PROTECTED TREES and a 16th century building were among the challenges for foundation contractor Roger Bullivant in piling and underpinning on an environmentally sensitive housing development (left) near Pershore, Birmingham.
Working for client developer Prowting Homes on the first phase of the project, the firm installed 194, 300mm diameter CFA piles for the new homes and also underpinned Besford Court, a 16th century timber framed building.
CFA was chosen to minimise damage to the many protected mature trees on site. The method also met the project criteria for a vibration free and relatively quiet solution.
Piles were installed by the firm's 5004 restricted access rig and were finished with pile caps and a total of 700m of precast square ground beams.
Besford Court is being converted into luxury apartments while retaining its original architectural features.
Underpinning was needed because of poor ground conditions, a high water table and what was believed to be an infilled moat running beneath the building.
A hybrid system was chosen to cope with the relatively high loads imposed by the building and its likely sensitivity to vibration.
Steel needle beams were installed through the existing foundations, tied together with cast insitu reinforced concrete ground beams. Tubular steel piles were then hydraulically jacked down to a maximum capacity of 300kN using the dead weight of the structure as the reaction force.
This work was almost silent and vibration free, with pile capacity verified by a digital load cell at the time of installation.
Roger Bullivant has now won the piling contract for the second phase of the development, involving installation of 600 piles and 2000m of ground beams.