(State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：Variation of wave velocity with stress in rock is very significant for the study of damage development. Nine different models were set with the particle flow code(PFC) to simulate the processes of wave propagation and attenuation，in which a velocity pulse was applied to the transmitter and the average velocity was recorded with the receiver. It was revealed that the coordination number was in linear relationship with the porosity. The branch vector distribution was directly related to the amplitude attenuation. Moreover，the wave velocity was mostly affected by the porosity，coordination number tensor and stiffness tensor. The stress-strain process was simulated under biaxial compression to explore the wave propagation. The micro cracks were mainly distributed along the axial direction. In comparison with the shear cracks，the angles between the dominant orientation of the tensile cracks and axis are smaller. With the increase of micro cracks，the anisotropic degree of wave velocity and the distribution of branch vector increased gradually. It was proved that the intrinsic reasons of the velocity variation were the formation of new contacts，the breakage of bonds and the separation of contacts. The wave velocity was essentially consistent with the square root of the corresponding component of stiffness tensor. It was a new method to quantify the damage and wave velocity through analyzing the stiffness tensor and branch vector distribution，which provided reference for the study of damage development.
2015, Vol. 34 
