Water conservancy project understanding

The hydraulics internship is an important part of the study of hydraulic engineering courses such as hydraulic structures. From March 21, 2005 to March 30, 2005, we conducted internships on the great water conservancy projects such as Gezhouba and the Three Gorges. Very big. Especially for the construction of China's largest water conservancy project - the Three Gorges Project is deeply touched. Combine the actual practice and my understanding of the immaturity of the Three Gorges Project.

One. Dam site and basic hub layout

The dam site of the Three Gorges Project was selected in Sandouping, Yichang City, about 40 kilometers upstream of the completed Gezhouba Water Control Project. The river valley in the dam site is wide, the bank slopes on both sides are relatively flat, and there is a small island in the river, which has good construction and diversion conditions. The foundation of the hub building is a hard and complete granite body. A special expressway with a length of 28 kilometers from Yichang to the construction site and a bridge across the river at 4 kilometers downstream of the dam, the Xiling Yangtze River Bridge, was built. A number of docks in the dam area have also been built. The dam area has good traffic conditions.

two. Important hydraulic building

1 dam

The river dam is a concrete gravity dam with a length of 2,309 meters, a top elevation of 185 meters and a maximum height of 181 meters.

The flood discharge dam section is located in the middle of the riverbed with a total length of 483 meters. It has 22 surface holes and 23 deep holes for flood discharge. The deep hole inlet elevation is 90 meters, the orifice size is 7×9 meters, and the surface hole width is 8 meters. The flow dome has an elevation of 158 meters, and both the surface hole and the deep hole are dissipated by the nose ridge.
The power station dam section is located on both sides of the flood discharge dam section and is provided with a power inlet of the power station. The inlet floor elevation is 108 meters. The pressure water transmission passage is a back pipe type with an inner diameter of 12.40 meters and a reinforced concrete structure.
When the flood is checked, the maximum discharge flow at the dam site is 102,500 cubic meters per second.

2 Hydropower station
The hydropower station adopts a post-dam layout scheme, and has two sets of left and right workshops and underground powerhouses. A total of 32 hydro-generator units were installed, including 14 on the left bank, 12 on the right bank, and 6 on the underground. The turbine is a mixed flow type, and the unit has a rated capacity of 700,000 kilowatts.
3 navigable buildings
The navigable buildings include permanent ship locks and ship lifts, all located on the left bank.

The permanent ship lock is a two-line five-level continuous cascade ship lock. The single-stage lock chamber has an effective size of 280 × 34 × 5 meters and can pass the 10,000-ton fleet.

The ship lift is a single-line first-level vertical lift design. The effective design of the ship's cabin is 120×18×3.5 meters, and one can pass a 3,000-ton passenger freighter. The total weight of the ship's design is 11,800 tons, and the total lifting force is 60 million Newtons.

three. Hub project quantity and schedule

The main engineering quantities of the main building and diversion works are: earth and earth excavation of 10.283 million cubic meters, earth and stone filling of 31.98 million cubic meters, concrete pouring of 27.94 million cubic meters, steel reinforcement of 463,000 tons, and hydroelectric generating set system 32 sets. set. All construction tasks are completed in three phases, with a total construction period of 17 years.
The first phase is construction preparation and the first phase of the project. The construction takes 5 years to mark the river closure.
The second phase is the second phase of the project. The construction takes 6 years to mark the initial storage of the reservoir, the first batch of generating units and the permanent ship locks.
The third phase is the third phase of the project, and the construction takes 6 years to mark the completion of the complete power generation and hub project of all units.

The first and second projects have been completed on schedule, and the third phase of the project is also under construction, and the ship lift is under intense pressure.

four. Great benefits of the Three Gorges Project

The Three Gorges Project is the largest water conservancy project in China and the world, and is a key backbone project for the governance and development of the Yangtze River. The reservoir of the Three Gorges Project has a normal water storage capacity of 175 meters and a total storage capacity of 39.3 billion cubic meters. The reservoir has a total length of more than 600 kilometers and an average width of 1.1 kilometers. The reservoir area is 1,084 square kilometers. It has huge comprehensive benefits such as flood control, power generation and shipping.

