Abstract: The reliability of calculation of the UDEC has been proved by an example which about the transmitting of stress wave through a joint.Ten kinds of models with different level of roughness joints has been established based on average centerline intercept and root mean square value of relief amplitude of joint.The numerical results show that transmittivity of stress wave decreases with root mean square value of relief amplitude increasing while keeping average centerline intercept same, and also transmittivity will increases with average centerline intercept increasing while the root mean square value of relief amplitude keeping same.

Key words: Joint, Roughness, Stress wave, Transmittivity