Abstract: This study takes the Sichuan Yanjiang Expressway Tunnels as the research object and employs data analy? sis and typical case study methods to systematically analyze the complex geological conditions of the tunnels. The study identifies and classifies the disaster-causing structures of water and mud inrush disasters. Through the analysis of typical cases of water and mud inrush disasters in the Ningnan Tunnel and Ninghui Tunnel, the study investigates the stratigraphic characteristics, geological structures, and hydrogeological features of different types of disaster-causing structures and reveals the role of karst conduits, underground rivers, karst cavities, and fracture networks in triggering the disasters. The research results show that karst-related disaster-causing structures dominate the disasters in the Yanjiang Expressway tunnels. Special geological conditions at the interface between soluble and non-soluble rocks significantly increase the difficulty of disaster identification and prevention. Based on the research results, prevention measures for tunnel water and mud inrush disasters are proposed, focusing on advanced detection and pre-grouting reinforcement.