The interdependency of pore structures and coal dynamic failures

ZHU Jie; ZHANG Bo; WANG Quanqi; JIANG Yaodong; HE Fa

Abstract：Taking bump-prone coal and gas-outburst coal as the research objects,the experiments of mercury porosimetry and nitrogen adsorption are used for the comprehensive analysis of coal pore structures.According to physical and mechanical characteristics (including pore structure parameters) of coal samples,the numerical model of coal seam is established to calculate the stress distribution and strain energy.The relationship between pore structures and coal rock dynamic failure characteristics is also discussed.The experimental results of liquid nitrogen adsorption and mercury porosimetry show that the dominant pores of Xinzhouyao coal are open pores.However the pores from Zhaogezhuang coal seam are mainly semi-open pores and a few ink-bottle pores.As for the pore amount,the seepage pore percentage of Xinzhouyao coal is much more than Zhaogezhuang coal,so gas released more easily in Xinzhouyao coal seam.Numerical model results show that when the overburden and horizontal stresses are same,the horizontal stress near the railway wall in Xinzhouyao coal seam is lower than that of Zhaogezhuang coal seam,but the vertical stress in Xinzhouyao coal seam is higher.Therefore the shear failure is more likely to happen near the railway wall.With the same overburden and horizontal stresses (6MPa),the variation of strain energy density in Zhaogezhuang coal seam is 2 times more than Xinzhouyao coal seam.So the strain energy is accumulated more easily in Zhaogezhuang coal seam.