ABSTRACT
The construction of 4 diversion tunnels in Jinping II Hydropower Station is currently China's deepest underground engineering project. The general depth is 1500–2000 m, and the maximum depth reaches 2525 m. The highest external water pressure is 10.22 MPa. Previously unresolved issues, such as the stability of the surrounding rock of the deep buried tunnels, support design, and soft rock large deformation, are directly related to the success of the project construction. During construction, a large amount of innovative scientific and technological research was carried out to develop key design technologies in deep buried tunnel engineering. Jinping II Hydropower Station was put into operation in 2014 and has since been running in a safe and stable condition. The research achievements obtained in the construction of the project promote advances in the technology of hydraulic tunnel construction and risk control, and are of milestone significance to underground constructions in China and worldwide.
