Roger Bullivant is using jacked down minipiles to underpin three listed buildings on a site in central Lancaster, all of which have been affected by subsidence.
'Our works are designed to create new foundations within each building to cater for greater loadings, ' explains Bullivant underpinning manager Andrew Miller.
Bullivant has cast a 450mm deep reinforced concrete slab within the basement of each of the stone buildings and is driving a total of 40 minipiles through pre-formed voids in these rafts.
The piles are formed from 175mm diameter recycled steel tubes and are being installed to a depth of 13m through gravels into sandstone using a hydraulic jack down rig exerting 800kN of force.
'We chose a vibration free method of working so as not to cause further distress to the structures, ' says Miller.
www. roger-bullivant. co. uk