- Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics.
- Very broadly, foundations can be categorised as shallow foundationsor deep foundations.
- Shallow foundations are typically used where the loads imposed by a structure are low relative to the bearing capacity of the surface soils.
- Deep foundationsare necessary where the bearing capacity of the surface soils is insufficient to support loads imposed and so they are transferred to deeper layers with higher bearing capacity.
- A pile cap is a thick concretemat that rests on concrete or timber piles that have been driven into soft or unstable ground to provide a suitable stable foundation.
- It usually forms part of the foundation of a building, typically a multi-story building, structure or support base for heavy equipment.
- The cast concrete pile cap distributes the load of the building into the piles.
- A similar structure to a pile cap is a “raft”, which is a concrete foundation floor resting directly onto soft soil which may be liable to subsidence.
NEED FOR PILE CAP
- Pile foundation is required when the soil bearing capacity is not sufficient for the structure to withstand. This is due to the soil condition or the order of bottom layers, type of loadson foundations, conditions at site and operational conditions.
- A pile foundation consists of two components: Pile cap and single or group of piles. Piles transfers the loads from structures to the hard strata, rocks or soil with high bearing capacity. These are long and slender members whose length can be more than 15m.