggests using dewatering and grouting to prevent and control sandinrush and water blasting through comprehensive analysis of the influence factors. Also thispaper explains the basic principle of different prevention and control technics in detail.(6) Application of the prevention and control technics at22404stope of Halagou coalmine. The author implemented the theoretic results and integrated prevention and controltechnics at22404stope. The sand inrush and water blasting accident was successfullyprevented by strict implementation of the technics. |
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