A Comprehensive Guide to Piled Raft Foundation Design

Piled raft foundation is a combination of reinforced concrete piles and reinforced rafts that help build a solid foundation for the superstructure. Piled raft foundation design can improve the structural stability of the superstructure. This blog can be helpful if you plan to construct a new building and need clarification about designing a solid piled raft foundation. We aim to discuss specific points that need to be considered for piled raft foundation design. For example, the size of the superstructure, soil quality, rebar quality, etc., determine its design.

Why is a piled raft foundation essential for buildings?

A piled raft foundation is essential for buildings where the ground is not firm and is likely to settle over time due to pressure from above. To protect buildings from settlement in weak soil, a piled raft foundation is used. Reinforced concrete piles are constructed to transform the load of the superstructure into a more robust foundation deep into the ground. A strong design for a piled raft foundation will help protect a structure from earthquakes and ground settlement.

How can a piled raft foundation design enhance structural stability?

In places with weak load-bearing capacity in soils, piled raft foundations can enhance the structural stability of buildings. It is often seen that the foundation's structural settlement is higher in the middle. Hence, settlement-reducing central piles can be used to protect the foundation's central settlement. Expert engineers can calculate the number of piles to be placed under the reinforced concrete raft to reduce local settlement. Placing reinforced concrete piles in different areas helps to strengthen the structure and make it settlement-resistant.

What are the challenges of designing a piled raft foundation?

In some design methods, load-bearing capacity is concentrated only on the raft, and piles are neglected. Some designs focus on piles and neglect the load-bearing capacity of rafts. Both designs are not economical and not optimised to the highest load-bearing capacity for piles and rafts. Another challenge is calculating the number of piles required to support the raft and protect it from settlement. Identifying the areas in the raft with the maximum chance of local settlement and placing reinforced concrete piles to reduce settlement is tricky. At Reinforced Concrete Contractors, our in-house expert engineers can offer you professional guidance and manufacture a solid piled raft foundation.

What needs to be considered for piled raft foundation design?

The following discussion will focus on the topics for an effective and efficient piled raft foundation.

Soil analysis

The most crucial task is soil analysis done by an expert. Engineers also have the expertise to understand the quality of soil. Based on soil quality, they can determine the number of piles to be constructed under the raft. Soil quality also helps to determine the type of piled rafts to be built, such as connected or unconnected (i.e., structural fill is used between the raft and pile heads to separate them).

Load of the superstructure

The superstructure load and soil quality are strong determinants of piled raft foundation design. Depending on these two factors, engineers construct piled raft foundations to carry the load of the superstructure and help reduce local settlement. If the area of the foundation is larger than usual and the load of the superstructure is significantly higher, a higher number of piles will be used. For example, the Burj Khalifa in Dubai is also constructed upon a reinforced piled foundation.

Construction materials

The quality of construction materials helps to determine the strength of the piled raft foundation. If good-quality rebar and concrete materials are used, the foundation will have better load-bearing capacity. The raft is not likely to develop local settlements and is vulnerable to structural damage. Choosing top-quality rebar will protect it from corrosion and help reduce the scope of structural damage to rebars.

Placing of piles

Placing piles under the raft is crucial for the design of the piled raft foundation. Depending on the soil quality and structural load, the engineer may decide on settlement reducing group pilling or distributed piling. The site engineer may also construct piles under the raft areas, which are more prone to local settlement.

Conclusion

The impact of piled raft foundations on improving a building's structural stability is significant. Elements like soil quality, superstructure loads, etc., are crucial in determining the design of piled raft foundations. An expert contractor like the Piled Raft Foundation can provide the industry's best services. Contact us today for a personalized service quotation.