Under which of the following conditions should you prefer a caisson foundation?

Explanation:

• A caisson foundation is a watertight retaining structure used for constructing foundations in deep water or soft soil conditions.

• Its main function is to transfer loads from the superstructure to a stable soil or rock layer beneath water bodies or poor soil.

• Commonly used for bridge piers, harbor structures, offshore platforms, and jetty foundations.

• Preferred in locations where conventional foundations are not feasible due to depth of water or unsuitable soil near the surface.

• Involves preparing the site, sinking the caisson by excavation and weight, and then sealing and filling it with concrete or backfill material.

• Requires precise alignment and leveling to ensure structural stability.

• Allows construction in deep or submerged conditions.

• Provides a stable and durable foundation under high loads.

• Reduces the need for dewatering in underwater construction.

Additional InformationTypes of Caisson Foundations

• Open Caisson: Hollow cylinder open at the bottom and top; sunk by excavating inside and allowing the structure to sink under its own weight.

• Pneumatic Caisson: Closed at the top and open at the bottom; compressed air is used to keep water and soil out during excavation—suitable for deep foundations below the water table.

• Box Caisson: Precast concrete boxes with a closed top and bottom; placed on a prepared bed—used where subsoil is stable and only placement is required.

• Floating Caisson: Similar to box caisson, but floated to the site and then sunk in place.