Simultaneous Effects of Joint Spacing and Orientation on TBM Cutting Efficiency in Jointed Rock Masses

Excerpt

Rock mass parameters including weak surfaces are the most important parameters which should be taken into account for an accurate analysis of the rock penetration by disc cutters. To date, many experimental, theoretical, and numerical simulation-based researches have been carried out on the interaction of TBM disc cutter performance and joint spacing and orientation. However, in most of these works, the influence of joint spacing and orientation on disc cutter performance and chip formation have been studied individually. Among them, the researches by Wanner and Aeberli (1979) on the influence of discontinuity frequency of different types of discontinuity on TBM specific penetration; Howarth (1981) on studying experimentally the impact of joint spacing on TBM performance; Lindqvist and Lai (1983) on the behavior of the crushed zone in rock indentation; Sanio (1985) on studying the effect of rock mass anisotropy, including bedding and schistosity on cutter load; Zhao et al. (1994) on indentation fracture mechanics and rock disc cutting; Tang (1997) on the numerical simulation of progressive rock failure and associated seismicity; Bruland (1998) on introducing a fracture factor in the NTNU model of TBM performance prediction; Kou et al. (1999) on the numerical simulation of the cutting of inhomogeneous rocks; Innaurato et al. (2001) on the performance and modeling of indenters and cutting tools in boreability assessment for rock tunneling; Liu et al. (2002) on the numerical simulation of the rock fragmentation process induced by indenters; Gong et al. (2005, 2006) on investigating the effect of joint orientation and spacing on rock fragmentation by TBM cutters using numerical modeling; Innaurato et al. (2007) on experimental and numerical studies on rock breakage with TBM tools under high stress confinement; Ramezanzadeh et al. (2008) on the impact of rock mass characteristics on hard rock TBM performance; Bejari and Khademi Hamidi (2009); Innaurato et al. (2011) on laboratory tests to study the influence of rock stress confinement on the performance of TBM discs; and Bejari et al. (2011) on the simultaneous effects of joint spacing and orientation on the penetration rate of a single cutter using numerical modeling should be noted. …