What are the different types of Bridge Foundations?

The foundation of the bridge structure is the base, which is involved in transmitting the load of the entire bridge to the ground. The foundation structure of the bridge should be sufficiently deep, as it will not be affected by the scour due to the flow of the river under the bridge.

The construction process of the bridge foundation employs critical design aspects and helps to provide support for the traffic load, as well as the overall load of the bridge structure. The bridge foundation also helps to ensure the stability of the entire bridge structure against settlement and shifting.

Discuss the different types of bridge foundations

The bridge foundation can be of different types, which can vary on the basis of different factors. For example, the type of soil, the depth of the water under the bridge, the river flow and others.

Spread foundation

This type of bridge foundation has been constructed on the dry ground to support he entire bridge structure. The spread foundation for the bridge is applicable for hard soil.

Raft foundation

The raft foundation can be constructed for those bridge structures, which has been located on the watercourse bed, that has been composed of soft clay. In the case of soil with low bearing capacity, the raft foundation can be applicable.

Pile foundation

The pile foundation for the bridge structure acts well in the case of heavy and concentrated loads that have been anticipated to be carried by the foundation structure.

Well foundation

The good foundation can be used in the case of the soil is about 3 m to 4 m below the river bed level, and the river bed level is made of sandy soil.

Inverted arch foundation

In the case of the depth of the foundation excavation is less, this type of bridge foundation can be constructed. This type of bridge foundation is appropriate for those areas where the soil has low bearing capacity.

Grillage foundation

In the case of the heavy and isolated footing of piers, the grillage foundation can be used.

Caisson foundation

In the case the hard strata are available near the river bed and the depth of the river water is too high, the cassion foundation is appropriate for the bridge.

Discuss the process of bridge foundation construction

The foundation structure of the bridge has been constructed by following several steps, which are as follows:

1. At first, it is essential to conduct a comprehensive planning and design for the construction of the entire bridge structure. In this context, the purpose of the bridge structure, the location of the bridge, the span length of the bridge, the condition of the construction site and the anticipated loads on the bridge need to be determined.

2. After the planning and designing phase, the construction site should be prepared to begin the bridge construction procedure. In this context, the vegetation should be cleared, the ground needs to be excavated, and the accessed road and temporary construction facilities should be established.

3. In the next step, the construction of the bridge foundation should be initiated, which is one of the important and critical steps of bridge construction. During the construction of the bridge foundation, the foundation area should be excavated properly, and the ground should be prepared to support the entire weight of the bridge structure.

4. After placing the foundation of the bridge, the sub-structure components of the bridge need to be constructed, which help to carry the load of the superstructure.

5. After completing the substructure construction, the superstructure components of the bridge structure should be erected on the basis of the design specifications of the bridge structure.

6. After that, the deck of the bridge was constructed on top of the bridge superstructure.

7. In the next step, the functionality and aesthetics of the bridge need to be ensured. The entire bridge structure should undergo thorough testing and inspection, which helps to ensure the load-bearing capacity and the structural integrity of the bridge structure.

8. Regular maintenance and inspection of the bridge is also required to ensure the safety and long-term durability of the bridge structure.

Determining the depth of the foundation of the bridge

The depth of the foundation for the bridge structure helps to ensure that the soil has the required safe bearing capacity. Before deciding on the depth of the bridge foundation, a proper investigation of the soil is required. The investigation process of the soil helps to determine the depth of the foundation structure through investigating the depth of the water table, soil properties, the load-bearing capacity, and other important factors.

To learn more, watch the following video tutorial.

Video Source: RGPV Official

The depth of the water table should be investigated to prevent scour below the soil, thus ensuring the stability of the bridge structure.

In the case of the cold countries, it needs to be ensured that the foundation structure should not be contracted at a shallow depth. It also needs to be considered that the pressure bulb of the foundation structure does not coincide, while the depth of the new foundation has to be taken under the depth of the existing foundation.