Simulation on Vibration Characteristics of Fractured Rock

Modal analysis theory of rock is proposed and the modeling of vibration characteristics of fractured rock is undertaken in this study. The modeling includes two aspects, namely, the natural frequency of rock with a single fracture and the crack expansion energy of rock with multiple fractures. Also, the results of numerical analysis are presented. Four main control parameters are considered, including the material properties, crack size, crack trend and the number of cracks. It is confirmed that the natural frequency of rock will be reduced by the cracks in it. The expansion energy of a single crack is inversely proportional to the number of such cracks in the rock. Namely, the more the similar cracks are, the less the energy required for a single crack expansion is and the smaller the excitation frequency needed for rock resonance is. The vibration characteristics of fractured rock are validated by numerical analysis. The natural frequency of rock increases with the increase of elastic modulus, and decreases with the increase of the angle, the length, the width and the number of cracks.