According to the actual situation of a water conservancy and hydropower project, on the basis of briefly introducing its temporary cofferdam construction, it deeply analyzes its sluice construction technology, including earthwork engineering, formwork engineering, steel bar engineering and concrete engineering, and finally concludes that the sluice construction of this project is successfully completed, and the adopted construction technology is reasonable and feasible, which has reference value.
Water conservancy and hydropower projects; Sluice construction technology
Sluice is an important part of water conservancy and hydropower project, and its construction quality plays a decisive role in the overall quality of the project and also affects the basic functions of the project. Therefore, relevant personnel must attach great importance to it and adopt reasonable and feasible technical methods to ensure the construction quality of the sluice.
1 project overview
A water conservancy and hydropower project is equipped with a flood gate with a clear width of 4.0m and a steel gate with a height of 4.7m. The main hoisting equipment is QPQ- 160(kN) single hoisting hoist. According to the actual situation of this project, the sluice construction technology is analyzed as follows.
2 temporary cofferdam
2. 1 section design
The water level ranges from 9.00 to 9.50 m from June 10 in this year to June 10 in the following year. After comprehensive consideration of safety factor, water level, wind and waves and other factors, the top elevation of the outer cofferdam is determined to be 10.5m, the width is determined to be 4.0m, and the slope of 1: 4 is set inward. On the water side, in order to resist the erosion of wind and waves, the method of laying ponchos is adopted. A wave-proof wall with soil bags is set at the outer side of the top, with a height of 50cm, and a filter layer with bagged stones is set at the foot of the inner slope, with a height and width of 1.0m and 0.5m respectively. Because the inner cofferdam is not affected by wind and waves, its top height is determined to be 8.5m, its width is determined to be 4.0m, and its outer side is 1: 4 slope [1].
2.2 Cofferdam Section
2.3 Cofferdam Filling
(1) Filling method is mainly adopted, which is constructed by two excavators. According to the site conditions and progress requirements, filling can be carried out on one side or both sides at the same time.
(2) After filling the water surface, fill the soil in layers with a thickness of 30cm. The particle size of the filler used should be controlled within 5cm and compacted by layers. After acceptance, the upper layer shall be filled.
(3) The filling material is embankment earthwork. Before filling, check the actual water content of soil materials, and the construction can only be carried out within the allowable range, otherwise the compaction degree will be affected [2].
(4) After the filling is completed, it will be crushed by bulldozer.
2.4 Cofferdam Removal
Before the completion of the project, the cofferdam shall be removed, and the removed water part can be used for backfilling, and the underwater part shall be transported to the designated place for storage in time, and it is not allowed to be piled up on site for a long time. 2.5 Decomposition method Each culvert gate shall be excavated once, and divided into inlet, outlet and culvert body. The culvert body shall be constructed first, and then the inlet and outlet sections shall be constructed [3].
3 Earthwork
3. 1 excavation construction
(1) Before excavation, set out elevation control piles according to the requirements of drawings, and locate them according to the excavation line.
(2) The excavation shall be carried out in layers and sections, the temporary drainage ditch shall be arranged step by step, and the excavation shall be carried out step by step. The basement is mechanically excavated to a thickness of 20cm, and then manually excavated.
(3) Excavation shall be carried out in sections from top to bottom, and excavation is prohibited. A certain slope should be formed during excavation to facilitate drainage.
(4) The site soil contains a large amount of sand. In order to ensure the construction safety, two temporary platforms need to be set up.
3.2 Backfill construction
After the earthwork is backfilled, it will be leveled and rolled by bulldozer. For the sections that cannot be leveled and rolled by local machinery, manual rammer shall be used for tamping. After the construction is completed, the degree of compaction shall be checked, and the degree of compaction must meet the design requirements.
4 template engineering
4. 1 system design
This project mainly adopts wood grain, with high-quality wood as raw material, and the panel thickness should be above 10mm, and it should be kept flat as far as possible, without unevenness and wrinkles, and should be checked before use.
4.2 template assembly
For a single template, its size is 1500mm×300mm, and the joints shall be filled with sponge to avoid slurry leakage. Two adjacent templates are connected by through bolts, and after assembly, the isolation agent is evenly coated on the inner side to prevent it from bonding with concrete and affecting the appearance quality of the structure [4].
4.3 formwork support
In order to make the structural strength of the formwork meet the requirements, it is necessary to reinforce the back, and the spacing in the horizontal and vertical directions is 800mm and 1000mm respectively. In addition, in order to avoid the movement of the formwork lower mouth, it is necessary to set anchor piles at the spacing of 1000mm at the lower mouth and connect them with short steel pipes in the middle.
4.4 template removal
In the process of dismantling the formwork, not only the drawings should be strictly followed, but also the following points should be noted:
(1) When dismantling the non-bearing side formwork, it shall be carried out when the actual strength of concrete reaches the edges and corners, and it will not be damaged due to formwork removal.
(2) When dismantling the "side formwork" in columns, piers and walls, the actual strength of concrete should reach above 3.5MPa, and formwork removal is prohibited when the strength is lower than this value.
