Mitigation Effect of Vertical Walls on a Wharf Model Subjected to Tsunami Bores

An experimental study was carried out to investigate the mitigation effect of vertical walls on a wharf model subjected to tsunami bores. Dam-break waves were generated in a flume to simulate tsunami bore propagation, the bore characteristics were observed, and the tsunami pressures on vertical walls and a wharf model were measured. Results indicate different characteristics for bores traveling on wet-bed and dry-bed. The tsunami bore impact on a vertical wall was shown to exhibit four stages, and the time-history of the pressure exhibits three phases accordingly. Based on the law of conservation of energy, an equation for estimating the pressure exerted on the mid-point of the wall was proposed with coefficient of 1.8–2.4, and found to be suitable in this experimental range. Based on experimental data, an equation of the mitigation effect of vertical walls on tsunami was proposed as a function of the inundation depth, the wall height and the deck height. The predicted values from the equation are generally within ±20% of the measured values.