CHESHIRE-BASED Concrete Control Technologies (CCT) is undertaking one of its first contracts as part of Ritchies, the geotechnical division ofEdmund Nuttall.
Ritchies' £230,000 contract at Upper Byron Place in the heart of Bristol was originally to have involved the refurbishment of an 8m high stone retaining wall using ground anchorages and sprayed concrete.
But when debris from a collapsed building was removed from site, it became apparent that a significant part of the wall was in much worse condition than anticipated. Structural engineer, Bath-based Mann Williams, responded quickly and following discussion with Brian Hawkins of HM Geotechnics, completely re-designed this element of the works.
About two-thirds of the wall had to be replaced and Ritchies constructed a new semicontiguous minipile wall, rock socketed into the underlying marl. Steel tube piles were installed using the Finnish developed Symmetrix concentric drilling system which ensured very good pile alignments.
Ritchies then placed 79 double corrosion protected Dwyidag bar anchors in five rows to support both the new piled and old stone wall. After construction of waling beams and placement of the surface steel mesh, CCT took over the project by applying about 60m3 of sprayed concrete with a minimum 100mm cover.
The brownfield development for Orbit Housing Association will provide sheltered accommodation in the centre ofBristol.