Written on 14 Aug 2013 in Blog
We’ve all heard of the Leaning Tower of Pisa. Without the ingenuity of Robert Mair and his colleagues, London could have had it’s own leaning tower.
In 1994, building started on the Jubilee Line Extension in London. It was to provide access to the Dome being built in Greenwich to celebrate the Millenium, but there were many problems to solve in order to complete the project.
One of the most delicate parts of the operation involved the station and new MPs office at Portcullis House, which were to be located opposite Big Ben. Built in 1858 on shallow foundations, and already leaning slightly to the north, the ground movement due to the huge 38m deep excavations needed for the Jubilee line could prove disastrous for the historic tower.
Professor Robert Mair, of the University of Cambridge Engineering Department, had come up with a solution when working on an earlier tunnelling project at Waterloo Station. He developed a process called Compensation Grouting, in which a complex web-like network of horizontal tubes is installed between the tunnel and the ground surface. These tubes have a series of holes so they can be filled with liquid cement at any point to prevent movement of the buildings above during the excavations. This ingenious solution has protected many historic buildings in London and around the world.
A world expert on all things digging-related, Prof. Mair has also worked on the Channel Tunnel and Cross-Rail projects, and recently chaired an important review into the process of shale gas extraction known as fracking.