Analysis on the pre-injection grout consumption at Strindheim Road Tunnel Project, Trondheim, Norway

Abstract

The improvement of road quality by introducing a road tunnel is one of the principles used in both urban areas and other major highway system in Norway. In general, due to good quality rocks, the tun-nels constructed here in the country do not demand full concrete lining. The long term stability condition along the tunnel is achieved by the use of bolting and fiber shotcrete application. On the other hand, the road tunnels passing through low overburden may constitute system of joint sets in the rock mass, which increase possibility of water inflow into the tunnel. It is important to treat the rock mass in such a way that all permea-ble joint systems are sealed and no water inflow takes place inside the tunnel. In this respect, pre-injection grouting principle is used in Norwegian road tunnels to achieve impermeability and to control water inflow in-to the tunnel within the target limit. This paper presents a case study with a main aim of highlighting water in-flow (leakage) limit and pre-injection grouting principles used at Strindheim road tunnel project. Paper also attempts to find link between pre-injection grout take, stopping pressure applied and Q-value parameters.