Damage laws of layered and jointed rock mass under the impact of cyclic loading

In order to study the accumulative damage laws on the jointed rock mass under the impact of cyclic and dynamic loading, one to three specimens, including layered and jointed rock mass, were precast separately, which are made of cement-mortar used as similar material. Ultrasonic wave velocity of each specimen could be measured every time by conducting shock loading one to five times separately. On the basis of ultrasonic wave velocity, the damage variable of the specimen is defined. Meanwhile, both the effect of shock damage degree on rock mass under the shock frequency and sets of joint could be obtained. The results show that under the same shock energy, the damage degree is closely related to sets of joint and shock frequency. In addition, when the shock frequency was small, the specimen only produced microcracks and gradually formed macro-destruction with the increase of accumulative shock frequency.