ABSTRACT
Mechanical excavation machines are widely used in civil tunnelling and subway construction, and in driving mine openings, such as drifts, ventilation shafts, and raises. In general, two types of cutting tools are used in mechanical excavation machines: (i) drag bits, and (ii) indenters. Machines that use the indentation cutting principle include Tunnel Boring Machines (TBMs), mobile miners, shaft borers and drills. Machines that use drag bit cutting include longwall shearers, road headers and continuous miners. Over 90% of TBMs are used for civil engineering purposes e.g. road tunnels, rail tunnels, hydroelectric scheme applications, sewers, rapid transit systems, military tunnels, etc. Significant research on rock indentation dates from the 1970’s (e.g. Wagner & Schuman, 1971; Nishimatsu, 1972; Cook et al., 1984; Pang et al., 1989; Lindqvist et al., 1994; Kou, 1998; Liu, 2003; Chen & Labuz, 2006).
