3D MODELING-BASED GEOMECHANICAL ANALYSIS OF A TUNNEL IN DEFORMED GRANITOIDS OF THE ÁGUAS MORNAS COMPLEX

Análise geomecânica baseada em modelagem 3D de um túnel em granitoides deformados do Complexo Águas Mornas, Santa Catarina, Brasil

Resumen

Geomechanical classification plays a critical role in tunnel construction, enabling preliminary assessment of rock mass conditions, identification of potential geological hazards, and optimization of excavation methods. Given the inherent uncertainties in the geotechnical characterization of subsurface rock masses, the use of three-dimensional geomechanical models has proven to be an effective tool for achieving more detailed and accurate analyses. In this context, the present study proposes the development of a 3D model for the integrated analysis of the geomechanical characteristics of a tunnel excavated in deformed granitoids of the Águas Mornas Complex. The model is based on a geomechanical mapping database collected from tunnel excavation faces and design documents. The design-stage zoning employed the Q-system and RMR classification methods to evaluate rock mass quality and subdivide it into four geomechanical classes (V, IV, III, and II). During construction, the excavation fronts were mapped by the technical oversight team (ATO) using the same classification criteria established in the design phase. The three-dimensional representation of the excavation data enabled accurate visualization of the spatial distribution of geomechanical classes and associated parameters, allowing the identification of zones of higher and lower rock mass quality and their correlation with local geomorphological and geological features. The results provide insights into the geomechanical behavior during tunnel excavation in gneissic to migmatitic rock masses, characterized by low rock quality at portal zones and the occurrence of shear zones along the tunnel alignment.