Exposed piled secant foundation wall forming part of an extension to a 20m deep basement for retail store in central London.
Secant piled walls are an innovative method of building retaining walls. They are formed by a series of interlocking drilled shafts and are invaluable where there is a high water table, or in unstable or otherwise unsuitable ground conditions. Secant piling offers minimal vibration and low noise levels and the flexibility to fit within complex site boundaries. Secant piling has the ability to penetrate underground obstructions such as steel, heavily reinforced concrete, granite and masonry whilst avoiding the risk of construction induced settlements to sensitive neighbouring structures. A heavy structure, like a tall building or a bridge, is usually built on piles if the ground beneath its base does not have an adequate weight-bearing capacity to support the structure. The piled foundation becomes an integral part of the structure that carries and transfers the load of the structure to stable weight-bearing ground, which may be located at some depth below the ground surface Historically, piles were made from timber but now are more likely to be fabricated from steel or steel-reinforced concrete. Deep foundation rotary bored piles are constructed by using a huge drilling rig mounted on a crawler crane (often with a combined weight of 40-80 tonnes). This rig will drill vertically into the ground inside a circular steel casing that has been driven down using a special vibrating hammer to provide temporary support to the excavation. The excavated ‘spoil’ is brought up periodically on the drill screw and is spun or shaken off. When a pile has been excavated to the design depth, a steel reinforced cage is inserted and the pile is filled with concrete. Once the concrete has set, the temporary casing is withdrawn using the vibrating hammer. Piles are drilled in a particular pattern and, once a section of piles is completed, a concrete ‘pile cap’ is formed over them which will distribute the weight of the structure evenly between the piles.
Size: 3310px × 3309px
Location: London, UK
Photo credit: © qaphotos.com / Alamy / Afripics
License: Licensed
Model Released: No
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