China assembles 3,500-ton TBM for Sichuan tunnel project

China has completed the assembly of a massive 3,500-ton dual-shield tunnel boring machine (TBM) named ‘Yue Xi’ for the Viet Xi tunnel project in Sichuan province. The machine, measuring 220 meters in length with a 13.01-meter diameter, is designed to excavate an 18.4 km tunnel for the Jin Kou He - Xi Chang expressway.

The project involves significant technical challenges, as the tunnel will reach depths of up to 1,011 meters through complex geological conditions. Approximately 81.6% of the route consists of Class IV rock, including soil mixed with gravel or pebbles, with risks of landslides, deformation, and rock bursts due to high geological pressure.

The ‘Yue Xi’ TBM is equipped with a 5,600 kW main drive and 83 roller cutters. It is designed to automate excavation, material transport, support, and lining installation, which is expected to be 3 to 5 times more efficient than traditional blasting methods in suitable conditions. This mechanized approach is particularly important because the tunnel passes through ecologically sensitive areas and near the active Chengdu-Kunming railway, necessitating limited use of explosives.