Abstract: Based on the improved split Hopkinson pressure bar (SHPB) testing system with the rock coupled static and dynamic loads, dynamic experiments on serpentinite are conducted under the condition of different static axial compressions and frequent dynamic disturbance to research its dynamic deformation properties, dynamic peak stress and strain, energy variation and failure modes. The results show that in the process of frequent disturbance under the high static load, there is a positive correlation between the dynamic stress and strain of rock prior to the peak dynamic stress, but there are two different dynamic deformation phenomena, i.e. dynamic deformation rebound and non-rebound after the peak dynamic stress. With the increase of number of dynamic disturbance, the peak dynamic strain increases while the dynamic peak stress and the dynamic deformation modulus decrease, and the energy variation of rock changes from the release of energy from rock into the absorption of energy from dynamic disturbance. As the static axial compression is larger, the damage of rock during one impact disturbance is heavier, the impact disturbance number for rock failure is fewer, the failure mode of rock transfers from the tensile failure mode to the shear failure mode, and the fragmentation distribution of broken rock becomes more inhomogeneous, and fragments become larger. All these results will be helpful for us to reveal the failure mechanisms of deep rock mass under the high static stress and dynamic disturbance produced by frequent excavation and blasting, and prove the feasibility of adjusting static stress state and excavation blasting to maintain the long-term stability of surrounding rock in field site.

Key words: serpentinite, high static load, frequent dynamic disturbance, dynamic deformation behavior, energy variation, failure mode