The observational method applied to the construcion of road tunnels in rock

Abstract

During the last five years serveral road tunnels have been constructed I Portugal. The aothors were involved in the geological and geothecnical studies, and in the desingn and monitoring of the construction. Those tunnels were excavated using the observational method. starting from a basic design including general specifications and bill of quantities, prepared for the invitation to tender. As selected case histories, the IP2-Gardunha an IP3-Régua and Varosa tunnels are focused in this paper, all of them excavated in rock masses whith different lithologies, weathering and fracturing degrees.