Project
The New Millenium Experience Company commissioned a large sculpture by Antony Gormley for siting on the River Thames adjacent to the Millenium Dome. This was constructed on a platform supported by existing caissons and the structure required designing to avoid any uplift forces within the caissons.
Soil Conditions
No ground information was available prior to construction and the initial desgn was based on interpolated information. Drilling proved the ground below the caisson concrete to consist of 7m of Thames Ballast overlying 5m of soft clay and 13m of London Clay above the Woolwich and Reading Beds.
Solution
SBMA Systems offered an anchor system to distribute the fixed anchor length of the anchors both within the lower caisson concrete and to remote depths in the underlying strata. A 900kN working load was offered without the installation of trial anchors, based on the successful use of the anchors for the foundations of the MIllenium Dome.
Construction
The ground anchors were installed by Keller Ground Engineering using a Casagrande C6S drill rig with a Klemm rotary percussive head to advance 178mm dia. drill casing through the caisson concrete. A 133mm dia. casing was then installed to the full depth of the anchor. Six multiple anchor units were installed into each anchor bore, each providing 150kN working load to provide the total prestress of 900kN.
The preliminary design of the anchor was modified as a result of the ground conditions revealed by the drilling and the distribution of unit anchors changed to found one unit in the caisson concrete, two units in the Thames Ballast, two units in the stiff clay and one unit in the Woolwich and Reading Beds.
Each 6 unit anchor was tested for compliance with 18 acceptance criteria prior to an anchor being accepted into the works.
| Client
and Engineer |
New Millenium Experience Company |
| Construction Manager |
MLJV |
| Architect/Artist |
Antony Gormley |
| Main
Contractor |
Tubeworks |
| Specialist
Sub-contractor |
Keller
Ground Engineering |
