Discussion on construction and design experience of earth dam in water conservancy project?

It is very important to discuss the construction and design experience of earth dams in water conservancy projects. Knowing more about other people's design experience is very helpful to our own development. Zhong Da Consulting will discuss and explain the construction and design experience of earth dams in water conservancy projects.

1. 1 geological conditions

Before the construction of earth dam of water conservancy project, we should be familiar with and understand the geological structure of dam foundation in design documents. If there are some abnormal conditions in the construction of earth dam, the construction unit, design department and supervision unit should jointly study and discuss and take some feasible measures, so as not to blindly construct regardless of the change of geological conditions, so as not to cause some unnecessary losses.

1.2 meteorological conditions

The regional weather station where the dam site is located should make long-term continuous observation and count the days when precipitation, temperature and other factors occur, so as to determine the influence degree of various factors on the construction. When making the earth dam construction progress plan, we should fully consider the meteorological conditions and appropriately speed up the earth dam construction progress in autumn and spring, because the clay has low water content and suitable temperature in these two seasons, which is beneficial to the rolling work.

2 earth dam construction technology treatment measures

In the construction of earth dam, the construction technology should be treated.

2. 1 dam foundation

The technical treatment of earth dam foundation can effectively prevent dam leakage, and the roots, branches, humus soil and spring soil at the dam foundation should be thoroughly removed.

2.2 Selection and protection of clay yard

When selecting clay materials, it is necessary to understand and analyze the physical properties of clay materials, so that their physical properties can meet the requirements of all aspects of dam materials, the texture of clay materials should be uniform, the storage capacity should be relatively concentrated, and the overall storage capacity should meet the needs of dam filling. In addition, clay materials should be reserved for dam closure, and the glass layer of the yard should be convenient for mining and transportation, so as not to occupy cultivated land as much as possible. Before the rainy season comes, properly improve the drainage conditions of the storage yard, prevent precipitation and groundwater from entering the storage yard, and increase the soil water content. In cold areas, to ensure that the yard has some warm-keeping measures, leaves, hay, snow and other methods can be used to cover it to ensure that the construction in the coming year will not be delayed.

2.3 Damming

The dam should be designed in strict accordance with the relevant regulations, and clay materials with high water content or exceeding the standard are not allowed to enter the dam. Because the shear strength of soil with high water content is also low, certain pore pressure will be generated during the construction of earth dam, which poses a threat to the stability of the dam. Moreover, the soil with high water content can not be crushed, and it is easy to produce a smooth soil contact surface, such as rubber soil, and the permeability coefficient will also increase. In the process of dam construction, if spring soil is found, it should be thoroughly dug up and the paving thickness of earth dam should be strictly controlled. Compacted dry bulk density shall be sampled and tested according to relevant regulations. In addition, soil construction should be arranged in the rainy season as far as possible. If it must be carried out in the rainy season, then it is necessary to choose the appropriate construction method, choose the appropriate soil material and take some rain-proof measures. During construction in rainy season, we should pay more attention to the local weather forecast and rain conditions, loosen the soil on the compaction operation surface in time, and try to avoid water in the operation area.

3 Jiangle Gaotang Hydropower Station Earth Dam Construction Design Analysis

Sichuan Jiangle Gaotang Hydropower Station is the seventh hydropower station in Jinxi River Basin, which is located 2.5km upstream of Gaotang Town in Jiangle County and about 14km upstream of Jiangle Chengguan. Jiangle Gaotang Hydropower Station is a medium-sized water conservancy project with comprehensive benefits such as power generation, flood control and irrigation. Its main components are left bank retaining dam, right bank retaining dam, power station, switch station and sluice. It started in June 2005 and took two years to complete.

3. 1 earth dam building materials

The backfill clay used in the earth dam construction of Jiangle Gaotang Hydropower Station in Sichuan comes from the clay yard on the right bank. The earth material meets the filling standard of earth dam. After consulting the design unit, it will be excavated by excavator, transported to the warehouse surface, rolled by roller and put into project. Thoroughly remove impurities containing grass roots and submit them to the supervision engineer for examination and approval before use. Gravel and drainage prism block ballast in earth dam engineering are all purchased, and qualified gravel and drainage prism block ballast are selected.