1 Flood control
The primary goal of the construction of the Three Gorges Project is to prevent flooding. The Three Gorges Water Control Project is a key backbone project in the flood control system of the middle and lower reaches of the Yangtze River. Through the storage of the Three Gorges Reservoir, a river-type reservoir with a storage capacity of 39.3 billion cubic meters is formed upstream, and the flood control capacity can be adjusted to 22.15 billion cubic meters, which can effectively intercept floods from above Yichang, greatly reduce flood peak flow and make the Jingjiang section The flood control standard has been raised from the current ten years to one hundred years. In the case of a catastrophic flood in the millennium, it can be used in conjunction with the flood storage project of the Jingjiang flood diversion to prevent devastating disasters on the banks of the Jingjiang River, to mitigate the flood damage in the middle and lower reaches and the flood threat to Wuhan. The conditions for the governance of the Dongting Lake District create conditions.

2 Power generation
The most direct economic benefit of the Three Gorges Project is power generation. Balancing the contradiction between China's rapid development of economy and severe energy shortages, clean renewable hydropower resources are undoubtedly the best choice. The total installed capacity of the Three Gorges Hydropower Station is 18.2 million kilowatts, and the annual average generating capacity is 84.68 billion kilowatt hours. It will provide reliable, cheap and clean renewable energy for the economically developed and energy-poor regions of East China, Central China and South China, which will play a major role in economic development and environmental pollution reduction.

The power resources provided by the Three Gorges Project, if calculated by thermal power, means that 10 more 1,000-kilowatt-class thermal power plants will be built, and an average of 50 million tons of raw coal will be mined every year. In addition to the environmental impact of waste residue, it will also emit a large amount of carbon dioxide that forms a global greenhouse effect every year, causing acid rain of sulfur dioxide, toxic gases such as carbon monoxide and nitrogen oxides, and generating a large amount of dust, dust, etc.; large-scale thermal power plants and waste slag yards The land occupation will take more land from the areas of East China and Central China where there are too many people. This will not only make China bear the pressure of a larger environment in the future, but also adversely affect the global environment.

3 shipping
The Three Gorges Reservoir will significantly improve the 660-kilometer Yangtze River channel from Yichang to Chongqing, and the 10,000-ton fleet will have direct access to Chongqing Port. The one-way annual pass capacity of the channel can be increased from the current 10 million tons to 50 million tons, and the transportation cost can be reduced by 35-37%. Adjusted by the reservoir, the minimum flow rate in the dry season of Yichang downstream can be increased from the current 3000 cubic meters / sec to more than 5000 cubic meters / sec, so that the shipping conditions in the dry season of the middle and lower reaches of the Yangtze River have also been greatly improved.

Fives. Problems in the construction of the Three Gorges Project

1 Sediment problem

The annual sediment transport volume of the Yichang section of the Yangtze River will be 530 million tons, which will silt the Three Gorges Reservoir. The normal water level of the reservoir is 175m high, with a total storage capacity of 39.3 billion m3, a dead water level of 145m elevation, a dead storage capacity of 17.2 billion m3, a flood storage capacity of 22.1 billion m3, and a storage capacity of 16.5 billion m3. The operation plan of the reservoir is: the 145m elevation of the water level is restricted during the flood season, and the flood is not regulated after the flood of 56,700m3/s in 3 years. The discharge of the deep hole and the hydropower station can reduce the sedimentation of the reservoir. When the flood came, the reservoir was flooded, and 56,700 m3/s was still discharged; The reservoir began to store water in September, about two months to a normal water level of 175m. In the next year, the reservoir water level was reduced to 155m elevation, and water was used to generate electricity. At the 155m water level, the Chuanjiang shipping can be maintained. In the flood season, the water level dropped to 145m. Due to the large flow at that time, the Chuanjiang shipping can still be maintained. This is an innovative reservoir operation plan.

2 Landslide landslide problem in the reservoir area

After detailed geological surveys, there are several potential landslides on the bank of the Three Gorges Reservoir, which can reach millions of m3. However, the potential landslide closest to the dam site is also farther than 26km. If a landslide occurs, the pulsating shock wave will be reduced to 2~3m before the dam, which will not affect the dam safety. In addition, if the reservoir bank slips, the reservoir will not affect shipping due to its wide and deep.

