OWNER:
Confidential
ENGINEER:
Confidential
GENERAL CONTRACTOR:
Confidential
MAIN FIGURES:
c.280 CMCs
Project Details
Menard was appointed to install Controlled Modulus Columns (CMC) under the Realigned Tunnel Avenue in Greenwich, London. Two distinct parts were considered on this project: 1) The Transfer Structure which allows the construction of the road on top of a pump room – this required that no loads were transmitted to the top of the pump room, hence the load on top of the road will span within either side of the structure; 2) a U-through structure filled with engineered fill in a concrete-based structure found on the majority of the site.
Ground Conditions
The ground was made up of Made Ground above Alluvium and River Terrace Deposits underlain by London Clay Formation and Lambeth Group. On the site, the ground conditions were homogenous across the site with a sand layer underlain by firm to soft clay above dense silty sands. We requested Cone Penetration Tests (CPT) to verify the parameters of the soft clay layer and to ensure the CMC embedment. The soft layers of clay were treated down to the dense silts, hence the depth of treatment ranged from 6 to 9m due to variation in layers’ thicknesses. We did not encounter any obstructions or voids.
Solution
Controlled Modulus Columns (CMC) was a feasible solution for this site due to the presence of a soft clay layer. Another factor was the proximity of the site to the Blackwall Tunnel as this needed a vibration-free ground improvement technique which we provided with CMCs. The CMCs also allowed the Main Contractor to undertake the remainder of the works within programme due to the speed at which CMC can be installed.
Sustainable Development
An optimized design was adopted to reduce the amount of concrete used, and a low carbon concrete was utilised.
