Determination of Rock Strength and Deformability of Intact Rocks   G. P. Tziallas Postgraduate Student, Department of Geotechnical Engineering, School of Civil Engineering, National Technical University of Athens e-mail: gtgtziall@hotmail.com G. Tsiambaos Associate Professor, Department of Geotechnical Engineering, School of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechniou, 15780, Zografou, Athens, Greece e-mail: gktsiamb@central.ntua.gr H. Saroglou Postdoctoral Researcher, Department of Geotechnical Engineering, School of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechniou, 15780, Zografou, Athens, Greece e-mail: saroglou@central.ntua.gr
			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), Young’s 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 (sc-SHV-?d). This comparison proved that Deere - Miller’s (1966) chart yields the better prediction of the uniaxial compressive strength. Additionally, the correlation between uniaxial compressive strength, sc, 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 Young’s modulus, uniaxial compressive strength and wave velocity (Et-sc-Vp) and an empirical correlation is proposed.

Keywords: Intact rock, Index properties, Point load strength, Uniaxial compressive strength, Modulus of elasticity, Statistical relationships

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