OWNER:
DDK Ltd.
ENGINEER:
Tunstall Consultants
GENERAL CONTRACTOR:
DDK Ltd.
MAIN FIGURES:
c.350 CMCs
Project Details
DDK approached Menard to develop a cost and programme efficient alternative to the original piling solution for the construction of external slabs and sprinkler tanks adjacent to an existing warehouse. The ancillary structures were designed to accommodate uniformly distributed loads ranging from 25 to 100 kPa, depending on their function. A key site constraint was the presence of an overhead electrical cable crossing the working area at an approximate height of 16 m.
Ground Conditions
The initial site investigation revealed relatively homogeneous ground conditions, with about 2 to 4 m of made ground underlain by 10 m to 12 m of tidal flat deposits consisting of very soft clay above Mercia mudstone formation. At the request of Menard, additional CPT have been carried out across the site to understand more precisely the softness of the soft clay and inform the detailed CMC design.
Solution
Menard proposed a Controlled Modulus Columns (CMC) solution to enable the construction of slabs beneath the structures. A smaller rig was selected to safely operate under the 16 m-high overhead cable, while maintaining a high production rate typical of displacement augering techniques. Compared to a traditional piling scheme, the ground improvement solution delivered significant project benefits, including a reduction in embodied carbon, a simplified and accelerated construction sequence, and overall cost savings.
The CMC design was developed to limit residual settlements to between 25 and 40 mm, with differential settlements maintained below 1/500. The works were completed on programme within one week on site and validated through a comprehensive quality control regime.
Given the constrained environment, careful coordination with other trades was essential, and site-specific measures were implemented to ensure the works were carried out safely and efficiently.
