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利用压汞法、低温氮吸附法、瓦斯等温吸附和解吸试验对平煤八矿构造煤和共生原生结构煤进行综合分析,探讨了构造煤孔隙结构与瓦斯耦合特性。结果表明,构造煤以微孔为主,中孔和大孔相对发育且含较多细颈瓶孔,孔隙连通性差。与共生原生结构煤相比,构造煤各孔径阶段的孔容和孔比表面积都有所增加。构造煤比表面积的增加具有阶段性,即孔径<1.2 nm时为慢增加阶段,孔径=1.2~4.9nm时为快增加阶段,孔径>4.9 nm时为稳定阶段。构造煤极限瓦斯吸附量a的增大与比表面积快增加阶段关系密切,但小于其BET比表面积的增幅。瓦斯解吸初期0~2 min内构造煤瓦斯解吸速度和解吸量明显大于共生原生结构煤,与中孔和大孔的变化一致,2 min以后瓦斯解吸迅速衰减。低煤体强度、高瓦斯含量的构造煤以气-煤共溶体形式储集更多弹性潜能,突然卸压时瓦斯膨胀能迅速释放,煤层中发育的构造煤增加了煤与瓦斯突出的危险性。
Using mercury intrusion method, low temperature nitrogen adsorption method, gas isothermal adsorption and desorption test, a comprehensive analysis was made on the structural coal and the symbiotic primary structure coal in Pingdingshan 8 Mine, and the coupling characteristics between the pore structure and gas in the tectonic coal were discussed. The results show that the coals are dominated by micropores, mesopores and macropores are relatively developed and contain more jacketed flask pores, and their pore connectivity is poor. Compared with the coexistence of primary structural coal, the pore volume and pore specific surface area of each stage of pore structure of coal are increased. The increase of specific surface area of tectonic coal is of a stage, that is, slow increase at pore size <1.2 nm, rapid increase at pore size = 1.2-4.9 nm and stabilization at pore size> 4.9 nm. The increase of limit gas adsorption capacity a of tectonite is closely related to the phase of rapid increase of specific surface area but smaller than the increase of its BET specific surface area. The gas desorption rate and desorption rate of tectonic coal within 0 ~ 2 min in the early stage of gas desorption were obviously higher than those of the coexisting primary structure coal, which was consistent with the change of mesopore and macropore. The gas desorption rapidly decayed after 2 min. The low-coal-strength and high-gas content tectonic coal accumulates more elastic potential in the form of gas-coal co-dissolved gas, and the gas expansion can be quickly released when a sudden pressure relief occurs. The structural coal in the coal seam increases the danger of coal and gas outburst .