Research on Impact Mechanical Behavior and Constitutive Relation of Outburst Coal

In order to explore the deformation features and dynamic constitutive relation of outburst coal under impact load, the impact compression test under different strain rate of outburst coal from B₆ coal seam in Huainan Coal Mine was carried out by split Hopkinson pressure bar (SHPB) of 75 mm in diameter. Combined with the existing constitutive model of rock material, a new dynamic constitutive equation for outburst coal has been proposed. The test result shows that the whole deformation process of outburst coal under impact load includes four stages basically: the initial nonlinear stage, yield stage, strain-hardening stage and unloading damage stage; and the fitted dynamic constitutive equation including damage effect and strain rate effect can fit dynamic stress-strain relationship of outburst coal before peak stress.