NEWS 2005

Posted May 9, 2005

May 10 2005

Cross Canada Lecture / Annual General Meeting 2005

The Construction of the Metro of Athens, Greece, in difficult ground. Challenges and solutions.

The Metropolitan Railway of Athens presents an excellent case study in indicating how the geological model can contribute to the choice of method of construction, efficient design, and the solutions of specific problems; many of them being related to archaeological sites.

The bedrock of Athens consists of a slightly metamorphosed flysch (the "Athenian Schist") with variability of lithological facies, structural complexity and tectonized zones.

The engineering geological assessment, with respect to a non-pressurized face TBM excavation, was applied within this highly heterogeneous system and considered mainly the rock mass competence on the basis of criteria related to lithology, tectonic deformation, and weathering, as well as geometrical, structural, and groundwater criteria. Hence this assessment calibrated the rock mass interaction with the TBM, with an emphasis on potential face failure and overbreaks. It was based on a geologically-minded extrapolation of factors that govern the behaviour of the ground, when subjected to mechanized boring. Consequently, the tunnel section, with "friendly", "moderate", or "adverse" tunnelling conditions with respect to overbreak development and propagation were identified. This was the basis for the selection of appropriate treatment and/or alternative excavation methods, where needed.

In one of the extensions of the project an open face shield (OFS) was used. This machine is effective in controlling any potential instabilities in a fair quality rock mass, but not when poor quality rock masses are present and the stand-up time is limited. A specific engineering geology classification of "Athenian Schist" is described in order to provide predictions for the behaviour of the rock masses under the conditions of an excavation with such a machine to assess the risks but also the need of remedial measures.

The estimate of properties was a real challenge for such heterogeneous and structurally complex rock masses. Based on back analysis, in-situ test data and geological judgement for the characterization of these weak rock masses, the applicability of the classification schemes was tested. In these rocks the Geological Strength Index (GSI) has been found to bridge efficiently the gap between geology and rock engineering in assessing the appropriate geotechnical parameters and provided a tool for the whole design.

About the speaker: Dr. Marinos is currently a Professor of Engineering Geology at the National Technical University of Athens. He graduated as a mining engineer from National Technical University of Athens in 1966. Following this he received a degree in Engineering Geology, and completed his Docteur Ingenieur at the University of Grenoble in 1967 to 1969. Dr. Marinos worked as an engineering geologist for several large companies in Greece up to 1974 at which time he became a private consultant and acted as individual expert or on panels for consulting activities in Greece, Jordan, Saudi Arabia, Nigeria, Iran, Portugal, France and Hong Kong. In 1987 he became a Professor at the University of Thrace for ten years. Since that time he has been a Professor at the National Technical University of Athens, Civil Engineering Department. Where he has had several appointments as the Director of the Geotechnical Engineering Division of the Civil Engineering Department.

Dr Marinos has published over 222 papers during his career and has acted as president of the Greek Tunnelling Society and the International Association for Engineering Geology and the Environment (IAEG). He is currently acting as the Chairman Elect of the board of the Geological Society of Greece. He has received the Hans Cloos medal from the IAEG in 2000, the André Dumont medal from the Societé Géologique du Belgique in 1997, and present the 6th Glossop Lecture in London, England in 2002. He has been named an honourary member of the International Association of Hydrogeologists.

Presenter: Dr. Paul G. Marinos, National Technical University of Athens
Location: The Petroleum Club 11110 - 108 Street
Time: cash bar 5:30; dinner 6:00
Date: Tuesday May 10, 2005
Cost: GSE Members: $30; Non-members $40; Students $15; payable at door
Register: Space limited. Please confirm attendance by
Friday May 6 by following this link or emailing kent.bannister@amec.com