1, principles of channel design for irrigation and water conservancy projects
The channel design of farmland water conservancy projects is mainly carried out according to the following principles: (1) In the process of channel design, it is necessary to ensure the maximum benefit of unit irrigation water, in other words, to improve the irrigation area and irrigation effect of unit water. (2) Waterway design should be combined with flood control, flood control, drainage, shipping, hydropower, urban industrial production and domestic water, and should meet the requirements of economic and social development to ensure comprehensive management of drought and flood disasters. (3) Channel design should ensure the balance of irrigation water resources, analyze irrigation efficiency, and then choose a reasonable and scientific irrigation channel design scheme.
2. Key points of channel design
2. 1 Hydraulic calculation In the channel flow design, considering that its main tasks are irrigation and water delivery, the design flow is all agricultural irrigation, and the channel irrigation method is designed as continuous irrigation, and 30% increased flow is considered in the flow design. At the same time, considering the selection of engineering measures, the lining structure is C 15 concrete channel with roughness of 0.0 17. The design flow of the channel is calculated and determined according to the following formula: where: Q—— the design flow of the channel (m3/s); Q- design irrigation rate (m3/s? Ten thousand mu), the design net irrigation rate of the project area is 0.6 1(m3/(s? Ten thousand mu)); A—— Irrigation area of canal section (ten thousand mu); J- channel flow increase coefficient, taking1.3; η-irrigation water utilization coefficient, 0.70.
2.2 Channel section design In order to save land resources, reduce channel engineering quantity, and then reduce the cost, combined with the actual terrain and geological soil, the channel section is optimized under the original section. 2.2. 1 profile design The design of profile is mainly the design of channel bottom slope. The channel bottom slope should be combined with the original channel bottom slope as far as possible to effectively avoid the occurrence of a large number of excavation and filling; For the continuous channel, it is necessary to avoid a lot of digging and filling, but also to meet the elevation requirements of channel irrigation and drainage. Most of the projects are channel reconstruction and anti-seepage lining projects. Measures such as reconstruction, lining, repair and anti-seepage are taken to improve the water delivery capacity of the channel and meet the needs of downstream agriculture. Therefore, the end face design of the channel is to take the elevation of the entrance and exit of the canal system building as a fixed elevation, so as to calculate the longitudinal slope of the channel section. 2.2.2 Roughness value is very important in channel section design. According to relevant specifications and actual conditions, the flatness of 15 concrete in this project is 0.0 17, and that of M7.5 mortar masonry is 0.025. 2.2.3 Velocity Control In order to ensure that the channel does not scour and deposit, a reasonable velocity should be selected in the channel section design. Too slow flow rate will lead to river siltation, and too fast flow rate will cause scouring effect, which will adversely affect the water intake of the next level of river, especially the river line in the engineering area is bent and the water flow is too fast, which will adversely affect the stability of river slope. The design of channel section should consider the above aspects at the same time and choose the optimal section.
2.3 The building design adopts C 15 concrete trapezoidal lining section for geological stability section, and retaining wall combined with stone-buried concrete trapezoidal lining section for collapse section. The design of all kinds of drainage buildings should be reasonable in structure, safe and applicable, convenient for construction and management, and their beautiful shapes can be considered when conditions and needs permit. The design flow of open ditch drainage at all levels should be based on its control area and runoff yield and confluence conditions, and the flow requirements of other utilization modes should also be considered when the channels for comprehensive utilization of drainage and irrigation meet the design flow of drainage. According to the practical experience of local or nearby similar areas, combined with the factors such as crop types, soil characteristics, hydrogeology and meteorological conditions in the treatment area, various open drainage ditches are selected according to the topographic conditions of the treatment area, and the route selection is based on the principles of high water and high drainage, low water and low drainage, nearby drainage and striving for self-flow.
3, irrigation and water conservancy channel construction management
3. 1 Site investigation and temporary facilities construction go deep into the site to know the construction geological conditions and hydrological data in time, set up the laboratory reasonably, and do a good job in wind, water and electricity systems and temporary facilities, so as to lay the foundation for ensuring the smooth progress of the project and improving the construction quality.
