Cobble Sea Defence

Abstract

A cobble sea defence appears to be an easy constructible protection, with relatively low total costs of ownership. Flume tests show that sand under such single layered constructions is stable. However, it is not exactly known how the hydraulic loading of a breaking wave is reducing in the filter. Two datasets containing pressure measurements in a revetment were available for identification of this reduction: 1) A dataset of a test performed in the Großer Wellenkanal (Hannover), for improvement of the understanding of all relevant processes in Elastocoast revetments (obtained from the Braunschweig University of Technology). 2) A dataset of tests in the Delta Flume, for the verification and optimization of the cobble shore design of the ‘Maasvlakte 2’ (obtained from PUMA). The dataset of the Großer Wellenkanal test was analysed to increase the insight in the behaviour of pressures in a filter resulting from (breaking) waves and to explain processes and test results of the Delta Flume model tests. Hydraulic loading at the top of a revetment exist out of two types of loads; impact and non-impact loads. The impact load, resulting from plunging waves, can be distinguished in an impact peak and a quasi-static part. The impact peak is very high (>10 kPa), last for only a fraction of time (