On the vast stage of urban underground space, the shield tunneling machine is like a steel dragon, using its powerful excavation capability to open up solid passages for urban rail transit construction. Since China Water Resources and Hydropower Fourth Engineering Bureau (Sinohydro Bureau 4) joined the construction of Shenzhen Metro in 2013, going from unfamiliarity to familiarity and from bewilderment to skilled operation, the Bureau 4 shield team, like a brilliant new star, has written a distinctive chapter in the Bureau's infrastructure construction over nearly a decade of development.

Accumulating strength and biding time, a decade of tempering forges a shield tunneling force

The Bureau 4 shield tunneling business originated from the Shenzhen Metro Line 7 project. Its starting point was not high: there were only two self-owned shield machines, equipment resources were stretched thin, and the technical reserve was relatively weak. In the vast world of shield construction, it was like a toddler learning to walk. Yet it was precisely under such difficult conditions that the pioneers of Sinohydro Bureau 4, carrying boundless enthusiasm and dreams for the shield tunneling cause, resolutely embarked on this challenging journey.

On January 29, 2016, the Shield Engineering Company of Sinohydro Bureau 4 Co., Ltd. was officially established, aiming to build a specialized, high-quality shield construction team and actively advance the shield construction business toward marketization and scale.

After nearly a decade of arduous struggle, the Bureau 4 shield team, like a butterfly emerging from its cocoon, has achieved leapfrog development. By the end of 2024, Sinohydro Bureau 4 had cumulatively operated more than 60 shield machines of various brands and models, both self-owned and leased, with 10 self-owned shield equipment sets, and 14 sets currently tunneling underground. These shield machines leverage their respective advantages under different geological conditions and construction environments, becoming capable "warriors" for Sinohydro Bureau 4 in overcoming difficulties.

In terms of construction mileage, the Bureau 4 shield team has cumulatively completed shield/TBM tunneling exceeding the 200-kilometer mark. This figure is not merely a simple accumulation of length, but powerful testimony to Sinohydro Bureau 4's outstanding shield construction capability. It means that Sinohydro Bureau 4 has reached a considerably high level in shield construction technology, management, and other aspects, and can accurately and efficiently complete tunneling tasks in complex underground environments.

At the same time, the Bureau 4 shield team has cumulatively constructed more than 40 stations, with projects widely covering more than 10 cities including Shenzhen, Wuhan, Harbin, Chengdu, Chongqing, Zhengzhou, Hangzhou, Jinan, Luoyang, Shaoxing, and Dongguan. From the bustling metropolises of the coastal special economic zones to important hub cities in the inland regions, the construction footprint of the Bureau 4 shield team spans the length and breadth of the country.

In the Xinjiang project, a single machine in the TBM2-2 section set a new Bureau record of 900 meters of tunnel excavation in a single month; in the Aksai Water Supply Project, the TBM tunnel achieved 700.72 meters of excavation in a single month... During shield construction, the Bureau 4 shield team has developed a series of effective construction techniques and technical solutions targeting different geological conditions. The highly collaborative management team ensures that all work on the construction site proceeds in an orderly manner—from equipment deployment and personnel arrangement to material supply, every link works closely together, providing solid guarantees for the smooth progress of construction. The hard work of all employees is even more indispensable: through cold and heat, they have always stood fast on the construction frontline, forging today's Bureau 4 shield team with their sweat and wisdom.

Building dreams with craftsmanship, cultivating industrial workers to create an iron shield force

The Sinohydro Bureau 4 shield industry team totals 798 people. By construction specialty: 113 in TBM and 685 in shield tunneling; by core job type: 15 machine captains, 30 team leaders, 30 shield/TBM operators, 30 segment erectors, 39 maintenance workers, and 46 electricians.

At present, the Central China Company under Sinohydro Bureau 4 operates and maintains 8 shield machines and matching specialized equipment for the entire company, with the original value of various types of shield machines and specialized equipment exceeding 300 million yuan. These fine pieces of equipment, like heavy weapons on the battlefield, are the solid foundation of the Bureau 4 shield construction.

