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nusq

127 karmajoined 12 năm trước

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nusq
·3 ngày trước·discuss
Those are tetrapods. In Portugal we only use tetrapods, Antifer blocks and rock slabs if avaiable with the right size and density. The weight of the blocks is a function of the design wave height and period, so we have blocks with different sizes but not shapes. Sometimes we use blocks with high density concrete, cause higher density works both ways, it inscreases weight and reduces volume. You can see this in Sines, the blocks change colour on the tip of the breakwater, because the concrete has a higher iron content. https://www.google.com/maps/place/37%C2%B056'28.2%22N+8%C2%B...

There is one exception. In the Azores, there are core-locs because the breakwater was designed by the US Military. https://www.google.com/maps/place/38%C2%B043'36.6%22N+27%C2%...
nusq
·4 ngày trước·discuss
Finnally something I have knowledge of. Dolosse were invent in South Africa many years ago, but they are only one type of concrete block for wave dissipation and protection. Many others exist and some of them are patented and require the payment of royalties to be used. Anyway, in Portugal we do not use dolosse ever. We used it once in Sines deepwater breakwater, which suffered a catastrophic collapse in 1979. The promise of dolosse is that the blocks work together because of their shape and thus the individual block can be lighter and cheaper. This does not work in practice, at least in high energy seas. The ocean is unforgiven. What happens is that if only a few blocks break the whole structure will quickly collapse during a storm. And things can break due to a series of problems and risks. Concrete is only good at resist compression stresses and reinforcement with rebar is almost always a bad idea in ocean conditions, so complex shapes are hard to make and to move without introducing unwanted stresses that reduce the design strength conditions. Other types of blocks rely mostly on their design weight and density, and the shape is just used for increasing energy dissipation and overtopping. For example, tetrapods can be moved with only compression forces on the block.