Reflection and transmission of acoustic waves at the interface between rocks in the presence of elastic-plastic deformations

Abstract

The problems of the reflection and transmission of acoustic waves at the interface between rocks in the presence of elastic-plastic deformations are investigated based on the acoustoelastic theory for elastic-plastic materials. The effects of statically elastic-plastic deformations on the energy reflection and transmission coefficients, reflected and refracted angles are investigated. The plane of incident wave can coincide with or deviate from planes of material symmetry. Elastic-plastic deformations are assumed to be locally homogeneous and to satisfy static boundary conditions. To explain the difference with the statically elastic deformation, the velocities are computed in a rock with elastic-plastic deformations. The variations of these energy coefficients with elastic-plastic deformations have been shown graphically. The velocities decrease, the energy is distributed, and the critical angles are changed when the rock undergoes elastic-plastic deformations compared with those of the statically elastic deformations. The directions of transmitted wave vectors are changed especially at relatively large incident angles when the material is subjected to statically elastic or elastic-plastic deformations. © 2007 Nanjing Institute of Geophysical Prospecting.