Elaboration and Interpretation of Ground Investigation Data for the Heterogeneous ‘Athens Schist’ Formation; from the ‘Lithological Type’ to the ‘Engineering Geological Formation’

Abstract

Line 4A of the Athens Metro will encounter the Athens Schist, a heterogeneous rock mass comprising a variety of slightly metamorphosed lithological types. Due to the complexity of the rock mass, interpretation of ground investigation data poses a challenge since the direct attribution of laboratory and in situ data to geotechnical design profiles is not appropriate. The methodology that was applied for the evaluation of these data is based on the scheme lithological type—engineering geological unit—engineering geological formation—geological formation, each being a subgroup of the latter. The main aspect of this approach takes into consideration the scale of reference of each assigned category of geomaterials. This elaboration and interpretation methodology, in conjunction with the engineering geological profile, which is compiled in terms of engineering geological formations, provides a comprehensive background for all subsequent geotechnical design needs.