公路隧道装配式仰拱结构形式优化设计

Optimal design of prefabricated inverted arch structure for highway tunnels

为研究公路隧道装配式仰拱结构形式及其受力变形特征,基于收集的国内外不同装配式隧道结构应用案例,对钻爆法公路隧道预制仰拱结构形式进行优化设计,并分析了其受力特征;针对钻爆法公路隧道断面特点,以甘肃省某高速公路隧道工程为例,从施工难度、施工速度、防排水能力、造价成本等方面对弧形、箱型预制仰拱结构形式进行综合比选,并分析了仰拱分块数量、仰拱厚度以及幅宽对箱型预制仰拱结构的最大位移、混凝土损伤破坏、钢筋应力的影响。结果表明:箱型预制仰拱为较为合适的仰拱形式,7分块、上部厚度20 cm、下部厚度40 cm、幅宽1.2 m的箱型预制仰拱结构形式最为合适;装配式仰拱和二衬结构调整,改善了隧道受力,对保证整体支护结构稳定作用明显。

In order to study the structure types and deformation characteristics of prefabricated invert arch structure in highway tunnels,firstly,by collecting application cases of different prefabricated tunnel structures at home and abroad.Then,the precast inverted arch structure of the drilling-blasting highway tunnel is optimized and its stress characteristics are studied.According to the section characteristics of the drilling-blasting highway tunnel,taking a highway tunnel project in Gansu Province as an example,the prefabricated invert type of arc-shape and box-shape was designed from the aspects of construction difficulty,construction speed,anti-drainage ability and cost.The influence of the number of invert arch blocks,invert arch thickness and width on the maximum displacement,concrete damage and reinforcement stress of prefabricated box invert structures are analyzed.The results show that the box-type precast invert is a more suitable structure.The box prefabricated invert structure with 7 blocks,upper thickness of 20 cm,lower thickness of 40 cm and width of 1.2 m is the most suitable.The assembled invert structure and the secondary lining structure adjust and improve the tunnel load,and play a significant role in ensuring the stability of the overall supporting structure.