Unusual Foundations over the Mersey Tunnel

This paper describes problems that were encountered, and solutions that were obtained, during the design and construction of foundations for a multi-storey building sited over the Mersey Tunnel in Liverpool. To ensure that the weight of the structure would not adversely affect the rock surrounding the tunnel, theoretical analyses were made to estimate existing stresses: and experiments on photo-elastic models were made to assess imposed stresses. The results showed that major loads would have to be transmitted to either side of the tunnel by air space foundations consisting of floating beams supported on end-bearing piles. A description is given of the piles and
the tests which were made to develop frictionless linings. Two floating beams and a floating slab are discussed in terms of analysis by finite element techniques: and their construction in post-tensioned concrete is discussed with special reference to mix design, types of shuttering: and concreting methods.

D.M. Bingham and A.J.M. Soane