Laboratory Measurements of Breaking Wave Impact Pressures on a Slender Cylindrical Member

Abstract

Slender cylindrical members form the major components of many of the coastal and offshore structures. These members are frequently subjected to breaking wave impact which often resulted in damages and failure of structures. In order to overcome this intricacy, it is essential to understand the physics of the breaking wave impact on offshore structural members and the resulting induced critical stresses. An experimental investigation has been carried out to measure the effect of breaking wave impact on a slender vertical cylinder. Simultaneous qualitative visual observations and quantitative pressure measurements were made to appreciate the impact induced effect. The induced impact pressure on the cylinder varies with the intensity of wave breaking and the relative location of the cylinder. The impact pressure is maximum when the wave profile reaches its maximum steepness just before the crest destabilization. Impact pressure observed due to a severe plunging wave is about nine times higher than due to spilling. The pressure rise time is found to be an important parameter in dictating the nature of impact.