On November 22, the No. 1 lower inclined shaft tunnel of the Hunan Pingjiang Pumped Storage Power Station was successfully holed through, marking the successful completion by "Tianyue," the world's first large-dip-angle, variable-diameter hard-rock tunnel boring machine (TBM) for inclined shafts, of the 583-meter excavation of the No. 1 lower inclined shaft, laying a solid foundation for the subsequent construction of the power station.

The Hunan Pingjiang Pumped Storage Power Station is located within Fushoushan Town, Pingjiang County, with a total installed capacity of 1.4 million kilowatts and a designed annual power generation of 1.009 billion kWh. It is currently the largest pumped storage power station under construction in Hunan Province. As the world's first pumped storage power station to adopt a large-dip-angle, variable-diameter TBM for inclined shaft construction, the project pioneered a launch method without a guide platform and an upward crawling excavation method on a steep 50-degree incline from bottom to top. A single variable-diameter TBM ranging from 6.53 meters to 8.03 meters in diameter was used for free switching, achieving full-face excavation and one-time completion of primary support for the two-stage water diversion inclined shafts. This solved the problems of long construction cycles, low safety, and high labor intensity associated with traditional guide shafts and drill-and-blast expansion excavation, creating a new model for the construction of pumped storage power station shafts in China.

The excavation of the water diversion inclined shaft is one of the most difficult construction nodes of the Pingjiang Pumped Storage Power Station. The TBM drives a total length of 2,092 meters at a dip angle of 50 degrees, with an elevation difference of 648 meters, which is 196 meters higher than the tallest building in Hunan Province. The entire TBM excavation process is divided into four sections, with a maximum burial depth of 600 meters. The geology consists mainly of Class II and III surrounding rock such as moderately weathered fresh porphyritic granite, and the route passes through six fault fracture zones, making water inrush, rockbursts, and collapses highly likely.

To ensure the smooth driving of the "Tianyue" TBM, since its launch in August 2023, the project department has adhered to the principles of "problem orientation, systematic analysis, and precise measures," using "Party building + scientific and technological innovation" to drive efficient construction. It has focused on refined process management, optimized process sequencing, and strengthened technical research. It organized Party member backbone personnel to establish the "Tianyue" (TBM) Party Member Vanguard Team, carrying out multiple optimizations to attitude control, main drive seal modification, and the cooling system. In response to the geological and construction characteristics of the inclined shaft, the project department modified the comprehensive rapid mucking system. By raising the muck chute and widening the belt conveyor in the lower curved section, it successfully overcame difficulties such as blockage of the muck chute and leakage of the mucking system under the flat-to-inclined conversion mucking mode, ensuring that the "Tianyue" TBM achieved safe and efficient excavation under extremely harsh construction conditions, with a monthly advance of 155.2 meters, setting a new single-month advance record. At the same time, the project department actively fulfilled its social responsibility by accepting interns from professional and technical colleges for talent development, giving play to the radiating and driving role of master craftsmen, and striving to cultivate young talent and technical backbones.