The geological survey of the dam site of Mozitan Reservoir began at 195 1 Foziling Reservoir. In June, 1955, 1 1, geologists from Institute of Geology of Chinese Academy of Sciences and Design Institute of Huaihe River Regulation Committee filled out the geological map of the dam site. 1In February, 1956, Team 93 1 of the Geological Department of People's Republic of China (PRC), together with the geological personnel of Huaiwei Committee, made a geological survey of the dam site. There are three dam sites to choose from: Mozitan, Shicao and Jilongjian. After preliminary comparison and selection, the upper dam site of Mozitan is selected as the main dam site, and the lower dam site is the auxiliary dam site for geological drilling. Submit the geological survey report in May, then supplement the drilling work, and finally select the second dam line of the upper dam site. The dam site belongs to the pre-Sinian metamorphic rock series, and amphibole gneiss, amphibole gneiss, accessory granite schist and amphibole schist are exposed in the rock strata. Although the joints are well developed, they close quickly in the deep, and only the local fault zone extends deeply and the permeability is weak.
10000 in February, 1955, the Surveying Corps of Huai Committee measured the topographic map of the reservoir area 1: 10000, and based on this, the reservoir capacity curve was obtained.
1955 "Planning Report on Reservoir Groups in Pi River Basin" makes it clear that the main purpose of building Mozitan Reservoir is to solve the problem of low flood control standard of Foziling Reservoir, and at the same time to solve the problems of promoting power generation and alleviating power load demand in central Anhui. Therefore, the planning of Mozitan Reservoir is closely related to the measures to improve flood control standards in Foziling. 1956 during the preliminary design, Mozitan Reservoir was planned according to the standard of once-in-a-thousand-year design and once-in-a-million-year check, and the expansion measures of the spillway of Foziling Reservoir were referred to. The principle of reservoir flood dispatching is that when the water level of Foziling Reservoir exceeds a certain level, Mozitan Reservoir stores flood for Foziling without discharging flood; When the flood volume of Foziling Reservoir is small and the water level drops, the flood discharge equipment can be turned on to discharge the flood. When the water level of Mozitan Reservoir exceeds a certain level, in order to ensure the safety of Mozitan Reservoir itself, the reservoir starts all flood discharge equipment to discharge flood.
After the preliminary design of the reservoir was submitted for approval, the Ministry of Water Resources and Electric Power put forward the reply that the design standards of Mozitan Reservoir and Foziling Reservoir should be matched, and the flood discharge equipment should be compared according to the design of secondary hydraulic structures. According to the examination and approval opinions, the characteristic water level and flood discharge and overflow facilities of the reservoir are determined in the technical design documents. During the tunnel construction, it was found that the geological rocks at the exit were broken and joints developed, so the tunnel diameter was changed, the bottom height and clear width of spillway were adjusted, and the spillway was controlled by installing gates. On this basis, the revised design of technical design spillway tunnel of Mozitan Reservoir is compiled. The document determines the dead water level of the reservoir as163m.
Limited water level in flood season 177m, water level after flood season 187m, once-in-a-century water level 197.2m, once-in-a-millennium water level 202.2m, dam crest elevation 202.9m, and breakwater crest height 204.0m.. The total storage capacity is 278 million cubic meters (considering the storage capacity after sedimentation). The diameter of the spillway tunnel is 5.7m, the crest elevation of the spillway dam is 194.0m, and the clear width of each hole of 7 holes is 8m, which is controlled by reinforced concrete gates. The installed capacity of hydropower station is 1 set10.6 million kilowatts, and the annual power generation is 0.6 1 100 million kwh.
By the end of 1958, the main project of the reservoir was basically completed and water storage began. However, due to limited funds, by the end of 1962, the tunnel could not be used and the spillway gate was not installed. The control basin area of Mozitan Reservoir should be revised from the original planned 670 square kilometers to 570 square kilometers according to the newly measured 1: 50000 aerial survey map, and the hydrological data should be changed accordingly, and various water levels should be adjusted. Since then, due to the expansion of Foziling Power Station, the development of Pi River irrigation area and the change of hydrological data, various water levels of the reservoir have changed again. 1975 After the August flood, reanalyze the design flood calculation according to1976 June. The flood control standard of Foziling and Mozitan reservoirs is once in 200 years, and the dam will not overflow for 300 years. Therefore, in June, 1978,/kloc-0 compiled and completed the Construction Plan for Danger Removal and Reinforcement of Bailianya Reservoir and Mozitan Reservoir in Foziling, and in June, 1980,/kloc-0 compiled and completed the Preliminary Design for Danger Removal and Reinforcement of Foziling Reservoir. 198 1 April, the Ministry of Water Resources and Electric Power instructed the Foziling Reservoir to be designed as a secondary building, and the reinforcement design standard was recently designed as 100, and checked as1000; It is preliminarily agreed that the height of Foziling dam should be increased by1.5m. According to the deficiency of 1.000, the schemes of the east coast spillway tunnel can be compared. On this basis, through the comparison of various flood discharge schemes, Foziling Reservoir chose the scheme of expanding the original spillway to 1 hole, and determined the recent water level characteristic value of Mozitan Reservoir. See table 4- 1-5.
