EXCAVATION OF ROCK MASS IN THE ZENICA TUNNEL

Abstract

This paper gives an overview of the excavation of rock mass in the Zenica tunnel on the highway of Corridor Vc. The technology of tunnel construction includes the following underground works: tunnel excavation, substructure works (primary support) and construction of the secondary lining of the tunnel. The most important feature for the selection of construction technology is the geology of the rock mass through which the tunnel passes. The combined excavation technology was applied at the Zenica tunnel: by machine and blasting ("drill and blast technique") and based on NATM - New Austrian Tunnel Method. The excavation of the Zenica tunnel was performed in very complex geological and geotechnical conditions. Since these are flysch sediments, tectonics was very pronounced with constant shifts of hard and soft rocks and large amounts of groundwater. The excavation of the tunnel was performed in several phases and in full profile, depending on the quality of the rock mass, while ensuring the excavation with a primary support. Engineering geological mapping of the rock mass of the excavation face was performed daily. Geomechanical classification - RMR was applied for the classification of rock mass. The excavation of the Zenica tunnel was performed in the rock mass of III, IV and V categories according to RMR.