Redevelopment of Knightsbridge Crown Court, London, UK

The redevelopment of Knightsbridge Crown Court was a highly complex mixed-use project consisting of seven storeys above ground and seven storeys below ground. A 25 m deep basement was constructed using 800 mm thick diaphragm walls and top-down techniques. The lowest level of the basement is linked to a department store by a 5 m diameter 75 m long tunnel accessed by a set of freight lifts. Topdown methods were also used to construct the lift shafts from an existing narrow lightwell within the main building. Conventional methods were used to keep ground movement to a minimum, and a comprehensive monitoring system was installed. Compensation grouting, based on the observations from the monitoring work, was successfully carried out to control settlements resulting from the tunneling. The complex transfer structures needed to deal with the different grids required at different levels are described and so are the constraints imposed on the project by the need to retain an existing façade along one of the major elevations.