Geological engineering problems associated with tunnel construction in karst rockmasses: The case of Gavarres tunnel (Spain)

Abstract

A representative example of the problems associatedwith the excavation and support of tunnels in karst ground is presented. It is a peculiar case in terms of heterogeneity and spatial distribution of zones of poor geotechnical quality, requiring the need to define, preferably in the study phases, adequate site investigation, suitable design procedures, efficient construction techniques and appropriate ground treatment. The difficulties associatedwith the instability of the karstified ground, and the presence of cavities, wholly or partially filled with soils of low cohesion, are discussed via retrospective analysis. The solutions adopted to solve the problems encountered during the tunnel construction enabled a systematic approach, useful for newconstruction projects in limestone terrains of medium to high karstification.