Mechanical properties of discontinuity in rock mass with different inclination angles under cyclic dynamic disturbance

In order to study the deformation characteristics and failure mechanism of discontinuous rock mass with different inclination angles in large cavern or slope under dynamic disturbance,some periodic dynamic perturbation mechanics tests of rocks with different dip angles were carried out using electrohydraulic servo universal testing machines.The experimental results show that a large number of vertical cracks along the specimens axial direction are generated and subsequently the rock structural specimens are broken into relatively thin pieces or strips of debris when the structural surface specimens are damaged under the dynamic disturbance.The loading and unloading curves of the rock mass discontinuity do not coincide,and a closed hysteresis loop curve is formed.The overall stressstrain hysteresis loop curve of the rock discontinuity under dynamic disturbance has three stages:sparse,dense and sparse.When the dip angle of rock discontinuity is constant,the area of hysteresis loop curve and the deformation modulus of rock mass increase with the increase of disturbance stress,which indicates that the increase of disturbance stress makes the disturbed rock accumulate more consumable energy in each cycle that is used for the consumption of stick slip between mineral particles,the growth of original micro cracks and the generation of new cracks.The total amount of cumulative irreversible deformation that leads to rock failure is reduced,which deteriorates the load resistance of the specimens.When the disturbance stress is fixed,the large variation range of the hysteresis loop curve increases with the increase of the dip angle of the structural plane and the deformation modulus of the rock mass decreases.The damping ratio of rocks with different inclinations decreases first,then stabilizes,and then increases,which reflects the process of fracture failure in rock from initial deformation (pore compaction) to constant deformation (stable development of micro fracture) to accelerated deformation (crack connection).There is a disturbance threshold which can be determined by static load and inclination of the structural plane.When the disturbance stress is lower than the disturbance threshold,with the increase of cyclic loading and unloading period,the plastic strain value tends to be stable,and the rock structural surface is not damaged.The number of loading and unloading cycles and the variation of the cumulative plastic strain correspond to a negative exponential function.When the disturbance stress is higher than the disturbance threshold,these values correspond to an inverse Langevin function.The physical significance of the undetermined parameters in the function is determined by analyzing the influence of undetermined parameters on the damage curve cluster,and the energy failure mechanism of rock under cyclic loading is revealed through the analysis of internal energy change process of rock discontinuity with different inclination angles under different amplitude dynamic disturbance.These results have practical significance and academic value for the engineering design,disaster prevention and control of deep rock structural plane engineering.