Study Of The Hydraulic Response Of A High Permeable Breakwater Using Physical Modelling

Abstract

Physical modelling tests were conducted in the wave flume of Artelia’s hydraulic laboratory to study the hydraulic response/stability of a rubble mound breakwater made with a non-standard core composed of crushed concrete blocks (tetrapod). This design carried out by EDF, is aimed at having high permeability and fits in an eco-design approach, through the reuse of existing materials already on site. Eventually, the hydraulic efficiency of three different sections were tested and compared, all sections having the same armour layer and the same main dimensions but different {core; filter} systems : core only made with crushed tetrapod, core and underlayer made with crushed tetrapod (no filter layers with rocks) and baseline design (quarry run core and rock underlayer). Several responses were studied: armour layer stability, overtopping and transmission of the structure and head loss on both sides of the structure with an inflow/outflow system in the rear side basin set up in the wave flume. This case study illustrates 1) the importance of the physical modelling approach to testing unusual structures, as part of an eco-design approach, where the use of standard design formulas does not allow to verify the hydraulic behaviour of a high permeable breakwater and 2) also shows that unconventional design can lead to satisfactory hydraulic results.