Abstract

Imagine a tower, founded on very soft material and slowly inclining to the point at which it is about to fall over. Worse still, the masonry is so fragile that it could explode at any time. This is a reasonable description of the state of the Leaning Tower of Pisa at the time that the Italian Prime Minister set up a Commission to stabilise it in early 1990. After years of study of its history, computer modelling and field trials, stabilisation measures started in February 1999. Using a novel method of soil extraction from beneath the high side of the foundation the Tower was gently brought back to its inclination in 1838. Recent measurements show that the stabilisation methods have been successful. Professor John Burland will share some of the challenges, frustrations and more worrying moments of participating in such a high profile and difficult engineering project.