TRENCHLESS | SMALL DIAMETER TBM/PIPEJACKING
Above, figure 2: Three tunnel boring machines installed in the thrust pit The existing culvert - NOC/23, and comprising
119-year old brick twin arches - showed signs of settlement since 1947 due to subsidence from local ground conditions. The local ground is mostly peat and has an underlying dissolution feature. The structure is undergoing regular remote monitoring due to its condition but has required replacement as part of the project’s need to increase the frequency of railway traffic. With the proposed works located in a flood zone,
consents approval was sought from the Environment Agency for both the temporary compounds and the permanent works. The consenting process began in 2020 for the works, located 16.2km south of York. The flood zone made the proposed works challenging due to unforeseen weather conditions and potential rising groundwater levels. The replacement culverts would be circular pipes and
jacked into position. Thrust and reception pits would be completed on opposite sides of the embankment, ahead of the pipe installations. This order of works was crucial to balance the movement of water and allow the permanent works to be undertaken.
Three small diameter tunnel boring machines (TBMs)
would work simultaneously side by side, jacking the pipes beneath the four-track railway. The works at the embankment were undertaken in
August 2023 for optimum weather conditions due to the site being located within the flood plain. They were completed in 54 hours during which the three pipes were safely installed below sequential line closures, with two lines open for a total of 45 hours to allow the railway to remain open to trains to achieve minimal disruption to services. The tunnel installation was successfully completed
on time throughout without overrun disruption to operational traffic and there were no accidents or incidents. This paper covers the design and installation works associated with these structures, with a particular emphasis of the permanent works designer’s remit.
EXISTING STRUCTURAL ARRANGEMENT The twin-arch flood relief culvert, NOC/23, was built in 1840 to carry the Leeds rail lines, and then it was reconstructed in 1903 to accommodate the Normanton
Above, figure 3: Section through existing culvert showing a significant fracture 12 | September 2024
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
