On November 1, the dam foundation pit excavation project at the Yalong River Lianghekou Hydropower Station, jointly constructed by Sinohydro Bureau 12 and Sinohydro Bureau 5, was fully launched, marking the station's official entry into the main construction phase.
Lianghekou Hydropower Station is located in Yajiang County, Garze Tibetan Autonomous Prefecture, Sichuan Province, and serves as the “leading” cascade reservoir station in the middle reaches of the Yalong River. It is reported that among the seven cascade hydropower stations planned for construction in the middle reaches of the Yalong River main stream, Lianghekou Hydropower Station has the largest installed capacity. With a total installed capacity of 3 million kilowatts and a designed multi-year average annual power generation of 11 billion kilowatt-hours, the station represents a total investment of 66.4 billion yuan. The hub structures consist of a gravelly soil core rockfill dam, spillway, flood discharge tunnel, emptying tunnel, power generation plant, water diversion and tailrace structures, among others. “The Lianghekou dam is built with local materials and stands 295 meters high, making it the tallest earth-rock dam currently built or under construction in China,” said a relevant person in charge from Yalong River Hydropower Development Co., Ltd. “The National Stadium ‘Bird’s Nest’ has a volume of about 6.8 million cubic meters, while the total fill volume of the dam body is 41.6 million cubic meters, equivalent to the volume of six ‘Bird’s Nests.’”
The foundation pit at Lianghekou Hydropower Station is 1.3 kilometers long and about 50 meters wide at the water surface, presenting extremely high construction difficulty.
Foundation pit excavation first requires dewatering and drainage of the pit, with an initial drainage intensity of 2,332 cubic meters per hour. The consortium project department has equipped two pumps with a drainage capacity of 1,260 cubic meters per hour at each of the upstream and downstream cofferdams, with one standby pump at each cofferdam. Due to the significant water level drawdown in the sump within the foundation pit near the upstream cofferdam, a floating boat-mounted pump configuration is adopted to achieve continuous pumping under high head differences. According to the construction schedule, upstream and downstream dewatering and drainage are to be carried out simultaneously, and upstream foundation pit excavation is to begin, marking the official entry of the Lianghekou Hydropower Station project into the main construction phase.