In the civil tunnelling field, the use of tunnel boring machines (TBM) has now overtaken the use of conventional excavation methods (drill and blast / roadheader). This is due to a number of reasons, including the increasing availability and reliability of TBMs, the ability to deal with a wider range of face conditions, and the reduced excavation cost that TBMs can bring. Mining companies have spearheaded the advances in shaft boring by mechanised means, both in blind and raise boring. However, mining companies have been slower to adopt mechanised tunnelling. When contrasted with a conventional mining contract, there are good reasons why TBMs in mining applications are relatively rare. A conventional decline contract may have very little geotechnical information. The decline alignment can be subject to change as the tunnelling progresses. The infrastructure requirements are less for a conventional decline, and the sunk cost prior to excavation commencing is lower. Contract documents can be very simple. The history of TBM use in mining is reviewed and lessons are described. From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology. We believe that despite the additional requirements for TBM declines, the cost and time advantage to mining companies is very attractive. The challenge is to recognise and to meet the requirements for success in a TBM drive to achieve the advantages of: ? faster advance rates ? reduced rock damage/overbreak ? reduced support requirements ? uniform muck characteristics ? greater personnel safety. From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology.
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