8. Main risks and countermeasures

8.1 Clogging

Clogging of the cutting wheel, most often encountered in plastic and sticky formations, can lead to a significant drop in the TBM's digging performance. The first type of clogging concerns the cutting wheel itself, with its wheel housings, arms and tools, which can lead to poor penetration and difficulties in cutting material. The second type of clogging is found between the rear of the cutting wheel and the plunging wall, making material extraction difficult. Regular cleaning operations are sometimes necessary, with a direct impact on the TBM's advance performance.

When the risk of clogging is known, there...