Abstract
After the gas drainage borehole is formed in the coal seam, its stress deformation process is a creep process without the influence of mining. By arranging boreholes on coal samples and carrying out creep loading test of porous coal through rock mechanics testing machine, the creep process of boreholes in actual coal seams is simulated. The results show that the creep loading test results of drilled coal are quite different from those of conventional loading. Creep loading produces large deformation due to rheological and aging characteristics. Compared with non-porous coal, the yield of drilled coal occurs earlier and the yield platform is wider during creep loading. Also, the larger the borehole diameter, the deeper the borehole depth, and the lower the peak stress. The up dip angle is easier to destroy than the down dip angle. Compared with hard coal, soft coal produces greater deformation under smaller peak stress. The research results have guiding significance for drilling gas drainage in the soft coal seam.
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