公路工程

为了解决既有支护段落洞内局部塌方段设计施工问题，以平伍高速公路古家洞隧道为工程实例，分析了目前隧道局部塌方处治存在的问题，采用工程类比及数值模拟方法，基于不拆除未损坏的格栅拱架、仅对已损坏的格栅拱架进行拆除并重新施作的微创修复理念，对既有支护段落洞内局部塌方处治进行了研究，结果表明：(1)采用对塌方体进行局部注浆、设置临时钢支撑形成护拱、拆除损坏拱架并重新施作、设置加密钢筋网形成模板效果、轻质泡沫混凝土填充塌腔、设置二衬仰拱并配筋等关键技术通过塌方段，可以保证隧道施工安全并兼顾施工便捷性和经济性；(2)建立了有限元数值模型，仿真分析了设计方案可行性，在施工过程中现场监测数据验证了方案合理可行。该设计施工案例，可供同类隧道参考。

To solve the design and construction problems of local collapse section within existing tunnel support sections, taking the Gujiadong Tunnel of Pingwu Expressway as an engineering example, the existing problems in local collapse treatment of tunnels were analyzed, using engineering analogy and numerical simulation method, and based on the minimally invasive repair concept of not removing the undamaged grid archesbut only removing and re-applying the damaged ones, the treatment of local collapse within the existing support sections was studied.The results show that:(1)Using key technologies such as partial grouting of the collapse body, setting up temporary steel supports to form a protective arch, removing and re-constructing the damaged arch, setting up a closely spaced reinforcement mesh to fachieve a formwork effect, filling the cavity with lightweight foam concrete, and installing a reinforced secondary lining invert to pass through the collapse section, can ensure tunnel construction safety while considering construction convenience and economy;(2)A finite element numerical model was established to simulate and analyze the feasibility of the design scheme; the field monitoring data during the construction process verified the reasonableness and feasibility of the scheme.This design and construction case can serve as a reference for similar tunnels.