Pre-Cast Concrete Driven Piles

Описание: Project Introduction
The Salvation Army contract was to replace an existing Worship Hall with a new Worship and Community Centre. The contract value was £1.3 million, and the programme time was 52 weeks. The site was highly congested, with both the existing and the proposed buildings occupying almost the whole site area. Consequently, the offices were set up at the end of an adjoining cul-de-sac. The offices comprise of 2 x 2 stacked container-like office modules. On the upper level there was the Agent’s Office and a meetings room, while below there was a secure store and a canteen/welfare room.

Pre-Cast Concrete Driven Piles
Driven piles are a very economical solution for small foundation loads in granular soils. They have the disadvantage of being noisy and causing vibration damage to nearby property.
The piles are manufactured off-site under factory conditions and transported to site by lorry. They are lifted into the hammer, positioned over a setting-out pin and checked for verticality. In the first few blows the earth around the base of the pile can be seen to heave. Progress is rapid at first, but slows as resistance builds up. The piles are driven to a “set”, rather than a specific depth. That is, they are hammered down until progress slows to a penetration of only 25mm for 10 blows. As the hammer is withdrawn, smoke bellows from the remains of a plywood packer on top of the piles, where the kinetic energy of the hammer has been absorbed and converted into heat energy. A new packer for the next pile is fixed into the hammer. The whole process is monitored and recorded by computer.



Piling Operation Description
An engineer set the piles out using co-ordinates input to a Total Station. As the underlying ground was wet chalk Continuous Fight Auger (CFA) Piles were used. This site required 93 piles of 400 mm diameter, aprox. 15m deep. The auger, which has a hollow central stem, is screwed into the ground. As it is withdrawn, concrete is pumped under high pressure down the auger to the base of the pile. The rate of withdrawal of the auger is matched to the concrete input to ensure that at no time any section of the bore is unsupported by either the auger or concrete. Only the top section of the pile needs to be reinforced. This is done by pushing a steel cage into the wet concrete.

Displacement Piles Description
Driven piles, also known as displacement piles, are a commonly-used form of building foundation that provide support for structures, transfering their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics.

Driven piles are commonly used to support buildings, tanks, towers, walls and bridges, and can be the most cost-effective deep foundation solution. They can also be used in applications such as embankments, retaining walls, bulkheads, anchorage structures and cofferdams.