Quantifying uplift loads on pile supported wharf structures, part 1: Tsunami bore

Tsunamis are shallow water waves which have caused a high toll of casualties, massive economic devastation, and damaged coastal buildings, bridges, highways and harbour facilities. An experimental study of the effects of tsunami bores acting on a wharf-deck structure is presented. The experiments were conducted in a tsunami wave flume (14 metres long by 1.2 metres wide by 0.8 metres high), which features a dry bed condition in front of the deck model. A tsunami bore was generated from an adjacent reservoir by suddenly lifting a sluice gate. The deck model was built on an adjustable sloping shore with heights of 20 cm and 25 cm above the dry bed. Using wave gauges and a video camera, detailed measurements of bore heights and bore velocities were recorded; different cases were used in the experiments, representing different bore strengths. The spatial distributions of the time histories of pressures were captured by pressure sensors. Results show that the time-history of the pressures has three stages: impulsive stage, runup stage, and quasi-steady stage. The impulsive pressure was measured for different bore strengths, different slamming positions, different slope angles and different ratios of the bore height to the deck height. Some results from the experiments presented in this paper (obtained for a tsunami bore) are compared with those presented in the companion paper (obtained for a solitary wave).