Estimation of crack initiation and crack damage stress by means of mechanical, physical and dynamical properties in brecciated marbles

Abstract

The objective of this study is the determination of the various stages of deformation of brecciated marbles, under uniaxial compression, and the application of regression techniques, to investigate the relations of these stages, with physical, dynamical, and mechanical properties. Therefore, a total number of fifteen specimens, prepared from samples obtained from various locations from the southern part of the East Attica Prefecture, Greece. The laboratory program involved the determination of the uniaxial compressive strength (UCS), the crack initiation (Cci) and crack damage stress (Ccd) levels, the static elastic modulus (Es), as well as the basic physical and dynamical properties, such as the dry density (γd), the effective porosity (neff) and the ultrasonic velocities of both primary (VP) and secondary (VS) waves. Results obtained from the mechanical tests reveal that the onset of stable (Cci) and unstable (Ccd) crack growth varies between 0.19–0.38 and 0.66–0.92 of the UCS values, respectively. Applying simple nonlinear regression models, it was found that crack initiation and crack damage stresses, decrease exponentially with the increase of effective porosity, while increase exponentially with the increase of static elastic modulus, dynamic elastic modulus (Ed), and the primary wave velocity.