Novelties in the islands and tunnel project of the Hong Kong–Zhuhai–Macao Bridge

• Published in: Tunnelling and underground space technology Vol. 120; p. 104287
• Main Authors: Lin, Wei, Lin, Ming, Liu, Xiaodong, Yin, Haiqing, Gao, Jibing
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2022; Elsevier BV
• Subjects: Artificial island; Artificial islands; Civil engineering; Composite foundation layer; Environmental impact; Green buildings; Highway construction; Immersed tunnel; Memory bearing; Sediment; Semi-rigid; Soil layers; Tunnels; Underground construction; Underwater structures; Hong Kong; Macao; Memory bearing; Semi-rigid; Sediment; Immersed tunnel; Composite foundation layer; Artificial island
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2021.104287

•This paper presents novel techniques in Hong Kong-Zhuhai-Macao Bridge project.•Method of deep piling cylinders and cells helps form artificial islands rapidly.•Semi-rigid system developed from segmented element and increases tunnel performance.•Composite foundation layer eliminates uncertainty making settlement pattern instant.•Element built with negative buoyancy is of great interests for long immersed tunnels. The Islands and Tunnel Project of the Hong Kong–Zhuhai–Macao Bridge is a design–build contract involving the construction of two artificial islands, each with an area of 100000 m2, that are connected by a 6.7-km-long underwater tunnel. The immersed section of the tunnel consists of 33 elements. This paper examines the novel techniques used during the design and construction of this project. To eliminate its environmental impact, deep piles consisting of steel cylinders and auxiliary cells were developed to build the artificial islands. Novel structural solutions the semi-rigid system were also developed to address the challenges of a high surcharge load and unfavorable layers of soft soil. Moreover, a foundation scheme consisting of a composite foundation layer and a combined foundation was developed to control settlement and prevent leakage. The factory method was implemented to prefabricate the 33 tunnel elements, including five plane-curved elements, where the mass of a typical element was 78000 t. Severe sediment-related problems were encountered during the immersion of elements of the tunnel that necessitated special measures as well as the development of a sediment warning and forecasting system. The closure joints were constructed by using a novel method involving deployable elements. The novelties introduced during the construction of this project are geared toward simplicity, which is conducive to green construction and sustainable solutions. The authors also provide suggestions for improvements if this kind of project were to be undertaken again.