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Interesting stuff. One thing I was hoping the video would touch on is how do they know exactly where they are and how they are oriented while boring large tunn
by BigJono 7y ago
Interesting stuff.
One thing I was hoping the video would touch on is how do they know exactly where they are and how they are oriented while boring large tunnels? If you're digging 30km of tunnel, being off by half a degree in any direction would be disasterous, no?
- abduhl 7y agoSurvey control is transferred down the tunnel from surface. How it gets down there depends on whether you launch from a shaft or pit, but once survey control is established in the hole it is straight forward to locate the TBM using standard survey techniques (eg - survey prisms). The TBM has a reflector that can be shot with a survey instrument to accurately place the machine head and the TBM itself is equipped with gyroscopic or accelerometers for backup control if survey is lost during mining.