Shenzhen Metro's "two lines and three hubs" will be put into operation before the end of October 2022, marking a new step forward in Shenzhen's urban rail transit construction. Among them, the operation of the Gangxia North Hub, Huangmugang Hub, and Universiade Hub will effectively ease urban traffic pressure, meet the public's travel needs, and promote sustained and healthy regional economic development. Since April 2020, under the leadership of Academician Chen Xiangsheng, Dean of the College of Civil and Transportation Engineering and the Institute for Future Underground Urban Space at Shenzhen University, the research team has carried out technical research and overcome a series of bottleneck problems in the construction of super-large hubs under complex conditions in bustling urban areas, providing strong technical support and safety assurance for the smooth opening and operation of the three major hubs.

In April 2020, Academician Chen Xiangsheng led the institute team to the Universiade site for investigation and inspection

The Institute for Future Underground Urban Space team provides full-process technical support for hub construction

The Huangmugang Comprehensive Transportation Hub project is a three-line interchange hub for Shenzhen's existing Metro Line 7, Line 14, and Line 24, and an important node on the central development axis of Shenzhen's rail transit. In the core area of the Metro Line 24 hub, a fish-belly V-shaped column structural system was adopted in underground space for the first time. There are 25 groups of steel columns, totaling 50, with a maximum single length of about 38.5 m, a weight of about 87 t, and an inclination angle of 1.3°-13°.

Underground space fish-belly V-shaped column structural system

Part of the hub foundation pit adopts the cover-and-cut top-down construction method. Before the V-shaped columns form the load-bearing system, each floor slab relies on temporary steel pipe columns for vertical support. After the construction of the V-shaped columns is completed, the servo system at the top of the temporary columns is used to complete the load system conversion. The structural force system changes multiple times, posing relatively high safety risks. The team determined the jacking threshold of the temporary columns through three-dimensional refined finite element analysis, adopted multi-source sensing technology of "distributed optical fiber + MEMS sensing + machine vision + automated total station," and systematically established a "coarse-sparse-fine-dense" intelligent sensing system for underground space structures. Through algorithms, the system conducts real-time assessment of system conversion risks and, combined with a high-precision hydraulic servo system, achieves millimeter-level control of structural deformation during the system conversion process.

On-site monitoring and risk assessment of "permanent-temporary" structural system conversion

The Universiade Hub is the only large comprehensive transportation hub in eastern Shenzhen that integrates metro, intercity railway, and bus. In the future, it will realize four-line interchange among Lines 3, 14, and 16 and the Shenzhen-Daya Bay Intercity Railway. The Universiade Hub covers an area of about 60,000 m², with a planned construction area of about 173,200 m². The roof adopts the theme of "Dance of the Bay Area," and the overall form is elegant and dynamic, highly aesthetic.

"Dance of the Bay Area" steel structure roof

The hub roof adopts a spatial truss steel structure system. Its load-bearing behavior is complex, processing and installation accuracy requirements are high, and construction is highly challenging. Based on the design and construction plan of the long-span steel structure roof, the team optimized the structural system and other key parameters affecting structural performance, and analyzed the safety of protective equipment, lifting equipment, transport equipment, and their supporting structures during construction, improving the technical advancement, economy, and safety of the project throughout the entire process from design to construction.

Research on hoisting safety of spatial truss steel structure system

The Universiade Hub and Huangmugang Hub were respectively expanded from the Universiade Station of Shenzhen Metro Line 3 and the Huangmugang Station of Shenzhen Metro Line 7. The newly built foundation pits of the hubs are large in area and deep, and are close to existing operating stations, making deformation control extremely difficult. Based on the characteristics of the hub strata and surrounding structures, Academician Chen's team established a three-dimensional refined model, analyzed the stress and deformation characteristics of existing aboveground and underground station structures and pile foundations during construction of adjacent deep and large foundation pits, and proposed targeted deformation control measures. Using MEMS sensors, automated total stations, visual displacement and other technologies, the team carried out intelligent sensing of deformation of the foundation pits and existing stations; developed a deformation prediction and early warning platform, embedded five artificial intelligence algorithms into the platform to predict and warn of structural deformation, and ensured the safety of the foundation pits and existing station structures throughout the excavation process.

Refined simulation of construction of a super-large deep foundation pit adjacent to an existing station

Intelligent deformation sensing and deep learning prediction and early warning system for hubs