Stepney Green cavern

Last updated

Map of Stepney Green Park, showing Crossrail tunnel junctions Stepney Green Park.jpg
Map of Stepney Green Park, showing Crossrail tunnel junctions

Stepney Green cavern is an underground junction which contains the junction where Crossrail divides into two branches: one to Shenfield and one to Abbey Wood. It is located below Stepney Green Park.

Contents

Construction began in March 2011. The cavern was built using spray concrete lining techniques. Excavation work was completed in 2013, with all major work completed in 2017. At the time of its completion, Stepney Green cavern was claimed to have been one of the largest mined caverns in Europe. [1]

Stepney Green Park above the caverns was subsequently restored following construction.

History

Construction of the Crossrail project begun shortly after the Crossrail Act 2008 received royal assent during July 2008. [2] [3] In addition to forming one element of the central underground section of the new railway, Stepney Green accommodated a critical junction, requiring care in its design. [4] [5] It was designed by Mott MacDonald. [6]

The engineering of Stepney Green cavern involved overcoming several challenges, as it was one of the largest excavated caverns to be constructed in Europe. [1] Its maximum dimensions are a width 13.4 metres (44 ft), a height of 16.6 metres (54 ft), and a length of 50 metres (160 ft). Following an evaluation of various techniques, it was decided to use a tunnelling technique known as spray concrete lining, which involved the excavation and removal of 7,500 m3 (9,800 cu yd) of subsoil along with the application of 2,500 m3 (3,300 cu yd) of shotcrete to support the walls. [1] [7] Due to the presence of highly permeable water-bearing sand that posed a hazard during the shotcrete application, depressurisation measures were employed. [8] The boring process was largely performed via multiple TBMs. [9]

Various measures were taken to support the construction effort. To supply the large quantities of concrete needed, a purpose-built batching plant was constructed to manufacture it on site. [1] A variety of sensors were installed in the vicinity of the cavern to closely monitor any instances of ground movement, vigorous measuring of the applied concrete's strength was also practiced. Furthermore, a specialised cutting tool was used to remove the temporary supports, which generated far less noise than conventional impact hammers. [1] Primary access to the site was via a rectangular access shaft that is located across the twin running tunnels just to the west of the junctions; this space also accommodates various utility spaces, including a ventilation facility, as well as providing an emergency access point. [5]

Construction

The contract to build tunnels from Limmo Peninsula to Farringdon and Pudding Mill Lane (including Stepney Green cavern) was awarded to a joint venture of Dragados and Sisk Group in December 2010. [10] [11]

During March 2011, shortly after being awarded the contract to construct the section, the contractor took possession of the site; initial activity centred around the excavation of the first large access and operations shaft. [5] During May 2013, the eastbound section of the cavern was completed ahead of schedule; [12] completion of the westbound section was achieved in August 2013. [13] The first breakthrough of a TBM into the cavern was achieved during the latter half of 2013. [14]

During June 2014, it was announced that one of the TBMs had finished its boring activity at Stepney Green; the occasion also marked the structural completion of all tunnels of the line's north east spur. [15] Upon arriving at Stepney Green, the TBMs were disassembled and removed in pieces, before being reassembled elsewhere to work on additional Crossrail elements. [9] During October 2017, Crossrail announced the completion of all work associated with Stepney Green cavern, which was stated to be a major milestone of the overall scheme. [1] A shaft building - allowing ventilation of the tunnels and access for the emergency services - was built on the part of the site. [16]

Stepney Green Park above the caverns was subsequently restored, with work completing in 2019. [17]

Related Research Articles

<span class="mw-page-title-main">Tunnel</span> Underground passage made for traffic

A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is enclosed except for the portals, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.

<span class="mw-page-title-main">Crossrail</span> Railway project in London, England

Crossrail was a railway construction project centred around London. It aimed to provide a high-frequency hybrid commuter rail and rapid transit system crossing the capital from suburbs on the west to east, by connecting two major railway lines terminating in London: the Great Western Main Line and the Great Eastern Main Line. The project was approved in 2007, and construction began in 2009 on the central section and connections to existing lines that became part of the route, which has been named the Elizabeth line in honour of Queen Elizabeth II who opened the line on 17 May 2022 during her Platinum Jubilee. The central section of the line between Paddington and Abbey Wood opened on 24 May 2022, with 12 trains per hour running in each direction through the core section in Central London.

