The sub-center station is located in the core area of Beijing's city sub-center.

More than 800 workers are pressing ahead with construction, with 4 large machines operating simultaneously and 3,000 cubic meters of concrete being poured... In the early hours of June 7, with the completion of the final concrete pour, the structure of the underground waiting hall level in the station building core area of Section 01 of the Beijing Municipal Administrative Center Station integrated transport hub was completed, officially transitioning to construction of the underground third-level platform structure.

The Beijing Municipal Administrative Center Station integrated transport hub project is located in the core area of Beijing's city sub-center, with an underground floor area of approximately 1.28 million square meters and a platform scale of 8 platforms and 14 tracks. It is a landmark project for advancing Beijing-Tianjin-Hebei coordinated development and plays an important role in three aspects: building a "Beijing-Tianjin-Hebei on rails," improving Beijing's passenger transport hub layout, and forming a "station-city integration" urban complex. Upon completion, it will become Asia's largest underground integrated transport hub, as well as the new gateway to the capital Beijing and the future transport center and vitality core of the city sub-center.

It is understood that the Beijing Municipal Administrative Center Station integrated transport hub project is a super-large, super-deep, and super-wide underground project, with an average foundation pit depth of 34 meters and a maximum depth of 43 meters. The station building adopts the top-down construction method, which is rare among similar station buildings: after pile foundation construction is completed, the roof slab is constructed first, and then excavation proceeds gradually downward. As the project continues deeper underground, there are multiple construction difficulties, including the difficulty of transporting large volumes of materials, the narrow on-site construction space, the large volume of rebar work, the large dimensions of components, the great difficulty of lifting and installation, and the high precision requirements for steel corbels and column joints.

To address these difficulties, the China Railway Construction Group project team for the Beijing Municipal Administrative Center, based on the spatial effects of the top-down construction of the underground structure and foundation pit excavation, adopted BIM technology and optimization algorithms to develop a new type of steel-soil ramp collaborative and intensive material transport system. According to reports, the main load-bearing structure of this transport system is designed with the concept of combining the project's permanent uplift pile foundations and the temporary steel pipe columns of the top-down construction as permanent-temporary works. It consists of steel structural beams, steel plate road surfaces, undisturbed soil layers, and concrete surface layers that together form the road pressure-bearing layer structure. It can meet construction traffic requirements while minimizing the amount of reserved earthwork in the ramp area, and through the design of embedded steel plates, it achieves effective connection between the steel structure and the main station building structure, further enhancing the overall stability of the transport system. This system is equivalent to the lifeline of project construction, controlling the project's construction schedule from four aspects: construction convenience, safety assurance, permanent-temporary integration, and economic rationality. Compared with traditional all-steel ramps, the steel-soil ramp collaborative and intensive material transport system can not only greatly improve transport capacity and safety, but also save 60% of costs, laying a solid foundation for the underground main structure construction of this "super project."

During the installation of the steel corbels in the waiting hall level, the precision requirements for the corbel-to-column joints are extremely high, with deviations needing to be controlled to within millimeters. To this end, the project team also independently developed 3D scanning technology to scan the beam-column joints. At the same time, by using professional algorithms to extract point cloud data, they modeled the steel structural corbels and, combined with preliminary installation error analysis, ultimately controlled the column top inclination to between 0.3 millimeters and 0.7 millimeters, meeting the verticality requirements.

It is understood that after Section 01 of the city sub-center station integrated transport hub enters construction of the underground third-level main structure platform level, the project will excavate toward the deepest target of 37 meters, and the main works portion undertaken by China Railway Construction Group is expected to be more than 85% complete this year. According to the plan, the project will be completed and opened to traffic by the end of 2024, at which time it will be possible to reach the Capital Airport directly in 15 minutes, Beijing Daxing International Airport directly in 35 minutes, and Xiong'an New Area directly in 1 hour.