Geotechnical classification systems are commonly used in the mining industry to estimate the geotechnical quality of rock masses and have several applications in the geotechnical and mining design.
All systems have been conceived for weathered rock masses characterized by open and weathered joints, except for the IRMR system (Laubscher & Jakubec, 2001) that evaluate the geotechnical quality considering the effect of both open joint and cemented microdefects and veins.
This first attempt was not followed by others in order to improve the classification systems for hypogene environments. Since last decades, block caving operations are facing the challenge to mine ore deposits at deeper conditions, with higher stress and to characterize, with the traditional systems, a rock mass with cemented veins and microdefects.
Recently, the IGSI has been proposed (Russo et al., 2020) as a method to quantify the GSI in hypogene environments, and now, as a second step, the authors propose a classification system to characterise rock masses in these environments.
The proposed system assigns a rating for the rock block strength and, as for IGSI, assigns ratings for the spacing of weaker cemented veins that are able to open during the mining activity and the hardness of veins mineral infill, including strong veins, as quartz veins, that contribute to the strengthening of the rock mass. The system has been applied to three cases study showing a good difference between the geotechnical units according to the mineral infill strength and their frequency.
The implementation of the hypogene system demonstrates that this method is able to show more differences than the traditional systems between the same lithology but with different types of alterations.
