457 ABSTRACT: This paper presents the identification of the geotechnical parameters of the Antalya karstic foundation rocks (travertine/tufa), whose mechanical behavior is highly variable due to their natural variability and structure. Antalya tufa rock mass is a different rock type, which has no well- developed joint systems. It is variably porous and is composed of different rock types with different structures. In order to reveal the controlling geotechnical parameters for the mechanical behavior of the Antalya tufa rock mass and to develop a comprehensive geotechnical database for the Antalya tufa, numerous field and laboratory geomechanics tests have been performed. Accordingly, the geological and geotechnical parameters of the rock material and rock mass underlying the City of Antalya have been attempted to identify. Rock mass classification has been proposed for the Antalya tufa rocks. 1 INTRODUCTION Antalya, which is one of the largest cities of Turkey, represents a rich tufa depositional environment (Figure 1). The Antalya tufa rock includes numerous types of tufa identified by Pedley (1990) and Glover & Robertson (2003). The tufa types, namely, microcrystalline tufa, phytoherm framestone, phytoherm boundstone, phytoclast tufa and intraclast tufa of the Antalya tufa rock mass are the subjects of this study. In order to geotechnically characterize the Antalya tufa rock, numerous laboratory and field tests have been performed. Laboratory testing involved determination of uniaxial compressive strength (UCS), triaxial compressive strength, indirect tensile strength (Brazilian), unit weight and porosity, while pressuremeter tests were performed in the field. EUROCK 2015 & 64 th Geomechanics Colloquium. Schubert & Kluckner (ed.) © ÖGG Geotechnical characterization of the Antalya karstic rock masses Evrim Sopacı Temelsu International Engineering Services Inc., Ankara, Turkey Haluk Akgün Middle East Technical University (METU), Department of Geological Engineering, Ankara, Turkey ISRM Regional Symposium EUROCK 2015 - Future Development of Rock Mechanics October 7 - 10, 2015, Salzburg, Austria ISBN 978-3-9503898-1-4