3 Hub engineering technical issues

The 185m high concrete gravity dam and the 18.2 million kW·h power house in the Three Gorges Project have a large amount of engineering, but they are all conventional projects after all, and China has more experience. The local foundation stability problem has been addressed to meet safety requirements. The 700,000 kW hydro-generator unit was first imported from abroad and later made by the country. More complicated is the two-line five-level ship lock, which is deeply excavated in the rock bank. The highest slope is 170m and the lower chamber is 60m vertical. The stability of the high rock slope is worrying. However, the engineers and construction personnel carefully studied the design, blasting and anchoring, and excavation, and the rock slope was stable for a long time. There is also a 3,000-ton passenger ship lift, the largest in the world, under design and research, and the pilot ship lifter.

6 Ecological and environmental issues

The favorable aspects of the construction of the Three Gorges Project for the ecological environment are: prevention and control of downstream land and urban inundation, reduction of thermal and electric air pollution, improvement of local climate, and reservoirs for fish farming. The unfavorable aspects of the ecology are: more than 300,000 mu of cultivated land, more than 200,000 mu of fruit land, and immigration to the highland of the reservoir, which will destroy the ecological environment. The hydrostatic water of the reservoir will weaken the self-purification capacity of the sewage, deteriorate the water quality, and affect the reproduction of wild animals. Therefore, there are advantages and disadvantages, and it does not hinder the construction of the Three Gorges Project. The disadvantages should be reduced to a minimum, mainly because reservoir immigrants should plant trees and grass, build terraces, protect the ecological environment, and not require food self-sufficiency. To do this, we must make great efforts and funds. Control pollution in cities such as Chongqing, Fuling and Wanxian, carry out sewage treatment, protect reservoir water quality, protect wild animals, and establish protected areas. Although it is difficult to protect the ecological environment, it must be solved and solved. As for the Three Gorges landscape, the rocky shore is nearly 1000 meters high, and the Three Gorges Dam is only 110m above the original river surface. The scenery is still basically the same, and the high gorge is out of Pinghu, which adds more beauty.

six. Immigration problem in the reservoir area

The Three Gorges Reservoir will inundate a land area of ​​632 square kilometers, involving 20 counties in Chongqing and Hubei provinces. The Three Gorges Reservoir is flooded with 2 cities, 11 county towns and 116 towns; 1599 industrial and mining enterprises affected by flooding or flooding, with a total of 24,500 hectares of cultivated land below the reservoir inundation line; 824.25 kilometers of flooded roads and 92,200 kilowatts of hydropower stations; The housing area is 34.496 million square meters, and the total population living in the inundation area is 844,100. Taking into account other factors such as population growth and secondary relocation during the construction period, the dynamic total population of the Three Gorges Reservoir resettlement will reach 1.13 million. The task is arduous, but the contradiction between economic development and severe energy shortage will be developed at a high speed. Clean renewable hydropower resources are undoubtedly the best choice. The total installed capacity of the Three Gorges Hydropower Station is 18.2 million kilowatts, and the annual average generating capacity is 84.68 billion kilowatt hours. It will provide reliable, cheap and clean renewable energy for the economically developed and energy-poor regions of East China, Central China and South China, which will play a major role in economic development and environmental pollution reduction.

The power resources provided by the Three Gorges Project, if calculated by thermal power, means that 10 more 1,000-kilowatt-class thermal power plants will be built, and an average of 50 million tons of raw coal will be mined every year. In addition to the environmental impact of waste residue, it will also emit a large amount of carbon dioxide that forms a global greenhouse effect every year, causing acid rain of sulfur dioxide, toxic gases such as carbon monoxide and nitrogen oxides, and generating a large amount of dust, dust, etc.; large-scale thermal power plants and waste slag yards The land occupation will take more land from the areas of East China and Central China where there are too many people. This will not only make China bear the pressure of a larger environment in the future, but also adversely affect the global environment.

3 shipping
The Three Gorges Reservoir will significantly improve the 660-kilometer Yangtze River channel from Yichang to Chongqing, and the 10,000-ton fleet will have direct access to Chongqing Port. The one-way annual pass capacity of the channel can be increased from the current 10 million tons to 50 million tons, and the transportation cost can be reduced by 35-37%. Adjusted by the reservoir, the minimum flow rate in the dry season of Yichang downstream can be increased from the current 3000 cubic meters / sec to more than 5000 cubic meters / sec, so that the shipping conditions in the dry season of the middle and lower reaches of the Yangtze River have also been greatly improved.

