Despite the advent of tunnel boring machines (TBMs) more than 70 years ago in the early 1950s, their use for mining infrastructure has been limited to a few access, exploration, drainage and water supply tunnels (Brox, 2013). TBMs have successfully been used for the construction of the majority of tunnels generally longer than 4 km (2.5 miles) for civil, hydropower and oil and gas infrastructure projects with more than 50,000 km (31,000 miles) of tunnels, and more than 10,000 TBMs have been manufactured (Zheng et al., 2014). TBMs offer many advantages over conventional excavation methods including improved safety and working environment, reduced ground support, reduced overbreak, higher advance rate and overall lower cost. Today, TBM suppliers can more easily design TBMs for the anticipated geotechnical conditions and to specifically design for any identified adverse conditions to de-risk the TBM from possible entrapment.
