(1. State Key Laboratory of Coal Mine Disaster Dynamics and Control，Chongqing University，Chongqing 400044，China；
2. State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam，Chongqing University，Chongqing 400044，China)
Abstract：Using self-developed meso-shear test equipment for coal or rock containing gas，tests of meso- characteristics of crack?s evolution of coal subjected to direct shear load under different gas pressures，were carried out to reveal general law of crack?s evolution and influence of gas on crack?s evolution. The results show that initial cracks nearby shear plane crazed firstly when at small angle to the direction of shearing. The principal displacement fracture is formed by transfixion of series of declined cracks(mostly from bottom left corner to top right corner) at various angles to the direction of shearing. Extension of these declined cracks increases as gas pressure increases. From shear load-shear displacement curves，and comparison analysis between level of cracking load Pk and level of transfixing load PG，conclusion was obtained that coal damaged to failure after crack craze more and more quickly as gas pressure increases because of fragmentation caused by gas. The angles of cracks show that cracks originated from non-crack area have small angles to the orientation of shear load；and mean angle decreases with the increasing gas pressure. The finally formed principal displacement fracture didn?t parallel to the orientation of shear load，a certain angle existed.
许 江1，2，梁永庆1，2，刘 东1，2，程立朝1，2，王 雷1，2，宋 晓1，2. 不同瓦斯压力条件下原煤剪切破裂细观特征试验研究[J]. 岩石力学与工程学报, 2012, 31(12): 2431-2437.
XU Jiang1，2，LIANG Yongqing1，2，LIU Dong1，2，CHENG Lichao1，2，WANG Lei1，2，SONG Xiao1，2. EXPERIMENTAL STUDY OF CRACK?S MESO-CHARACTERISTICS
OF RAW COAL SUBJECTED TO DIRECT SHEAR LOAD
UNDER DIFFERENT GAS PRESSURES. , 2012, 31(12): 2431-2437.
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2012, Vol. 31 
