On November 1, the dam foundation pit excavation project of the Yalong River Lianghekou Hydropower Station, jointly undertaken by Sinohydro Bureau 12 and Sinohydro Bureau 5, was fully launched, marking the station's official entry into the main construction phase.
The 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, the 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 project structures consist of a gravel-soil core rockfill dam, spillway, flood discharge tunnel, emptying tunnel, power generation plant, water diversion and tailrace structures, etc. “The Lianghekou dam is built with local materials and has a height of 295 meters, making it the tallest earth-rock dam currently built or under construction in China,” said a relevant person in charge of Yalong River Hydropower Development Co., Ltd. “The volume of the National Stadium ‘Bird's Nest’ is about 6.8 million cubic meters, while the total filling volume of the dam body is 41.6 million cubic meters, equivalent to the volume of six ‘Bird's Nests.’”
The foundation pit of the Lianghekou Hydropower Station is 1.3 kilometers long and about 50 meters wide at the water surface, making construction extremely difficult.
Foundation pit excavation first requires pumping and drainage of the pit, with an initial pumping and drainage intensity of 2,332 cubic meters per hour. The joint venture project department has equipped two pumps each with a drainage capacity of 1,260 cubic meters per hour at the upstream and downstream cofferdams of the dam, with one standby pump at each of the upstream and downstream cofferdams. Because the water level in the sump within the foundation pit near the upstream cofferdam drops to a relatively large depth, pumps are mounted on floating boats to achieve continuous pumping under high head differences. According to the construction plan, pumping and drainage will be carried out simultaneously for upstream and downstream construction, and excavation of the upstream foundation pit will begin, marking the official entry of the Lianghekou Hydropower Station project into the main construction phase.