Discussion on dynamic response mechanism of dynamic load-induced unloading coal

To investigate the dynamic response mechanism of impact-induced instability of unloaded coal induced by dynamic loads,large-scale dynamic material testing machine (MTS-1500)was used to conduct dynamic tests on large-size and bursting liability coal samples.The dynamic mechanical properties of the sample are analyzed from the macroscopic mechanical behavior and damage characteristics of the sample under dynamic load.The characterization of the elastic energy index and the area of the hysteresis loop is deepened to describe the characteristics of energy accumulation and dissipation under dynamic loading.The test results show that the occurrence of dynamic load rockburst requires a certain static load basis.The higher the static load level,the more obvious the dynamic load disturbance and the greater the probability of occurrence of rockburst.Dynamic load damage is different from dead load damage.The maximum value of damage depends on the coupling value of dynamic and static loads.The elastic energy index and the dynamic load hysteresis area of the dynamic load can be used to characterize the accumulation and dissipation of energy in the dynamic loading process of the coal body,which show regular changes in the dynamic load loading process.Comprehensively,the coupling effect of dynamic load disturbance,insufficient damage,energy accumulation and dissipation characteristics is a dynamic response mechanism of unloading coal under dynamic load.