III Międzynarodowa Konferencja Naukowo-Techniczna „Nowoczesne technologie w budownictwie drogowym” Poznań, 8–9 września 2005 3rd International Conference „Modern Technologies in Highway Engineering” Poznań, 8–9 September, 2005

Lysandros Pantelidis Aristotle University of Thessaloniki, Greece

DETERMINATION OF SOIL STRENGTH CHARACTERISTICS PERFORMING THE PLATE BEARING TEST
Summary: In the international literature there is often confusion between the terms Modulus of Elasticity EYoung and Modulus of Deformation EDef for homogenous, isotropic masses, which, sometimes, plainly referred as Modulus E, without any further explanation. In this paper a distinction between the EYoung and the EDef is being done and the interest is concentrated in the Plate Bearing Test, which is commonly used in highway earthworks. Moreover, a soil classification diagram is given, in which the soils are classified by their shear strength parameters and their behavior, as totally elastic or elastoplastic, under specific loading applied by rigid circular plate. Finally, a method for the estimation of the soil parameters is proposed, using only the in-situ Plate Bearing Test. The study and the documentation were supported by a presentation of theoretical examples, based on the Finite Element Method.

1. INTRODUCTION
In highway earthworks the knowledge of the Modulus of Elasticity of the soils is very important, whether the projects are in the stage of design, construction or compaction check and this is required to be obtained by an easy manner. Due to the complexity and difficulty in determining the Modulus of Elasticity in the laboratory by the Triaxial Test, which is usually not available on the worksite, the common practice for the designer is to determine the Modulus of Deformation with the in situ and easier Plate Bearing Test. It must be mentioned that, though the soils under load