黏弹性节理岩体的位移不连续模型研究

A displacement discontinuity model for viscoelastic jointed rock mass

选用三参数标准线性固体作为岩石本构,提出了一种考虑岩体黏弹性的位移不连续模型;根据一维黏弹性波的特征线法,推导了节理处质点速度、应力和应变递推公式。首先,基于分离式霍普金森压杆(SHPB)对砂层进行试验,得到其应力-应变关系,并换算出砂层节理的法向刚度;接着,通过一维强间断黏弹性波的波速公式、高频波衰减系数以及任一频率下的衰减系数,确定出数值算法中的三参数。最后,基于自制的摆锤装置,探讨了一维应力波在节理岩体中的传播规律,试验中以两根长1 000 mm、直径为68.50 m的岩杆作为入射和透射杆,以3 mm砂层模拟节理。试验和数值结果吻合度良好,进一步验证了该方法的可靠性。

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 cart 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.