Abstract: Frequent water inrush disasters in mountainous highway tunnels pose a serious threat to construction safety. To establish a quantitative and precise prevention and control method for water inrush disasters in mountainous highway tunnels by determining the minimum safe detection distance, thereby enhancing the safety and reliability of advanced geological predictions. A multifactor coupling analysis framework was developed by comprehensively considering three core disaster-inducing factors: construction disturbances (influenced by rock hardness), surrounding rock load (arching effect), and water-bearing structures (risk of extrusion breakthrough). Four calculation formulas (disturbance thickness, load height, protective thickness, and comprehensive detection distance) and 13 evaluation indicators were established to construct a quantitative model and complete indicator system. Safety thresholds based on minimum protective thickness were determined through a mechanical mechanism analysis and engineering parameter calibration. The reliability and advancement of the model were verified by comparison with traditional empirical methods using typical tunnel inrush cases. Engineering validation demonstrated that this method offers advantages such as multi-factor quantification, clear mechanisms, and high safety compared with traditional empirical approaches. It achieves a shift from passive reliance on experience to active quantitative control, significantly improving detection efficiency and providing a technically standardized solution for advanced geological prediction. Conclusion This study provides a standardized quantitative tool for the early warning of tunnel construction disasters, significantly enhancing the initiative and reliability of prevention and control measures.