Tweet Share

• Send by email

  Send by email

  

  Design of Precast Segmental Tunnel Primary Lining for Tideway Central Contract

  Tideway project is a 25km long combined sewage storage and transfer system along the River Thames in Central London, UK. The project has been split into three design and build contracts with the limits of each contract determined primarily by geology along the alignment. The Contract for the Central section, the biggest and most challenging one of the three, consists of 12.7km of tunnel and 8 worksites with deep inlet shafts and ancillary structures.The Central Contract tunnel primary lining has an internal diameter of 7.8m and is to be constructed using a steel fibre reinforced precast segmental lining. There will be a concrete secondary lining bringing the finished internal diameter down to 7.2m. The tunnel is required to be able to sustain high internal surge pressures and to limit water ingress and egress through the joints to a negligible amount. The biggest design challenge has been to produce a single design solution for the primary lining crossing different stratigraphy ranging from London Clay, Lambeth Group, Thanet Sand and Chalk. This paper provides an introduction to the Tideway project, the ground through which the tunnel is passing and the methods of numerical analysis adopted for the precast segmental lining design. Extensive parametric studies for different ground parameters have been carried out using PLAXIS 2D to identify the worst design scenarios for the tunnel lining. LUSAS 3D modelling has also been conducted for critical cases with both radial and circumferential joints modelled explicitly. The results of the joint opening for internal surge pressure cases are calibrated with the PLAXIS 2D analysis in which the radial joint is also explicitly modelled. Standard design techniques are unable to assess the impact of the opening of the joints on the design of precast segmental linings so this advanced and detailed numerical modelling gave the designer confidence that the tunnel lining will be able to resist the external and internal pressures and satisfy the employer’s requirements. : Tideway, Tunnel Lining, Numerical Analysis, Joint 1.

  Recipient :

  Name ^* :

  E-mail address ^* :

  ^* Required fields

  Send   or  Cancel

• Print