To ensure that these machines always remain in good operating condition, the Central China Company has established a comprehensive equipment management system. From routine maintenance and periodic overhaul to troubleshooting and emergency response, every link has strict standards and procedures. A professional equipment management and maintenance team keeps constant watch on equipment operation, promptly identifying and resolving problems, providing reliable guarantees for the safety and quality of shield construction.

To effectively safeguard shield construction safety and quality to the high standard of zero failure, the Bureau 4 shield team has always firmly adhered to the self-performed construction model. The main management and technical personnel in shield construction are all self-owned employees, while key production positions are filled by self-cultivated industrial workers.

After rapid development in recent years, a shield industry worker team of more than 800 people has been successfully cultivated. This team covers operators of specialized equipment such as shield machines, gantry cranes, battery locomotive consists, and mortar mixing stations, as well as key positions such as mechanical-electrical-hydraulic maintenance and segment erectors. Highly skilled and experienced, they can readily meet the demanding requirement of up to 25 shield construction operations of various types per year at peak.

In cultivating industrial workers, Sinohydro Bureau 4 emphasizes combining theory with practice. On the one hand, systematic training courses are offered, with industry experts and internal technical backbone staff invited to teach employees professional knowledge and operating skills; on the other hand, employees are provided with extensive practical opportunities to accumulate experience in actual work and continuously improve their operating proficiency. At the same time, a comprehensive incentive mechanism has been established, giving commendation and rewards to outstanding employees to stimulate their enthusiasm for learning and work.

Among this industrial worker team, many outstanding role models have emerged. Yang Yang, with his superb skills and exceptional professional quality, was honored with the title of National First "Shield Craftsman"; Zhao Jintao, also for his outstanding performance, received the National First "Shield Craftsman" finalist award. Their success is not only testimony to the strength of the Bureau 4 shield industrial workers, but also a powerful reflection of the Bureau 4 shield construction level.

Technology leads the way, overcoming difficulties demonstrates brand strength

Technology is the fundamental guarantee for the Bureau 4 shield team to ride the tide; only with superior technology can one go steady and far. After years of unremitting effort and deep technical accumulation, the Bureau 4 shield team has fully conquered and mastered the technical challenges of shield tunneling under complex geological conditions such as full-face hard rock, upper-soft lower-hard strata, water-rich sand layers, water-rich sand and gravel, mucky clay, and karst caves, reaching industry-leading standards in shield tunneling technology.

When facing full-face hard rock geology, shield machine cutters wear severely and tunneling efficiency is low. The technical team developed a targeted cutter configuration scheme and tunneling parameter optimization method, effectively improving the shield machine's tunneling efficiency and cutter service life in hard rock strata. For upper-soft lower-hard geology, where the shield machine tends to "nod" or "float up," the problem was successfully solved by adopting articulation control technology and adjusting shield machine attitude. In water-rich sand layers and water-rich sand-gravel strata, where the risk of water and sand ingress is high, advanced grouting water-stop technology and muck conditioning technology were developed to ensure construction safety.

In actual construction, the Bureau 4 shield team has successfully crossed waters such as Kaiyuan Lake, the Luo River, the Shenzhen River, the Taoyang River, and the Jin River on multiple occasions. These water-crossing operations are extremely challenging, requiring full consideration of numerous key factors such as hydrogeological conditions, shield machine adaptability, and safety risk prevention and control measures during construction.

Taking the crossing of the Shenzhen River as an example, the surrounding environment is complex, water levels vary greatly, and geological conditions are unstable. Before construction, an expert team was organized to conduct detailed geological surveys and risk assessments and to formulate a meticulous construction plan. During construction, by strictly controlling shield machine tunneling parameters, strengthening simultaneous grouting and secondary grouting, and real-time monitoring of shield machine attitude and surrounding environment changes, the Shenzhen River was successfully crossed, ensuring construction safety and engineering quality.

In addition, the Bureau 4 shield team has successfully passed beneath (or alongside) various complex pipelines such as gas, oil transmission, water supply and drainage, and military optical cables, as well as dense urban building clusters such as shopping malls, gas stations, elevated bridges, residential communities, and industrial plants. In the Wuhan Metro Line 12 project, it successfully passed beneath 47 operating railway tracks; in the Shenzhen Metro Line 7 project, it successfully passed beneath the operating Shenzhen Metro Line 1 at a vertical distance of only 1.21 meters; in the Wuhan Metro Line 7 project, it successfully passed beneath the operating Wuhan Metro Line 2 at a vertical distance of 2.7 meters. These successful cases fully demonstrate the Bureau 4 shield team's superb construction capability and exquisite technical level in complex environments.

