Installation of a sculpture by Antony Gormley in Cambridge has been secured following completion of a ground investigation for the scheme by Harrison Group Environmental.
Free Object has now been installed on the banks of the River Cam as part of Trinity College’s 700th anniversary and will remain on site in the Sunken Paddock for 12 months.
Harrison, working for Trinity College, drilled three window sample boreholes to collect ground data for the design of the foundation for the heavy iron sculpture, which is nearly 5.5m high and up to 1.2m wide but sits on a base just 430mm by 668mm.
Consultant Simmonds Studio calculated the considerable height and weight of the iron sculpture on such a small base required a bearing capacity of 50kN/m2. However, it was soon clear the underlying very soft cohesive alluvium would not support even a modest bearing capacity.
“This meant the original shallow pad foundation design would not have been sufficient and would have resulted in excessive settlement,” explained Harrison managing director Steve Williams. “There was also a risk of differential settlement of the alluvium and overturning of the statue due to wind loading.”
Instead, small diameter displacement piles were recommended, end bearing in the river terrace deposits below 5m. The base will remain in place following the statue’s removal and will be used for future art installations at the college.