The Yangzhou Dilong EPB2980 earth pressure balance shield machine has been successfully deployed for a tunnel project in Taiwan, China. Featuring an ultra-compact body, flexible steering performance and excellent stratum adaptability, the machine is well matched to the complicated local working conditions and has completed the tunneling section successfully. The project fully demonstrates the advanced manufacturing capacity of China’s ultra-small diameter shield equipment.

This tunnel project in Taiwan, China faces distinctive construction challenges. The tunneling section mainly passes through cobble and gravel layers with particle sizes ranging from 10 cm to 80 cm. The stratum features complex structures, uneven particle distribution and fluctuating tunneling resistance. Construction risks such as cobble jamming, difficult muck discharge and unstable excavation are likely to occur, setting extremely high standards for equipment trafficability, cutterhead compatibility, body compactness and steering flexibility. Conventional large-diameter shield machines cannot adapt to confined working spaces and complex cobble-gravel strata. Therefore, dedicated ultra-small diameter shield equipment serves as the key to smooth construction.

The EPB2980 earth pressure balance shield machine adopted in the project is China’s first ultra-small-size EPB shield and currently the smallest-diameter EPB shield domestically developed. It is specially designed for tunnel construction scenarios with narrow cross-sections, small-radius curves and complex cobble-gravel strata. Optimized to match project requirements, the machine boasts an excavation diameter of 3.05 m, a main body length of 7 m, an 8.5 m main unit including the screw conveyor, an overall machine length of 72 m and an installed power of 460 kW. With a compact and streamlined layout, it delivers steady and sufficient power output, making it ideal for narrow-section tunnel environments. In addition, the machine achieves a remarkable minimum turning radius of 35 meters. It can flexibly cope with tunnel alignments with complex routes and sharp curves, effectively addressing industry pain points including confined-space construction and small-curve tunneling.

During construction, the EPB2980 earth pressure balance shield machine was tailored to the on-site cobble-gravel strata with 10–80 cm particles. Supported by a stable power system, optimized cutterhead structure and precise earth pressure balance control system, it efficiently handles construction difficulties including high tunneling resistance and irregular particle distribution in cobble-gravel layers. The equipment operates smoothly with continuous excavation, reducing risks such as machine jamming, eccentric cutter wear and ground settlement. It ensures construction safety, tunnel quality and project progress throughout the works, highlighting the unique strengths of ultra-small diameter shield machines under special geological and operational conditions.

The successful application of the EPB2980 earth pressure balance shield machine in the project in Taiwan, China not only completes the small-diameter tunnel construction task in complex cobble-gravel strata, but also fills the domestic application gap for ultra-small-size EPB shield machines and fully verifies the reliability and advanced performance of domestic ultra-small diameter shield equipment. Meanwhile, it accumulates valuable construction experience for tunnel projects worldwide involving narrow cross-sections, small-radius curves and cobble-gravel strata, showcasing the strong technical capability of domestic shield manufacturers in refined and customized equipment development.