Rock Stress Measurements in Alpi Apuane quarry sites by means of hydraulic fracturing (HF).

The paper summarizes part of the experience gained by the authors in Apuane Alps marble basins with reference to different quarry sites. Stress measurements were performed using the Hydraulic Fracture (HF) technique in two quarries subjected to quite different geo-morphological and geo-structural conditions. One of the sites is located at the bottom of a valley: HF measurements were carried out in horizontal and vertical holes located in the lower part of the natural impluvium, below a high rock wall, residual of past exploitation. The other site is located in a quarry basin which has a regional fault that crosses the exploitation yards and it is developed both as open pit and underground excavations. In this case, the stress measurements were performed in vertical holes on the two side of the fault. A general evaluation of the results and a brief description of the measurement device are reported.