What to Know about Drilling Caissons?
Caissons, likes piles, are a deep foundation type that are most often used when shallow, spread footings are not feasible. The first distinction of caisson types is pneumatic or open air. Pneumatic caissons (or compressed air caissons) have air tight sides and top and are open on the bottom only. Usually a double air lock door is used at the top of the caisson and the caisson is pressurized. Open caissons can also be broken down into two types: sheet pile box and drilled pier. The sheet pile box caisson is formed using conventional excavation equipment and some type of sheet piling (see above discussion of sheet piling). There are several different sequences for excavating and driving sheet piles that yield an acceptable sheet pile box caisson. The specific circumstances will dictate the sequence of work for the Construction Supervisor. Some projects require the caisson sheeting to be removed while other projects require the sheeting to remain. This question must generally be approved
