Por: Antonio Samaniego, PhD. en Mecánica de rocas, director de SRK Consulting (Perú) y Víctor Góngora Pérez, ingeniero de minas, consultor de proyectos geomecánicos, SRK Consulting (Perú).AbstractThe geomechanical evaluation of the San Rafael mine consisted on a site investigation of logging 25,000 meters of geotechnical drilling and 400 geomechanical stations and 140 rock laboratory tests, which were validated and consolidated on a data base that were used to determine the geomechanical characteristics of the rock mass. Likewise, a structural model of main faults was defined, allowing us to estimate the orientation of the maximum main stress as well as their extension, characteristics, and location. During field investigations, 4 in situ stress measurements were made at different depths of the San Rafael veins and a retro-analysis was performed to calibrate the stresses through in situ observations. Seismic monitoring information from 2010 to 2018 was reviewed in order to learn about the evolution of seismicity through the years and to evaluate the need for dynamic support for the different parts of the mine access, development and working stopes. The influence of blasting on seismic activity was also evaluated. With the geomechanical characteristics of the rock mass, an optimization of the dimensions was carried out by using the graphical method of stability, and validated using an elastic three-dimensional numerical model to evaluate the induced stresses in the stope walls and sill pillars. Finally, a mining sequencing was recommended in order to minimise risk of stope failures.