Jinping-II Hydropower Station

The world’s largest diversion type power station, it has a capacity of 4,800MW giving multi-year average annual generation of 24.23TWh, which is transmitted from the southwest to east of China.

Four parallel headrace tunnels cut across the 150km river bend of the Yalong to divert water for power generation. The project is characterised by large-sized headrace tunnels, each with a length of 16.7km and diameter of 12.4-14.6m, large overburden of up to 2,525m, super-high in-situ stress up to 100Mpa, and ultra-high external water pressure of up to 10Mpa.

A series of technical difficulties were overcome, such as tunnelling and structural safety under interaction of ultra-high stress and ultra-high external water pressure, prediction of and engineering measures for severe rock-burst, and handling of high pressured gushes of large-flow underground water, leading up to successful completion of the world’s largest and deepest complex of hydraulic tunnels.

The differential surge chamber complex is the largest world-wide both in volume and pressure difference.

J. A. Hudson, former chairman of International Society for Rock Mechanics and Rock Engineering, and academician of British Royal Academy of Engineering, is of the opinion that “construction of the deep-buried hydraulic tunnels of Jinping-II has enriched the existing theories of rock mechanics, with profound influence on development of rock
mechanics”.

In terms of installed capacity, the eight units of 600MW each, which is the world’s largest unit for the 300m-range water head, make Jinping-II the world’s largest diversion type power station.