Abstract

This paper examines long wave loading on a building array behind a high-elevation, varying-length seawall through laboratory experiments conducted in Oregon State University's Directional Wave Basin. Long wave forcing in the form of solitary waves and error function waves was applied to both pre-inundated high water level conditions with currents, and to low water level runup loading without currents. Behind the wall, the cross-shore peak load declined as a function of the sheltering angle; on the other hand, the highest loads occurred with seawall lengths that exposed the instrumented structures. Flow concentration around the end of the wall caused higher velocities when a structure was just exposed, and led to large loads for nonbreaking waves at these wall lengths. For cases with breaking waves, particularly for inundation conditions, the wave breaking location was also a determining factor of the magnitude of loading, as larger loads were observed when a wave broke far enough in front of the first structure that a strong bore had developed. These results will serve to provide a better understanding of the wave impact to a coastal urban region in a tsunami event when the seawall is breached.