HEAVE OF TUNNELS BENEATH THE SHELL-CENTRE, LONDON, 1959-1986

It was estimated by Williams (1957) that excavations in the London clay for the large basements of the Shell Centre on the South Bank would create upward displacements of the underlying Bakerloo line tunnels of between 20 mm and 30 mm. The maximum heave measured up to 1986 was 50 mm in the southbound Bakerloo tunnel immediately under the basement and 41 mm in the lower northbound tunnel. The rate of heave shows little sign of decreasing although the excavations took place over 27 years ago. This note updates the data published by earlier authors.