New design methods for wave impact loadings on vertical breakwaters and seawalls

This paper discusses wave impacts on vertical and composite breakwaters and related coastal structures. It describes types of vertical walls in use, with particular reference to older walls that may be much more influenced by wave impacts. Methods to estimate wave forces are identified. Analysis of performance suggests that these under-predict wave impact loads, and cannot identify combinations of geometry and wave conditions which lead to impacts. Comprehensive 2-dimensional hydraulic model tests have been conducted using random waves to measure wave pressures (and other responses) on a wide range of simple and composite vertical walls. The test results have been used here to: • Identify the ranges of geometry and wave conditions which lead to wave impacts; • Develop a simple method to estimate wave forces under impact conditions. Analysis of % of impacts has defined a new design diagram to identify wave conditions and wall / mound geometries which cause impacts. These results are intended for engineers analysing vertical or composite walls in deep water, in harbours, or along the shoreline.