The joints have a certain effect on stress wave propagation across rock masses. This paper presents an experimental study on stress wave propagation across joints with different joint matching coefficients by carrying out ultrasonic wave tests. The steel cylinders with different contact areas were adopted to simulate the joint rough surfaces and simplify the specimen preparation. Through the tests, the initial pulse of the transmitted wave across the joints is obtained. By comparing the measured results, the attenuation effect of single joint and two parallel joints with different joint matching coefficients on wave propagation is investigated. The experiment results show that the transmission coefficients for the jointed specimens are influenced by various parameters of joint, such as Joint Matching Coefficient (JMC), distribution type of contact area of joint surface, the number of joints and joint spacing.


Rock joints are common type of the structural planes existing in natural rock masses. When a wave propagates across the joints, it is often attenuated and slowed, so the presence of the joints has great effect on stress wave propagation (Pyrak-Nolte 1996). A lot of researches have been carried out to study stress wave propagation across one joint or joint set. The Equivalent Medium Method (EMM) (e.g. Schoenberg & Muir 1989, Cook 1992) is one of the theoretical methods in common use, which describes the macroscopical property of the jointed masses based on principles of continuum mechanics. The other theoretical method used widely is the Displacement Discontinuity Method (DDM) (e.g. Schoenberg, 1980, Pyrak-Nolte et al. 1990), which considers that the stress across the joint are continuous, but displacements across the joint are not.

This content is only available via PDF.
You can access this article if you purchase or spend a download.