What Are The Types Of Bridge Foundation ?

1. Spread Or Open Foundation

This type of bridge foundation is suitable for moderate height, to be built on dry ground which is sufficiently firm to support the bridge structure.

It is best suited in situations where hard soil is available within 1.5 to 3 m below the bed level of watercourse and when the scouring is minimum.

2. Raft Foundation

This type of foundation is suitable for bridge when the bed of the watercourse consists of soft clay and silt and the hard soil is not available within reasonable depth (1.5 to 2.5 m) below the river bed.

It is best suited in situations where the allowable bearing capacity of the soil is low or when the bridge loads are heavy. Raft foundation is also suitable when the soil bed has some soft pockets which are compressible and there is possibility of unequal settlement.

3. Grillage Foundation

This type of bridge foundation is suitable for heavy and isolated footings of piers where deep foundations are to be avoided. It is best suited where sub-soil conditions are poor.

4. Inverted Arch Foundation

This type of bridge foundation is suitable when the depth of excavation for foundation is less. It is best suited where the bearing capacity of the soil is less, especially when the sub-soil has some soft pockets and there is possibility of unequal settlement.

5. Pile Foundation

This type of bridge foundation is suitable when the soil is very soft and the hard strata are not available at a reasonable depth below the bed level of the river.