Elephant Road

Expanded Geotechnical were appointed to design and construct the secant piled wall and the preliminary test piles for Oakmayne Plaza at Elephant and Castle. The design had to consider a 9m dig for the basement car park and the foundations for the three towers of residential rooms and the podium for retail. 

Oakmayne Plaza is a mixed use development and comprises of three towers of 23 storeys linked by a three storey podium. The podium includes an open space for the community and the car park includes a bike station. 

Expanded Piling introduced their BG36 and B300 piling rigs which were mobilised in CFA mode to install the secant wall. The concrete guide wall was already constructed along the line of the proposed secant piled retaining wall to ensure positional accuracy of the pile heads. 

309no 750mm diameter un-reinforced female piles were progressively constructed at an 8m depth through made ground and water bearing alluvium, to seal into the London Clay. 306no 750mm diameter reinforced male piles were bored through the edges of the female piles to depths ranging from 10m-22.5m to form the secant piled wall.  

Preliminary test piles were installed to provide information for the design of the bearing piles that were installed at a later date. Four 750mm diameter test piles 27m deep each with four anchor piles 23m deep were installed. Two test piles had strain gauges over the 12m cage to provide more detail to ensure the most effective design could be modelled.