<p>Karst tunnel construction is frequently accompanied by severe geological hazards due to the concealed distribution of cavities, heterogeneous fillings, and complex groundwater systems. Excavation-induced disturbance can rapidly activate coupled mechanical and hydraulic processes, leading to face instability, collapse, and water or water-mud inrush events with limited warning time. Although numerous forecasting, monitoring, and emergency control techniques have been developed, current practice often treats these measures as isolated tools, resulting in delayed decision-making and ineffective risk mitigation. This review systematically examines the mechanisms, precursor characteristics, and management challenges of karst tunnel hazards, with particular emphasis on the dynamic evolution of CD, ID, and MM scenarios. Advances in ahead-of-face geological forecasting, multi-parameter monitoring technologies, and emergency response measures are synthesized and critically evaluated. On this basis, an integrated Forecast Monitor Response (FMR) framework is proposed, in which hazard scenarios are continuously updated through evidence fusion, and trigger based graded interventions are implemented in a closed loop manner. A quantitative composite risk index based on multi-parameter normalization, weighted evidence fusion, and dynamic updating is further introduced to improve engineering applicability of the proposed framework. The proposed framework highlights the importance of scenario awareness, uncertainty management, and feedback control in karst tunnel safety governance. By linking prediction, observation, and intervention within a unified decision logic, this review provides both a conceptual foundation and an engineering-oriented workflow for improving early-warning reliability and reducing accident risk in karst tunnel construction.</p>