The final scale of Mozitan is related to the scale of Bailianya Reservoir and the reinforcement measures of Mozitan Reservoir. Various water levels, flood discharge facilities and dam crest elevation of Mozitan Reservoir need to be determined later.
Second, design.
According to the river valley topography, dam site geology, building materials, construction equipment and experience, Mozitan Reservoir Dam emphatically compares four dam types: concrete gravity dam, big head dam, flat plate dam and multi-arch dam. Finally, through the comprehensive comparison of economy, safety, durability and construction difficulty, the concrete big head dam is selected. At that time, this type of dam was the first in China. In the design, the finite difference equation of stress function method (namely network method) is used to calculate the dam stress, and the photoelastic test method is used for the first time in China to check it.
In the design, the ratio of the water retaining width of rib pier to the cross section of rib pier foundation, the relationship between the slope of upstream and downstream surfaces and the volume of rib pier and the project cost are studied, and the most economical cross section size of the dam is determined under the condition of satisfying the stability and stress at the same time. The dam has two piers on the riverbed. In order to save stone excavation, reduce the lateral height difference of pier foundation and improve the lateral stability, the bedrock on both sides of the bank slope is excavated into steps along the slope, and the dam body adopts a single pier. Influenced by the west coast geology, the dam axis turns upstream. There are faults in the bedrock of some rib piers on the east and west banks. Excavate and backfill concrete, strengthen curtain and consolidate grouting. An insert is arranged at the joint between the dam head and the pier, and a joint grouting system is arranged in the contraction joint of the pier. Expansion joints are arranged between adjacent stacks, two U-shaped copper sheets are arranged upstream and downstream of the joints, and an asphalt well is arranged in the middle. U-shaped iron pipes are buried in the well, and hot air is introduced to melt asphalt. A drainage well is set downstream of the joint to prevent possible water seepage.
The total length of the designed dam is 33 1 m, which consists of two double piers in the middle 12, three single piers on the east and west banks, the turning section on the west bank and gravity dams on both banks. The elevation of dam crest is 202.9 meters, and the elevation of breakwater crest is 204.0 meters. When the dam crest is below10m, the slope of the upstream surface of the dam is1:0.3; 10 ~ 20m is1:0.4; 1:0.5 in the direction of 20m; The slope of the downstream surface should be 1: 0.4. The width of dam top is 4m, the width of dam bottom is 7 1.5m, and the maximum dam height is 82m.. The clear width of the two main walls of the stack is 6 meters, and a semicircle with a diameter of 4 meters is formed near the head; The width of downstream face plate is 14.4m, the thickness of pile wall is 4.2m, and the span of dam pile is 18.
rice. The design is proved to be successful through the inspection of 1969 overflow dam.
The spillway tunnel is located on the west bank of the dam. The diameter of the original designed tunnel was 7 meters, but it was changed to 5.7 meters due to geological problems during construction, and the tunnel entrance moved 50 meters upstream. Behind the inlet straight pipe is a horizontal elbow with a radius of 40 meters, and the included angle of the elbow is 60 degrees. The total length of the cave is175m. The entrance is provided with a 2.5m× 6m double-hole drum-type flat steel gate; A 4.5m× 4.5m high-pressure isolated steel gate is set at the exit. The tunnel entrance bottom elevation is 132.7m, and the maximum flow is 6 14m 3/ s.
The spillway is located in the valley near Guanjiaao on the west bank of the dam, and the entrance and exit are far from the dam. The bottom height, bottom width and control form of spillway have undergone many changes. Finally, the bottom elevation of spillway is 196m, with 6 holes, the clear width of each hole is 10m, and the radial steel gate is 6.2m high, with the maximum discharge of 2,270 cubic meters per second.
