Common applications of well (caisson) foundations Well foundations are most commonly adopted as foundations for which of the following types of structures?

Introduction:
Well (caisson) foundations are large, hollow substructures sunk to substantial depths, often under water. They are designed to transfer loads to competent strata while resisting scour and lateral forces. Knowing where they are typically used aids in selecting suitable foundation systems for major civil works.

Given Data / Assumptions:

• Rivers or estuaries with deep alluvium.
• High vertical loads combined with horizontal forces and moments (e.g., from water flow or traffic).
• Need for construction below water level using pneumatic sinking or dredging methods.

Concept / Approach:

Bridges commonly require deep foundations for piers and abutments situated in waterways. Well foundations provide adequate bearing, settlement control, and resistance to scour and lateral loads. They can be constructed in segments and sunk to the design depth, then filled with concrete to form a robust substructure.

Step-by-Step Solution:

Verification / Alternative check:

Case histories of major river bridges (e.g., caisson-founded piers) confirm widespread use of well foundations for such structures.

Why Other Options Are Wrong:

Water tanks and buildings often use raft or pile foundations; reciprocating machines prefer block foundations with vibration isolation; rock sites for wind turbines typically use direct anchorage or piles, not wells.

Common Pitfalls:

Confusing well foundations with open caissons for dry land structures; underestimating scour depth in design.

Final Answer:

Bridges