Recently, three small-diameter slurry shield tunnel boring machines (TBMs) independently developed by China Railway Construction Heavy Industry (CRCHI) have entered operation simultaneously on a cable tunnel project in Gyeonggi-do, South Korea.

Two of the TBMs have completed the transition from segmented launching to full-machine tunneling, with their combined excavation distance exceeding 300 meters. The third machine is currently carrying out stable segmented launching operations.

The project involves complex geological conditions, including high-strength hard rock, fractured zones and weathered rock. It also presents challenges such as long tunneling distances, high rock uniaxial compressive strength, high groundwater pressure and a minimum tunnel curve radius of only 150 meters.

To address these conditions, CRCHI adopted a coordinated rock-breaking solution featuring a conical cutterhead and shield body. The design helps maintain excavation efficiency while reducing the risk of pipeline blockage and ensuring stable muck discharge in water-rich and complex strata.

The TBMs also feature an asymmetric trailer structure, providing wider personnel passageways and improved operational safety. The integrated component layout facilitates equipment inspection and maintenance.

In response to the 150-meter small-radius curve challenge, CRCHI's technical service team provides 24-hour equipment support and works closely with overseas operations and R&D teams to develop dedicated solutions. The first TBM has successfully completed tunneling through the 150-meter-radius curve, demonstrating the equipment's adaptability in demanding conditions.

With three TBMs operating steadily, the project is progressing smoothly. A fourth CRCHI TBM has been fully assembled and is ready for shipment to South Korea, further supporting the country's cable tunnel construction with advanced Chinese tunneling technology.