Unless you work on infrastructure and some other specialty structures, you’ve probably always wondered how underwater structures are built. It’s always admittedly been a bit of a mystery to me, as I only encounter relatively small amounts of water on my retail construction sites. Some dewatering here and there or a small creek relocation can add some difficulty to a project, but they’re manageable.
Building bridges over oceans and rivers, like the New NY Bridge, or this pretty awesome underwater restaurant in Norway takes considerable care and expertise to keep workers safe and the water from compromising the strength of the structure. We’ve come across some cool tools, like this power drill you can use underwater, but those can only take you so far.
The YouTube channel called Practical Engineering just recently explored how underwater structures are built and I thought it gave a great overview of the process of how they are are supported, beginning with decades old methods and continuing to more modern methods.
The video explains that coffer dams are commonly used, which can be as simple as building a dam from soil to block the water and dewatering the area within the dam. At its most basic form, this method can be compromised by weak soils and require continual dewatering efforts due to leaching water.
Caissons have been used for decades whether underwater or just in regular ole soil, but in the past workers had been sent down inside the caissons to dig out the soil and mud to allow the concrete to be placed inside. Build up of pressures inside the caisson not only could allow water to seep in, but also resulted in workers contracting “caisson disease,” which is a lot like what underwater divers can get if they rise to the top too quickly.
Now, most underwater structures can be built without the need to send humans down into hazardous circumstances, but we’ll let the video explain that.
You can watch the full video from Practical Engineering below:
