Caracterización geomecánica de los materiales graníticos y metamórficos de Morona Santiago, Ecuador

Abstract

CONDITION FOR PUBLICATION OF PROJECT. Subsoil characterization is a fundamental aspect in the planning and design of hydroelectric projects, as it allows for the evaluation of the technical and geotechnical viability of the proposed infrastructures, ensuring their stability and functionality. According to Hoek and Brown (1997), understanding the geomechanical properties of the rock mass is essential to anticipate its behavior under static and dynamic loads, minimizing risks during construction and operation. This study focuses on the geomechanical characterization of rock masses in the areas of "Santa Rosa" and "El Rosario," located in Morona Santiago, Ecuador, with the aim of determining key parameters for the design of hydroelectric projects. Field and laboratory tests were conducted, including uniaxial compression tests, Brazilian tensile tests, point load tests, tilt tests, and geomechanical classifications using the RMR and Q indices. The results show that igneous rocks, such as basalt and andesite, exhibit mechanical properties ranging from moderate to high, with unconfined compressive strengths exceeding 120 MPa in the case of basalt, classifying them as strong rocks. In contrast, metamorphic rocks, such as chert, show lower strength, with values between 69.69 MPa and 90.63 MPa, classifying them as moderately resistant. The values of the RMR and Q indices reflect a variable quality of the rock mass, from excellent in areas of diorites and granites to low in zones with significant discontinuities and alterations. Additionally, variations in basic friction angles were identified, with values ranging from 18.58° to 38.35°, which directly influence the stability of the projected structures. These data, integrated with numerical models and empirical analyses, provide a solid foundation for the design of tunnels minimizing geotechnical risks. In conclusion, this study highlights the importance of geomechanical characterization to ensure the technical viability of hydroelectric projects, providing key information for the design and development of safe and sustainable infrastructures in the region. Keywords: geomechanical characterization; rock strength; hydroelectric projects