中央大道海河沉管隧道基础注浆施工技术

Grouting Construction Techniques for Large Immersed-Tube Tunnel Foundation

基于天津市滨海新区中央大道海河隧道工程处于滨海相软土地质、高地震区进行设计与施工,为满足管段基础承载力与抗震性能要求,基础采用60cm厚碎石与40cm厚膨润土砂浆相结合。碎石基础在管段沉放前完成,浆液基础在管段沉放对接完毕后进行,基础施工分为三阶段,即管段预制、管段浮运沉放、基础注浆阶段,经历了管道预埋、水囊袋安装、管段碎石初步锁定、排气通道设置、管内注浆等工序环节,施工工艺复杂,水下施工安全影响因素多,质量控制难度大。在注浆过程中应用较为先进的冲击映像法监控技术进行综合评价,保证了施工质量安全,经后续施工部位验证以及监控测量,密实度达96%以上,满足了设计沉降量、密实度、强度等相关性能要求。

Considering the fact that the Haihe River Tunnel project of the Central Avenue of the New Binhai District of Tianjin is located and built in the soft coastal stratum and high seismic area,its foundation is to be made up of a 60cm-deep crushed stone combined with a 40cm-deep bentonite mortar to meet the requirements in bearing performance and anti-seismic performance.The crushed-stone foundation has to be completed before the pipes are lowered,while the mortar foundation has to be built after the pipes are lowered and are made to meet each other.The construction of the foundation may be divided into three stages,namely,the pre-casting of pipes,the floating-transporting and lowering of pipes,and the grouting of the foundation,with the pre-burying of pipes,the provision of water bags,the preliminary locking of the crushed stone for the pipe,the provision of the exhaust shroud,the slip-casting inside the pipe,etc.involved.As the construction processes are complex and there are many safety-affecting factors existing in the under-water construction,the quality control is very difficult.In the course of the grouting construction,the relatively advanced monitoring technique of the shock image method is applied to the comprehensive evaluation,with the safety of the construction quality ensured.Through the subsequent construction section tests and supervision survey,it is found that the density is up to more than 96%,and the project meets all the performance requirements such as the designed settlement,density,strength,etc.