The Lyon-Turin base tunnel, the world's longest railway tunnel at 57.5 kilometers, represents a major technical and organizational challenge at the heart of the European Mediterranean Corridor. With an investment of €11.1 billion and commissioning scheduled for 2033, this binational Franco-Italian project mobilizes the most advanced technologies in underground engineering while crossing Alpine geological formations of exceptional complexity. In this context, risk management constitutes a fundamental issue to ensure compliance with objectives in terms of costs, schedules, safety, and social acceptability. This thesis presents a comprehensive analysis of the risk management system developed by TELT (Tunnel Euralpin Lyon-Turin), the binational public promoter of the project.