HARD ROCK EXTREME CONDITIONS IN THE FIRST 10 KM OF TBM-DRIVEN BRENNER EXPLORATORY TUNNEL

摘要

This first part of the Brenner exploratory tunnel was bored entirely through veryrnhard granitic rocks under high cover. In certain locations extremely adverse geologicalrnevents were encountered by the TBM. A long section of the tunnel was confronted byrnextensive rock burst phenomena.In another section of the tunnel the thrust of high pressurernground water on the tunnel walls caused the sudden collapse of 40 m of precastrnlining immediately behind the TBM. This paper describes in detail these occurrencesrnas well as the methods and special design measures implemented to overcome them.rnAlong the entire tunnel the rock mass parameters were measured. RMR (RockrnMass Rating) and RME (Rock Mass Excavability) values and classes were determinedrnand are presented here. The RMR and RME classifications are compared with and correlatedrnto the TBM advances and penetration rates. The TBM advances were predictedrnusing the formula based on RME and compared with the ones actually achieved.rnMore than 2500 cutter changes were performed and the relevant data are presentedrnalso in relation with the RMR and RME classes.