Experimental study on the irreversible displacement evolution and energy dissipation characteristics of disturbance instability of regular joints

To investigate the disturbance‐induced shear instability mechanism of structural catastrophe in the deep rock mass, MTS 815 material testing machine was used to carry out quasi‐static loading tests and disturbance shear tests on symmetrical regular dentate joints of two materials at three undulation angles under specific initial static stress, disturbance frequency, and peak value. The test results indicate that: (i) the total ultimate instability displacement is only related to the intrinsic properties of the joints but not to the initial static stress and disturbance parameters; (ii) the cumulative irreversible displacement required for the disturbance instability conforms to the logistic inverse function relationship with the number of disturbances, displaying the variation trend of “rapid increase in the front, stable in the middle, and sudden increase in the rear”; (iii) the accumulation of plastic deformation energy is consistent with the evolution law of irreversible displacement of joints and the overall proportion of hysteretic energy is not large; (iv) the dissipated energy required for the instability of each group of joints is basically the same under various disturbance conditions, and this energy is mainly controlled by the initial shear stress and has no connection with the disturbance parameters. The stability of the total disturbance deformation and the disturbance energy law of the joints revealed in the tests provide data support for reasonably determining the disturbance instability criterion of joints. In this study, to investigate the effect and underlying mechanism of the failure process under disturbance, a series of quasi‐static loading tests and disturbance shear tests in the vicinity of the strength limit is conducted on symmetrical regular dentate joints. Combined with the “locked patches” theory of typical gradual sliding, the failure law and morphology of joints under quasi‐static loading are summarized. Further, the variation rule of irreversible displacement under disturbance and the fitting prediction is also examined. Besides, the energy evolution process of joints under disturbance is analyzed based on the energy damage and energy storage mechanism. Overall, the findings of this study can provide test support for reasonably determining the disturbance instability criterion of joints under high initial stress Highlights The total ultimate instability displacement is only related to the intrinsic properties of the joints. T