Long-Term Safety Analysis of Tunnel Structure Based on the Performing Degree of Support Strength

At present, the new Austrian tunneling method is basically used as the theoretical guidance for domestic tunnel design, which shows that the primary support is not progressed by durability design in the light of service life in the practical work generally acting as the temporary support structure during the period of construction. After the long-term tunnel operation, owing to the erosion of groundwater and the changes of internal stress and external load of surrounding rock, the reinforced of primary support system will be rusted; the bolt, grille arch frame and I-beam will be partially invalidated; the stress of tunnel structure system will be readjusted gradually from the original load-bearing state with dominant position of primary support into the load-bearing state by secondary lining. The Long-term safety analysis refers to the analysis of secondary lining internal force and safety coefficient by load structure model, and the long-term safety analysis of Qingshashan tunnel which is in season frozen zone with complex geological conditions is very necessary.