TBM dismantling is a cutting job before it is a lifting job. Here is how the cutting side gets planned when a tunnel boring machine has finished its drive and has to come out in pieces.
Why TBMs are cut, not craned out whole
A tunnel boring machine at the end of its drive is often somewhere a whole machine can never leave: a retrieval shaft too small for the shield, a dead-end cavern, or a bored tunnel that will be lined behind it. The cutterhead alone can weigh more than any crane pick available at the bottom of a shaft. So the machine is segmented where it stands, and every segment is sized by two numbers: the crane chart at that radius, and the clear opening it has to pass through on the way up.
Steel, concrete and grease in the same cut
A TBM is not a clean steel structure. Shields carry hardened wear plates, the cutterhead carries cast steel and tungsten, and the annulus is full of grout, grease and compacted spoil. Diamond wire handles this mix better than any other method because the wire does not care what it is passing through. The planning question is not whether the wire will cut, but how much wire is in the machine. Long cuts through a shield bury many metres of wire in the kerf at once, and the wire saw needs the storage capacity to keep tension and keep moving as the cut deepens.
The sequence is the safety case
Segmenting a machine that weighs hundreds of tonnes means every cut changes how the remaining mass is supported. A proper TBM cutting plan reads like a structural staging plan: which segment comes off first, what carries the load once it does, where the lifting lugs are welded before the cut is completed, and what stops a segment moving when the wire breaks through. On top of that sits ventilation for underground work, hot work controls if any oxy or arc cutting supplements the wire, and water management for the cutting slurry in a confined invert.
What to ask a cutting contractor before you commit
Ask for the segmentation drawing, not just a rate. Ask how the panel weights were confirmed against the crane chart. Ask what wire storage the saws carry, and what the plan is when a cut binds. If the answers come back as engineering rather than as reassurance, you are talking to the right people.
Read more about our TBM and tunnel cutting service, or the thinking behind why wire storage matters more than motor power.
DeconCut acknowledges the Aboriginal and Torres Strait Isander people as Traditional Custodians of the country on which we live and work. We pay our respects to the Traditional Custodians and Elders past, present and future, and honour their connection to the land and ongoing contribution to society.