Abstract: Based on the elastic wave theory, the stress wave field will separate when it is oblique incidence across a linear elastic joint. The propagation of stress waves in rock mass including oblique joints is analyzed; and the computation of transmission and reflection coefficients is conducted with a universal distinct element code (UDEC), according to different approaching times of incident, transmitted and reflected waveforms. When stress waves is oblique incidence across a single joint, the simulated relationships between transmission coefficients and joint stiffness, incident angle agree well with the classic theoretical solutions, as well as the reflection coefficients. Furthermore, the situation of stress waves propagate through a set of parallel joints is analyzed. The results show that the transmission coefficients Tpp, Tss of the same kind wave firstly increase to maximum values and then decrease to stable values with the increasing of joint space; and the stable value becomes smaller when the number of joints is larger. Additionally, the critical values of joint space when transmission coefficients approach maximum values are approximately identical for different numbers of joints; but the inflection values of joint space for the situation of stable values gradually become larger with the increasing of joints number.

Key words: stress waves, joint, transmission and reflection coefficients, numerical simulation, UDEC