平面波在黏弹性节理岩体中的传播特性 数值模拟研究

Numerical modeling of plane wave propagation characteristics in viscoelastic jointed rock masses

  • 摘要: 揭示黏弹性节理岩体中二维平面波的传播规律是研究远场爆破应力波传播的重要内容。使用ANSYS/LS-DYNA建立了波阵面与黏弹性节理面平行的典型工况数值模型。定义测点在岩体短轴方向的相对位置d/L来讨论波阵面上的幅值衰减与透反射系数,对比了闭合无充填节理与黏弹性节理模型中波的传播特性差异,分析了冲击速度与节理厚度对透反射系数的影响。研究结果表明:平面波幅值与波阵面幅值的分布均匀性随传播距离增大而降低;随着d/L的增大,入射波幅值I、透射波幅值T、反射波幅值R减小,但其减小速率不同导致透射系数Tc与反射系数Rc的平面分布差异,总体上Tc表现为缓慢振荡衰减趋势,Rc起初增减幅度较小,接近d/L=1处迅速下降到最小值;与闭合无充填节理模型相比,黏弹性节理模型中的TTc较小,RRc较大,即黏弹性节理阻碍透射波的传播;随着冲击速度增大,产生了更高频率的入射波,传播方向幅值衰减率增大,TcRc减小,但是入射波幅值I的平面分布差异缩小;随着节理厚度的增大,节理对波传播的阻碍作用增大,Tc大幅减小,Rc增减幅度较小。

     

    Abstract: The investigation of two-dimensional plane wave propagation in viscoelastic jointed rock masses constitutes a crucial aspect of studying far-field blast stress wave transmission. A typical numerical model was established using ANSYS/LS-DYNA, where the wavefront was parallel to the viscoelastic joint plane. By defining the relative position of measurement points along the rock mass minor axis as d/L, amplitude attenuation on the wavefront and transmission/reflection coefficients were analyzed. Differences in wave propagation characteristics between models with closed unfilled joint and viscoelastic joints were compared. The influences of impact velocity and joint thickness on transmission and reflection coefficients were examined. Results indicate that the spatial uniformity of plane wave amplitude distribution relative to the wavefront diminishes with increasing propagation distance. While the incident wave amplitude (I), transmitted wave amplitude (T), and reflected wave amplitude (R) all decrease with increasing d/L, their differing attenuation rates lead to distinct spatial variations in the transmission coefficient (Tc) and reflection coefficient (Rc). Overall, Tc exhibits a slowly oscillatory decay, whereas Rc initially shows minor fluctuations before decreasing rapidly to its minimum near d/L=1. Compared to closed unfilled joint, the viscoelastic joint model exhibits smaller T and Tc values but larger R and Rc values, demonstrating that viscoelastic joints hinder transmitted wave propagation. Increasing impact velocity generates incident waves with higher frequencies, increases the directional attenuation rate along the propagation path, and reduces both Tc and Rc, while simultaneously reducing spatial variations in incident wave amplitude (I). As joint thickness increases, the hindering effect of joints on wave propagation intensifies, resulting in a significant reduction in Tc, while the change in Rc remains comparatively minor.

     

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