Abstract: Using a modified split Hopkinson pressure bar (SHPB), the tests were conducted on deep rocks under three-dimensional (3D) high-static load and frequently dynamic disturbance. Then dynamic stress-strain curves were obtained for describing general features, which can be divided into four stages, namely, steady development of microcracks, non-stable development of microcracks, fatigue damage, and fatigue destruction. Particularly, two stages after the peak value were in the dynamic stress unloading process. Based on the continuous divisor, strain equivalent principle and statistic damage principle, a fatigue variable of rock was defined and a damage evolution equation was deduced. Then, a combination model was adopted to establish a damage constitutive model. Compared with testing data, a damage evolution law of rock and the established damage constitutive model were verified. The damage variable was also calculated using the deduced damage evolution equation. Experimental results show that the relevant curves between the damage variable and dynamic strain conform to damage law of rock samples. It is also found that the established fitting curves of constitutive equations show comparatively good agreement with experimental curves. Hence, it indicates that the established damage constitutive model can be used to predict dynamic mechanical characteristics of deep rock under 3D high-static load and frequently dynamic disturbance.

Key words: deep earth rocks, 3D high-static load, frequently dynamic disturbance, damage characteristics, constitutive model