The influence of initial stress on wave propagation and dynamic elastic coefficients

The governing equations of wave propagation in one dimension of elastic continuum materials are investigated by taking the influence of the initial stress into account. After a short review of the theory of elastic wave propagation in a rock mass with an initial stress, results indicate that the initial stress differentially influences <i>P</i>-wave and <i>S</i>-wave propagation. For example, when the initial stress is homogeneous, for the <i>P</i>-wave, the initial stress only affects the magnitude of the elastic coefficients, but for the <i>S</i>-wave, the initial stress not only influences the elastic coefficients but also changes the governing equation of wave propagation. In addition, the <i>P</i>-wave and <i>S</i>-wave velocities were measured for granite samples at a low initial stress state; the results indicate that the seismic velocities increase with the initial stress. The analysis of the previous data of seismic velocities and elastic coefficients in rocks under ultra-high hydrostatic initial stress are also investigated.