Value: £210,000 Size: 167m2 Duration: 14 weeks Rig: Super Kitten Mini Piling Rig
Scope of work:
Abbey Pynford was approached by the structural engineers to provide an underpinning solution to stabilise five properties which were suffering from ground movement.
A piled raft underpinning scheme was considered to be the best solution to overcome the variable thickness of the made ground. It was also able to accommodate any future ground heave from the clay based subsoil following the removal of the vegetation to facilitate the original development.
The piled raft was designed by our in house design team and comprised of 200mm diameter SFA (Sectional Flight Auger) piles installed to the depth of 13m. The piles were installed with temporary casings to overcome the made ground and seal off the perched water at the interface with the London Clay below.
A 225mm thick reinforced concrete slab was installed on 160mm clayboard to provide a heave void beneath. The existing walls were supported on Pynford Stools to allow the slab / antiheave precautions to be installed above the existing foundation. The stools were removed internally, preventing any external excavations and reinstating the surface finishes.