Systems of waterproofing for existing masonry lined tunnels

Existing technology has been drawn together with additional development work in order to develop Systems of Waterproofing for Existing Masonry Lined Tunnels (SWET). The goals were to stop visible water ingress and to reduce the water content of the brickwork to below that affected by freeze/thaw cycling. Waterproofing options are considered and trials to examine some of these options, the materials, plant and methodology are included. The most recent trial resulted in a 99% reduction in water ingress. Limitations applied to acceptable methods are given. Techniques used in the characterisation of tunnels are discussed including non destructive testing methods. Problems involving the risk of collapse of the tunnel lining, methods used to monitor lining movement and assessment of stress/strain are discussed. The 4 year Project has 12 months to run and results reflect this status. Reference is made to plans for future work.