A whole-chain technical system for multi-factor coupling mechanism, risk grading and control of frost damage in cold-region tunnels

Amid the predicament of repeated frost damage in cold-region tunnels, the multi-factor coupling mechanism of such damage and precise evaluation based on segmentation and grading have received inadequate attention. Thus, a whole-chain technical system (investigation-diagnosis-prediction-assessment-treatment) is developed. By investigating frost damage types, characteristics and distributions from 2012 to 2024, the frost damage database and indicator database are established. Accordingly, comprehensive diagnosis of frost damage triggers is conducted by analyzing temperature, water, lining, surrounding rock, and their mutual coupling effects. Focusing on the frost-heaving mechanism, theoretical and numerical multi-factor coupled frost-heaving models are established and calculated frost-heaving force, while key influencing factors, evolutionary laws, and sensitivity were analyzed. Grading systems for frost-heaving, frost damage risk, and risk prevention and control are also proposed, realizing segmented and graded evaluation of frost damage risk and corresponding control measures. This technology is successfully applied in engineering practices, achieving favorable treatment effects. In conclusion, “database + grade evaluation system + intelligent platform” technical framework is formed. Approximately 13 kinds of frost damage are predominantly distributed in the portal and fault zone. The depth of local ice accumulation plays the most critical role for the 7 key parameters. Frost-heaving systems is classified into five grades: none, slight, weak, moderate, and strong; Frost damage risk and its corresponding prevention and control systems are categorized into six grades: very low, low, moderate, relatively high, high, and very high. This provides a systematic technical paradigm for frost damage and theoretical-practical foundations to enhance tunnel safety and operational efficiency in frigid environments.