In recent years, with the acceleration of urbanization, building subways has become a ** solution for major cities to address traffic problems. As the most important part of the subway system, subway stations have complex construction procedures and often face multiple challenges and risks. The continuous upgrading and application of new construction methods, prefabricated construction, and smart site technologies have made subway station construction safer, greener, and more intelligent.

Safety: Innovative Construction Methods

Groundwater leakage, foundation pit deformation... The geological environment is the main source of hidden dangers in subway station construction. Its complexity and unpredictability increase construction difficulty and safety risks. How to ensure construction safety in complex geological environments requires great attention.

Liuzhoudong Road Station on the first phase of Nanjing Metro Line 11 in Jiangsu Province is an underground four-level island station. The deepest excavation of the station's main structure reaches about 32 meters underground, and the deepest diaphragm wall reaches 70 meters underground. The upper two levels of the station are constructed using the open-cut sequential method, while the lower two levels use the covered excavation reverse construction method.

"The combination of open-cut and covered excavation can keep the structure relatively stable during construction and reduce the risk of foundation pit deformation," said the project manager. In the open-cut sequential foundation pit, 277 orange steel supports are densely arranged to support the excavated space and prevent deformation.

In Shijiazhuang City, Hebei Province, Jiefang Dajie Station on Metro Line 5 is a special station. It is understood that based on geological and hydrological conditions, the base is located at the groundwater level. Considering the many impacts of groundwater level rise during construction and the special underground structure here, the main enclosure structure of Jiefang Dajie Station adopts a support system of "diaphragm wall + internal support" with a buried depth of 50 meters, providing sufficient support for subsequent excavation operations.

Compared with the bored pile enclosure structure of ordinary stations, the diaphragm wall enclosure structure used in this station is an "upgraded version," mainly serving for support, water cutoff, and seepage prevention. The construction process mainly consists of trenching, steel cage lifting, concrete pouring, and other steps. The noise generated during trenching construction is low, making it suitable for construction in dense urban areas.

This construction method is applicable to various geological conditions, from soft alluvial strata to dense gravel layers, and all foundations can use the diaphragm wall technique. At the same time, its high rigidity and integrity can effectively improve the stability and bearing capacity of the engineering structure, and it has good seepage prevention performance.

Green: Application of Prefabricated Technology

Under the guidance of the "dual carbon" goals, prefabricated buildings have become a new trend. In urban rail transit construction, many projects are exploring the application of prefabricated building technology, building stations like assembling cars, accelerating green and low-carbon transformation, and cultivating new quality productive forces.

In the West Coast New Area of Qingdao, Shandong Province, six stations on Metro Line 6 are all built with modules.

Prefabricated buildings are not new in the construction industry, but their use in subway stations is still rare. The station components are centrally produced in prefabrication plants, transported to the construction site, and assembled in sequence. The beams, slabs, columns, and walls of the subway station are 100% prefabricated and assembled.

"With this construction method, 30 people can complete the assembly of a station in 3 months," said the project manager. Compared with traditional cast-in-place structure stations, the number of construction personnel for each prefabricated station is reduced from 150 to about 30, and the construction period is shortened by 4 to 6 months.

When conventionally building concrete stations, components are basically mixed and poured on site, generating a lot of dust. Now with factory production, there is no noise, dust, or vibration from concrete pouring on site, which can reduce construction waste by 60% and greatly reduce the impact on the surrounding environment. It is understood that subway stations built using prefabrication can save about 800 tons of steel and 800 cubic meters of wood, reduce carbon emissions by about 20%, and also reduce or even eliminate decoration.

In addition to underground spaces, subway station entrances and exits can also be prefabricated. At Exit A of Lijiangdao Station on Tianjin Metro Line 10, a fresh and simple entrance is presented. This entrance is the ** prefabricated subway station entrance in the area.

In response to the national "dual carbon" strategic requirements, Tianjin has carried out research and application of integrated design and construction technology for prefabricated diaphragm walls with "permanent-temporary combination." The diaphragm wall construction of this entrance has achieved factory-based and standardized prefabrication, eliminating on-site operations such as rebar arrangement, binding, and formwork closing, which not only improves construction efficiency and quality but also has less impact on the surrounding environment and residents' lives.

Intelligence: Achieving Digital Construction

With technological progress, intelligent and information technologies are widely used in subway station construction, effectively ensuring construction safety and improving construction efficiency.

The eastern extension of Guangzhou Metro Line 3 in Guangdong Province involves many disciplines, complex geological conditions, high requirements for professional coordination, and relatively high construction risks. The construction unit has developed a smart construction management system that integrates BIM (Building Information Modeling) management, schedule management, quality management, safety management, resource management, data analysis, and other functions, providing a collaborative management platform for all participating parties.

With the help of BIM technology, construction simulations and secondary detailed designs are carried out for disciplines such as track, HVAC, water supply and drainage, power distribution and lighting, fire protection, and communication systems, effectively reducing rework and rectification during construction, lowering construction costs, and shortening the construction period.

During construction, builders use digital technology to simulate passenger flow and potential safety hazards during operation, and optimize the station's design and decoration by comprehensively considering factors such as passenger comfort, intelligence, and green energy saving.

During the construction of Qingdao Metro Line 5, facing the problems of a large and diverse workforce on site and scattered hot work locations, in order to ensure the safety of on-site hot work, the project department fully adopted a digital management online hot work system. The basic personal information and qualification certificates of welders were uploaded and entered into the smart site integrated platform in advance, real-time control of hot work locations was achieved, and "smart" construction and "intelligent" operations were applied to every management detail.

On-site team leaders initiate hot work applications by scanning codes. During the application process, they provide detailed descriptions of the hot work personnel, hot work location, fire watcher, on-site safety officer, supervision site safety engineer, and other relevant information. After submission, it is automatically sent to relevant approvers for approval, greatly saving approval time and improving efficiency.

Walking into the construction site of Xinyang Road Station on Wuxi Metro Line 5 in Jiangsu Province, a red "robot" is lifting the bottom slab beams and columns and precisely placing them into predetermined positions like an "automatic assembly machine" on a modern factory assembly line. It is understood that these operations can be seen as a scaled 3D model on the background computer screen, and the entire station's structure and construction process have been digitally simulated.

"Using robots to install a station on site can reduce labor costs and reduce environmental pollution caused by construction," said the station manager. Digital subway station construction is a powerful measure for Wuxi rail transit construction to leverage new quality productive forces. During the station construction process, new equipment such as "intelligent assembly trolleys for prefabricated building component installation," "multifunctional gantry cranes," and "360-degree rotating spreaders" were innovatively developed, achieving simulation of the entire construction process including production, lifting, and assembly of prefabricated components. In addition, the station will also use digital technology in later mechanical and electrical installation, decoration, and other stages to achieve precise processes and efficient construction.