Author(s): G. Müller; G. Wolters

Linked Author(s):

Keywords: Aeration; cracks; pressure; propagation; wave impact pressure

Abstract: Transient or fluctuating pressures, generated for example by a wave impact on a sea wall or a water jet plunging into a pool, have been shown to propagate into water filled cracks or fissures of structures and rock. Model studies revealed the characteristics of impact generated pressure pulses, which were observed to travel at very low speeds of 60–160 m and to attenuate, whereby higher frequencies were preferentially damped out. Other effects, such as reflection and dynamic amplification also indicated that the pulses constituted waves propagating through an elastic 2-phase medium consisting of water and a small amount of air. Based on these observations, concepts for a numerical model of pressure pulse propagation in water were developed and implemented. It was found that the numerical model approximates the physical model test results well, both in the linear and the non-linear range and including the transition from an initial steep pressure pulse to wave-like forms. The damping coefficient was found to be a constant, independent of the degree of aeration. The results from the numerical studies imply that, within very short time frames, water behaves like a visco-elastic solid rather than as a fluid.

DOI: https://doi.org/10.1080/00221686.2004.9641186

Year: 2004