For bridges, deep-sea platforms, and marine wind turbines, engineers have to build secure foundations able to withstand extremely heavy loads. Just how do they do this? One technique — driven piles — is as simple as driving poles into the ground. This is the method medieval engineers used to establish the city of Venice, but the origins of the technique are lost to history. Driving piles compacts the ground around and beneath the foundation, enabling it to withstand far greater loads.
In some applications, hammering piles just isn’t practical. Drilling piles is another common technique. In this method, the drilled hole is reinforced with an outer casing, then concrete is pumped in to harden. Drilled piles will work even underwater, as long as the concrete gets pumped in from the bottom. Then it can push water up and out of the casing without absorbing enough water to change its properties. (Video and image credit: Practical Engineering)