Effect of stress path on pre-peak damage in rock induced by macro-compressive and -tensile stress fields

The importance of the stress path on pre-peak (micro-) damage in rock material is addressed. Cracks, induced by macro-compressive stresses and macro-tensile stress fields are studied systematically on thin slices of crinoidal limestone samples. The effect of the sequence of macro-compressive and tensile stress fields, on the presence of the cracks is quantified. Firstly, samples damaged by compressive stresses only or tensile stresses only are studied. Hereafter, as a first case, a sample damaged firstly by compressive stresses and secondly by tensile stresses is studied. As a second case, samples damaged firstly by a tensile stress field, followed by compressive stresses are studied and compared to the first case. In the discussion, also the recorded cumulative acoustic emission energy and the clustering of acoustic emission events are used. The differences of both cases are highlighted: in the second case, more damage is observed than in the first case.