氯盐和冻融循环复合作用对浅埋公路隧道安全性能的影响

Safety influenced by combined action of chloride and cycles of freezing and thawing to shallow highway tunnel

对氯盐和冻融循环复合作用后Ⅴ级围岩中埋深为10 m的隧道,运用同济曙光软件建立荷载—结构法拉压弹簧模型进行分析计算。计算表明:1)随着环向裂缝宽度(钢筋锈蚀程度的增加)以及纵向裂缝深度的增加,隧道安全性能逐渐降低;2)衬砌具有相同钢筋锈蚀程度和纵向裂缝深度时,拱顶处病害比拱腰处病害对隧道安全性能的影响大;3)当环向裂缝宽度小于0.2 mm时,环向裂缝宽度的变化对隧道衬砌安全性能影响不大。

This study, using GeoFBA, generates a load-structure method tensile-compressional model for analyzing and calculating the tunnel that is 10m-depth-embedment surrounding rock V and is eroded by combined action of chloride and cycles of freezing and thawing. The calculation indicates that first of all, the tunnel safety falls down gradually with the increase of circumferential crack width （the degree of corrosion of reinforcement） as well as longitudinal crack depth; furthermore, when lining suffers the same corrosion degree of reinforcement and the same depth of longitudinal crack, the problem occurs on the arch crown which would bring up bigger effect to the tunnel safety than that occurs in the haunch;In addition, the change of circumferential crack width, which is smaller than 0. 2 mm, would make less influence to the tunnel lining safety.