In terms of technical achievements, in the Chengdu Metro project, the Bureau 4 shield team independently developed and successfully applied construction methods including the three-axis ultra-long synchronous tensioning construction method for shield segments in the launching section, the green cyclic treatment construction method for shield slurry, the construction method for shield tunneling beneath existing metro lines using automated monitoring linked control of settlement, and the directional deviation correction construction method for shield rolling angle based on a steel wedge device. Through innovative construction techniques and processes, the above methods effectively improved construction efficiency, significantly reduced construction costs, and provided valuable reference experience for similar projects. At the same time, multiple patents were obtained, further enhancing the Bureau 4 shield team's core competitiveness in the shield construction field.

In terms of project awards, multiple projects undertaken by the company have received high industry recognition. By the end of 2024, the Bureau 4 shield team had obtained 8 provincial and ministerial-level quality innovation achievements, including "shield method construction with walking-type integral station passing" and "rapid construction of open TBM in water-rich environments," as well as 18 provincial and ministerial-level quality QC group achievements and 9 trusted teams, covering shield machine close-distance crossing beneath existing lines, segment erection quality, cutter replacement under pressure, and grouting plugging techniques. These awards are not only high praise for the company's project quality, but also comprehensive affirmation of the Bureau 4 shield team's overall strength.

Diversified expansion, opening up markets to achieve sustainable development

In the fierce competition of the construction market, only by daring to explore can one face challenges. While fully ensuring the high-quality and high-efficiency completion of shield construction tasks within the Bureau, the Bureau 4 shield team actively practices the market expansion strategy of localized operation and promoting contracting through performance. In 2016, Sinohydro Bureau 4 successfully undertook the 1,270-meter shield construction task for the Houhu Avenue Station–Baibuting Huayuan Road Station section of the Wuhan Metro Line 21 BT1 bid project from China Construction Third Engineering Bureau. The undertaking of this project opened a new局面 for the Bureau 4 shield team in cooperation with external enterprises and accumulated valuable practical market experience.

Since then, the Bureau 4 shield team has continuously intensified market development and actively participated in bids for various projects. In 2019, it undertook the 4,873-meter shield construction task for the Nanhu Xincheng Station–Laoyuhang Town Station section of the Hangzhou–Lin'an Intercity Railway Project Section 8-1 from Xiaohong Construction Group Co., Ltd. The smooth implementation of this project enabled the Bureau 4 shield brand to be showcased in the Yangtze River Delta market for the first time. In 2023, Sinohydro Bureau 4 contracted the shield construction tasks for the Daqingcun Station–Huahuiyuan Station and Huahuiyuan Station–Longxi Station sections of the civil works Section 3 of Chongqing Metro Line 4. Through deep participation in Chongqing metro project construction, the company's market share in Southwest China has been further consolidated and expanded.

In addition to undertaking shield construction tasks, the Bureau 4 shield team also actively expands equipment leasing business. In 2018, a lease contract was signed for one idle shield machine. In 2024, lease contracts were signed for two idle shield machines and one idle pipe jacking machine, effectively revitalizing idle assets. The development of the equipment leasing business not only effectively improves the utilization rate of the company's equipment, but also opens up new economic growth points for the company. At the same time, through cooperation with leasing clients, the brand awareness and market influence of "Bureau 4 Shield" have been further enhanced.

Ten years of strenuous effort, ten years of fruitful results. In the field of shield construction, Sinohydro Bureau 4 has gone from difficult exploration at the start to industry leadership today. Along the way, it has been full of challenges and hardships, and has also reaped honors and glory. On the road of future development, the people of Bureau 4 will continue to uphold the spirit of pioneering, innovation, and striving for excellence, taking technology as the guide, talent as the support, and the market as the orientation, continuously expanding business areas and enhancing overall strength, contributing more wisdom and strength to China's urban rail transit construction and infrastructure development, and writing even more splendid and colorful chapters.