<span class="mw-page-title-main">Tunnelling shield</span> Protective structure used during the excavation of tunnels

A tunnelling shield is a protective structure used during the excavation of large, man-made tunnels. When excavating through ground that is soft, liquid, or otherwise unstable, there is a potential health and safety hazard to workers and the project itself from falling materials or a cave-in. A tunnelling shield can be used as a temporary support structure. It is usually in place for the short-term from when the tunnel section is excavated until it can be lined with a permanent support structure. The permanent structure may be made up of, depending on the period, bricks, concrete, cast iron, or steel. Although modern shields are commonly cylindrical, the first "shield", designed by Marc Isambard Brunel, was actually a large, rectangular, scaffold-like iron structure with three levels and twelve sections per level, with a solid load-bearing top surface. The structure protected the men from cave-ins as they laboured within it, digging the tunnel out in front of the shield.

<span class="mw-page-title-main">Tunnel boring machine</span> Device used to excavate tunnels

A tunnel boring machine (TBM), also known as a "mole", is a machine used to excavate tunnels. Tunnels are excavated through hard rock, wet or dry soil, or sand, each of which requires specialized technology.

The New Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wall reinforcement techniques based on the type of rock encountered as tunneling progresses. This technique first gained attention in the 1960s based on the work of Ladislaus von Rabcewicz, Leopold Müller, and Franz Pacher between 1957 and 1965 in Austria. The name NATM was intended to distinguish it from earlier methods, with its economic advantage of employing inherent geological strength available in the surrounding rock mass to stabilize the tunnel wherever possible rather than reinforcing the entire tunnel.

<span class="mw-page-title-main">Shotcrete</span> Concrete or mortar building material

Shotcrete, gunite, or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface. This construction technique was invented by Carl Akeley and first used in 1907. The concrete is typically reinforced by conventional steel rods, steel mesh, or fibers.

<span class="mw-page-title-main">Shaft sinking</span> Process of excavating a vertical or near vertical tunnel from the top down

Shaft mining or shaft sinking is the action of excavating a mine shaft from the top down, where there is initially no access to the bottom. Shallow shafts, typically sunk for civil engineering projects, differ greatly in execution method from deep shafts, typically sunk for mining projects.

<span class="mw-page-title-main">Hindhead Tunnel</span> Road Tunnel in Hindhead, Surrey, England

The Hindhead Tunnel, opened in 2011, is part of the 4-mile (6.4 km) dual-carriageway that replaced one of the last remaining stretches of single-carriageway on the A3 road which connects the cities of London and Portsmouth. It was built to bypass the village of Hindhead in Surrey. At 1.14 miles (1.83 km) in length, the tunnel is the longest non-estuarial road tunnel in the United Kingdom, and takes the road beneath the Devil's Punch Bowl, a Site of Special Scientific Interest.

Steel fibre-reinforced shotcrete (SFRS) is shotcrete with steel fibres added. It has higher tensile strength than unreinforced shotcrete and is quicker to apply than weldmesh reinforcement. It has often been used for tunnels.

In civil engineering a shaft is an underground vertical or inclined passageway. Shafts are often entered through a manhole and closed by a manhole cover. They are constructed for a number of reasons including:

<span class="mw-page-title-main">Stepney City Farm</span> City farm in London, England

Stepney City Farm is a city farm in Stepney, London, England. It is situated on Stepney Way with its entrance on the roundabout leading onto Stepney High Street and Belgrave Street towards Limehouse. The land is owned by Tower Hamlets Council through a trust, "The King George's Fields Trust" chaired by the Mayor of Tower Hamlets.

<span class="mw-page-title-main">Station box</span>

A station box is a term in the construction industry: It describes a box-like underground structure for a transportation system, for example a metro or tube station.

<span class="mw-page-title-main">Laird station</span> Future underground LRT station in Toronto, Canada

Laird is an underground light rail transit (LRT) station under construction on Line 5 Eglinton, a new line that is part of the Toronto subway system. It is located in the Leaside neighbourhood in East York at the intersection of Laird Drive and Eglinton Avenue. It is scheduled to open in 2024.

<span class="mw-page-title-main">Tunnel construction</span> The construction method for building a tunnel

Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management. Tunnel construction is a subset of underground construction.

<span class="mw-page-title-main">Tunnel rock recycling</span>

Tunnel rock recycling is a method to process rock debris from tunneling into other usable needs. The most common is for concrete aggregates or as subbase for road building. Crushers and screeners normally used in quarries are stationed at the tunnel site for the purpose which is to crush and screen the rock debris for further use. The largest tunnel rock recycling facility ever to be created was for the construction of the Gotthard Base Tunnel which took 17 years, finishing in 2016. 1/5 of the rock debris excavated for the tunnel was recycled and used as aggregates for the concrete lining inside the tunnel.

Linda Jean Miller is an American civil engineer who works for Bechtel. She is currently director of the excavation works for the Sydney Metro project, having recently been in charge of Crossrail's Farringdon Station.

