Since the first unit of Wan 'an Hydropower Station was put into operation in 1990, the comprehensive benefits of the project have been fully brought into play. In terms of power generation, the power station has installed 5 units, with a single unit capacity of1000 MW, and the cumulative power generation by 2003 was16 billion kW h. In addition to power efficiency, it also plays the role of peak shaving, frequency modulation and accident standby in the system. In shipping, eighteen dangerous beaches from Wan 'an to Ganzhou have been flooded, which has completely improved the 90km navigation channel in the reservoir area and increased the navigation depth of 0.2m downstream in dry season. The ship lock is a 2×500-ton first-class ship lock with an effective size of175×14× 2.5m.. By the end of 200 1, the floodgates had been opened for 206 12 times, with 44,000 ships passing by/kloc-0, and the total freight volume was 8183,000 tons. In terms of flood control, major floods occurred in 1994, 1995 and 1997, with a maximum inflow of 14300 m3/s and a maximum discharge of115300m3 after storage by the reservoir. The water level of Ganjiang River in downstream and Nanchang was reduced by 0.3 ~ 0.1m, which played the role of flood detention and peak shifting. In 1994, the irrigation canal head on the left bank began to supply water and irrigated 40,000 mu of farmland.
The total investment of Wan 'an Hydropower Station is 210.80 billion yuan. Main quantities of main works: earthwork excavation of 2.53 million m3, earthwork backfilling of 2.07 million m3, concrete pouring1510.00 million m3, curtain grouting of 23,000 m, consolidation grouting of 23,300 m, and metal structure anchorage of12,840 t.
Main engineering features
The dam site of Wan 'an Hydropower Station is located at the outlet of the canyon, and the river surface is about 450m wide in dry season. Although the geological conditions are not very complicated, faults, weak interlayers and deep weathered troughs are the main engineering geological problems of the dam foundation. The main feature of the project is the large peak flow, and the check flood once every 10,000 years reaches 33,900 m3/s. At the same time, the requirement of comprehensive utilization is high. Because Ganjiang River is the north-south water transport artery across Jiangxi Province, it is required to keep sailing during the construction period. According to the above characteristics, the general layout of the hub is selected as follows: flood discharge buildings and main powerhouse are arranged in the main river bed, and the ship lock is arranged on the right bank, so that the main buildings are in harmony with each other and conform to the river regime well, which meets the requirements of comprehensive utilization of the hub. The design makes full use of technological innovation, mainly including:
1, Wan 'an Shiplock is the single-stage shiplock with the highest design head in China at present. According to the design code of shiplocks at that time, the complex decentralized water conveyance system should be selected. The water conveyance system of single-stage shiplocks with high head (above 30m) abroad is very complicated. In contrast, Wan 'an Shiplock only adopts a simple decentralized water conveyance system, which successfully solves the hydraulic problems of high-head shiplocks and the requirements for berthing conditions, greatly simplifies the structural layout and saves the project investment. At the same time, it is the first time in China to use the permanent lock to solve the problem of temporary navigation during construction, so that the permanent lock can be used for temporary navigation after the main river bed is closed.
2. The dam height of Wanan RCC overflow dam is 44m, and the dam axis length is 164m. The design of the dam section adopted some new technologies that were leading and advanced in China at that time, such as the research results of the national "Seventh Five-Year Plan" research project "Application of Roller Compacted Concrete Dam Construction Technology in Large Water Conservancy and Hydropower Projects". In terms of construction technology, the belt conveyor is used to transport concrete for the first time in China, which successfully solves the technical problems such as aggregate separation of high-drop concrete. Due to the adoption of overflow cofferdam and long intermittent construction of RCC in flood season, technical difficulties such as concrete temperature control and crack prevention, flood season protection and combination of new and old concrete have been increased, which have been overcome in construction. 1992 The RCC Overflow Dam of Wan 'an Hydropower Station has been included as an example of RCC dam built in China in the Design Guide for RCC Dam issued by the Ministry of Energy and the Ministry of Water Resources.
3. The powerhouse of Wan 'an Hydropower Station is another large riverbed powerhouse after Gezhouba Hydropower Station in China, which is at the leading level in the design of similar powerhouse in the same period. The structure of the factory building is complex and the shape is unplanned, which is prone to cracks. By optimizing the structural shape and adopting reasonable layers and blocks to reduce the hydration heat of cement as much as possible in the concrete mix ratio, only a few surface cracks have occurred in the concrete of the factory building, which is rare in the built projects at home and abroad.
4. The dam section of the bottom hole adopts closed pumping apron, and a closed impervious curtain is set around the apron to block seepage from all sides into the foundation of stilling basin, and vertical and horizontal drainage ditches are set to form a unified drainage network, thus comprehensively reducing uplift pressure, reducing the thickness of apron from 4m to 2.5m and reducing concrete by about 20,000m3. At the same time, the block size is reasonably adopted, and the side length is less than 10m. During the construction and operation, no cracks are found in the apron block, which ensures the pumping effect. After prototype monitoring, the uplift pressure at the bottom of apron is lower than the design value, and the total displacement is only 50 ~ 60L/min, which tends to decrease year by year, and good results have been achieved.