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 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.
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
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