Fives. Problems in the construction of the Three Gorges Project

1 Sediment problem

The annual sediment transport volume of the Yichang section of the Yangtze River will be 530 million tons, which will silt the Three Gorges Reservoir. The normal water level of the reservoir is 175m high, with a total storage capacity of 39.3 billion m3, a dead water level of 145m elevation, a dead storage capacity of 17.2 billion m3, a flood storage capacity of 22.1 billion m3, and a storage capacity of 16.5 billion m3. The operation plan of the reservoir is: the 145m elevation of the water level is restricted during the flood season, and the flood is not regulated after the flood of 56,700m3/s in 3 years. The discharge of the deep hole and the hydropower station can reduce the sedimentation of the reservoir. When the flood came, the reservoir was flooded, and 56,700 m3/s was still discharged; The reservoir began to store water in September, about two months to a normal water level of 175m. In the next year, the reservoir water level was reduced to 155m elevation, and water was used to generate electricity. At the 155m water level, the Chuanjiang shipping can be maintained. In the flood season, the water level dropped to 145m. Due to the large flow at that time, the Chuanjiang shipping can still be maintained. This is an innovative reservoir operation plan.

2 Landslide landslide problem in the reservoir area

After detailed geological surveys, there are several potential landslides on the bank of the Three Gorges Reservoir, which can reach millions of m3. However, the potential landslide closest to the dam site is also farther than 26km. If a landslide occurs, the pulsating shock wave will be reduced to 2~3m before the dam, which will not affect the dam safety. In addition, if the reservoir bank slips, the reservoir will not affect shipping due to its wide and deep.

3 Hub engineering technical issues

The 185m high concrete gravity dam and the 18.2 million kW·h power house in the Three Gorges Project have a large amount of engineering, but they are all conventional projects after all, and China has more experience. The local foundation stability problem has been addressed to meet safety requirements. The 700,000 kW hydro-generator unit was first imported from abroad and later made by the country. More complicated is the two-line five-level ship lock, which is deeply excavated in the rock bank. The highest slope is 170m and the lower chamber is 60m vertical. The stability of the high rock slope is worrying. However, the engineers and construction personnel carefully studied the design, blasting and anchoring, and excavation, and the rock slope was stable for a long time. There is also a 3,000-ton passenger ship lift, the largest in the world, under design and research, and the pilot ship lifter.

6 Ecological and environmental issues

The favorable aspects of the construction of the Three Gorges Project for the ecological environment are: prevention and control of downstream land and urban inundation, reduction of thermal and electric air pollution, improvement of local climate, and reservoirs for fish farming. The unfavorable aspects of the ecology are: more than 300,000 mu of cultivated land, more than 200,000 mu of fruit land, and immigration to the highland of the reservoir, which will destroy the ecological environment. The hydrostatic water of the reservoir will weaken the self-purification capacity of the sewage, deteriorate the water quality, and affect the reproduction of wild animals. Therefore, there are advantages and disadvantages, and it does not hinder the construction of the Three Gorges Project. The disadvantages should be reduced to a minimum, mainly because reservoir immigrants should plant trees and grass, build terraces, protect the ecological environment, and not require food self-sufficiency. To do this, we must make great efforts and funds. Control pollution in cities such as Chongqing, Fuling and Wanxian, carry out sewage treatment, protect reservoir water quality, protect wild animals, and establish protected areas. Although it is difficult to protect the ecological environment, it must be solved and solved. As for the Three Gorges landscape, the rocky shore is nearly 1000 meters high, and the Three Gorges Dam is only 110m above the original river surface. The scenery is still basically the same, and the high gorge is out of Pinghu, which adds more beauty.

