Experiments by Invited Researchers


Forces on (flood) walls and buildings by wave overtopping

Project acronym: HyIV-CIEM-03
Name of Group Leader: Dr. Giorgio Bellotti
User-Project Title: Forces on (flood) walls and buildings by wave overtopping
Facility: CIEM Flume
Data Management Report: Report

User-Project Objectives

In many countries several coastal areas are protected with defences with too low freeboards (e.g. the harbour of Oostende and the surrounding coastal areas; similar situations in the Netherlands). Often there is no space for extension of the flood defences, which leads to solutions with storm walls or strengthening the walls of existing buildings. The waves hit the quay wall or dike slope and then the overtopping waves rush along the boulevard. Finally they hit a (storm) wall or a building. Theoretical formulae don’t exist to calculate the impact forces caused by this kind of overtopping waves. Full-scale impacts were tested, for realistic coastal defence structures, using the Wave Overtopping Simulator and small scale model tests in the wave flume of Ghent University. However there still is a missing link between the small scale and the “simulator” tests. If the forces are measured in the CIEM large wave flume, the scale effect can be estimated and the validation of the small scale overtopping tests can be made. The objectives of this research are: - Determine the scale effects on impact forces of overtopping waves on a boulevard - Find the link between the small scale model tests (wave conditions) and the simulator impact tests - Measure for sloping dikes and vertical walls flow depths and flow velocities on a boulevard and derive prediction formulae - Measure effect of friction elements on this large scale and find prediction formulae. - Measure impact forces on structures behind the storm wall.

Highlights of important research results

During the tested conditions different equal time series (Hs, period, spectral parameter) were done but with different initial seeding number to create the random phase time series. As expected the Overtopping values changed considerably, up to 100 % in one case, but the values gathered along the different tests also report the changes in the pressures and forces along the vertical dike and the quay dike configuration.