Physical Modelling of Wyndham Harbour Breakwaters, Victoria

Client: Water Technology Pty Ltd
Year: 2007
Project Reference: 07036
WRL Technical Report: Physical Modelling of Wyndham Harbour Breakwaters (2008/03)

A new marina development is proposed to be constructed at Wyndham Harbour in Port Phillip Bay, Victoria. Conceptual design investigations for each of these structures have been undertaken by Water Technology Pty Ltd in association with Vantree Pty Ltd. Three main coastal protection structures are proposed as part of this development: a main breakwater, northern breakwater and northern groyne. WRL was commissioned to undertake 2D modelling of the main breakwater at two different critical sections in the 1 m wave flume.

Testing was conducted at two different scales: 1:20 and 1:16. Bathymetry offshore of the breakwater was constructed in the flume with marine plywood panels. The breakwater is proposed to be constructed as a rubble mound structure with only core and primary armour layers.

Upon construction of the core, the surface of the core material is to be mechanically raked to bring larger stones to the surface, to form a quasi-secondary armour layer upon which the primary armour layer will be seated. This procedure was simulated in the physical model by fabricating a scale “rake” and running this through the core; bringing larger stones to the surface. The breakwater designs were subjected to a range of water level and wave height conditions, for which analysis of armour stability, wave overtopping and transmitted wave conditions were undertaken.

The WRL test program indicated that the quasi-secondary armour layer performed satisfactorily demonstrating that the primary armour stone mass could be reduced from 2.8 t to 1.4 t and advised that the crest elevation in the original design could be reduced by 1.0 m in one section of the main breakwater.