On July 7, 2023, the world's first variable diameter TBM Tianyue will be officially put into use in Hunan Pingjiang Pumped-storage hydroelectricity.

The Tianyue is the world's first specialized tunnel equipment with large slopes, vertical curves, and variable diameters, with a length of 87 meters and a total weight of approximately 900 tons. This equipment will be used for the excavation of the diversion inclined shaft of the Pingjiang Power Station, which can achieve a diameter of 6.5-8 meters and a 50 degree super large inclination angle tunnel excavation. It combines the continuous construction technology of the flat tunnel and inclined shaft. It is equipped with multiple anti slip and emergency safety protection systems, which will solve the problem of R40m ultra small vertical curve turning, as well as the problem of cutter head and shield body changing diameter in a large range for the first time globally. It can adapt to various working conditions of efficient excavation in flat tunnels, inclined shafts, and curved sections.

The excavation of the inclined shaft of the diversion tunnel is one of the most critical and important nodes of the Pingjiang Power Station. The excavation of the inclined shaft of the diversion tunnel was carried out using a TBM tunneling machine, with a total excavation length of approximately 2278m. The original construction method for the excavation of the inclined shaft of the diversion tunnel was the traditional drilling and blasting method, which had problems such as multiple processes, complex construction organization, long construction period, large amount of over and under excavation, and poor safety compared to the TBM method. The world's first large slope TBM adopts a 50 ° large slope crawling construction technology from bottom to top, which can achieve full section excavation and initial support of a two-stage diversion inclined shaft, effectively solving the drawbacks of traditional construction methods such as long construction cycles, high safety risks, and high labor intensity, and achieving more efficient, safer, and intelligent inclined shaft construction. At the same time, it has laid a solid foundation for Pingjiang Pumped-storage hydroelectricity to generate power ahead of schedule in 2025. Editor/Xie Li