Technical note – Experimental Studies on the mechanical behaviour of two thermal cracked marbles

The speci®c aim of this paper is to ®nd an experimental methodology which could measure crack density in rock and its in¯uence on the behaviour of the rock material. The results of both experimental and numerical simulations showed that rock behaviour is mainly ruled by crack density within a speci®c rock volume. The behaviour of a rock with di¨erent crack densities has been studied by several authors, from the theoretical point of view and through experiments. Experimental works (Sage, 1988; Rotonda, 1991; Franzini, 1995; Homard- Etienne and Houpert, 1989) have con®rmed that a large, damaged area in a rock material induced by heating determines variations of rock properties that are closely connected to the degree of fracturing of the material. It has been shown that the overall moduli of elasticity and tensile strength are in¯uenced by the presence of cracks (Yin and Ehrlacher, 1996; Wong et al., 1996; Laws and Brockenbrough, 1982; Bertagnini at al., 1993).