Dynamic Mechanical Properties of Deep Coal Rocks Under Three-Dimensional Dynamic and Static Loading

Understanding deep coal rock's dynamic mechanical characteristics is crucial for safe design and assessment of coal rock engineering. This article tested triaxial coal samples with SHPB on deep Test coal samples and equipment using the split Hopkinson pressure bar in different conditions. Coal stress-strain curves under combined triaxial dynamic-static loading show a consistent pattern. The first axial prestress prevented compaction in the stress-strain curves. The dynamic peak stress and secant modulus of deep coal samples rose linearly with constraint pressure and strain and decreased with axial prestress. Axial prestress changes occur at 8 MPa (44% of compressive strength). The amount of energy deep coal samples absorb during impact loading varies with axial static prestress at the same strain rate and confining pressure. It rises then falls. Coal samples went from shear damage to shear and tension damage as axial static tension rose. This research helps avoid coal rock dynamic catastrophes and evaluate mining engineering stability.