Including the influence of waves in the overall slope stability analysis of rubble mound breakwaters

An offshore breakwater is designed for the construction of a LNG-terminal. For the slope stability analysis of the rubble mound breakwater the existing and the extreme wave climate are considered. Pore water pressure variations exist in the breakwater and its permeable foundation. A wave trough combined with the moment of maximum wave run-up results in a decrease and increase of the pore water pressure, respectively. Therefore, the wave actions have on overall effect on the slope stability of the breakwater. To include the wave actions in the slope stability analysis a simplified method is used. For the slope stability analysis, a specific piezometric line is determined. This piezometric line consists of a wave profile and the profile of wave run-up. The slope stability analysis are performed with GEO-SLOPE/W 2007. For the geotechnical design of the breakwater load cases of extreme and normal waves combined with, respectively, extreme and normal water levels are analysed. All the load cases which included the wave actions result in lower stability safety factors than the load cases with only still water levels. Therefore the wave actions are the determining load case for the geotechnical stability of the breakwater and it should be studied in detail

Waves in the North Sea: powering our future?

Ocean waves contain huge amounts of energy which almost haven’t been exploited up to now. Along the West European coastline the wave power resource is varying between 30 and 70kW/m crest length (Thorpe, 1999). These huge amounts of wave power increase the potential energy capture on the one hand but hamper installation on theother hand. Furthermore the survivability of conversion systems could be in danger in these severe wave conditions.The wave climate in the North Sea is less aggressive due to the sheltering effect of Great Britain. The wave power resource and potential areas for installation of a farm of Wave Energy Converters (WECs) in the North Sea will be discussed during the presentation.Wave energy is a renewable energy type that is becoming more and more important. Many conversion principles have been invented and are currently being developed, tested and improved. Research on power optimization, structural design, etc. is going on while interest of private investors is increasing.Although many concepts have been invented, only a limited number of systems have already been built in prototype size and have experienced real sea trials. Even fewer have reached a commercial stage. Among them is the Pelamis the converter which is probably most ahead of the others. This system, sometimes called ‘sea snake’ consists of four hinging cylinders that produce electricity via a hydraulic intermediate stage. The Portuguese consortium Enersis will shortly install three units of 750kW each in front of the Portuguese coast. Some other systems that have experienced sea trials - mostly at scaled size - are Wave Dragon, FO³, Wave Star, AquaBuOY, OPT Power Buoy, Pico power plant, Limpet device,… Some of these systems will be treated more in detail during the presentation

Numerical modelling of wave energy absorption by a floating point absorber system [POSTER]

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