DEVELOPMENT CENTRIFUGAL FLUID-WAVE GENERATING SYSTEMS

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A fluid-wave generating system for use in geotechnical centrifuges has been developed, with the aim of providing a new research tool for investigating into wave-seabed interaction. The wave generating system developed in this research included a servo-motor driven flap-type wave generator, a wave tank, a wave absorber of vertical slotted wall construction, and a sediment trench. With this system it has proven possible to generate a range of nearly progressive waves in a wave tank, and to look at the response of sediments to passage of wave trains, under a prescribed steady-state centrifugal acceleration.One of the important considerations was to select a fluid so as to facilitate the control of dynamic viscosity of the fluid, according to the level of the centrifugal acceleration imposed. This particular procedure was effective to meet simultaneously the requirements of similitude as to wave propagation as well as consolidation processes. The experimental program in this research consisted of two series of wave tests. The first series of experiments was concerned with wave tests over a "non-deforming" base and aim to assess the performance of the wave-absorbers with a range of structural parameters, such as the slotted area ratio and the length of a reservoir behind the wave absorber. It was found that under most favorable test conditions, the reflection coefficient of the wave absorbers was as low as 15%. The second series of experiments was concerned with nearly progressive wave tests with sandy sediments. The accumulation of excess pore pressures in the sediments due to wave action has clearly been observed, indicating the capability of this experimental system for investigating into wave-induced liquefaction or such other important physical processes.