CRITICAL ISSUES TO ASSESS ROCK BLASTABILITY AS A FUNCTION OF GEOMECHANICAL PROPERTIES AND LOCAL CONDITIONS BASED ON TERRESTRIAL LASER SCANNER (LIDAR) SURVEYS AND NUMERICAL ANALYSES

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As our cities grow denser and larger, infrastructures are increasingly built underground in rocks. In conjunction, the increasing demand for mineral commodities requires a large number of mining operations, often with deeper excavations and a bigger footprint. Rock blasting represents the fastest and most cost-effective means of breaking rock for excavation purposes. Conventional blasting by means of drilled holes loaded with explosives is used extensively in civil and mining engineering for the construction of transportation tunnels, storage caverns, vertical shafts, and for surface and underground mines. Advanced tools and techniques for optimal rock blasting are needed to further improve operational standards for safety, reliability, efficiency, and environmental footprint related to civil and mining infrastructures. Well controlled blasting practices are essential for ensuring safe ground control and working conditions, long term stability of infrastructures, and reduce explosives consumption. Optimal blast design also significantly reduces energy consumption from comminution and materials handling downstream. Rock blasting is a complex process that combines thermodynamics, chemistry, seismicity, geological engineering and rock mechanics. This inherent complexity has led to the development of empirical guidelines often based on generic observations. Such guidelines, still applied, typically categorize geological media and geometrical settings in few simple groupings to assist in the determination of blast pattern configurations (spacing between holes; hole diameter; amount of explosives). In reality, the large number of influence factors raises many challenges to evaluate local blasting requirements, so the commonly used approaches often fail to provide optimal conditions for rock extraction. This research program proposes steps to improve our understanding of the blasting processes in various types of rock and to develop blastability indicators based on single hole blast (SHB) testing and LiDAR measurements. The results will be used to quantify blasting requirements considering geomechanical properties and operational conditions. The research program focuses on three primary orientations: remote sensing and point cloud processing, small and large scale experimental testing, and numerical analysis of dynamic and time-dependent geomechanical behavior. The research program relies on the original use of remote sensing technologies to provide rapid and efficient means of quantifying geomechanical and geometrical parameters, and evaluating blasting results to develop blastability indicators. A number of small and large scale field trials involving single hole and two-hole blast tests will be carried out to quantify the cratering behavior (with remote sensing tools) for different geological media and local geometry. Numerical modelling work will complement field experiments to evaluate the effect of geomechanical and geometrical conditions.