On April 18th, the "Dayu Tunneling Machine," the world's largest rectangular pipe-jacking machine, began construction at the Shasan Station of the Shenzhen Metro Line 12 project, marking a major innovation in the construction method for subway stations in China. This breakthrough fills the gap for mechanized subway station construction. The machine is tailored for the Shasan Station, with a width of 11.29 meters and a height of 13.55 meters. It consists of two devices assembled vertically, with multiple cutter heads arranged in a spiral control system, using micro-stepping excavation, posture measurement and control technologies, enabling it to achieve shallow soil cover, large cross-section, and zero-distance excavation functions.
The Guangdong-Hong Kong-Macao Greater Bay Area is crucial to China's modern urban agglomeration construction planning, and has an enormous demand for urban rail transit due to dense cities, developed economies, and populations. Traditional open-cut construction for subway stations in busy urban areas face challenges such as traffic congestion, numerous pipelines, green space, property relocation, high labor costs, low mechanization, high safety risks, difficult quality control, long construction periods, and high costs.
To solve these issues, Professor Chen Xiangsheng, an academician of the Chinese Academy of Engineering, led a team to form a research team comprising Shenzhen Metro Group, Shenzhen University, China Railway Engineering Equipment, and POWERCHINA. They carried out the Guangdong Provincial Key Area R&D Plan "Key Technologies for Subway Stations in Busy Urban Areas," with the Shasan Station serving as a demonstrative application project. The station is an underground two-story island-type station located in a busy urban area with complex geological conditions, underground water, and a newly built culvert buried at a depth of 4.2 meters. The research team developed a new type of underground excavation equipment, the "Dayu Tunneling Machine," a rectangular pipe-jacking machine, achieving a major breakthrough in super-high soil and water pressure balance on the tunnel face and zero-distance construction equipment technology.
By revealing the rules of space deformation and establishing a comprehensive risk assessment system for underground subway station construction, the research team adopted the creative use of a combination rectangular pipe jacking machine to construct the main structure of the station in two steps, i.e. constructing the left- and right-substructures of the station step by step. They proposed the design theory and method of subway mechanized underground excavation station, developed an assembled station structure, and solved design problems such as the conversion of multi-hole assembled pipe jacking and station structure system. The research team also built an information-based intelligent management platform for underground subway station construction in the prosperous coastal city, which enables real-time information-based intelligent control of the station construction process. The assembly of large-section pipe sections is another problem that needs to be solved during the pipe jacking process. As early as 2020, POWERCHINA and other relevant parties began to promote the design and manufacturing of auxiliary tools for pipe section assembly, which consists of two sets of truss structures, including flipping platforms, lifting beams, assembly tools, and mobile carts, ensuring precise positioning and safe transfer of the pipe sections.
According to reports, the Sha San Station's underground subway station in China has achieved a significant milestone by introducing a super-large-section assembled rectangular pipe jacking machine into the field of subway construction, which is the first of its kind in China. The project research team overcame various technical challenges, including underground assembly of super-large-section assembled pipe jacking station segments, starting and receiving, left and right line close construction, close-range underpassing of box culverts and deformation control, and structure system conversion. They successfully developed a complete set of construction technology for underground subway stations in prosperous urban areas. The application of this technology in the demonstration project of Shasan Station has resolved the contradiction between large-scale and rapid construction of underground rail transit in the region and the urban environment, economic development, and social harmony in the prosperous urban areas. The use of mechanical excavation has resulted in reduced labor input, decreased safety risks, improved engineering quality and efficiency, shortened construction period, reduced comprehensive costs, and achieved industrialization of subway station construction.
The successful launch of the "Dayu Tunnelling Machine" at Shasan Station of Shenzhen Metro Line 12 has marked the formal implementation stage of the demonstration project of "key technologies for underground subway station construction in prosperous urban areas." This accomplishment represents significant improvements and progress in China's engineering theory and technology level, as well as in key equipment research and development and manufacturing capabilities in the field of complex environment underground construction in prosperous urban areas. It has promoted the development and progress of railway transportation construction technology and taken a crucial step towards intelligent construction.