3.2 Soil experiment

Before the earth dam filling construction, the compaction test was carried out on the earth material in the borrow site planned by the owner, and the optimum water content and maximum dry density of the earth material in the borrow site were determined. The test project was handed over to the engineering laboratory of Sanming Highway Bureau. After obtaining the optimum water content and maximum dry density of the soil, under the supervision of the supervision engineer, the testers of the central laboratory of Minjiang Bureau and the field testers of Gaotang Project Department carried out the soil bulk density test to determine the paving thickness, compaction times and rolling equipment required for filling the coal seam with clay from the earth dam.

3.3 Earth Dam Construction

Firstly, the total station is used to set out the excavation scope of dam foundation on site, and the target is displayed with a small red flag. The sample is provided by the inspector. Before the earth dam is built, the overburden in the dam foundation should be removed in strict accordance with the design requirements, and excavators should be used from left to right. When some places that are difficult to clean are found, manual cleaning is adopted.

Secondly, after the foundation excavation is completed, the foundation shall be compacted before construction. Legotang Hydropower Station adopts 18t vibratory roller, taking the "S" route, and starts the vibratory roller when walking, so that each block can be rolled for no less than 5 times. When the dam foundation observation instrument is buried, it shall be carried out according to the designed earth dam foundation, and it shall be buried on the two sections of 0+ 13 1 and 0+203 on the right side of the dam respectively.

Thirdly, when pushing the drainage prism block, artificial stacked prisms with the thickness not exceeding 1m are used, and there are no horizontal joints and vertical connections between the prisms. During the construction of sand and gravel drainage body, the sand and gravel drainage body in front of the drainage prism is also piled up manually, and all the sand and gravel materials are purchased from the outside. After piling, spread fine gravel on the surface. Before clay filling, the sand and gravel drainage body is buried behind the dam body, and a layer of geotextile is wrapped inside in strict accordance with the design requirements, and the paving work is completed by the staff. Clay construction should be carried out after paving, and the interval should be shortened as much as possible. If it cannot be done in time, plastic film should be used to cover and protect the surface from sunlight. When filling clay in earth dams, it should be carried out in strict accordance with the technological process. First of all, we should choose a good soil material factory, and the soil material experiment should be reported to the supervisor for approval. Then carry out the filling process experiment, record the experimental data and report it to the supervisor for approval. Finally, the packing shall be transported and rolled, and sampling experiments shall be carried out. After the experimental data are recorded and reported to the supervisor for approval, the next layer of construction can be carried out, that is. Finally, the dam crest construction is carried out. The main projects include wave release strength, drainage ditch and concrete pavement construction. The sequence is pouring breakwater, drainage ditch and concrete pavement. After completion, the downstream surface of the earth dam will be constructed, mainly including turf slope protection, plain concrete edging and drainage ditch at the toe of the prism slope. Before planting turf, plain concrete grids and edges are poured, the foundation is excavated manually, the concrete is transported to the back of the dam by dump trucks, the material is discharged at the top of the dam, and the material is taken manually and transported to the warehouse surface. The drainage ditch at the foot of the downstream drainage prism starts after the drainage prism is stacked, and the foundation is excavated manually. The concrete pouring method is the same as other parts, and the backfill work will be carried out five days after concrete pouring.

conclusion

Through the study of Jiangle Gaotang Hydropower Station, it can be seen that in the process of earth dam construction, all construction procedures should be carried out in strict accordance with relevant regulations. According to the construction test results of Jiangle Gaotang Hydropower Station, the raw materials, weathered soil content, organic matter content and gravel content of earth dam construction meet the relevant standards and requirements. Through the above research and analysis on the construction conditions and technical treatment of earth dam of water conservancy project, it tells us that in the construction design of earth dam of water conservancy project, we must strictly abide by the relevant national norms and standards, and give full play to the value of earth dam construction design in combination with the actual situation of construction.

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