Geological application of uav photogrammetry and terrestrial laser scanning in marble quarrying (Apuan alps, italy)

Workplace safety in quarries can be evaluated and improved through an accurate risk assessment of mining activities. Rock slopes stability is dominantly influ-enced by the structural setting which, in combination with exploitation methods, affects the risk. This paper describes studies carried out in the Apuan Alps, where several quarry walls reach hundreds of meters in height and are dominated by natural slopes with complex morphology. Aim of the present paper is to determine the detailed structural-geological setting of a quarry wall and to identify potentially unstable zones. In such an environ-mental context, data obtained from engineering-geological surveys, collected at the foot of the slope and along the wall by climbing technicians, may be used for rock mass characterization. This data, which holds important statistical value, has been integrated with other info coming from a terrestrial photogrammetric survey, that was realized using an unmanned aerial vehicle, and from terrestrial laser scanning. The stereoscopic and high resolution images and the 3D model from point clouds have been processed and interpreted in order to provide a deterministic information of the complete slope setting. The geometrical and geo-engineering data was utilized for a stability analysis carried out through a 2D nu-merical modelling based on the distinct element method. Results of this study have been used to assess the safety conditions necessary to continue the exploita-tion activities and, eventually, to plan for proper remediation.