Westfield M7 is a commercial development at Westfield’s Stratford City Estate. When complete, Office A will be a 12-storey building, with the upper nine storeys being constructed partially above the existing M7 building of the Westfield Shopping Centre. Bachy Soletanche was appointed by Westfield Europe to deliver the geotechnical package for this development.
Bachy Soletanche was tasked with designing a suitable piling layout that would support the structure above and provide an efficient and cost-effective solution.
The final scheme opted for CFA piles that would carry the scheduled loads in a combination of skin friction and end bearing. The design included a depth of pile that would reach the Thanet Sand and therefore be able to take advantage of the high load bearing capacity. Bachy Soletanche has previously piled sites in close proximity to M7 and therefore was able to draw on this knowledge when designing the scheme.
The site team installed 157 CFA bearing piles with a diameter of 750mm. The average depth was approximately 24.5m, bored into the Thanet Sands. In addition to this, the team installed one working test pile and four anchor piles.
The piling platform was approximately 7.5m below the road surface providing the team with a logistical challenge for mobilisation and on-going site deliveries. The allocated access was via the West Service Yard (John Lewis’s loading bay), which had a restricted height of four metres, as well as a ramp and bend that needed negotiating. In addition to this, all deliveries required booking in 48-hours prior to arrival and any abnormal loads could only access the site between 02:00 and 06:00 to minimise any disruption to the local community.
The restricted nature of the site meant that planning was essential to the successful delivery of this project. Close collaboration with the client and other trades ensured that any challenges were overcome, and the geotechnical works were completed as expected.