Bridges and wind farms

[propergomper]

How do they get a base or foundation in the sea for bridges and wind farms without it washing away?

[Iggle Piggle]

The same as oil rig platforms, they send divers down to bolt the framework to the bedrock under the water.

[Panic Button]

Surely not Iggle. Its a bit muddy down there.

[Panic Button]

I think sometimes they float a concrete base into position then just keep adding more concrete to the top until it stops sinking

[Panic Button]

But that doesn't explain why it doesn't fall over!

Come on you civil engineers, we need some help here!

[sddsddean]

What you are vaguely describing PB is the method used for a gravity rig. This purely uses its own weight to sit it on the sea floor.

Bridge piers and other permanent structures are usually built within caissons. These are temporary coffer dams where the water is pumped out from inside. Obviously in deep water this is impractical, so piles are driven or drilled into the bedrock from drilling barges. A structure can then be built up on this network of piles.

There are several other methods available to over come the problem; you just have to use the one most suitable.

Forgot to say, caissons are sometimes pressurised to keep the water out, so the muck/rock can be dug out. Early navvies who worked in these often came down with the 'bends' (as the problems of nitrogen bubbles forming in the blood weren't really understood). As no one knew why this was happening, it came to be known as 'caisson sickness'. The first pressurised caisson in the world was used by IKB to build the centre pier foundation for the Royal Albert bridge at Saltash.

[pawwaw17]

often on the soft river beds and seafloors if its shallow with strong currents then they will add a mat of concrete blocks meshed together to stop the muds being eroded as the water speeds up as it passes around the obstical that would normaly errode around the legs,

[Panic Button]

When I hammered a socket for my rotary airer into the lawn it went a bit wonky.
How do they avoid that if they are sinking a foundation for a wind turbine in the sea? It would look silly if its like my rotary airer.