As the core carrier of urban public transportation, the construction scale and efficiency of urban rail transit directly affect the completeness of urban transportation network and the quality of residents' travel. Shield tunneling has become the mainstream construction method for urban rail transit section tunnels due to its advantages of safety, efficiency, and minimal disturbance to the surrounding environment. In recent years, with the deep integration of intelligent and digital technology and high-end equipment manufacturing, shield tunneling construction technology has continued to iterate and upgrade, gradually transforming from traditional manual control and single function mode to digital autonomous operation, multi-functional adaptation, green and efficient construction, effectively solving industry problems such as complex geology, narrow space, and efficient construction, comprehensively assisting the high-quality and efficient promotion of urban rail transit engineering, and providing solid technical support for the construction of urban rail transit network.
The breakthrough in digital technology has propelled shield tunneling construction into a new stage of autonomous operation, which is the core direction of the current iteration of shield tunneling construction technology. Traditional shield tunneling construction highly relies on manual experience, and the control of excavation parameters, assembly of pipe segments, and transportation of materials require manual collaborative operations. This results in significant efficiency fluctuations, difficulty in precision control, and high risks of human error. In recent years, the digital intelligent shield tunneling technology with intelligent decision-making and autonomous control as its core has been applied on a large scale, equipped with AI intelligent decision-making system and multi-sensor fusion sensing module, achieving the full process of "push put operation" autonomous operation.
In terms of autonomous excavation, Shuzhi Shield integrates ACTT autonomous axis control technology, integrating multiple autonomous control functions such as excavation, attitude control, synchronous grouting, and shield tail oil sealing. Based on real-time geological perception data and AI algorithm models, it automatically optimizes parameters such as thrust, speed, and grouting volume, eliminating dependence on manual experience and achieving millimeter level precision control of shield posture by the Shanghai State owned Assets Supervision and Administration Commission. Compared to traditional construction, autonomous excavation can reduce the frequency of manual intervention, improve construction continuity by more than 30%, and increase the accuracy of axis deviation control by nearly 50% compared to traditional modes.
In the segment assembly process, the assembly robot equipped with i-SEE intelligent module becomes the core equipment. Through visual recognition and precise positioning technology, it independently completes the entire process of segment identification, grasping, alignment, and assembly. The visual recognition and end control accuracy are controlled within 1 millimeter. The amount of segment assembly errors and the uniformity of gaps are significantly optimized, effectively avoiding the deviation, damage, and other problems that traditional manual assembly is prone to. Shanghai State owned Assets Supervision and Administration Commission. At the same time, independent assembly and excavation operations can achieve parallel operations, transforming traditional "serial" construction into "parallel" promotion and significantly shortening the single ring construction period. Shanghai State owned Assets Supervision and Administration Commission.
In terms of material transportation, unmanned electric locomotives are paired with automatic single beam and automatic feeding machines to form an underground material automatic transportation system. Through the integration of radar and machine vision technology, the positioning, transportation, and unloading of materials such as pipe segments, mortar, and slag are accurately completed, achieving seamless connection of material transportation from the ground to the assembly area, reducing manual scheduling links, and ensuring continuous and efficient construction. The practice of projects such as Shanghai Metro Line 13 has shown that under the autonomous operation of the intelligent shield tunneling machine, each link is smoothly connected, the construction efficiency is improved by 25% compared to the traditional mode, and the quality pass rate remains stable at a high level.
Multi functional shield tunneling equipment iteration, solving complex geological and special working conditions problems, and expanding the applicable scenarios for urban rail transit construction. Urban rail transit lines often cross soft soil, water rich sand layer, hard rock, upper soft and lower hard and other composite strata, and need to deal with special working conditions such as small radius turning, ultra shallow overburden, integrated construction of stations and sections, and traditional fixed diameter, single mode shield is difficult to adapt. In recent years, new types of equipment such as variable diameter shield tunneling, dual-mode shield tunneling, and customized shield tunneling have emerged one after another, achieving "one machine with multiple capabilities and adaptable working conditions", greatly improving construction adaptability and efficiency. Xinfeng County People's Government.
The application of the world's first in-situ continuous large-size variable diameter shield tunneling machine, "Variable Diameter No.1", is a landmark breakthrough in the iteration of shield tunneling functions by the Xinfeng County People's Government. This equipment breaks through the limitations of traditional shield tunneling with a single diameter, and the diameter of the cutterhead can be infinitely adjusted between 8.83 meters and 12.45 meters, innovatively achieving the construction mode of "one station, two tunnels, continuous forming" by the Guangdong Provincial Department of Science and Technology. In the construction of urban rail transit, small diameter rapid excavation of section tunnels can be carried out first. After reaching the station area, the platform layer tunnel can be excavated in situ by expanding the diameter, and then the diameter can be reduced to continue excavation. The entire process does not require dismantling machines or adding work wells, effectively solving the problems of large environmental disturbance, long cycle, and high cost in traditional section and station separation construction. Foshan Municipal People's Government. This technology is applied to the Fangbai Intercity Guangzhou Railway Station project, which can reduce more than 3 construction processes and shorten the overall construction period by about 20%, according to the Guangdong Provincial Department of Science and Technology.