six. Immigration problem in the reservoir area

The Three Gorges Reservoir will inundate a land area of ​​632 square kilometers, involving 20 counties in Chongqing and Hubei provinces. The Three Gorges Reservoir is flooded with 2 cities, 11 county towns and 116 towns; 1599 industrial and mining enterprises affected by flooding or flooding, with a total of 24,500 hectares of cultivated land below the reservoir inundation line; 824.25 kilometers of flooded roads and 92,200 kilowatts of hydropower stations; The housing area is 34.496 million square meters, and the total population living in the inundation area is 844,100. Taking into account other factors such as population growth and secondary relocation during the construction period, the dynamic total population of the Three Gorges Reservoir resettlement will reach 1.13 million. The task is arduous, but it is necessary to resettle the immigrants, improve their lives, and help immigrants to create production conditions. After 20 years of hard work, they will be rich. Most immigrants retreated to the highlands and some migrated to the field. The Three Gorges Reservoir will inundate a land area of ​​632 square kilometers, involving 20 counties in Chongqing and Hubei provinces. The Three Gorges Reservoir is flooded with 2 cities, 11 county towns and 116 towns; 1599 industrial and mining enterprises affected by flooding or flooding, with a total of 24,500 hectares of cultivated land below the reservoir inundation line; 824.25 kilometers of flooded roads and 92,200 kilowatts of hydropower stations; The housing area is 34.496 million square meters, and the total population living in the inundation area is 844,100. Taking into account other factors such as population growth and secondary relocation during the construction period, the dynamic total population of the Three Gorges Reservoir resettlement will reach 1.13 million.

1 Development and openness of the Three Gorges immigrants

In the construction of the Three Gorges Project, the State implements the developmental immigration policy. The relevant people's governments organize and lead the resettlement work, coordinate the use of resettlement funds, and rationally develop resources. Based on agriculture, combining agriculture and industry, through multiple channels, multiple industries, and multiple forms. Multi-methods properly resettle immigrants, and the living standards of immigrants meet or exceed the original standards, and create conditions for the long-term economic development and the improvement of immigrants' living standards in the Three Gorges reservoir area. The developmental immigration policy is a major reform of reservoir immigration in China. This policy is based on the lessons learned from the immigration work since the founding of New China and the pilot of the eight-year immigration in the Three Gorges reservoir area. At the beginning of the immigration of the Three Gorges Reservoir, it implemented the principles and policies for the development of immigrants, adhered to the principles of state support, preferential policies, support from all parties, and self-reliance. The government came forward to develop local resources, expand the resettlement capacity, and help Provide supporting services, broaden the production and life of the road, so that it can achieve the goal of “moving, stable, and gradually getting rich”. At the same time, the state approved the Three Gorges Reservoir Area as the “Three Gorges Economic Open Zone” and enjoyed some special policies for opening up the coastal areas. It also called on developed provinces and cities to support the Three Gorges immigrants, and promoted the immigration enterprises and related production factors to a broader extent. The big market. The governments at all levels in the Three Gorges reservoir area have also introduced some preferential measures to carry out counterpart support and attract investment. The immigrants in the reservoir area have shown a benign situation of promoting development through openness and promoting resettlement through development.

2 Reorganization and expansion of the Three Gorges immigrants

The Three Gorges immigrants are a cause involving social reconstruction and resource reorganization in the reservoir area. Recombination is one of the distinctive features of the Three Gorges immigrants, and it is also the fundamental difference from the traditional simple compensatory immigration and the original relocation. The implementation of the developmental immigration policy will inevitably require the relocation of production factors in combination with the relocation of immigrants, thereby improving the efficiency of resource allocation and the formation of new productive forces. The so-called expansion is not only the expansion of scale, but also the improvement of structure, the enhancement of functions and the improvement of quality. From the perspective of development economics, the process of implementing developmental immigration is the process of economic expansion in the reservoir area. From the beginning of the implementation of expansion to the expansion of developmental immigrants, the entire process of relocation and reconstruction of the immigrants runs through the expansion of the economy and is full of yearning for future expansion. Of course, in actual operation, we must pay attention to everything from the actual situation of immigration and insist on rational expansion.

Seven. Investment and benefit issues

The static investment of the Three Gorges Project was 90.09 billion yuan, and the dynamic investment was about 200 billion yuan when the project was completed. The sources of investment in the Three Gorges Project include: state loans, the price of electricity from state-owned power stations is 0.4-0.7 cents per kWh, the electricity bill income of Gezhouba Hydropower Station, and the electricity bill income after power generation of the Three Gorges Hydropower Station. The state has this financial guarantee to ensure that investment is in place.

Regarding the benefits, it is estimated that within 10 years after the completion of the Three Gorges Project, the total project investment principal and interest, including engineering fees and resettlement fees, can be repaid with electricity income, and no investment is allocated for flood control and shipping. The benefits of flood control, power generation and shipping in the Three Gorges Project are long-term and there are huge social benefits. It can be seen from the above that the benefits of the Three Gorges Project are very large. Even if the investment is slightly increased, the repayment period is slightly extended, which is very reasonable.