The work is for a 3.6ha, city centre, multi-use development being built by main contractors Sir Robert McAlpine and HBG for joint developers Multi Development UK and Morley (GE May).
The 71 wall anchors secure two of the four basement retaining walls into the rock sub-strata, to allow excavation for a three-level underground car park.
The three-strand and four-strand anchors have been installed using two Casagrande M9 rigs fitted with rotary percussive heads, to depths of up to 32m. All drilling is being conducted through specially designed gland (stuffing box) systems to control any artesian water encountered.
Site workers secured the anchors at the face with reinforced concrete beams. Anchors are pre-tensioned to load before locking off.
Additionally, 1038 compression / tension anti-flotation minipiles will be installed in phase three, after excavation, to control basement raft uplift and car park loading.
The six-building development, which has an investment value of £360M, will include 58 retail premises, 93 apartments, public spaces and a large open square. It includes a £13M bus station and £6.5M development for Bath Spa rail station.
Keller's anchor systems and tension piles contract is valued at £1.5M and will be completed at the end of 2008. Southgate, Bath is expected to open by 2010.