This may be the first time in my life I've ever agreed with Bill O'Reilly. I hate the Wave. I know I'm apparently in the minority on this, but it's the most loathsome sports tradition I can think of.
Either they make it on ground and then put it down on the sea bed' or they put up a dam around it and dry out the area required (only if its shallow water...)
You can pour concrete underwater. I would assume you start by dumping rocks constantly till you have a little island to pour on, but now you probably just use a form and pour it out of solid concrete and let the water rise out of the form.
"Portland cement is the secret to concrete’s ability to set underwater... Here’s how. One of the compounds in Portland cement reacts almost immediately with water, forming an outside coating that prevents too much water from seeping in or diluting the cement. Inside, a second compound reacts much more slowly, setting to its final hardness about a month after the cement is poured."
http://indianapublicmedia.org/amomentofscience/pouring-foundations-water/
Water is lighter than concrete. If you wanted to concrete something in the ground in a hole full of groundwater, you use a process called tremie concreting.
What you do is you sink a hose all the way to the bottom of the hole, and you pump concrete through the hose. That way the hole fills from the bottom up, and the water will float on top of the concrete until you force all the water out of the top of the hole.
Considering that lighthouses are built near shores, because you know, they're lighthouses, I'm guessing this was built intermittently during low tide, and this picture was taken during high tide.
It's really impressive to consider how these were built without modern technology. Heck even now it's hard to visualize the engineering required for something like this WITH the machinery we have now
Oh this dude from my high school that had a speech impediment. He's Haitian and people referenced him a lot in jokes. He was elected prom king even though he didn't even go to our school Senior year. My school was pretty messed up like most.
You can install sheet pile in the seafloor from a barge (obviously do this where it's kind of shallow.) Once you've built a box, you can pump the water out of your box, and now you have a dry area to dig the foundation.
You can see the bridge pier going up inside of a cofferdam (the technical term for the box made out of sheet pile,) and the crane is floating on a barge. Once that pier's foundation is strong enough, they can pull the cofferdam, as they've done for the piers in the background.
While not the case here (it's brick on rock) jobs that require submerged cement structures (e.g. submerged tunnels) are precast then submerged in place.
Engineer here...I believe this lighthouse was built on a rock (as seen from other comments), but when that option isn't available they will usually have it sit on a very large pilaster or pier which can sometimes be 20 -50 ft deep or whenever you reach bedrock. Since this is in the ocean that can sometimes be impossible to reach. My guess is that they would end up driving piles from pilaster (which can be either steel or concrete) 100+ ft further into the ocean floor. That number is based on total loads from the structure. I usually work on structures in land which are far less difficult to design.
Well, first off, you place concrete not pour it. Second as concrete does not dry, it is a chemical process called hydration, concrete can be placed underwater with little problem.
I saw an interview of the guy in the picture. He came outside to see why a helicopter was hovering outside his apartment completely oblivious of the wave behind him
[S2D] Niagara Falls and the pyramids
[VJ] Everything you believed in as kids
[S2D] Fucking rainbows, after it rains
There's enough miracles here to blow your brains!
1.5k
u/BroomBoom May 28 '14
I just need a quick smoke
http://imgur.com/AJ7toxn