Influence of cyclic dynamic disturbance on damage evolution and zoning effect of coal-rock under local static load constraint

In order to obtain the characteristics of the influence of cyclical impact loading on coal-rock damage under local static load constraints, the evolution laws of damage factors and cracks during the process of constant impulse cyclic impact and incremental impulse cyclic impact on raw coal and briquette were studied. The experimental results show that the existence of local static load restraint improves the impact resistance of coal-rock, and the damage factor of coal-rock shows obvious zoning characteristics. When the coal-rock is in an elastic state, the partition with a larger static load restraint area has stronger impact resistance; when the coal-rock is in a plastic state, the partition with a larger static load restraint area has a weaker impact resistance; Increasing impulse cyclic impact has a higher damage efficiency to coal-rock than constant impulse cyclic impact. The difference in rock breaking efficiency between the two cyclic impact methods is mainly reflected in the partition with the largest constrained area; The crack propagation on the coal-rock surface is more consistent with the partition characteristics of the damage factor. When the static load constrained zone is in an elastic state, the static load has an inhibitory effect on the crack growth. When the static load confinement zone is in a plastic state, the cracks mainly propagate in the static load confinement zone, and the constrained zone mainly consists of tensile cracks that grow in the vertical direction, while the cracks in the non-constrained zone mainly grow in an oblique direction. Finally, fracture mechanics was applied to analyze the failure type of the sample.