There are many microcracks and micropores in the rock, which will initiate, propagate, and coalescence under dynamic loading, leading to rock instability and failure. When blasting excavation is carried out, the retained rock mass will be subjected to the dynamic loading generated by cyclic blasting, resulting in cumulative damage, which will lead to the reduction of the rock mass strength, and even failure. In order to simulate this physical process, the existing rock dynamic damage constitutive model, which could perfectly describe the rock dynamic damage induced by blasting, was embedded into FLAC through secondary development to analyze the cumulative damage of rock mass under cyclic blasting. And then it was adopted to simulate the damage effect and stability of the rock slope with the locked segment under cyclic blasting. The stability of the slope under cyclic blasting was determined by the displacement criterion method, and the safety factor of the slope after each blasting was obtained by the strength reduction method. Finally, the relationship between the failure mode and stability of the slope and the location of the locked segment was discussed by analyzing the damage, displacement field, and safety factor of the numerical models for different locations of the locked segment in the soft interlayer. The results show that the slope stability gradually decreases with increasing the number of cyclic blasting after considering the cumulative damage effect of the rock slope. For the rock slope with the locked segment, the damage of the locked segment firstly occurs at both ends, and then propagates to the middle, in which the rock mass shows a progressive failure mode. Because the cumulative damage of the rock slope is considered, the safety factor of the slope will decrease after each blasting. When the cumulative damage is not considered, the safety factor of the slope is basically unchanged. The failure mode of the rock slope with a locked segment under cyclic blasting is the combination of dynamic tensile failure and shear failure caused by rock mass slip. The location of the locked segment in the weak interlayer affects the failure mode and stability of the slope. Therefore, when carrying out similar engineering activities, the cumulative damage effect of rock mass should be considered to avoid engineering accidents.

In practical engineering, rock frequently suffers from recurrent dynamic disturbances, posing serious threats to engineering safety. To investigate the dynamic mechanical behavior of jointed rock under cyclic dynamic disturbances, cyclic impact tests of single-jointed gabbro (SJG) were conducted using a split Hopkinson pressure bar (SHPB) test system. The stress equilibrium during the tests was verified using the three-wave method and the force balance coefficient method. The dynamic mechanical behavior of the specimens was comprehensively analyzed in terms of impact resistance, stress-strain relationships, energy and damage evolution, as well as dynamic failure mechanisms. The results show that single-jointed rock specimens can achieve stress equilibrium under cyclic impact conditions. The failure mode of the specimens under cyclic impacts is splitting, and the joint inclination angle significantly influences the impact resistance of the specimens. As the joint inclination angle increases, the impact resistance of the specimens also increases. During the cyclic impact process, strain rebound occurs in all specimens, and their mechanical properties do not monotonically degrade with an increasing number of impacts. The peak stress of the specimens generally exhibits a decreasing trend with the number of impacts. The cumulative damage coefficient, represented by dissipated energy, increases approximately linearly with the number of impacts, while the increase rate decreases with larger joint inclination angles. Under low-stress impact loading, the compressive-shear stress within single-jointed specimens is insufficient to generate shear cracks. The failure of specimens primarily results from the progressive propagation of tensile cracks induced by tensile stress, which eventually coalesce with the joint. The failure mechanism of multi-jointed rock masses resembles that of single-jointed rock masses. During cyclic impact loading, both compaction of micro-defects and initiation of micro-cracks at joints occur simultaneously. However, the impact resistance of multi-jointed specimens depends on whether the cracks can interconnect the joints. For intact rock specimens, the failure process initially involves compaction of micro-defects, followed by probabilistic activation of micro-cracks, ultimately leading to specimen failure.