Performance Evolution and Prediction Model of Dam Polyurethane Insulation Materials Under Multi-Field Coupling Conditions in Hot Summer and Cold Winter Climate Zones.

This study evaluates the performance degradation of spray rigid polyurethane foam (RPUF) insulation on reservoir dam structures under multi-physics coupling conditions. Focusing on characteristic environmental exposures in Hot Summer and Cold Winter (HSCW) climate zones, accelerated aging tests simulating coupled temperature-humidity effects were conducted to comparatively analyze the thermal resistance and durability evolution between unprotected and encapsulated RPUF configurations. Scanning electron microscopy (SEM), infrared spectroscopy (IR), and other methods were used to characterize and analyze the structure of RPUF. Research has shown that in HSCW climate zones, the thermal conductivity of RPUF gradually increases with the number of degradation cycles, and the insulation performance decreases, mainly due to the damage of the pore structure caused by temperature aging and the combined effect of moisture absorption aging. In comparison, the RPUF after protection can effectively slow down the rate and degree of decline of its insulation performance. On this basis, a time-varying prediction model for the thermal conductivity of RPUF under long-term service in HSCW climate environments was fitted, providing a scientific basis for the durability evaluation of reservoir dam insulation.