Bridge Foundations and their Types
The Foundation of the bridge is the most critical and essential part of the bridge structure, the reason behind this is that the foundation ought to maintain an entire load of the bridge and flowing traffic and then transfers safely to the soil through Abutments or Piers.
There are following major types of bridge foundations are used as per the requirements.
Spread Foundation
Spread Foundation is also known as Open Foundation. Spread Foundation is suitable for the bridges of average height on the dry earth to transfer the load of structure towards the soil. The spread foundation is best for those areas where there is a low scouring and the hard ground surface starts from 1.5–3 meters below the level of the watercourse.
Raft Foundation
This type of Raft Foundation is used in those areas, where the allowable bearing capacity of the soil is low and watercourse beds contain soft clay as well as clay. Raft Foundation is best in the absence of hard soil within the depth range of 1.5–2.5 meters below the watercourse.
Pile Foundation
The Pile foundation in the bridge structure is the most basic substructure which is supported by piles under abutments or piers etc. Pile foundation is used in soft soil where hard strata are not available at the required depth.
Well Foundation
The Well Foundation is the type of deep foundation which is provided below the water level for those bridges, whose bed contains sandy soil and hard soil is available at 3 to 4 meters below the level of the watercourse.
Wells have various shapes and the name is given accordingly to their shapes,
- Circular Well
- Double D Well
- Twin Circular Well
- Double octagonal well
- Square / Rectangular Well
Caisson Bridge Foundation
This type of caisson foundation is used where the hard stratum is faced near the bed of a river with excessive water depth and economically it is not possible to remove the water to enable sinking wells for the Well Foundation.
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