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Abstract: Based on China''s coal mine particularly serious accident data from 1981 to 2010, the times and death toll of PSCA are described by statistical methods; the relative indexes according to time, output, employee are analyzed by statistical methods, and the results show the developing trend of PSCA is grim. According to month, area and accident type, some useful and important analysis conclusions are drawn. At last, the main factors of PSCA are analyzed by granger causality test, impulse response function and variance decomposition. The result can provide reference for decision-making. [Copyright &y& Elsevier]

Abstract: The high-gas and low-permeability are the common problems of China coal mine, which restrain the mining of coal resources safely and efficiently. To solve the low permeability of coal-seam, the variation of permeability was studied experimentally with coal effected by supercritical CO2 and low-carbon alcohol solution (including methanol solution, ethanol solution and isopropyl alcohol solution). The results show the permeability of coal after injecting supercritical CO2 is nearly one order of magnitude over former testing. This is principally resulted from that supercritical CO2 will extract some organic matters of coal substrates. Meanwhile, the permeability of sample effected by low-carbon alcohol solution is apparently higher than former experiment without solution. Moreover, the bigger volume concentration to certain low carbon alcohol solution, the greater the permeability will increase. As to the three different low-carbon alcohol solution, the isopropyl alcohol solution has a biggest influence on improving coal permeability, whereas the methanol solution has a smallest one. [Copyright &y& Elsevier]

Abstract: The mechanical characteristics and electromagnetic emission rules during the uniaxial compression of the combined coal-rock were investigated in laboratory and its mechanical property was analyzed; the relation between mechanical characteristics and electromagnetic emission of the combined coal-rock was discussed. The results show that the combined coal-rock strength under the uniaxial compression is obviously different from that of single coal or rock and the fracture process of the combined coal-rock is gradual, accompanied by electromagnetic emission. This research has an important significance to further understanding of the mechanism and forecasting method of coal or rock dynamical disasters in theory and practice. [Copyright &y& Elsevier]

Abstract: In this paper, based on field observations and theoretical analysis, we discussed the ground pressure behavior law and its characteristic at fully-mechanized face and the material roadway of 10# seam in Fenxi-Shuguang coal mine. The analysis results indicates that ground pressure at material roadway increased sharply when the working face advanced to place 40∼50m away from it, and as the advance of the working face, the deformation of the two-sides is clearly bigger than that at the roof and floor in material roadway; Therefore, support in material roadway should be strengthened to ensure the safe mining of working face. We use the ZDYJ-IIA type computer-round figure apparatus to observe the ground pressure of the fully-mechanized face, which can help us analyze the relation of the fully-mechanized mining technique with ground pressure as the advance of the working face, as well as obtain the ground pressure behavior law of fully-mechanized face and calculate pace length of the periodical roof pressure. Analysis on the real-time monitoring results of the setting load and the work resistance show that the hydraulic powered supports used at the working face can fulfill the needs of the working face pressure. Finally, we can obtain the conclusion that the method of the ground pressure observation is scientific and feasible, which includes the real-time monitoring on the fully-mechanized face and placing the observation stations in the material roadway to observe the deformation of material roadway. [Copyright &y& Elsevier]