抄録
On tunnel excavation, a prediction of geological conditions ahead of face is of the utmost importance to keep rapid driving and safety works. Fukui et al. in 2004 investigated the drilling performance at Suzuka tunnel with special care to the effect of hole length up to 50 m, and proposed V* (normalized penetration rate) to estimate rock mass properties ahead of face. In this study, the method proposed by Fukui et al. was fully discussed and slightly modified. Thereafter, the method was applied to estimate rock mass properties at Suzuka tunnel and systematic in-situ measurements of V* were carried out through the tunnel. It was found that the reciprocal of V* is a good indicator for rock mass properties and suits the in-situ usage. The reciprocal of V* has strong correlation with rock mass strength estimated by TBM cutting force and very useful to estimate and predict the rock mass properties ahead of face. For example, a fracture zone can be predicted by an abrupt change of the magnitude.
