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Abstract According to Xin′an coal mine，the mechanism of coal and gas outburst in “three-soft”coal seam under the condition of rockburst is discussed by means of investigation，test，laboratory test，theoretical calculation and analogy. The results show that：(1) Because of the in-situ rock stress and mining-induced stress，the high elastic modulus sandstone strata of roadway floor bends to the upward，which makes the ordinary gas ventages close. The generating cracks in coal make the adsorptive gas desorb as dissociative gas，which provides the external preparation conditions of coal and gas outburst. (2) The impact of the floor strata with large Young′s modulus opens the gas′s channel，which provides the external trigger conditions. (3) The rockburst energy near the heading face is more than 105 J. The inoculation and generation processes of rockburst make the coal wall close and fracture. For the coal seam with the initial expansion energy contained in 1 m3 coal less than 1.3×106 J (the gas pressure less than 0.74 MPa)，the gas outburst or unusual gas emission would be induced；and for the other coal seam，the coal and gas outburst would be induced. In order to prevent the risks mentioned above，it is suggested that the drilling or blasting measurements should be used for the high elastic modulus strata.
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2011, Vol. 30 
