Field investigations of long term ground loading on an old tunnel in London Clay

This paper presents the results of a field study carried out early in 1998 to investigate the current ground conditions around an old cast iron lined tunnel in London Clay. The eventual loading carried by these tunnel linings is unknown, but concern exists that there may be a gradual increase in loading with time. Considerable lengths of the London Underground network run through London Clay in tunnels constructed with cast iron segmental linings. The investigation therefore provides information vital to the estimation of the remaining design life of London’s underground transport infrastructure.