Tunnelling Induced Strains and Deformations at Central Line

In October and November 2012, Imperial College installed electrical resistance strain gauges, potentiometric displacement transducers and tape extensometer eye bolts at selected locations in the Central Line eastbound running tunnel between Lancaster Gate and Marble Arch. The instrumentation was installed shortly before the first of the Crossrail tunnel boring machines (TBM) passed below the Central Line tunnel at this interface.

The Crossrail twin tunnels begin at Royal Oak Portal in Westbourne Park, West London, and traverse westwards towards Farringdon. The Crossrail tunnels had a clearance of 4.2m to 4.9m under the Central Line twin tunnels east of Lancaster Gate station running at approximately 40 degrees skew (Figure 1). The Crossrail westbound tunnel passed under the Central Line eastbound tunnel at Crossrail chainage 2085m. The Crossrail eastbound tunnel passed under the Central Line eastbound tunnel at Crossrail chainage 2111m.