I Feel the Earth Move: How Crossrail Has Moved the Ground Across London

Posted on June 27, 2018
Archive : June 2018
Category : Site Investigation

We have all heard the expression “on solid ground”… but is the ground really as solid as we think? Last month, GE Magazine reported that Imperial College London researchers had released a map showing how the ground has moved across the city throughout the construction of Crossrail.

Using satellite images between May 2011 and April 2017, the researchers have shown how the ground has changed in a relatively short space of time. In blue areas, the ground has risen by up to 2mm, while the red areas have experienced subsidence of up to 2mm. The red spot to the East of Canary Wharf has been caused by dewatering of the deep Chalk Aquifer as part of construction.

Movement like this is perfectly natural, but it is something that people don’t always appreciate. Geotechnics chairman Len Threadgold spoke to GeoDrilling Magazine after giving the John Mitchell Award lecture at the ICE: “Structures are manufactured to a defined framework using materials that are selected, specified and quality controlled. By contrast, the ground, which is fundamental in every sense to construction is inherited and the legacy of geological and climatic processes since the Earth was formed, as well as more recent human activity.”

The ground can even move after construction. This is why it is important to plan monitoring and testing throughout the entire project lifecycle. Through monitoring – allied with desk studies and specialist advice, site investigation and laboratory testing - you can find out more about this unknown variable to de-risk your project and reduce costs.