Tunnel behaviour and support in molassic rocks. Experience from 12 tunnels in Greece

摘要

Molasse consists of a series of tectonically undisturbed sediments of sandstones, conglomerates,rnsiltstones and marls, produced by erosion of mountain ranges after the orogenesis. Molassic rock masses mayrnhave very different structure close to the surface as compared to those confined in depth, where bedding planes,rndo not appear as clearly defined discontinuity surfaces. The present paper focuses on the tunnelling experiencernthrough molassic formations, based on data from the design and construction of twelve tunnels in EgnatiarnHighway in northern Greece. The fundamental tool for this research was TIAS database, which has been used forrnthe storage, retrieval and correlation of the available data. The rock mass behaviour that was anticipated duringrnconstruction is described and the molasse specific GSI chart is validated. In conclusion, a standardization ofrnthe geotechnical behaviour of molassic rock mass types and the temporary support categories that have beenrnsuccessfully implemented is presented.