Significance of geological parameters for predicting water leakage and challenging pregrouting in the Mælefjell tunnel
One of the most challenging aspects of tunnelling is prognostication of water inflows and wa- ter control. During excavation of the Mælefjell road tunnel, located between Gvammen and Århus in Tele- mark County in Norway, high-pressure water inflow has been encountered. A summary of grouting technique used and geological conditions in the most challenging weakness zones will be given. The main rock type is quartzite with some dykes/bodies of metagabbro. The rock overburden is high, up to 1190 m, and several fault zones has been encountered. This paper will compare amount of water ingress and water pressure with geo- logical parameters and factors such as structural geology, orientation of in-situ rock stress, orientation of wa- ter-bearing fractures, rock cover, rock type and/or boundaries. The analysis will give increased knowledge of the main factors influencing water leakage in hard rock tunnels.