Abstract

Deterioration of old infrastructure is a looming problem in developed countries, and the Minnesota Bridge collapse warns of catastrophy if the problem is not addressed. Worryingly though, owners can only guess the condition of their infrastructure. Long-term monitoring seems to offer more data, but its interpretation is limited by the lack of knowledge concerning how the structure changes with time.

A prime example of ageing infrastructure is seen in the oldest metro tunnels in the world: the London underground system. Its owners, Tubelines, are collaborating with the University of Cambridge to find out how to remediate these deteriorating tunnels. This seminar presents research addressing how to assess these tunnels: by exploring how the tunnels change with time.

The research applies substantial 3D coupled-consolidation finite element analyses to explore how twin tunnels deteriorate. New constitutive models for London Clay are proposed, together with a successful simulation of a twin tunnel construction in the heart of London. Supplementary permeability tests on fissured London Clay and unique grout specimens from the London underground provide further insights into the long-term behaviour.