Author: D. Lazarus (Arup) and H-I Jung (Arup)
2 July 2018
D. Lazarus (Arup) and H-I Jung (Arup)
The damage assessment and monitoring carried out comprised a significant element of work in terms of the resources involved, both human and financial. The background to this work was the experience from a number of tunnelling projects in London, probably most significantly that from the London Underground Jubilee line extension. While all assets along the alignment were subject to the same process, the impact of the works around the stations and shafts was calculated to be greater than along the bored tunnels, and the extent of instrumentation and monitoring was correspondingly higher. Both automated and manual methods were used, with instrumentation installed and readily visible on many buildings in these areas throughout the duration of the works.
This paper looks at the damage assessment and monitoring of buildings around the stations, focusing in particular on the new station at Tottenham Court Road. It also provides an overview of the two very different tunnel construction methods used on the project – the so-called tunnel boring machine (TBM) and sprayed concrete lining (SCL) methods – and describes how these lead to the ground movement that is the principal source of potential damage to the buildings.
Finally, the paper considers briefly some of the lessons learned and how these might be applied to future urban tunnelling projects.
There is something special about megaprojects that brings out the best in engineering design and construction. It could be that the longer-term durations for the planning, design and build phases allow more measured and thoughtful decision making; it could be that the weight of public exposure and expectation creates an added incentive to succeed; it could be that the prestige of being part of the programme attracts the best teams in the best organisations; it could be that the extended schedule nurtures a team spirit and a collaborative way of working that is difficult to achieve in a typical shorter-term project.
All the articles from the July 2018 issue - a special issue on 'Structural engineering for the Elizabeth line'.
This paper covers the engineering design of the platform edge screens for five Elizabeth line tunnel stations in central London. Full-height platform edge screens are a signature feature of the Elizabeth line’s station platforms, and their design presented many challenges. To gain maximum uniformity, the edge screens were developed as a common reference design, which was then issued to each of the station contractors. The paper describes the technical challenges from the point of view of a structural engineer, but in doing so, it draws in interfaces with disciplines as diverse as tunnel ventilation, electrical engineering, and rolling stock procurement. The reference design approach allowed unique features of the platform edge screens to be prototyped and tested before construction.