Geotechnical and geophysical investigation of a rock mass for the design check of an ornamental stone quarry

The design of an open-pit quarry must continuously adapt to the real conditions of the excavation faces, to meet safety requirements and maximize the effectiveness of the operational process. The case study of an ornamental stone quarry characterized by great value and challenging excavation geometry is analyzed in this study. The exploited rock mass is characterized by a nonubiquitous discontinuity distribution due to the presence of highly fractured bands, mainly parallel to the excavation faces. The discontinuity network needs to be analyzed to forecast the rock mass mechanical behavior during excavation. In this regard, the integration of geotechnical and geophysical surveys allows the rock mass to be studied from the surface to a considerable depth. Trace mapping on scaled digital images was combined with traditional geomechanical methods and GPR surveys, executed on the excavation faces, to assess the variability of discontinuity spacing and to characterize the fractured bands.