Brief History of Geological Development of Qiyi Reservoir

Qiyi Reservoir is located on the west side of Tangli Mountain in the middle reaches of Jinsha River, a tributary of Xinjiang River in Poyang Lake system, and is 16.0km away from Yushan County. See figure 1. 1 for the geographical location map of the project. The planning and design of engineering survey began in 1956, and construction was started in July of 1 with the approval of 1958, and it was named Qiyi Reservoir. The control basin area above the dam site is 324.0km2 (this review, the same below), with a total storage capacity of 228 million m3. The irrigation area of the reservoir is 105 1 10,000 mu, and the installed capacity of the power station is 9250kw. It is a large-scale (2) reservoir with comprehensive benefits such as flood control, power generation and aquaculture. The main buildings of the hub project include: main dam, auxiliary dam, spillway, irrigation and power generation diversion tunnel and power station.

According to Classification and Flood Standard of Water Conservancy and Hydropower Engineering (SL252-2000), the project grade of reservoir hub is Grade II, and the main permanent buildings are Grade II. The normal water level is 160.40m (Huanghai elevation, assumed elevation in the early stage of this project, Huanghai elevation = assumed elevation +66.399m, the same below), and the corresponding storage capacity is 20 1 10,000m3; The design flood standard is/kloc-once every 0.00 years, the design flood level is 16 1.6 1m, and the corresponding storage capacity is 2132,500 m3. The check flood standard is once in 2000, the check flood level is 163.02m, and the corresponding storage capacity is 228 million m3.

1 project overview

1. 1 main dam

The main dam was originally designed as a massive core dam. At present, the crest elevation is 167.40m (the crest elevation of mass core wall is 165.60m), the crest length is 420.0m, the crest width is 12.0m, and the maximum dam height is 53. 10m. The upstream and downstream of the dam are provided with stone and turf slope protection respectively, and the slope ratio of the upstream dam is 1:3.0, 1:4.0, 1:3.75, 1: 2.78 from bottom to top. The slope ratios of downstream dams are 1:3.0, 1: 2.75, 1:2.75, 1:2.75, respectively. The total thickness of clay blanket at the upstream dam foot is about 6.3~9.0m, which is divided into two layers: old and new. The old blanket was completed when 1960 was built, and the new blanket was completed when 1974 was expanded and strengthened. The elevation of drainage crest at downstream dam foot is120.40m.

C20 normal concrete cutoff wall is adopted for seepage control and reinforcement of 20 10 main dam, and the seepage control label of wall material is W6. The cutoff wall is made of plastic concrete with a thickness of 0.60m, and the bottom of the cutoff wall goes deep into the middle and lower limit of the strongly weathered layer. Reinforcement of left bank leakage by curtain grouting.

The upstream slope is protected by precast concrete blocks with a thickness of 0. 14m. The downstream slope is treated as a whole slope,