What is a deep foundation caisson?

A deep foundation caisson is essentially a type of foundation that consists of large, round concrete columns that extend deep into the ground. This design is primarily used when the surface soil conditions are inadequate to support a structure, necessitating a foundation that reaches down to more stable, deeper soil or bedrock.

Caissons are typically drilled or excavated and then filled with concrete, allowing them to handle significant loads and resist various forces such as lateral loads from wind or seismic activity. They are particularly advantageous in conditions where soil may be weak or loose at shallow depths, ensuring that the structure is securely anchored to stronger soil layers.

This method is distinct from shallow foundation options, which are typically placed closer to the surface and rely on the strength of the top layers of soil. The other choices do not accurately describe the characteristics or purpose of caissons, reinforcing the understanding that option B correctly identifies the function and design of a deep foundation caisson.