Experimental study on the dam-break-induced surge impact on an inclined wall

The front faces of coastal structures are not always perpendicular to its foundation. To investigate the surge impact characteristics on an inclined wall, laboratory experiments about the dam-break-induced surge impact were conducted on downstream walls with four different inclination angles, i.e., −30°, −10°, 0°, and 10° (positive for forward inclination). Before the water tongue forms, surge water in front of the wall can be classified into the bottom solid water and the upper aerated water. Although the measured maximum water level is the largest in front of the vertical wall, it contains a large proportion of aerated water. In contrast, the −30° wall exhibits the largest proportion of solid water, which is associated with the force exerted on the wall. As the wall inclines forward, the impact pressure experiences an increase in its peak value and spatial extent, while a decrease in its duration. The maximum impact pressure and the maximum horizontal force induced by the initial impact increase from the backward to forward inclination, while the maximum horizontal force in the transition or quasi-static phase increases as the wall inclines. In addition, it is found that the calculation method for designing breaking wave loads on nonvertical walls underestimates the surge-induced maximum horizontal force. Regarding the potential sliding/overturning failure, the 10°/−30° wall presents the highest risk among the considered cases under the same incoming hydrodynamic conditions. These findings extend our understandings on the surge–structure interactions, being helpful for the safe design of relevant coastal structures.