Structural foundation or deep foundation is a type of foundation that is used to transferring the structural loads in to the subsoil. These are several ways of transferring structural loads into the subsoil on sites where ground conditions are unfavourable. The bearing capacity of the subsoil can be increased by ground improvement techniques such as :

• replacement of non-load bearing layers of soil close to the surface.
• soil consolidation using pre-loading or vertical drains.
• soil compaction using grout injection; deep vibration or stone columns.

Alternatively, structural loads can be transferred to stronger competent strata at depth by the use of :

• bored piles
• diaphragm wall elements
• mixed in place (MIP) piles
• piles reinforced by steel bars
• vibrated concrete columns

Technical literature on all these special alternative construction techniques is available on request from foundation contractor. There are several ways to build structural foundation or deep foundation, they are retaining wall and bored piles.

Retaining Wall

Retaining wall is a type of structural foundation or deep foundation, which is used to transfer the structural into the subsoil. The problem of providing stable retaining structures close to existing buildings or of constructing watertight excavation pits can be solved in a number of ways. However, the most appropriate solution is almost always the installation of a bored pile retaining wall.

Bored Piles

In general bored piles offer the most economical foundation as they can be constructed in a wide choice of diameters, typically ranging from 300mm to 1800mm, and to depths of up to 70m at rakes of up to 1:4. They can thus be tailored precisely to the particular requirements of the building or excavation. This flexibility means that bored piles can provide solid foundation elements suitable for almost all site conditions.

* Friction Pile

* End Bearing Pile

Bored piles can be classified into two main groups, according to their load bearing behaviour: friction piles, which transfer loads mainly by frictional resistance along the shaft; and endbearing piles in which load is primarily transferred to the surrounding soil of through the pile base. Depending on the structural requirements, bored piles may be constructed singly, in groups or as walls using secant, contiguous or king piles, with or without infill.

* Single Piles

* Pile Groups

* Vertical And Raked Piles

* Piled Wall

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ICP piles is another type of piling, it’s also known as Pretensioned Spun High Strength Concrete Piles (ICP PHC Piles) which offer an economical foundation system with consistent and superior quality compared to the ordinary concrete piles.

ICP Piles are circular in cross-section and are manufactured in sizes ranging from diameter 250mm to 1200mm with standard lengths varying from 6m to 46m in single pieces. ICP Piles can be easily joined to any combination of length as per design requirement. ICP piles are manufactured with steel end plates for splicing.

Today, with the state-of-the-art autoclave curing system, ICP Piles can be installed immediately after autoclaving. ICP piles have been used extensively as foundation piles for power stations, highrise buildings, civil engineering works, bridges, marine structures, harbours, schools and government project, etc.

Materials For ICP Piles

1) Aggregates
Coarse aggregates shall be 20mm granite. Fine aggregates shall be clean river sand or washed mining sand.

2) Cement
Ordinary Portland cement.

3) Prestressing Steel
High frequency induction heat treated bars.

4) Spiral wire
Hard drawn wire.

Joint

The joint is designed to have the same performance as the main body particularly in respect of bending strength. All ICP piles will be supplied with steel extension plates for splicing.

Lifting Points

Two lifting point will be marked on all piles exceeding 9m. No special lifting bolt or wire rope is cast into the piles. Lifting is by wrapping wire ropes round the piles at specified points.

Pile Shoes

All ICP Piles will be supplied either open ended, with a flat shoe or with an X-pointed shoe.

Curing

After casting, the piles are steam cured. When the concrete reaches the specified transfer strength, the piles are demoulded, marked and checked for quality. The piles can normally be transported and driven when the cube strength reaches 50 N/mm2. Today with the state-of-the-art autoclave curing system, the piles can be installed immediately after autoclaving.

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