After comparison of various schemes, the powerhouse behind the dam is adopted for the location and layout of the hydropower station, and the bedrock is granite and timely gneiss with a distance of 15m from the toe of the dam under the No.9 pile. The penstock is introduced into the workshop through the No.9 pile. Two 8000 kW units were originally designed and installed, and 65438+6000 kW units were adopted at the suggestion of Harbin Electric Machinery Factory. The hydraulic turbine is HL-2 1 1-LJ-225, and the installation elevation of the center of the hydraulic turbine is 126 meters. The factory building is 22.7m long, 0/3.3m wide and 27m high. The above-water and underwater structures of the workshop are integral reinforced concrete structures. The switch station is arranged downstream of the factory building.
East side.
The design of Mozitan Reservoir and Power Station is undertaken by the Design Institute of Huaihe River Regulation Committee.
Third, architecture.
The construction of Mozitan Reservoir is in the form of general contract. For Party A (the owner), Huaihe Management Committee will set up an office at the construction site, which will be responsible for the inspection and supervision of construction progress and project quality, the acceptance of concealed works, the signing of contracts, the nuclear payment of project prices, the filling and delivery of capital construction reports, and help solve construction problems. The Construction Bureau of Huaihe River Regulation Committee, as Party B, contracted all the projects and established Mozitan Reservoir Engineering Bureau, which was directly responsible for the construction of all buildings, facilities and large temporary facilities. 1March, 956, the preliminary work of reservoir construction was started, the road from Foziling to Mozitan was built, and the factory building was built. On September 8th 1956, the State Construction Committee agreed that the open channel of Mozitan Reservoir Tunnel, foundation clearing on both sides, plant layout and sand and gravel mining should be started first. On September 19, the tunnel was drilled with open slots, and on September 22, the dam foundation cleaning, plant layout and sand pebble mining started one after another. The diversion scheme of spillway tunnel was originally planned, but in order to strive for the dam to play a flood control role in the flood season of 1957, considering the favorable conditions of shallow riverbed cover, it was modified to stage riverbed diversion, which accelerated the construction progress.
The foundation cleaning work is mainly due to the deep stone weathering on the left bank hillside and the right bank dam head, and the excavation workload is heavy. After the test, chamber blasting was used to speed up the excavation progress.
Dam concrete pouring started in June 1956 1 1 and ended in June 1957 1, and piles 7 ~ 10 were cleared. Due to the favorable construction conditions, such as less reinforcement arrangement, more concrete radiation surface and the height of one-time pouring exceeding 5 meters, the hollow dam pile is used for lifting bucket transportation, which speeds up the concrete pouring progress. According to the construction pouring height and project progress, the transportation system of four mixing stations is set up. The concrete label is at the big end, and 170 concrete is used for the crib wall and the crib base of the riverbed below the elevation of187m and137m. The rest is 140 concrete. Concrete ingredients are weighed manually, stirred by 0.4 and 0.8 cubic meters mixers, transported by double-bucket lifting tower and sloping bucket, sprayed with water, manually closed and mechanically vibrated.
In the construction of Mozitan Reservoir, the method of sectional flow operation was adopted, and the systems and methods such as "project task list", "piece rate" and "attendance reward salary" were implemented, which improved the labor enthusiasm. Strengthen inspection to ensure construction quality. The dam concrete project is about 300,000 cubic meters. 1956, 13 started in February, and 1958 was completely poured on June 9. The speed at that time was also rare in China.
The engineering quality inspection and acceptance of Mozitan Reservoir is the responsibility of the engineering laboratory of Mozitan Reservoir Engineering Bureau, with the cooperation of quality inspectors from all construction units. 1958 In late June, an inspection team composed of relevant parties inspected the dam. Dam foundation treatment, dam concrete quality, dam expansion joint and contraction joint quality and dam foundation grouting quality basically meet the design requirements. All remedial problems found in the acceptance will be dealt with.
The construction of spillway tunnel is subcontracted by Mozitan Engineering Bureau to the grouting engineering team of Huaihe River Regulation Committee Construction Engineering Bureau and the installation company of Anhui Provincial Construction Department. On September 1956, the open channel of the tunnel was formally excavated. The tunnel body was excavated from both ends of the tunnel, and the pilot tunnel was fully excavated on the afternoon of June 5438+February 9. The tunnel excavation was basically completed at the end of March 1957, and the tunnel concrete lining began on June165438+1October 19. Because the tunnel bears high water head, in addition to using higher grade concrete, vacuum operation and pre-earthquake mortar are widely used to improve strength and wear resistance. At the end of March, 1958, the concrete lining of the tunnel body was completed except for the exit section, and the construction of the entrance and exit section was suspended because the embedded parts of the gate did not arrive. 1June, 959, the upstream gate was installed and the reservoir was officially filled with water. The high-pressure radial gate at the exit of the tunnel is installed at 1960.
