The influence of rock fabric on excavation damage in the Lac du Bonnett granite

This paper documents the contribution of rock fabric oil excavation damage development in the granite of the Lac du Bonnet Batholith (LDBB). It is Concluded that the LDBB contains structural elements and distinct textural varieties which differ significantly in their response to rock properties testing and to excavation. Data collected in this study demonstrate the highly heterogeneous internal structure characteristic of apparently homogenous batholiths. and the influence of this heterogeneity on rock mass response. Evidence for anisotropy of the rock mass is demonstrated to have occurred on the geological time-scale and its influence is still present in recent excavations. This anisotropy exists at a wide range of scales. from the localization of fault zoned along low-dipping layering at the kilometre-scale, to the localization of failure around tunnels by separation along this and other weakness directions. (C) 2004 Elsevier Ltd. All rights reserved.