The Crossrail project is the multi-billion-pound project to deliver the Elizabeth line, a 118km train line across Greater London, which will increase its rail capacity by 10% and help regenerate the capital.

We carried out grouting operations as part of the Crossrail development. This was the largest compensation grouting project to date in the UK, costing £40 million.

Project Highlights:

• We injected three million litres of grout between Bond Street and Tottenham Court Road.
• Working on a 24/7 schedule, our team carried out more than 1,300 passes.
• We fed all the data digitally, providing greater visibility, understanding and verification.
• The key to success on these works was tight collaboration with the excavation and monitoring teams.

Protecting history

Working from several shafts near Bond Street and Tottenham Court Road, we installed over 40,000 metres of tube-a-manchettes, under a number of historic listed buildings. This enabled over three million litres of grout to be injected.

We covered over two kilometres of tunnels and caverns with these works, protecting a wide range of buildings, foundation types and underground structures. Monitoring the buildings above ground through remote surveys, we ensured the works caused no damage to the fragile buildings.

All-night work rotations

Our team operated 24/7 to match the work patterns of the cavern excavation and tunnelling works. With our engineers on hand throughout grouting, we were able to monitor how the ground reacted and could adjust injection schedules if needed. Keeping staff on site through a 24-hour rotation created immediate costs. However, this way of working saved time and money overall, as we were able to catch irregularities quickly, and avoid ground settlement.

Digital design

A technology-led approach, we sent grout designs to digital models on site, where we specified volumes, pressures and injection points. Our team fed all the data into the digital model to provide greater visibility, understanding and verification. This method allowed us to work with reliable accuracy, and helped us manage risks with time to spare.

The key to success on this project was working collaboratively with the excavation and monitoring teams, using digital drilling and grouting records effectively. From start to finish, our data interchange was slick and transparent, which allowed us to design grout injection passes without any differential movement – something that often causes the most damage.