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Bullivant solves science problem with CHD piles


TEACHING OF science in schools is set on solid foundations, with 245 continuous helical displacement (CHD) piles for the National Science Learning Centre at the University of York.

Contractor Roger Bullivant started piling in September and the £9M development is scheduled to open in autumn 2005.

Each pile has a core diameter of 300mm with a 600mm diameter flight and were installed to a depth of 11m using a Bullivant 7000 series rig.

The piles are designed to accommodate a 400kN load.

The CHD piling system was chosen to suit the site's difficult ground conditions. Interbedded layers of sand and clay traversing the site mean that the piles need to be both end bearing and reliant on skin friction.

A CHD pile is created using a helical shaped auger attached to the end of a shaft that is screwed into the ground. The bullet displaces material laterally and, at full depth, concrete is pumped down the centre of the shaft under pressure. Rotation of the auger is reversed and concrete fills the profile made by the auger to form a continuous spiral of concrete.

The three storey building will feature a 300 seat lecture theatre, science laboratories and residential accommodation.When complete it will form the centrepiece of a £50M network of nine new regional learning centres.

These will be used to train school teachers and technicians to understand some of the latest advances in science and technology.

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