|Design of concrete armour layers|
van der Meer, J.W. (2000). Design of concrete armour layers, in: Losada, I.J. Coastal Structures '99: proceedings of an International Conference, Santander, Spain, 7-10 June 1999. pp. [1-9]
In: Losada, I.J. (2000). Coastal Structures '99: proceedings of an International Conference, Santander, Spain, 7-10 June 1999. Balkema: [s.l.]. 2 vol. (1156 p.) pp., more
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Most rubble mound breakwaters in the world have an armour which consists of two layers of units. Well known examples are rock, cubes, tetrapods and dolosse, but there are many more. The Accropode is the first unit that has been used in many applications as a randomly placed one-layer system. Recently the Core-loc has been added as a similar system. Also cubes in one layer have been tested and gave a similar behaviour with respect to damage development. Stability formulae have been presented for all these units and advantages and disadvantages discussed.
General stability formulae for cubes and tetrapods will be treated first. The influence of crest height on stability was investigated recently by changing the crest height of a breakwater with tetrapods. This influence can be described by an exponential function and can be added to the existing stability formula. Another influence on stability is the packing density. This influence has also been investigated for tetrapods, leading to an addition to the general formula. In fact, the additions for crest height and packing density can also be added (as a first guess) to the stability formula for cubes.
One-layer systems are discussed, starting with a stability formula for the accropode. A comparison is made with the Core-loc. Recent interest has been focussed on armour layers with a single layer of cubes or tetrapods. The tests for tetrapods showed very low stability, but the tests on cubes were very promising. Finally, all the concrete units have been compared.