Non-linear extreme random forces on a vertical wall given by very high sea wave groups

Nonlinear wave pressures and wave forces exerted on a vertical type of breakwater, due to long-crested wave groups, when an exceptionally high wave crest occurs, are investigated. The analytical investigations are based on the closed form solution for the reflection of long-crested wave groups, derived previously by the authors. It is obtained that the effects of non-linearity strongly affect the linear processes of both wave pressures and wave forces. In particular, a very important result is the occurrence of double positive peaks in the wave force process. Beneath the highest wave crest a local minimum of the wave force is observed with the formation of two maxima for each wave crest impact.