Abstract: Aiming at the problems that the traditional gravity drainage system is prone to clogging due to freezing and failure caused by low air pressure in high-altitude and cold tunnels, the adaptive design and vacuum stability research of the vacuum drainage system in extreme environments were carried out. The system design method introducing air pressure, temperature and seepage correction factors was constructed. The pump efficiency environmental correction model and the zonal redundancy layout strategy were proposed, and the field deployment and operation monitoring were completed in the plateau tunnel. Based on the SCADA platform, a coupled response model of vacuum degree and environmental parameters was established, including seal degradation, increased flow resistance and pump efficiency fluctuations as the dominant disturbance mechanisms. The results show that the gauge pressure inside the pipeline can be stably maintained within -75 to -60 kPa, with a fluctuation of less than 3.5 kPa, and the maintenance rate is over 98% under extremely cold conditions. The control test verified the significant improvement effect of the sealing structure and thermal control measures on the steady-state operation of the system. The research systematically established the design theory and operation control method of vacuum drainage suitable for high-altitude and cold environments, providing theoretical references for tunnel drainage projects in cold regions.

Key words: cold and high-altitude tunnel, vacuum drainage system, vacuum stability, pump efficiency correction, low-temperature seal degradation