Sprayed Concrete, Deckdrain, Network Rail, Werrington, UK
|Contractor:||Morgan Sindall / BAM Ritchies|
|Consultant:||Tony Gee and Partners LLP|
|Product:||Deckdrain 700S/ST170 Drainage Geocomposite|
|Benefits:||- All-in-one drainage & barrier|
- High flow capacity
- Excellent bonding with shotcrete
- Fast and safe installation
- Significant 55% carbon saving
As part of a study into increasing capacity and reducing journey times on the East Coast Main Line (ECML) for long distance, high speed passenger services; Network Rail identified that a new grade separated junction at Werrington would be required. Through an option selection process it was determined that dive-under would allow slow moving freight traffic to pass below the ECML.
The site is situated at Werrington Junction, 5km to the northwest of the city centre of Peterborough. The existing land was primarily agricultural with a relatively high water table.
Network Rail appointed Morgan Sindall to implement the scheme, with Mott MacDonald and Tony Gee as appointed as partners to undertake the detailed design.
As the new tracks will pass below the ECML at circa 8m below existing ground level, ramps of a suitable gradient (1 in 110) are required to bring the tracks back to the level to connect to the existing railway. The ramps required a solution that considered a number of factors such as construction cost, minimising land take and construction duration. The chosen solution for a section of one ramp was a 60deg soil nailed slope with concrete facing to ensure
long term stability of the clay naturally present clay.
The challenge was to design a retaining structure that would reduce required excavations, enable fast installation, reduce transport cost, enable substantial carbon savings and meet design requirements on this sensitive location.
ABG worked with the designer to develop a geosynthetic solution that provides the required drainage flow capacity and an effective barrier to ensure long term performance.
The BBA certified ABG Deckdrain 700S/ST170 geocomposite drainage was specified for this application. Deckdrain geocomposite with impermeable back HDPE cuspated drainage core provided an excellent bond for the shotcrete, requiring reduced excavation and saving a significant 696t of carbon. The geocomposite was installed against the embankment and 10m long soil anchors were drilled and grouted to achieve the required stability.
Two layers of reinforcement mesh were installed and a 250mm thick shotcrete wall was sprayed to the bank.
ABG Deckdrain 700S/S170 Geocomposite for vertical wall drainage
The ABG Service
ABG provided design assistance and technical support during the design, trial and installation on this project.
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