Xbase® development and application of a special concrete toe unit for extreme conditions

One of the most critical factors involving the design and construction of a breakwater is the design of the toe. Especially for single layer interlocking armour units, an under designed toe, or badly constructed toe can lead to significant damage and possible failure.

At Swakopmund, Namibia, a small craft harbour will be constructed. The site conditions will be challenging (a constant presence of swell from the Atlantic Ocean) and consequently the Xbloc® was chosen as armour unit for the breakwaters by the designers, WSP Africa Coastal Engineers, because of its fast and easy placement. During the hydraulic model tests at CSIR a special concrete toe unit, the Xbase®, was developed to guarantee high stability and easy placement of the toe. The Xbase proved to be very stable and additional 2D and 3D tests for other projects confirmed the results of the Swakopmund tests. This paper describes the development of the Xbase and its application at the Bar Beach shore protection in Lagos, Nigeria. Furthermore it describes its application as a crest unit on the rehabilitated breakwater of the Port of Poti in Georgia, Asia Minor.

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xbase_xblocs_special_toeunit_venice2007.pdf