Abstract:
With the increase of mining depth, the geological mechanical environment of the coal body undergoes significant changes. From the relatively simple stress state at the shallow layer, it gradually transforms into a state with high stress, high gas pressure, high temperature, and strong disturbance, featuring multiple strong coupled fields. The dynamic response pattern becomes significantly more complex. In recent years, domestic and foreign scholars have carried out a large number of impact dynamics tests for coal under complex stress and gas environment and obtained fruitful research results. The latest progress in experimental research and experimental results of impact dynamics of gas-bearing coal in recent years is systematically reviewed. The development and evolution of split Hopkinson pressure bar (SHPB) experimental system for gas-bearing coal from uniaxial(
σ1≥
σ2=
σ3=0), conventional triaxial (
σ1≥
σ2=
σ3≠0) to true triaxial (
σ1≥
σ2≥
σ3 ≠ 0) are reviewed. The main components of different types of gas-containing coal Hopkinson pressure rods are introduced. The requirements for the shape and size of the test samples needed for different gas-containing coal impact pressure rods, as well as the data calculation methods, are analyzed. It comprehensively summarizes the stress-strain curve evolution, peak strength and strain, impact failure mode, energy dissipation and gas emission laws of the coal body under different loading conditions. The dynamic constitutive model of gas-bearing coal based on experimental data and its expansion in damage evolution and seepage coupling are reviewed. It also discusses the mechanical properties and degradation mechanisms of gas-containing coal under dynamic and static loads. Finally, the future research directions are prospected, and it is pointed out that true triaxial multi-field coupling-dynamic-static combined loading, intelligent monitoring of multi-source signal of gas-bearing coal under dynamic and static load combination, and in-depth study on the catastrophe mechanism of coal impact instability under the superposition of high static load, gas and dynamic load , will become an important development trend in this field of gas coal impact dynamics.