Bank Station Capacity Upgrade: Design Drawing Packages Submitted

The Northern line and DLR design drawing packages have now been submitted. The assessment of the existing structures has been finished.

The Bank Station Capacity Upgrade design is entering its final stage. After the recent submission of the Northern line, Docklands Light Railway (DLR) and Whole Block site packages, only the running tunnel and pile interceptions are still to be submitted.

The complex layout of the tunnels is the greatest technical challenge for the Northern line and DLR packages (Figure 1), with some of the new tunnels in very close proximity to each other as well as existing assets. In addition, some of the new tunnels are designed with large breakouts having relatively narrow pillars between them.

A good example of this is the Northern line Interchange Tunnel that hosts four openings in its central section; one for each side of Northern line Cross Passages 1 and 2. The pillar between the passages requires local thickening of the lining. The finite element analysis model, produced in Abaqus for this project, is a vital tool in order to fully understand the stresses in this area and optimise the lining.

In addition to the tunnel design, the Dr. Sauer & Partners team is also responsible for the Deep Tube Tunnel Assessment; the impact assessment of the proposed works on the existing underground structures for the six underground lines at the station. The team responsible for the assessment of the LU civil assets at Bank has successfully completed the third stage of assessment for review.

This last stage includes stress/strain analysis of the structures and further investigation of the serviceability impacts from the predicted movements. The analysis takes into account the different geometry, material and lining condition of the various assets. The forces and movements are calculated using the deformation values obtained from the finite element analysis models.

The analysis of the existing structures will now focus on the development of the instrumentation and monitoring drawings, due for submission in the coming weeks. This will include the trigger values for integration into the construction phase Action Plan.

Figure 1: FE Analysis Model for Northern line and DLR