A comprehensive study on natural and induced stress state in large underground marble quarry

The design of large underground caverns is usually made combining data coming from onsite geological surveys, test measurements and numerical models. Numerical models are used for estimating the stress and strain induced by excavations, becoming fundamental tools for the evaluation of the overall stability of all the elements of caverns (e.g. pillars, diaphragms, roof, etc.). Moreover, designing these caverns requires a detailed rock mass characterization in order to obtain geometrical and mechanical features of both rock matrix and discontinuities. The identification of the natural stress and its orientation is also an important aspect to consider since it allows a correct and realistic calibration of the numerical model. In the Carrara basin, located in the Apuan Alps (Central Italy), there are many large underground marble quarries that have been monitored in the last years. This study presents a comprehensive analysis on the evaluation of natural an induced stress in some monitored quarries in the Apuan Alps. Several onsite measurements, together with observed geological evidences, were analyzed and combined, allowing the authors to put forward some hypotheses and interpretations of tectonic effects on the induced stress state after cavern excavation.