Rock Mechanics and Rock Engineering (07232632)
The effects of rock joint dimensions on transmitted hydrodynamic pressures in bedrock joints in unlined plunge pools, due to the plunging jet impact, are experimentally assessed. The investigated dimensional properties include the rock joint aperture (opening), length, and width. The findings indicate that as the aperture increases, the pressure fluctuations and dynamic pressure resonance frequency increase. Increasing the aperture reduces the air concentration inside the joint and the internal friction of the joint walls. As the joint length increases, the mean dynamic pressure inside the rock joint increases, and the internal friction effects of the wall joint increase. As a result, pressure fluctuations are reduced. Joint elongation increases the duration of the pressure wave pulses and decreases the corresponding frequency of the resonance conditions. Increasing the width of the joint up to twice the diameter of the jet leads to an increase in the intensity of pressure fluctuations and the frequency corresponding to resonance conditions, while wider rock joints show a reduction in pressure fluctuations and resonance frequency. The concentration of air inside a rock joint is proportional to the joint width; as the width increases, more air is able to enter the rock joint. The dimensions of rock joints affect air concentration and joint wall friction, thereby causing changes in pressure wave celerity propagated in rock joints. The findings of this article indicate that when calculating the rock scour mechanism through models based on bedrock joint pressure, the effect of the dimensional characteristics of rock joints should be considered. © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2025.
