ABSTRACT
Crossrail Contract C121, awarded to Mott MacDonald, dealt with the design of the SCL (sprayed concrete lining) structures of five new underground stations in London. This paper describes the design methodology of permanent (secondary lining) structures such as junctions between platform tunnels and cross passages, shafts and cross passages and a combination of them. The paper provides a comprehensive explanation of the numerical modelling process for 3D complex geometry of junctions using FEM (finite element method) software, describing challenges like application of loads (ground and water pore pressures, surcharge, etc.) and how they are transferred from the primary to the secondary lining in the long term. A practical approach to assess the structural behaviour of different types of junctions and interpretation of results based on technical standards like RILEM and Eurocode 2.0 will be discussed as well as recommendations on bar reinforcement detailing.
