大跨超厚回填土明洞衬砌结构选型及设计优化研究

Study on Lining Structure Selection and Design Optimization for Large-span Super High Fill Open Cut Tunnels

随着城市建设的发展,高速铁路等基础设施与市政规划结合建设越来越多,出现了超厚回填土明挖隧道的案例。文章探讨了大跨铁路明洞衬砌结构在超厚回填土荷载下结构选型及设计优化,对不同断面型式明洞结构受力特征、经济性、功能性、施工难易等开展研究,大跨超厚回填土明洞衬砌结构推荐采用高跨比较优的拱形仰拱结构型式,该型式明洞衬砌受力及空间利用合理、施工简便。同时为解决明洞衬砌大体积混凝土结构水化热和温度裂缝难题,通过不同层厚组合的双层衬砌浇筑温度场、温度应力场及超厚填土荷载下结构受力分析,推荐采用外衬厚度大于内衬的双层混凝土衬砌结构断面型式,以减少大体积混凝土水化热对衬砌结构的影响。

With the development of urban construction, more and more combination between infrastructures such as high-speed railway and municipal plannings results in super high backfill open cut tunnel. This paper discusses the structure selection and design optimization for large-span railway open cut tunnel lining structure under super high fill load. The research focuses on stress characteristic, economical efficiency, functionality and construction difficulties of open cut tunnels with different section forms. The inverted arch structure form is recommended to adopt for the large-span super high backfill open cut tunnel lining structure, its construction difficulty is relatively small, and load carrying capacity and space utilization are more reasonable. To solve the hydration heat and temperature cracking of mass concrete structure of open cut tunnel lining, by means of force analysis of structure of double-layer lining casting temperature field, temperature stress field with different layer thickness combination and under super high fill load, double-layer concrete lining structure section form with its outer lining thickness greater than that of the inside lining is recommended, to relieve the influence of the hydration heat of mass concrete to lining structure.