Wave propagation and diffraction through non-persistent rock joints: An analytical and numerical study

Abstract

The presence of joints, persistent and non-persistent ones, within rock masses has a significant influence on wave propagation. However, previous studies were limited to wave propagation across persistent joints. To understand P-wave propagation and diffraction across non-persistent jointed rock masses, theoretical and numerical analyses were carried out in this paper. A theoretical method was introduced to investigate P-wave propagation and diffraction across a single non-persistent joint, by combining the displacement discontinuity method and the angular diffraction theory. With this proposed theoretical method, analytical solutions for wave propagation and diffraction across a single non-persistent joint were derived. After validation through comparison with theoretical solutions, FEM-based numerical simulations were carried out to study wave propagation and diffraction across multiple parallel non-persistent joints. Results showed that the wave field after passing through a single non-persistent joint is two-dimensional, which is different from plane wave propagation across the persistent joint. Obvious enhancement regions and suppression regions exist, which are determined by the combined effect of wave transmission across the joint segments and wave diffraction at the rock bridges. In addition, spatial parameters including rock bridge length, joint segment length, joint spacing, propagation distance and joint dislocation have a remarkable influence on wave propagation across multiple non-persistent joints. The findings in this paper could fill in the gap between wave propagation across persistent and non-persistent joints and thus facilitate a better understanding of wave propagations across discontinuous rock masses.