Las Leñas International Tunnel – Geomechanical challenges in large‐scale tunneling projects across The Andes.

Developing large‐scale tunnelling projects in orogenic regions implies enormous technical challenges. Las Leñas International Tunnel Project through the Andes Main Cordillera of Chile and Argentina has been a long‐awaited infrastructure project, whose geological and topographic settings suggest several complex singularities to be considered, analyzed, and assessed during its development. Throughout the course of this feasibility study, the complex geological subsurface interpretation offers a broad spectrum of technical demands to be fulfilled. The overburden conditions, the presence of certain lithologies such as expansive clays or soluble evaporitic sequences, along with regional stress assessment, are major technical challenges. Through extensive geological, geotechnical, and hydrogeological mapping, subsurface 3D modelling interpretation, along with numerical analysis and its relationship with similar projects in the region, brittle, and plastic behaviour are analyzed. A wide range of modern techniques are used to assess those mentioned tasks, which enable an extensive comprehension of the geological and geotechnical conditions of the area. The purpose of this contribution is to enrich the knowledge on geological and geomechanical challenges faced in large tunnelling infrastructure projects in high‐mountain environments and what specific lessons may arise from them for similar future projects. [ABSTRACT FROM AUTHOR]