Abstract
Tunnel Boring Machines (TBMs) have been used in mining in decades past, but their use has been limited and sporadic. This has changed in recent years, with TBMs being used at Stillwater Mine, Grosvenor Coal Mine Slopes, Sirius Minerals potash mine, and more. These machines are all full face, circular TBMs. With their circular bores these machines have thus far have been unable to tackle a larger issue for mines: typically a flat floor is needed for mining vehicles to traverse. Thus, despite the fact that many more kilometers of tunnel are typically built every year in mines than in civil tunneling, methods such as drill and blast are often used. Drill and blast, as well as roadheaders, are less economical methods with lower excavation rates in long, underground hard rock tunnels.
A novel type of non-circular boring machine is now answering the need to quickly reach underground ore bodies while cutting a rectangular profile in hard rock. This cross section allows for use of typical mine trucks and other rubber-tired mine vehicles. It provides more useable space, compared to a circular profile, and minimizes the amount of excavated rock that must be hoisted out of the mine. This machine uses disc cutters to cut the rock, and has a support structure similar to an open type TBM; however, the cutting geometry is entirely different. The machine is currently cutting an access tunnel at a silver mine.
This paper reviews the design and operation of the novel non-circular tunnel boring machine, and describes possible future adaptations to provide safe, sustainable underground mine development in rock.