The dual-mode shield tunneling technology enables one click switching between mud water and soil pressure modes, accurately adapting to complex geological mutation scenarios. The soil pressure balance mode is suitable for rock layers and cohesive soil layers, with convenient operation and controllable cost; The mud water balance mode is designed for water rich sand layers and high water pressure formations. By accurately regulating the mud pressure to balance the water and soil pressure on the palm surface, the surface settlement can be controlled within 3 millimeters, and the settlement control accuracy is improved by 40% compared to the soil pressure mode. In the application of projects such as Foshan Metro Line 4, dual-mode shield tunneling has achieved smooth progress at 95 geological transition points, with a maximum daily footage of 15 meters, effectively avoiding water and mud inrush risks and ensuring efficient construction in complex geological formations.
In addition, for special working conditions such as small radius curves, ultra deep burial, and cave development, customized shield tunneling machines are equipped with special configurations such as reinforced cutterhead, wear-resistant rolling cutter, and advanced detection system. Combined with intelligent monitoring and parameter control technology, the excavation tasks of complex geological rail transit sections in cities such as Jinan and Chengdu have been successfully completed, with a 40% increase in tool life and a 30% increase in excavation efficiency.
The coordinated upgrading of green and efficient supporting technologies achieves safe, environmentally friendly, and low consumption construction, which meets the requirements of high-quality construction of urban rail transit. With the promotion of the "dual carbon" target and the improvement of urban environmental protection standards, the iteration of shield tunneling construction technology focuses on greening and low consumption, optimizing and upgrading from the aspects of slag treatment, energy consumption control, safety prevention and control, and building an efficient and environmentally friendly construction system.
The technology of waste soil resource treatment achieves reduction and resource utilization. In response to the large amount of waste soil and mud generated during shield tunneling construction, technologies such as mud pressure filtration separation and waste soil improvement solidification are introduced to separate the mud into clean water and dry soil. The clean water can be recycled for shield tunneling construction, and the dry soil can be used for roadbed backfilling and building material production. The utilization rate of waste soil resources reaches over 85%, reducing the frequency of waste soil transportation and environmental pollution. At the same time, the application of new soil improvement technologies such as sodium bicarbonate not only enhances the plastic flowability of the excavated soil, ensures smooth excavation, but also reduces the risk of chemical pollution, which meets the requirements of green construction.
Energy consumption and safety control technology are optimized synchronously, and permanent magnet synchronous motors and variable frequency drive systems are widely used in shield tunneling equipment, reducing energy consumption by 15% -20% compared to traditional motors and reducing construction carbon emissions. The construction of a comprehensive intelligent monitoring platform integrates real-time data collection, geological radar scanning, AI analysis and early warning functions, and monitors the shield posture, ground settlement, equipment operation, surrounding environment and other dimensions to achieve risk pre warning. The application of safety equipment such as automatic anti slip hook devices and intelligent blocking devices in sections effectively prevents construction hazards, reducing the accident rate by more than 35% compared to traditional construction.
From the perspective of technological iteration effectiveness, the comprehensive application of intelligent, multifunctional, and green shield tunneling technology has become the core driving force for efficient construction of urban rail transit. In recent years, the average monthly footage of shield tunneling construction in domestic urban rail transit has increased from the traditional 150-200 meters to 250-300 meters, and some smart shield tunneling projects have exceeded 350 meters; In terms of construction quality, the damage rate of pipe segments and the leakage rate of tunnels have decreased by 60% and 50% respectively, while the acceptance rate of the project has remained high. At the same time, technological iteration effectively shortens the construction period and reduces comprehensive costs. The average construction period of a single interval tunnel is shortened by 15% -25%, providing strong support for the networked and large-scale construction of urban rail transit by the Guangdong Provincial Department of Science and Technology.
Currently, urban rail transit construction is developing towards deeper, denser, and more complex directions, and shield tunneling construction technology will continue to deepen and iterate around intelligent autonomy, functional expansion, and green low-carbon. With the deep integration of technologies such as digital twins, large model algorithms, and remote intelligent operation and maintenance, shield tunneling construction will gradually achieve unmanned and remote control throughout the entire process; The application of new materials and modular design will further enhance the adaptability and reuse rate of shield tunneling equipment. In the future, the continuously improving shield tunneling construction technology system will continue to solve the problems of urban rail transit construction, help build a more efficient, safer, and environmentally friendly urban rail transit network, and inject strong impetus into the modernization development of cities.
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