Abstract:ELASTOCOAST revetments are highly porous structures made of mineral aggregates (e.g. crushed stones) which are durably and elastically bonded by polyurethane (PU). Despite their numerous advantages as compared to conventional revetments and the large experience available from several pilot projects (e.g. in The Netherlands and Germany), physically-based design formulae to predict their hydraulic performance, wave loading and response are still lacking. Therefore, the present study aims at improving the understanding of the processes involved in the interaction between wave, revetment and foundation, based on large-scale model tests performed in the Coastal Research Centre (FZK), Hannover/Germany, and to provide formulae/diagrams for the prediction of (i) the hydraulic performance (wave reflection, wave run-up and rundown), (ii) the wave load on and beneath the revetment as well as in the subsoil for a wide range of wave conditions, including both impact and non-impact wave loads, (iii) the response of the revetment (flexural behaviour) and its foundation (pore pressure and effective stress). The failure of one of the three ELASTOCOAST revetment model alternatives A, B and C tested at prototype scale is also analysed on the basis of the data simultaneously recorded by more than 80 transducers synchronously connected to two video cameras. As a result, it is shown that the weakest ELASTOCOAST alternative failed due to transient liquefaction of the sand core beneath the revetment while another ELASTOCOAST alternative, synchronously tested under exactly the same wave conditions, did not fail. Generic implications are then drawn from these results for the design of bonded permeable revetments subject to water waves. Finally, a brief outlook is provided on the planned future research directed towards numerical modelling and the incorporation of these results in a design manual for polyurethane bonded aggregate (PBA) revetments.
Keywords:Bonded permeable revetments -Wave impact loads -Wave-structure-subsoil interaction -Wave-induced pore pressure -Transient soil liquefaction
709Thème 5 -Ouvrages portuaires, côtiers et offshore 1. Introduction "ELASTOCOAST" has been introduced in 2004 for the shore protection of Hamburger Hallig as a new type of highly porous revetment made of mineral aggregates such as crushed stones which are durably and elastically bonded by polyurethane (PU). Since then ELASTOCOAST has been applied at 15 further coastal sites in Germany, four pilot sites in The Netherlands, four in France, two in the UK and one in Canada (see www.elastogran.de). As compared to their conventional counterparts, ELASTOCOAST revetments have many advantages. Wave run-up, and thus also the required height of the defence structure, can be substantially reduced as compared to smooth impermeable revetments. Moreover, wave reflection which may affect both navigation and sea bed stability is also reduced. The high porosity combined with the durable elastic bonding may result in a much smaller revetment thickness requir...
