Energy dissipation and fractal characteristics of weakly cemented red sandstone under disturbance impact

To explore the energy dissipation law and failure mode of soft rock interlayer in western mining areas of China after dynamic disturbance, the dynamic impact failure tests on weakly cemented red sandstone are carried out by using the separated Hopkinson compression bar device. Under the impact of this red sandstone under different loading rates, different times of disturbance and whether there is the disturbance or not, the energy dissipation and fractal characteristics of the samples during the same loading rate impact failure are analyzed. The experimental results show that under different disturbance impact rates, with the increase of disturbance impact times, the reflection energy increases, while the transmission energy and dissipation energy decrease. The reflection energy of the samples under the impact of high-speed disturbance is higher than that of the low-speed disturbance impact, while the dissipative energy is the opposite. Moreover, the dissipative energy of the samples under the impact of low-speed rate disturbance is opposite. The energy dissipation rate and energy dissipation density are higher than those of the high-speed disturbance impact, which indicates that the energy utilization rate of the samples is higher under the impact of low-speed disturbance. In the impact failure tests, with the increase of the number of disturbance impact, the fragmentation degree of the sample after the low-speed rate disturbance is more serious than that of the undisturbed and high-speed rate disturbance. The low-speed rate disturbance of fractal dimension D_b > undisturbed > high-speed rate disturbance shows that the fractal dimension is positively correlated with the number of disturbance shocks. The results show that the impact rate is negatively correlated with the disturbance. Under the same number of disturbance impact, the cumulative dissipation energy and energy density of D_b of the low-speed rate-disturbed samples are higher than those of the high-speed disturbed samples, while the cumulative reflection energy is opposite.