Service performance prediction model of tunnel structure in alpine freezing-thawing environment

In order to analyze the influence of alpine freezing-thawing environment with large temperature difference on the long-term service performance of highway tunnel lining structure, the temperature variation law of Jiangluling Tunnel portal was obtained by field test method, the calculation formula for the mechanical property deterioration of lining concrete in freezingthawing environment was obtained based on indoor freezing-thawing cycle test, and the load structure method was used to establish the spatial and temporal prediction model of service performance for lining structure in alpine freezing-thawing environment. Research result shows that after the insulation layer with the thickness of 5cm and the thermal conductivity of 0. 03W·(m·℃)^-1 is laid, the number of equivalent indoor freezing-thawing cycles for Jiangluling Tunnel in one year decreases from 8to 0.32. When there is no insulation layer and concrete is saturated, 5, 10, 15, 20 years later, the safety coefficients of arch foot section respectively decrease by 0.6%, 23.7%, 41.1%, 69.8% compared to the original service time. After 20 years of service, the safety coefficient of second lining cannot meet structure load requirement. After the insulation layerwith the thickness of 5cm and the thermal conductivity of 0.03W·(m·℃)^-1is laid, the safety coefficient of second lining still meet the load requirement after 100 years of service. The severe degree of freezing-thawing cycles has significant influence on the long-term service performance of lining structure, and the insulation layer can effectively improve the freezing-thawing environment of concrete.