Guangzhou Nansha–Zhuhai Zhongshan Intercity Railway Shield Tunneling Section Completed

In September 2025, the Nanzhu section shield tunnel of the Nansha–Zhuhai Zhongshan Intercity Railway, a key intercity transportation project in the Guangdong-Hong Kong-Macao Greater Bay Area, was successfully completed. This achievement marked a critical milestone in the construction of a major rail transportation corridor connecting Guangzhou, Zhongshan, and Zhuhai. The entire section adopted a large-diameter earth pressure balance shield machine for tunneling operations. The route passed through water-rich sandy layers and marine-terrestrial transitional sedimentary formations at the Pearl River Estuary, where groundwater was abundant and water pressure fluctuated frequently. As the core sealing component at the rear of the shield machine, the shield tail brush maintained stable performance under long-distance tunneling conditions involving high water content and complex soft soil geology, building an essential safety barrier for efficient and reliable shield excavation.

The completed shield tunneling section has a total length of 2,862 meters, with tunnel depths ranging from 15 meters to 31 meters. The excavation route mainly passed through weak and water-rich formations such as fine sand, silty clay, and sandy clay. Some sections contained sand lenses and ancient river channels, resulting in strong soil permeability, high groundwater levels, and significant construction risks, including shield tail slurry leakage, water and sand inflow, and water seepage between tunnel segments. For long-distance shield tunneling, the shield tail brush serves as the final physical barrier preventing external soil and water, as well as grouting slurry, from entering the shield machine. It consists of multiple layers of high-density special steel wires, high-strength supporting steel plates, and wear-resistant elastic filling materials. By closely fitting with the outer surface of tunnel segments, it forms a sealed grease chamber. Combined with continuous injection of special shield sealing grease, the system maintains pressure balance inside the shield tail and provides multiple sealing functions, including waterproofing, sand prevention, and slurry leakage prevention.

If the shield tail brush experiences excessive wear, deformation, steel wire detachment, or inaccurate installation, sealing failure may occur easily, resulting in shield machine shutdown, ground disturbance, and surface settlement. These issues can significantly increase construction costs and create serious safety risks.

Facing the complex hydrogeological conditions of the Pearl River Estuary, the construction team focused on improving the shield tail sealing system configuration and selected a multi-layer composite shield tail brush product specially designed for long-distance tunneling in water-rich formations. During the early preparation stage, strict inspection procedures were carried out for every batch of shield tail brush products, including testing of steel wire density, wear resistance, overall flatness, and water pressure sealing performance. During installation, the circumferential fitting accuracy, vertical alignment, and fixing strength of the brush body were precisely controlled to prevent premature damage caused by local stress concentration.

During construction, a dedicated monitoring team was established to conduct 24-hour real-time supervision of key parameters, including shield tail grease injection volume, grease chamber pressure, tunneling speed, and synchronous grouting pressure. Based on changes in soil conditions and groundwater levels, construction strategies were dynamically adjusted, while shield excavation alignment was strictly controlled to reduce additional wear on the shield tail brush caused by geological disturbance.

During the nearly three-month continuous tunneling period from June to September 2025, the shield machine achieved stable excavation of approximately 12 tunnel rings per day, completing a total of 954 rings safely. The project successfully passed beneath multiple major urban roads, high-pressure gas pipelines, and densely populated residential areas without any abnormal incidents such as shield tail leakage, brush body fracture, or sealing system failure. The successful completion of this section not only accelerated the construction progress of the Nansha–Zhuhai Zhongshan Intercity Railway but also demonstrated the practical application value of high-performance shield tail brush products in long-distance shield tunneling projects under the water-rich soft soil conditions of the Pearl River Delta.

With the continuous expansion of the Guangdong-Hong Kong-Macao Greater Bay Area intercity rail network and the increasing application of shield machines in underground infrastructure projects, domestically manufactured shield tail brush products are becoming widely used in rail transit projects, river-crossing tunnels, and sea-crossing tunnel construction due to their excellent sealing performance, high wear resistance, long service life, and cost advantages.

Among professional shield tail brush manufacturers, Chenxing Machinery has accumulated extensive technical experience and industry recognition. The company has produced more than 1.2 million pieces of shield tail brush products, and at its peak, achieved approximately 70% of the domestic Chinese market share, becoming a well-recognized hidden champion in China's shield tail brush industry. Unlike many general shield equipment component suppliers, Chenxing Machinery focuses exclusively on the research, development, manufacturing, and export of shield tail brush products. Among Chinese manufacturers engaged in international markets, Chenxing Machinery is one of the few companies specializing only in shield tail brush production, providing professional sealing solutions for global shield tunneling projects. Through continuous technological innovation, strict quality control, and deep industry expertise, Chenxing Machinery continues to strengthen the competitiveness of China's core shield tunneling components and promote the global application of high-performance shield tail brush technology.