On January 19, 2024, Shasan Station of the Phase II Project of Shenzhen Metro Line 12 achieved full breakthrough as a large-cross-section rectangular pipe-jacking mined station, a milestone event marking a historic breakthrough in the field of urban rail transit construction for the Guangdong Provincial Key Special Project "Key Technologies for Mined Metro Stations in Bustling Urban Areas," led by Academician Chen Xiangsheng of the College of Civil and Transportation Engineering and the Future Underground City Research Institute of Shenzhen University. This also represents the world's first successful practice of the close-fitting construction technology of combined large-cross-section rectangular pipe jacking, filling an important gap in China's mechanized construction of mined metro stations and holding milestone significance for the development history of metro station construction.

(Figure 1 Receiving Ceremony for the World's Largest Cross-Section Rectangular Pipe Jacking)

The Guangdong Provincial Key R&D Program "Modern Engineering Technology" Key Special Project "Key Technologies for Mined Metro Stations in Bustling Urban Areas" is headed by Chen Xiangsheng, Academician of the Chinese Academy of Engineering and Dean of the College of Civil and Transportation Engineering of Shenzhen University, with Shenzhen Metro Group Co., Ltd. as the lead unit, jointly with Shenzhen University, Shenzhen Municipal Design & Research Institute Co., Ltd., PowerChina Southern Construction Investment Co., Ltd., Sinohydro Bureau 11 Co., Ltd., China Railway Engineering Equipment Group Co., Ltd., China Academy of Railway Sciences (Shenzhen) Research and Design Institute Co., Ltd., Guangzhou Jintu Geotechnical Engineering Technology Co., Ltd., China Railway Construction Heavy Industry Corporation Limited, and Nanjing Paiguang Smart Sensing Information Technology Co., Ltd., to systematically explore green, efficient and intelligent mechanized mined construction technology for metro stations.

(Figure 2 Successful Breakthrough of Both Tunnels at Shasan Station)

Background and Challenges

Shasan Station is located at the intersection of Ditang Road and Shajing Road and is an underground two-level island-platform station. The station lies in a bustling urban area surrounded by numerous buildings; the soil in the station area is relatively loose with abundant groundwater, and a newly built concealed culvert with a buried depth of 4.2 meters exists beneath the station site. The station adopts a single-column double-span frame structure with a total length of 208 meters and a standard section width of 23 meters. If traditional open-cut construction technology were adopted, it would face the enormous challenge of traffic diversion, require extensive relocation of buildings, involve a large labor input, and simultaneously face a series of major difficulties such as high engineering risks, long construction periods and complex construction conditions.

(Figure 3 Academician Chen Xiangsheng Being Interviewed by News Reporters)

Innovation Highlights

To address the above challenges, Academician Chen Xiangsheng led the research team in collaborative efforts. In terms of theory, a complete set of design theories and methods for mechanized mined metro stations was proposed, the mechanical characteristics of the structural system transformation of multi-tunnel combined pipe-jacking segments and stations were revealed, and a comprehensive risk assessment system for mined metro station construction was established. In terms of technology, key technologies such as new mined construction equipment and supporting construction were focused on and breakthroughs were made, and the world's largest cross-section (11.29 meters wide and 13.55 meters high) rectangular pipe-jacking machine, "Dayu Tunneling No. 1," was developed. The machine adopts a combined arrangement of multiple cutterheads and multiple screw conveyors; through the coordinated operation of multiple cutterheads and screw conveyors, it pioneered major breakthroughs in water-soil pressure balance on ultra-high excavation faces and zero-clearance construction equipment technology for both left and right passes. At the same time, a complete set of excavation construction technologies featuring micro-bench, shallow cover, large cross-section and zero clearance was established, overcoming a series of major technical difficulties such as assembly of ultra-large cross-section pipe segments, deformation control during underpassing of underground box culverts, alignment control of closely spaced left and right tunnel construction, and ground surface settlement control, thereby ensuring the safety and efficiency of station construction.

(Figure 4 Scene of Dayu Tunneling No. 1 Exiting the Tunnel)

At the same time, the research team also established an intelligent monitoring system for the entire life cycle of station construction and operation-maintenance integrating multi-source sensing technology. Through an information-based intelligent management platform, full-process real-time information-based intelligent monitoring and management with functions such as information management, risk assessment and intelligent early warning were realized, forming a complete set of construction technologies for mined metro stations in bustling urban areas. This system provides comprehensive intelligent monitoring and management for station construction and subsequent operation and maintenance, ensuring the safety and sustainable operation of the station throughout its entire life cycle.

Economic and Social Benefits

In interviews with multiple media outlets, Academician Chen Xiangsheng pointed out that compared with open-cut construction, the successful implementation of mechanized mined technology has achieved remarkable results, including a 35% reduction in carbon emissions, a 15%-20% saving in construction period, a 40% reduction in earthwork transport, and a 20% cost saving, realizing the industrialization of metro station construction for the first time. The successful application and demonstration of the new mechanized mined construction technology package of this project marks a comprehensive leap in engineering theory, key technologies and equipment manufacturing capabilities in the field of mined construction in complex environments in bustling urban areas of China, leading a major transformation in metro station construction techniques and greatly advancing the comprehensive progress of low-carbon, intelligent, efficient and safe development technologies for urban underground space.

(Figure 5 On-site Photo of the Receiving Ceremony of the Future Underground City Research Institute Team)