W. K. Lis
Superstar
The TBM's used to tunnel under the English Channel (The Chunnel) are still there. If you can get at them, that is.
From wiki.answers.com, at this link:
In other words, the TBM's are recycled.
From wiki.answers.com, at this link:
In late 1990, the service tunnel was almost complete. The moles had approached each other closer to the British end. France, however, didn't gloat in its accomplishments. Both countries had come together for a common good. This isn't to say that some friendly competition hadn't fueled the tunnel's construction. When the two tunnel boring machines were about 50 meters from each other, the English moles drove off-line to the right into the narrow gap between the service tunnel and the running tunnel south (Fetherston, p. 342). The British machine stopped once it lay parallel and head to tail with the French machine. The English mole was stripped of anything salvageable. It was then entombed within concrete. The French tunneling machine than was hollowed out. Its outer shell would serve as the tunnel lining.
In other words, the TBM's are recycled.