Effective wave velocity in rock masses with double-scale discontinuities under in-situ stresses

Abstract

The effective velocity of stress wave in rock masses with double-scale discontinuities subjected to in-situ stresses was investigated in the present study. An improved model that comprehensively considers the deformation of macrojoint and wave velocity of microdefected rock mass under in-situ stress was proposed to study the effective velocity of stress wave. The effect of in-situ stress on effective velocity was systematically analyzed using the presented model. The effect of the propagation distance, incident wave amplitude and incident wave frequency on effective velocity under in-situ stresses were further discussed and compared with the results of traditional study that disregards the influence of in-situ stress. The findings demonstrate that the small in-situ stresses have a substantial effect on the effective velocity. The effective velocity shows a trend of rapid increase followed by slow increase as increases of in-situ stress. Additionally, the effective velocity increases with propagation distance and amplitude. In the low and high-frequency regions, the effective velocity remains approximately at minimum and maximum values. A significant increase in the effective velocity is observed as the frequency increases in the mid-frequency region. However, it is noted that the effective velocity does not change significantly with increasing amplitude for sufficiently large in-situ stresses, and the influence of amplitude on the effective velocity can be disregarded. Furthermore, it is found that the effective velocity resulting from the present study is consistently larger than that resulting from the traditional study due to the effect of the in-situ stress. The findings of this investigation offer useful theoretical guidance for research into the effective velocity in deep rock mass.