<span class="mw-page-title-main">Woodsmith Mine Tunnel</span> Tunnel in North Yorkshire, England

The Woodsmith Mine Tunnel is a 23-mile (37 km) long tunnel that will stretch between Woodsmith Mine at Sneatonthorpe near Whitby in North Yorkshire and the Wilton International complex on Teesside, England. The tunnel has been in development since 2016, but cutting of the tunnel bore did not start until April 2019, with a projected finish date of 2021, but it was still not complete by the end of 2023. By the end of July 2020, over 4 miles (6.4 km) of tunnel had been dug.

The Chiltern Tunnel is a high-speed railway tunnel currently under construction in Buckinghamshire and Hertfordshire, England, and will upon completion carry the High Speed 2 (HS2) railway line under the Chiltern Hills. The twin-bore tunnels, which are 16.04 km long, will be the longest on the HS2 line. Each tunnel will also have additional 220 m (720 ft) entry and 135 m (443 ft) exit perforated concrete portals to reduce sudden changes in air pressure and subsequent noise.

<span class="mw-page-title-main">Northolt tunnel</span> Twin-bore tunnel for HS2 railway

The Northolt Tunnel is a high-speed railway tunnel currently under construction in Greater London, England, and will upon completion carry the High Speed 2 (HS2) railway line under the West London suburbs. The twin-bore tunnels will run for 8.4 miles (13.5 km) between Old Oak Common and Ruislip. As of January 2024, the first tunnel boring machine has completed 35% of its bore length.

<span class="mw-page-title-main">Euston tunnel</span> Twin-bore tunnel for HS2 railway

Euston tunnel is a tunnel currently planned in London that will carry the High Speed 2 (HS2) railway between Euston railway station and Old Oak Common railway station.

References

  1. 1 2 3 4 5 6 Lawson, Tom (15 May 2013). "Construction of East Bound Cavern at Stepney Green Complete". Crossrail. Archived from the original on 8 June 2013. Retrieved 14 October 2017.
  2. ↑ "Crossrail Bill 2005". Crossrail. Archived from the original on 3 August 2009. Retrieved 30 December 2009.
  3. ↑ "Soho shops make way for Crossrail". BBC News. 13 November 2009.
  4. ↑ "Building the Rail Tunnels". Crossrail. Archived from the original on 9 June 2015. Retrieved 7 March 2020.
  5. 1 2 3 "SCL to create Crossrail junction caverns". tunneltalk.com. September 2012.
  6. ↑ Hansford, Mark (9 July 2009). "Crossrail to let three contracts". New Civil Engineer. Retrieved 27 April 2023. Package C121 − Sprayed Concrete Lining: Mott MacDonald £9M
  7. ↑ Uhrin, Michal; Schultheis, Thomas; Tucker, Nicholas; Black, Mike; Dodge, Christian; Lawrence, Ursula (2 September 2015). "Stepney Green Cavern – Design Concepts and Performance of SCL Lining". Institute of Civil Engineers.
  8. ↑ Harris, David; Linde-Arias, Emilio; Davis, Andrew (June 2015). "Depressurisation for the excavation of Stepney Green cavern". Proceedings of the ICE - Geotechnical Engineering. pp. 215–226. doi:10.1680/geng.14.00061.
  9. 1 2 "Eastern tunnels – Pudding Mill Lane to Stepney Green". Crossrail. Archived from the original on 22 September 2015. Retrieved 23 August 2020.
  10. ↑ "Crossrail awards £1.25bn tunnelling contracts". Construction Index. 10 December 2010. Retrieved 27 April 2023. C305 – Eastern Running Tunnels (Limmo Peninsula to Farringdon; Limmo Peninsula to Victoria Dock; Stepney Green to Pudding Mill Lane): JV of Dragados, John Sisk & Son – value £500m.
  11. ↑ "Crossrail, London, UK". John Sisk and Son. Retrieved 27 April 2023.
  12. ↑ Lawson, Tom (15 May 2013). "Construction of east bound cavern at Stepney Green complete". Crossrail. Archived from the original on 8 June 2013.
  13. ↑ Thomas, Tris (15 August 2013). "Stepney Green Westbound cavern complete". tunnellingjournal.com.
  14. ↑ "Crossrail TBM reaches Stepney Green Cavern". railtechnologymagazine.com. 8 November 2013.
  15. ↑ McDougall, Hamish (16 June 2014). "Crossrail Tunnelling Machine Ellie Completes Journey at Stepney Green". Crossrail. Archived from the original on 25 June 2014. Retrieved 14 October 2017.
  16. ↑ "Crossrail Intermediate Shafts". Weston Williamson + Partners. Retrieved 27 April 2023.
  17. ↑ "Granting of Lease to Stepney City Farm" (PDF). London Borough of Tower Hamlets. 6 March 2018. Retrieved 27 April 2023. at Stepney Green the works are programmed for completion in late summer

51°31′01″N0°02′38″W / 51.517°N 0.044°W / 51.517; -0.044

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.