What is the shear strength?
Drop caissons are a type of pier foundation and literally mean watertight structures mostly used in structures like bridges, piers, abutments, foreshore protection and lake docks. These are mostly hollow structures that are sunk to the depth up to which concrete has to be filled. It is not removed after the concrete hardens and thus becomes a part of the main structure.
Caissons are closed airtight structures, especially boxes that have no floor below them. So, when it is put underwater, it does not get filled up with water.
Caissons can be provided when:
01 - Soil masses contain huge boulders, which prevent the pile to penetrate.
02 - Huge substructures need to be sunk below the rear bed so that it remains stable against destructive forces due to score and floating objects.
03 - The foundation needs to bear massive lateral loads.
04 - The depth of water level is quite high.
05 - River forces act as loads on the foundations.
06 - Load has to be carried at the end of the hard rock.
07 - Groundwater level flows aggressively.
Types of Caissons
01 - Box Caissons
02 - Excavated Caissons
03 - Floating Caissons
04 - Open Caissons
05 - Pneumatic Caissons
06 - Compressed air Caissons
07 - Monolithic Caissons