In a bid to rescue the trapped Lovat TBM, Maureen, on Yorkshire Water‘s $91.4m Humbercare tunnelling project, contractor Miller is re-deploying Gloria, the Lovat machine previously used on the contract’s other completed drive.
At the end of last year, a 15m section of the 3.6m diameter tunnel, approximately 150m behind the advancing TBM, distorted, causing sand, silt and water to fill the tunnel and trap the TBM. The area was stabilised using compressed air and subsequently filled with water while investigations began to ascertain the cause of the collapse.
Miller has now sunk an additional shaft 50m west of the site of the collapse, from which Gloria will tunnel back to gain access to the trapped machine. Upon freeing the machine, Gloria will complete the tunnel drive. Of the decision to redeploy Gloria, Yorkshire Water project manager Steve Tindall says, "Now we are going to tunnel back west to east using Gloria, as that will save us a lot of time in the future, and the location of the additional shaft will mean Maureen will eventually have to travel only 50m."
The collapsed section of the tunnel will be dug out by miners and a specially designed reinforced concrete lining will be erected.
The collapse is not seen as a threat to the imposed EC deadline for completion. Tindall continues, "As regards the final sections of tunnelling following the unfortunate accident last year, Maureen’s concluding drive from east to west was running 12 weeks ahead of schedule and so we remain within the original project deadline for next November."
