Overtopping physical model tests for the rehabilitation of Sines west breakwater

Abstract

The failure of the West Breakwater of the Portuguese harbour of Sines in 1978/79 is well known and much was learnt from it by the scientific and technical communities. The paper presents an historical perspective on the design, construction, failure and rehabilitation of the breakwater, as well as on the overtopping physical model studies performed to check the effectiveness of the different proposed solutions for its rehabilitation. Studies are now being conducted for Sines Port Authority for the final rehabilitation of the breakwater, with the primary objective of reactivating Berth1 but also to generally improve the shelter and operating conditions within the port. The paper presents the three proposed solutions for the West Breakwater, which differ mainly in the crest area. It describes the two-dimensional physical model tests of stability and wave overtopping carried out in 2008 at the National Civil Engineering Laboratory, Portugal, to check the effectiveness of the three proposals. The mean overtopping discharges measured in the tests for Solution 3, having a higher crest level with a recurved concrete superstructure, were significantly lower than for Solutions 1 and 2 (which were similar). All three proposed solutions were structurally stable under design conditions. The paper also illustrates the application of a new version of the NLSW numerical model, AMAZON, and of the methodologies/tools recommended in the EurOtop overtopping manual to study the mean wave overtopping discharge over the breakwater. There was good agreement between the physical model data and the AMAZON results for Solutions 1 and 2, although AMAZON tended to slightly overpredict the discharges, especially for Solution 2. The CLASH Neural Network mean overtopping discharges tended to under-predict the physical model results, especially for Solution 3. For the three solutions, the physical model results were within the confidence intervals obtained with the Neural Network. The Empirical Methods considerably over-predicted the mean overtopping discharges