Abstract: A viscoelastic displacement discontinuity model is proposed, in which the rock mass is viewed as a three-parameter standard linear solid. The recurrence formulations of particle velocity, stresses and strains at joint are developed based on the characteristic line method for the 1D viscoelastic wave. The dynamic stress-strain relationship of the sand layer is first determined by the split Hopkinson pressure bar (SHPB), which can be converted to the normal stiffness of joint. Then the three parameters for the standard linear solid are evaluated through the velocity formulation and the high frequency attenuation coefficient along with the arbitrary frequency attenuation coefficient of 1D strong discontinuity viscoelastic wave. Finally, by using two rock bars with a length of 1 000 mm and a diameter of 68.50 m as the incident and reflected bars, respectively, the propagation of 1D stress wave in jointed rock mass is analyzed based on a homemade pendulum by using 3 mm sand layer as the alternative joint. Good agreement between the experimental and numerical results are demonstrated, showing the reliability of the proposed method.

Key words: rock, viscoelasticity, displacement discontinuity model, characteristic line method, wave propagation coefficient