Contractors battle to extract TBM after silt breaches tunnel

Preston tunnel project, Lancashire, UK, where TBM is stuck

Preston tunnel project, Lancashire, UK, where TBM is stuck

A TBM is stuck on a 2.85m diameter stormwater tunnel in Lancashire, UK. The tunnel is planned to be 3.5-km long, but has been stalled since November when the silt intrusion stopped the tunnel boring machine. Solutions being considered for freeing the machine include excavating from the surface, or stabilizing the tunnel with ground freezing or jet grouting to allow removal. [Source: New Civil Engineer. Image: NCE]