Secondary Pressures of Waves Breaking on Seawall

Secondary pressures resulting from the waves breaking on a vertical wall are studied experimentally with beaches having four different slopes. Pressure history of the wave impact consists of two distinct parts: The first peak and the second peak. The magnitudes of the second peak pressure are found to be much lower than those of the first peak pressures. The duration of the second peak pressure is considerably longer than the first peak pressure. The vertical distribution of simultaneous second peak pressure is almost linear vertically and this pressure is somewhat similar to a hydrostatic pressure. The major parameter affecting the second peak is the initial wave steepness. The effective pressure head is about the wave crest for low waves and moves below it for steep waves.