The construction of spillway tunnel has been delayed for many years, and the quality acceptance in the early stage of construction is strict; The later installation time is too long, and the acceptance cannot be strictly controlled.
The stone excavation of spillway was subcontracted by Mozitan Reservoir Engineering Bureau to the mechanical construction engineering team of Huaihe River Regulation Committee Construction Engineering Bureau. 1958 1 month excavation, ending on May 25th. Concrete pouring began in August, and construction stopped in mid-June at 5438+ 10, and construction did not continue until the completion of the reinforcement project of Foziling Reservoir at 5438+0966 in June. 1968 10 month, complete all projects such as pouring and installation of gate hoist.
The spillway project was completed in June 1966 and June 10, and the water resources department of Anhui province, together with relevant parties, accepted the completed project. The quality of the project basically meets the design requirements, and the minutes of the acceptance meeting are written.
The construction of the hydropower station is jointly undertaken by the mixing team of Mozitan reservoir work area, Mozitan reservoir management preparation office and water conservancy installation team. 1September, 958, excavation of powerhouse pit and booster station;1February, 25, 959, first-stage concrete pouring;1June, 959, the powerhouse was poured to the top. The second phase of concrete will be poured in July. At that time, the supply of equipment and materials was insufficient, and the spiral case and water delivery steel pipe were made of steel plates on site. The installation of hydraulic turbine and concrete pouring were carried out in parallel, and the generator rotor was hoisted in sections. Finally, power generation was officially started in 1959 12 17, and the task was completed eight days ahead of schedule. Although the hydropower station is built by three units, due to the quality standard problems in construction, after the completion of the power station project, it basically meets the design specification requirements after testing.
1969 After the flood overtopped the dam in July, the bedrock behind the dams on both banks was washed away, and the leakage of some dam piles increased.
The restoration and reinforcement began on June 1969 and was undertaken by the construction and installation detachment of Anhui Provincial Water Resources Department, and was completed on June 1970.
Fourthly, compensation for relocation of flooded areas.
1June, 1956, Huai Committee approved the compensation scope for the inundation and relocation of Mozitan Reservoir: "All the land below the elevation of 190 meters will be relocated without using the land; Houses with an elevation of 190 ~ 198 meters will not move, and the land will be used as usual. " According to the investigation, 4898.6 mu of cultivated land and 569 1.6 mu of mountain forest were flooded in the whole flooded area; Flooded 3009 houses; There are 1250 households and 54 16 people who need to be relocated and resettled. The above figures were forwarded by the CPC Lu 'an prefectural committee to the CPC Anhui Provincial Committee and the Huaihe River Control Committee, and were approved by the CPC Anhui Provincial Committee on June 29th, 956+165438+. According to the principle of "nearby resettlement, overall planning, collective migration, decentralized cooperation, consolidation and improvement of cooperatives, development of diversified production, increased investment and improvement of life" determined by Anhui Provincial Party Committee and Lu 'an District Committee, the approved compensation subsidy fund is * * * 2 16 1387 yuan. /kloc-0 started the relocation and resettlement in September 1956, and/kloc-0 basically ended in February 1956. According to the survey of 1984, the production income of immigrants in reservoir areas is generally about a quarter lower than that in non-reservoir areas, and 45% of immigrants have not solved the problem of food and clothing. Since 198 1, Huoshan county has adjusted its industrial structure according to the principle of paying equal attention to resource development, utilization and protection, taking into account economic, social and ecological benefits. Return part of the extracted power generation income to the reservoir area for productive development. This work is being implemented year by year, and some results have been achieved.
Verb (abbreviation for verb) management
1April, 958, the project management and preparation office of Mozitan Reservoir in Foziling was established. After the power generation of the hydropower station, Mozitan Hydropower Station of Foziling Hydropower Station in Anhui Province was established in May 5438+0960+ 10, which is in charge of reservoirs and power stations, and has a biotechnology unit and a maintenance team. March 196 1 changed to mozitan substation of foziling hydropower station.
In the early stage of reservoir management, there were rules and regulations such as Dam Observation System and Reservoir Dispatching Standard. In the future, the management unit took power generation production as the center and formulated some systems around safe power generation. It was destroyed in the Cultural Revolution. After the "Cultural Revolution", it gradually recovered. 1984, when the enterprise was restructured, the "post and economic responsibility system" was established.
