An Investigation of Wave Forces Acting on Vertical Coastal Structure

Abstract

Research on wave forces attacking a vertical structure has been conducted worldwide. Morison’s equation commonly used to describe the phenomenon of the action for offshore structures, while for nearshore structures Goda’s equation is more reliable. Wave impact on vertical breakwaters is dangerous for vertical structures, both for walls and columns. Wave pressure distinguished for wave crest and wave trough, assumed to be distributed as a trapezoidal shape like along the vertical wall. The wave force consists of wave pressure on the front of the vertical wall and buoyancy, and uplift pressure in the vertical direction. In this research, a 2-dimensional physical modelling is carried out to observe the response of a vertical structure due to a wave action. Wave forces are measured using a flexi force sensor for both horizontal and vertical forces. Time series of incident wave and waveforces acting on the structure are recorded simultaneously and it clearly depicts the relation between them. The wave forces at the structure are linear to the height of the action waves. Periodical wave action results in the pushing forces at the structure to be higher than the pulling forces, as extra drift forces appear due to the shallow water wave condition.