港珠澳大桥深水地基载荷试验技术

Loading test technology in deep water for Hong Kong-Zhuhai-Macao Bridge

港珠澳大桥沉管隧道长约6.7km,最大埋深为44m,管节分别埋置在不同深度、不同类型的土层上。为避免隧道在不同类型地基上产生较大的差异沉降,分别采用挤密砂桩、块石夯平等地基处理技术,并在处理后的地基上铺设1.3 m厚的碎石垫层。为获得处理后地基及地基上铺设的碎石垫层在荷载作用下的沉降,设计了水下载荷试验系统,成功获得了不同水深处的地基沉降,验证了不同类型地基的变形协调性,同时为碎石垫层预抬量设计提供了实测数据。试验揭示了不同方法处理后的地基沉降特性,经过与隧道沉降数据对比,试验揭示的地基沉降特性与沉管沉降特性相符,验证了该试验系统的可靠性。

The immersed tube tunnel of Hong Kong-Zhuhai-Macao Bridge is about 6.7 km long and 44 m deep under water. Because of the complexity of the geologic conditions, different ground treatment measures are used in this project, such as SCP and heavy-tamping broken stone piers. The deformation compatibility of ground treated by different methods should be verified before the immersed tube installation. In this paper, a loading test system designed for deep water is recommended. This system was used during the construction of Hong Kong-Macao-Zhuhai Bridge. The settlement of macadam bed in deep water is obtained and the deformation compatibility is verified by this system. Instant settlement is also obtained, which provides the basis for the elevation design of macadam bed. Settlement characters of the load test are the same as the settlement characters of immersed tube tunnel. So the reliability of the test system is verified.