After the dam begins to store water, hydrological observation, dam top plane displacement observation, dam foundation settlement observation, seepage observation and dam body crack observation are set up. Hydrological test shall be undertaken by hydrological station. There are six hydrological and rainfall stations in the reservoir area, such as Huangwei River and Kuotan River, to observe hydrology, flow, sediment concentration and rainfall.
The normal vertical line method is used to observe the plane displacement of dam crest. The plane displacement of dam crest is related to reservoir water level, temperature, concrete shrinkage and creep and foundation deformation. The observation results show that concrete temperature and reservoir water level have great influence on displacement. Through the observation before and after the dam overflow, there is no abnormal phenomenon in the displacement change.
The settlement of dam foundation is observed by carl zeiss precise level. The settlement of dam foundation is affected by the change of reservoir water level, and the observation results show that the dam works normally.
After the dam was completed, cracks appeared in the dam body one after another. After years of operation, the cracks are not serious. The shrinkage joint of the pile cracked. 1963 asphalt waterproof layer is used to repair the cracks on the upstream surface, and sprayed concrete is used to treat the seepage of rib pier, which has achieved good results. After the overflow of the dam at 1969, there is no obvious change in cracks and seepage.
By observing the dam foundation, the overall seepage is not large. 1964, 123 drainage holes were drilled on both sides of the rockfill; 1966 curtain grouting is carried out on the slopes on both sides of the upstream. After the dam overflowed at 1969, the seepage flow behind the dam increased, but the destructive displacement of bedrock did not occur due to the leakage of dam foundation. During the reconstruction and reinforcement of 1970, three measures were taken, including adding deep hole curtain, deep hole consolidation and drilling drainage holes, and the water seepage situation was improved.
After the completion of the safety reinforcement and heightening project in Foziling, the recent flood control standard only reaches 1000. The flood control dispatching principles of Mozitan Reservoir are as follows: the water level of Foziling Reservoir is lower than 12 1 m, the water level of Mozitan Reservoir exceeds the limited water level in flood season 177 m, the unit is full, and the tunnel is opened for flood discharge; When the water level of Foziling Reservoir reaches 65,438+0,265,438+0 m, Mozitan Reservoir will not only generate electricity and discharge water, but also close tunnels and spillway to store flood for Foziling Reservoir. When the water level of Mozitan Reservoir reaches 202 meters, tunnels and spillway will be opened for flood discharge to ensure the safety of Mozitan Reservoir.
Since the reservoir impounded to 1988, the peak flow of more than 1000 cubic meters per second has been impounded 12 years. Except 1969, the flow under the dam is 3 160 cubic meters per second. In other years, only power generation water is discharged or tunnels are opened for flood discharge, which ensures the flood control safety of Foziling Reservoir. It began to rain in July 1, 65438, 0969, and by July 7, it had rained 229.2 mm above Mozitan Reservoir. At 20: 00 on the 7th, the water level of the reservoir exceeded the limited water level in flood season, reaching 1.8 1.4m, and the flood discharge failed in time. By 12, the accumulated rainfall was 402.9mm. At 20 o'clock on July 13, the water level rose to192.9m.. In order to stagger the flood peak of the downstream Foziling Reservoir, the tunnel has not been opened for flood discharge.
14, 10, the reservoir water level soared to 199.66 meters, and the inflow reached 4000 cubic meters per second, so the tunnel was opened for flood discharge. When the gate is opened to two-thirds height, the power supply is interrupted. At this time, the Foziling Reservoir has overflowed the dam and communication has been interrupted. The water level of Mozitan Reservoir is still rising. 1 1, it is decided to open the spillway gate manually. At 13, the water level of the reservoir is close to the dam crest, and the flood overflows the dam crest at 13. 18, the dam overflowed for 4 hours and 48 minutes, and the highest water level of the reservoir exceeded the top of the breakwater wall by 0.48 meters. The maximum inflow peak flow of this flood is 5780 cubic meters per second. The main reason of dam overflow is that Foziling Reservoir has not been regulated according to regulations.
Degree, the water level is too high, so that there is no flood discharge when the flood could have been discharged, and then the flood peak of Foziling Reservoir is stored; The power supply was interrupted during the flood discharge, and the discharge was not so good. Secondly, it is also an important reason that there is no standby power supply when flood discharge equipment is turned on. Mozitan Reservoir regulates runoff, which improves the regulation performance of Foziling Reservoir. Mozitan, Foziling and Xianghongdian Reservoir jointly irrigate the Pi River irrigation area, reaching 1988, with a total of11000000 mu. The operation of Mozitan Hydropower Station has reached 1988, and the cumulative power generation has reached13.6 billion kWh.