3.2 Equipment and materials are prepared to strengthen the quality inspection and re-inspection of raw materials and semi-finished products, obtain the relevant materials list, factory certificate and other materials in time, and save and report them according to regulations. Seriously organize the mobilization management of equipment required for construction, and strengthen the normal inspection and maintenance of mechanical equipment. Strictly control materials. Raw materials, semi-finished products and various pre-processed products used in the project should adhere to the inspection system. (1) Having a certificate of approval for construction products; (2) There are quality certificates and test reports; ③ The finished products or products shall be identified. To prevent unqualified materials and products from being used in engineering. When necessary, re-examine the materials with qualified material certificates, and copy the material certificates in time according to the parts used for traceability. This is an important work, which must be constantly grasped and run through the whole process of engineering construction.
3.3 Prepare the construction operation design of key working procedures and special working procedures. According to the nature, scale, characteristics and structural form of the process, the chief engineer shall organize the preparation of work instructions in advance, the engineering management department shall be responsible for technical disclosure, and the quality and safety inspector shall check and supervise. Do a good job in quality requirements, operating procedures, quality patrol inspection and concealed engineering inspection during construction. For example, put forward countermeasures for concrete quality, require concrete quality to be in a controlled and stable state, and formulate monitoring measures.
3.4 Adhere to the system of self-inspection, mutual inspection and preview. Operators of each type of work should consciously check themselves, and team members should check each other; Before the previous working procedure is transferred to the next working procedure, the person in charge of each type of work shall conduct handover inspection. In this way, problems can be found and corrected in time, the unqualified products produced in the construction of subdivisional work can be eliminated in the bud, and the quality of subdivisional work can be guaranteed, thus ensuring the overall quality of subdivisional work.
3.5 Pay close attention to the prevention and control of common quality defects and the protection of finished products, and control the "roughness" and "crack" of structural parts; The plane facade should not "leak" or "change". Effective measures such as "protection", "package", "cover" and "sealing" should be taken to protect finished products. "Protection" is to protect the finished product from being damaged by trampling; "Bao" is to prevent and control the pollution of Bao.
3.6 The materials (cement) used in the construction key point control project shall have the product certificate and product performance test report issued by the manufacturer; Coarse aggregate and sand should be tested for performance, and the stone used should meet the requirements of the specification. The quality control level of masonry engineering in this project is Grade A, and the setting-out size should be checked before foundation laying. The allowable deviation of axis and elevation should meet the requirements and should not be greater than or less than10 mm; ; The laying sequence shall meet the following requirements: ① When the foundation elevation is low, it shall be laid from the lower part and from the higher part to the lower part, and the overlapping length shall not be less than the height of the enlarged part of the foundation; (2) The corner and junction of masonry should be built at the same time. If it cannot be built at the same time, it should be left and connected according to regulations. Cement used in concrete and masonry mortar should be qualified products, and concrete mixing should be carried out in strict accordance with the corresponding norms and regulations; Sand materials shall not contain harmful sundries, and the silt content shall not exceed 5%. Mortar should be used as it is mixed, and the mixed mortar should be used up within 3h. The strength of mortar test block should meet the requirements of design specification. Stone used for masonry should be solid in texture, free from weathering, peeling and cracks, uniform in color and fresh in mouth. The width, length and thickness of the mouth surface of the seat plate shall not be less than 20 cm, 30 cm and 30 cm respectively. Parallel up and down, roughly flat, without sharp corners and thin edges. Mortar masonry should meet the following requirements: ① Before masonry, the dirt on the stones should be washed out of the masonry, and the surface of the masonry should be kept wet during masonry. (2) The mortar shall be laid in layers, with the thickness of 3~5cm, and it shall be laid with the increase of the spread. Mortar in mortar joint shall be compacted with flat iron. (3) The upper and lower floors of masonry should be staggered, and masonry should be laid in rows. Masonry should be built inside and outside, staggered up and down, pulled by stones and cut into pieces, and masonry joints should be horizontal and vertical. The staggered distance between upper and lower vertical joints should not be less than 10cm, and there should be no vertical joints between upper and lower Shi Ding; (4) After the initial setting of mortar, if you need to move the paved stones, the original mortar should be cleaned and paved again. (5) joint should be filled with mortar, fullness is not less than 95%. 6. After masonry, the side wall and bottom plate of the pool must be smooth and straight, and the arc must be smooth and natural.
I believe that after the above introduction, everyone has a certain understanding of the design points of farmland water conservancy channels. Welcome to Zhong Da for more information.
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