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George Tsiambaos

National Technical University of Athens
School of Civil Engineering
Department of Geotechnical Engineering
gktsiamb@central.ntua.gr
NAME : George Tsiambaos, Professor of Engineering Geology
National Technical University of Athens, Greece
School of Civil Engineering, Dept. of Geotechnical Engineering
Phone: +30 210 7723748, e-mail: gktsiamb@central.ntua.gr

PLACE AND : Athens, Greece, 1951
DATE OF BIRTH
STATUS : Married, two children

I. EDUCATION
1974 : Diploma of Geology, Department of Geology, University of Athens, Greece.
1979 : Master of Science and DIC, University of London, Imperial College of Science and Technology. Title of M.Sc. Thesis: "Mechanical behaviour of Rock Salt under uniaxial compression".
1988 : Doctor of Geological Sciences, field of Engineering Geology. Department of Geology, University of Patras, Greece. Title of thesis: "Engineering geological characters of Iraklion Marls, Crete".

II. PROFESSIONAL EXPERIENCE
1979-1989 : Senior Engineering Geologist, Public Works Research Center, Ministry of Environment, Physical Planning and Public Works, Athens, Greece.
1989-1995 : Head of Engineering Geology and Rock Mechanics Section. Department of Geotechnical Engineering, Central Laboratory of Public Works, Ministry of Environment, Physical Planning and Public Works.
1995-1999 : Head of Geotechnical Engineering Department, Central Laboratory of Public Works, Ministry of Environment, Physical Planning and Public Works.
1999-2005 : Assistant Professor of Engineering Geology, National Technical University of Athens, School of Civil Engineering, Dept. of Geotechnical Engineering.
2005-2009 : Associate Professor of Engineering Geology, National Technical University of Athens, School of Civil Engineering, Dept. of Geotechnical Engineering.
2009- : Professor of Engineering Geology, National Technical University of Athens, School of Civil Engineering, Dept. of Geotechnical Engineering.

