London: Kings College Hospital Basement

DAWSON-WAM was contracted by Gilbert-Ash to design and construct an 8m deep secant basement for the New Fetal Medicine Clinic in Kings College London.

In total over 150m of secant piles and 37 load bearing piles were installed with piles ranging in length up to 17m. The secant pile wall was consisted of 630mm diameter Hard Hard piles at 550mm centres with a small section of 450mm diameter secant in a restricted section of the works. All piles were installed through 1.5m of made ground and were founded in the stiff London Clay.

The scheme involved retention of a 4 storey terrace housing façade and piles were required to be installed within 100mm of this structure. DAWSON-WAM used their Cased CFA System to complete this close proximity work with the added benefit of the system protecting the existing foundations from ‘flighting’.

As part of the works DAWSON-WAM designed, excavated, installed and removed the temporary propping for the scheme and used an innovative chain support system to carry the propping so as not to foul the construction of the permanent liner wall below.

DAWSON-WAM designed, excavated and installed the piling platform for the works using a geogrid membrane to reduce the piling platform thickness.

The site was located within a busy hospital complex and due to access restrictions all plant and equipment was delivered in specialist rear steer articulated lorries.