Reliability Analysis of Geotechnical Failure Modes for Vertical Wall Breakwaters

Vertical wall breakwaters are usually designed as concrete caissons placed on the top of a rubble mound foundation or a rubble bedding layer. The purpose of the breakwater is usually to protect the area behind the breakwater from being flooded by large waves. The area protected can for example be a harbour of small or large importance, an important industrial area or a heavily populated coast line. This implies that vertical wall breakwaters are used under quite diAerent conditions and therefore the consequences of a complete or partial failure also are very diAerent. This implies that the accepted probability of failure also varies considerably which also can be observed from the actual observed failure rates. A number of diAerent failure modes are relevant to consider for vertical wall breakwaters (e.g. [1]). Foundation failure modes include sliding of the breakwater relative to the rubble mound and diAerent foundation failure modes with failure within the rubble mound and the subsoil (sand or clay). Hydraulic failure modes include wave overtopping, wave transmission and wave reflection. Structural failure modes involve failure or partial failure of the concrete caissons. In this paper only geotechnical failure modes are considered. In order to estimate the reliability, stochastic models for the uncertain parameters in the limit state functions are formulated. The main horizontal and vertical (uplift) loading on vertical wall breakwaters are wave loads, including both pulsating and impact wave loads. Stochastic models for the wave loading are presented. These