Geotechnical characterization of a Miocene clay for a tunnel of the Lisbon metro

Abstract

A tunnel of the Lisbon Metro was almost entirely excavated in a miocéne formation known as "Prazeres Clay". ln the paper the geotechnical characterization of this unit, involving in situ and laboratory tests, is presented. Particular attention was devoted to the definition of shear strength parameters and different strain moduli and, also, the mathematical modelling of the stress-strain curves obtained from undrained triaxial tests.