Abstract
Abstract To tackle the critical engineering problems of airport runways in permafrost regions—ultra-wide pavement without side slopes, large hardened heat-absorbing areas, and severe thermal instability leading to permafrost degradation and freeze–thaw diseases—a novel parallel ventilation subgrade is proposed as an active cooling solution for temperature stability control. Based on the pure heat transfer numerical simulations, this study systematically reveals the evolution laws of the runway temperature field under different ventilation conditions, perforated vent spacings, and parallel ventilation burial depths, and optimizes the key design parameters of the parallel ventilation system. Supplementary hydro-thermal coupling simulations are further conducted to verify the coupling relationship between the temperature field evolution and moisture migration/ice phase change, confirming the scientific rationality of the optimized parameters. The research finds that runway temperature conduction has an obvious time lag. Shallow structural layers are notably affected by seasonal thermal disturbances, while deep layers maintain thermal stability relying on the natural thermal inertia of permafrost. A dynamic balance is formed between the active temperature regulation of ventilation conditions and environmental heat intrusion, where low-velocity and short-term mechanical ventilation can effectively balance the cooling effect and frost heave risk by regulating the temperature field to control the intensity of moisture migration and ice segregation. A 3 m perforated vent spacing realizes the optimal synergy of cold energy among adjacent vents, forming a continuous low-temperature barrier in the subgrade. When the parallel ventilation is buried in the middle of the crushed rock layer (a functional layer for heat exchange and cold storage in permafrost subgrade design), a uniform cold storage field is formed, which can effectively maintain the long-term negative temperature of the subgrade and achieve the best temperature stability control effect. The results provide the optimal key parameters and theoretical support for the collaborative temperature control of active ventilation and passive thermal insulation for airport runways in permafrost regions.