5 Broadgate Re-development, City of London, 2012
The TensarTech™ TR2 Wall System was used to form a temporary vertical bund for a heavy piling rig
BENEFITS TO CLIENT
A stable, low cost retaining wall solution where appearance is not a priority, which can be quickly built without the need for crane lifts, foundations or specialist skills.
On a very congested Central London site, there was a requirement for a temporary vertical faced bund up to 6.6m high to support a heavy piling rig operating close to the face.
A TensarTech™ TR2 Wall System was used to create the vertical face of the bund. The system incorporates a welded wire facing and granular fill reinforced with layers Tensar Geogrid. Various load cases had to be analysed in conjunction with possible rig positions.
Tensar International were approached by John F Hunt and their Consultant, Contractors’ Design Services Ltd to provide a design and supply solution for a vertical 6.6m high temporary bund to support a 100 tonne piling rig operating close to the steep face.
The critical case for tensile capacity was with the rig operating with a track pressure of 350 kPa. The geogrid strength was checked with the track leading edge positioned only 1m from the face and then at other positions on 0.5m increments further away from the face. The critical case for sliding occurs when the rig is positioned near the rear of the reinforced earth structure. Since the rig is not operating in this position, a lower pressure could be applied here to ensure the most economic solution.
The TensarTech TR2 system was selected as it is a robust and low cost solution. In this project, appearance was not a priority due to the temporary nature of the retaining structure. The face is formed from steel mesh panels to which layers of Tensar uniaxial structural geogrids are connected. The face is lined with a robust needle punched geotextile to prevent loss of granular fill through the mesh openings. For this structure recycled granular fill material (HA Class 6F2 Capping) was selected. JF Hunt’s Project Manager Chris Toseland commented, ‘TensarTechTR2 system was simple to build and using our own operatives, we quickly mastered the installation technique and work progressed to plan’.