Advanced Shield Tail Sealing Technology Enhancing TBM Tunnel Construction Safety

Tunnel construction using shield machines and full-face tunnel boring machines (TBMs) is increasingly applied in complex working conditions, including high-water-pressure soft strata, long-distance tunneling sections, and densely built urban areas. For shield machines applied in soft soil and composite strata, the Steel wire sealing brush is a core component of the shield tail sealing system, which guarantees the structural integrity of the tail sealing system and supports safe and stable tunneling operations.

In hydropower and water diversion projects involving soft rock, fault fracture zones and high-water-pressure complex strata, shield-type TBMs and composite shield machines rely heavily on reliable shield tail sealing structures. The Steel wire sealing brush maintains continuous close contact between the shield tail shell and segmental lining, effectively blocking groundwater infiltration and slurry backflow, and provides a stable sealing condition for synchronous grouting of the shield tail void.

Shield tail steel wire sealing brushes are generally fabricated from high-strength carbon steel or alloy steel wires with a dense layered arrangement. The steel wire filaments are fixedly mounted on reinforced steel strip bases, forming a flexible and high-durability sealing structure. The structure can withstand long-term frictional wear and variable shield tail pressure fluctuations during tunneling. It can adapt to slight segment misalignment and minor tunnel contour deviation, maintaining stable overall sealing performance.

In modern shield tunneling engineering, the shield tail steel wire sealing brush forms a matched working system with the synchronous grouting system. Its reliable sealing performance stabilizes the annular pressure of the tail void during segment assembly and tunneling, effectively suppressing grout leakage, preserving surrounding rock and soil stability, and ensuring the precise installation and positioning of precast concrete segments. This sealing configuration is widely used in urban metro tunnels, soft soil railway tunnels, and long-distance hydropower headrace tunnels with complex soft strata.

The shield tail steel wire sealing brush adopts a modular segmented structure, which is a major technical advantage for long-distance tunneling. In long-term construction, the sealing wires are subject to abrasive wear from stratum particles, cyclic pressure impact and frictional extrusion with segments. The integrated modular design supports rapid disassembly and replacement of worn single brush segments during routine maintenance, effectively reducing equipment downtime and guaranteeing continuous and efficient tunneling operation.

From the perspective of engineering construction, shield tail sealing performance is a key indicator that directly determines tunneling safety and construction quality. In urban metro projects, the Steel wire sealing brush effectively controls slurry leakage and tail void seepage, reduces construction disturbance to surrounding soil mass, and protects adjacent underground pipelines and building foundations. In soft-stratum railway tunnels and complex hydropower tunnels, it stabilizes the pressure environment of the shield tail area, ensures safe and accurate segment erection, and avoids ground settlement and structural deformation risks caused by grout loss and water and soil leakage.

Continuous upgrading of manufacturing and surface treatment processes has greatly improved the structural durability and stratum adaptability of shield tail steel wire sealing brushes. Specialized steel wire surface treatment technologies enhance corrosion resistance and anti-fatigue performance, while integral precision forming processes ensure uniform wire density and stable sealing contact pressure. The optimized products can maintain reliable sealing performance in diverse complex strata such as clay, sand, gravel and mixed composite strata.

With the continuous development of shield tunneling and special TBM technology towards large diameter, ultra-high water pressure and ultra-long distance tunneling, the technical importance of high-reliability shield tail sealing systems has become more prominent. As the key core sealing component of shield tunneling equipment, the Steel wire sealing brush guarantees the safety, continuity and high efficiency of underground tunnel construction, and is indispensable in modern urban and hydraulic underground infrastructure projects.