Prestressed Concrete Pile

Prestressed concrete piles have commonly closed-ended tubular sections of 400 mm to 600 mm diameter with maximum allowable axial loads up to about 2 700 kN. Normal pile elements can be up to about 20 m long and are usually welded together using steel end plates. Prestressing concrete piles has several benefits. Tensile stresses, which can be set up in a pile during driving, can be better resisted, and the pile is less likely to be damaged during handling. Bending stresses, which can occur during driving, are also less likely to produce cracking. However, the ultimate strength in axial compression is decreased as the level of prestressing is increased. Therefore, prestressed piles are more vulnerable to damage from striking obstructions during driving. They are also difficult to cut after installation, and special techniques have to be employed. As a result they are most suitable for applications where the pile length is predictable and constant. Prestressed concrete piles require high-strength concrete and careful control during manufacture. Casting is usually carried out in a factory, where the curing conditions can be strictly regulated. Special manufacturing processes such as compaction by spinning or autoclave curing can be adopted to produce high strength concrete. This type of pile is generally less permeable than reinforced concrete piles and may be expected to exhibit superior performance in a marine environment. Hard steel points (fixed or attachable driving shoes) can be used at the toe of jointed piles for protection when penetrating soils containing boulders, or in weak rock.

Source: http://www.geoforum.com/info/pileinfo/view.asp?ID=37

Follow @all2gotweets