Journal articles

2009
G P Tziallas, G Tsiambaos, H Saroglou (2009)  Determination of rock strength and deformability of intact rocks   Electronic Journal of Geotechnical Engineering 14 G: 1-12  
Abstract: The paper presents the results of laboratory tests performed on a large number of intact sedimentary rock specimens (limestone, sandstone, siltstone) and metamorphic rocks from Greece. The physical properties (porosity, dry density), mechanical properties (uniaxial compressive strength), Youngâ冱 modulus, point load index, Schmidt hardness) and dynamic properties (wave velocity) were determined. Furthermore, laboratory results of intact rock properties were collected and evaluated. From the statistical analysis of the data, regression equations were established amongst intact rock parameters. The ratio of rock strength and deformation modulus was investigated and its range was determined for all rock types. A comparison was made between existing empirical equations for the correlation of uniaxial strength, Schmidt hardness and dry density (Ïツ-SHV-Ï‥). This comparison proved that Deere - Millerâ冱 (1966) chart yields the better prediction of the uniaxial compressive strength. Additionally, the correlation between uniaxial compressive strength, Ïツ, and point load strength, Is50, shows that an exponential fit gives a significantly better fit than a linear one. Finally, a multivariable analysis was done between tangent Youngâ冱 modulus, uniaxial compressive strength and wave velocity (Et-Ïツ-Vp) and an empirical correlation is proposed.
Notes:
G Tsiambaos, H Saroglou (2009)  Excavatability assessment of rock masses using the Geological strength Index (GSI)   Bull of Engineering Geology and the Environment (online):  
Abstract: In the present study a new classification method for the assessment of ease of excavation of rock masses is proposed, based on the Geological Strength Index and the point load strength of the intact rock. The data originate from excavation sites in Greece in sedimentary and metamorphic rock masses. A wide variety of rock structures were considered, ranging from blocky to disintegrated and different excavation methods have been used (blasting, hydraulic breaking, ripping and digging). The proposed method cannot be applied to heterogeneous rock masses and soft rocks/ hard soils.
Notes:
2008
A Antoniou, A Papadimitriou, G Tsiambaos (2008)  A Geographical Information System managing geotechnical data for Athens (Greece) and its use for automated seismic microzonation   Natural Hazards 47: 369-395  
Abstract: This article presents a geographical information system (GIS) which manages geotechnical data obtained from detailed geotechnical surveys as well as from in situ observations in Athens, Greece. Thoroughly examined data from more than 2,000 exploratory boreholes and trial pits located in the wider area of Athens have been incorporated using a relational database system. From the analysis of these results, thematic maps are compiled to illustrate the distribution of engineering geological information (e.g. the depth of the ââ連thens schistââ head). In addition, a methodology for an automated GIS-aided seismic microzonation study is outlined and is being employed taking into account the aforementioned geotechnical and engineering geological information, as well as existing seismological data to estimate the variability of seismic ground motion for the southern part of Athens.
Notes:
H Saroglou, G Tsiambaos (2008)  A modified Hoek-Brown failure criterion for anisotropic intact rock   Int J Rock Mech Min Sci 45: 223-234  
Abstract: The Hoekâ釘rown criterion parameters (sci, mi and s) are signiſtantly inï¬Venced by the strength anisotropy of intact rock. In the present study, the criterion was modi﬑d by incorporating a new parameter (kb) to account for the effect of strength anisotropy, thus being able to determine the strength of intact anisotropic rock under loading in different orientations of the plane of anisotropy. The range of the parameter (kb) for the rocks tested has been analytically investigated by carrying out triaxial tests, in different orientations of the foliation plane. The proposed modiſtation was studied for metamorphic rocks (gneiss, schist, marble), but could also be applied to other rock types exhibiting ââ亙nherentââ anisotropy, e.g. sedimentary as well as igneous rocks. The proposed modi﬑d criterion is intended for use for prediction of strength of intact rock, but can also be extended to rock masses.
Notes:
N Sabatakakis, G Koukis, G Tsiambaos, S Papanakli (2008)  Index properties and strength variation controlled by microstructure for sedimentary rocks   Engineering Geology 97: 80-90  
Abstract: A large number of laboratory tests were performed on intact chemical and clastic sedimentary rocks (marlstones, sandstones and limestones). Index properties such as total porosity, dry unit weight, Schmidt hammer value and point loading index as well as the strength under uniaxial and triaxial compression were determined. The material constant m i which constitutes an input parameter for Hoek and Brown failure criterion, was also estimated by analyzing the results from triaxial compression tests. From the statistical analysis of the data, regression equations were established among rock material parameters, while conversion factors relating index properties and strength were also determined. The petrographic characteristics of the studied rocks such as mineral composition and microstructure were analyzed in thin sections and their intrinsic influence on the measured strength parameters was also investigated
Notes:
2005
G Koukis, N Sabatakakis, G Tsiambaos, N Katrivesis (2005)  Engineering geological approach to the evaluation of seismic risk in metropolitan regions: case study of Patras, Greece   Bull Eng Geol Environ 64: 219-235  
Abstract: The city of Patras in western Greece has experienced several destructive earthquakes during the past centuries. The engineering geological conditions of the area have been analyzed and described using a relational geotechnical database management system including geotechnical and geological information obtained from exploratory boreholes, cone penetration tests and cross hole seismic prospecting. The foundation soils of the city were grouped into individual geotechnical units and several engineering geological maps and geotechnical cross sections were compiled. Criteria are proposed for the approximate evaluation of the eï¬ect of local soil conditions on ground motion, especially on the distribution of ampliſtation features.
Notes:
2004
2003
2001
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1985

Conference papers

2008
P Marinos, G Tsiambaos, H Saroglou, V Marinos (2008)  Rockfall hazard and risk for a figh promontory: Monemvasia historical site, Greece   In: ICL - International Consortium on Landslides, The First World Landslide Forum 206-209 United Nations University, Tokyo  
Abstract: The paper presents the kinematics of rock instability of a high promontory, where Monemvasia historical site is situated, in the Peloponnesian peninsula. The instability phenomena pose a significant threat on the town situated immediately down slope. Rock fall episodes occurred in the past, whereas, due to the relaxation of the high cliff, significant undermining of the castle frontiers has been observed at the slope crest. The predominant types of kinematic instability are of planar or wedge failure and toppling of large blocks. In order to investigate the existing stability conditions and decide upon the protection measures, stability and rockfall analysis were carried out for numerous slope sections under different loading conditions. A rock-fall risk rating system is proposed, which is based on morphological, lithological and structural criteria and on vulnerability. The rating system is applied for individual sections along the slope and a risk map was produced, which depicted areas having different degree of risk against rockfall occurrences. Protection measures were designed based on the stability analysis as well as the hazard map. Moreover, an assessment of the residual risk which could remain after the stabilization would be made by taking into account additional special criteria.
Notes:
2007
2006
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