(3) The concrete strength should be strictly checked during the process of removing the bottom formwork.
5 reinforcement engineering
5. 1 material control
Check the quality certificate when the steel bar enters the site, and the on-site supervision engineer will conduct inspection, and take samples for inspection according to the actual requirements to determine whether the tensile force and elongation of the steel bar meet the requirements. If the steel bar test results do not meet the requirements, it is not allowed to be used in construction, and the manufacturer should be contacted immediately for treatment.
5.2 steel processing
(1) The surface of reinforcement shall be kept clean and free from damage, and rust and pollution shall be removed before use. If the reinforcement has particles and old rust, it is not allowed to be used in construction [5].
(2) Steel bars must be straight and without bending, and the following regulations should be strictly observed when straightening: ① When straightening steel bars by cold drawing, the cold drawing rate of Grade I steel bars should be controlled within 4%; For grade II and III steel bars, the cold drawing rate should be controlled within 65438 0%; (2) The machining size should meet the requirements of the drawings. After the machining is completed, verify whether the deviation is within the ideal range.
5.3 steel binding
Before construction, lofting and blanking shall be carried out according to relevant technical specifications and combined with design requirements. Twist two iron wires into four strands, which are used for binding iron wires, so as to ensure that the binding position is accurate and the joint is in the compression zone. If it is impossible to distinguish between compression zone and tension zone during construction, it should be treated as tension zone.
5.4 reinforced protective layer
After the side formwork is supported, precast mortar blocks with no lower than concrete grade shall be bound on the side of the stressed steel formwork. According to the construction drawing, the thickness of the cushion block is determined, and the iron wire is embedded in it to create the necessary conditions for subsequent binding. After the steel bar is installed, it should have sufficient stability and rigidity. Before pouring construction, the specific position of embedded parts should be checked, and any changes should be corrected in time.
6 concrete engineering
6. 1 raw materials
Using ordinary silicon 32.5 cement, the test report must be complete, and its stability and strength can only be tested after arriving at the site, and it can only be used for construction after it is confirmed to be qualified. Yellow sand and gravel should be selected in the nearby yard as far as possible. Before construction, samples shall be taken for inspection under the correct guidance of on-site supervision engineer, and can be used for construction only after they are confirmed to be qualified.
6.2 concrete mixing
JZC-350 mixer is used to mix concrete, which has the advantages of short time, easy quality control and fast unloading speed. When mixing, the slump should be checked. If it is found that it does not meet the requirements, it should be corrected immediately after finding out the reasons. Because the mixer is used for mixing, the mixing time is controlled at 90 s.
6.3 concrete transportation and pouring
Concrete is transported by double rubber-tyred vehicles, and the vertical transportation system is mainly supported by scaffolding. Its first climbing height should be controlled within 2.5m, and the total transportation distance should not exceed 150m. In order to prevent concrete segregation due to vibration, the pavement must be kept flat and clean, and meet the following basic requirements:
(1) Strictly prevent concrete segregation, which will become uneven and affect pouring and vibrating;
(2) Avoid the loss of cement slurry, and the means of transport used cannot absorb water and leak slurry;
(3) Concrete shall not be initially set during transportation, otherwise it will affect the combination of the upper and lower layers, resulting in non-vibrating. Pouring shall be carried out in blocks and layers. When pouring culvert concrete, ensure that the concrete on both sides rises evenly until it is completely horizontal. The concrete put into storage during pouring must meet the quality requirements. If the workability cannot meet the requirements, it is necessary to strengthen vibration to ensure the construction quality [6].
6.4 concrete curing
Strictly control the temperature stress after pouring, and the temperature difference between inside and outside must be less than 25℃. Immediately after pouring, cover a layer of plastic film for water conservation, and generally the effective maintenance time shall not be less than 14d. After the actual strength of concrete meets the requirements, dismantle the formwork and start comprehensive maintenance to make the appearance quality of concrete meet the requirements.
7 concluding remarks
So far, the sluice construction of this project has been successfully completed. After testing, all technical indexes meet the expected requirements, which shows that the above construction technology is reasonable and feasible, which can ensure the quality of the project and provide reliable reference for similar projects.
refer to
Li Xiuling, Meng Fansheng, Zhong Chongsheng. Analysis of sluice construction technology and quality control [J]. Scientific and technological innovation and application, 20 14 (6): 188.
Yan Li. Sluice construction technology in water conservancy projects [J]. Water conservancy technical supervision, 20 1 1, 19 (6): 72 ~ 74.
Jin changqiang. Management measures of sluice construction in water conservancy construction [J]. Scientific and technological innovation and application, 20 12 (22): 197.
Xiong Zhijun, Wu Jialun. Analysis of sluice construction management measures in water conservancy construction [J]. Science and Technology Vision, 20 14 (9): 30 1.
Subo Analysis of sluice construction management measures in water conservancy construction [J]. Prospect of science and technology, 2015,25 (35): 26 ~ 27.
Ke Xia Heng. Analysis of sluice construction technology in water conservancy and hydropower projects [J]. China Dwellings (next issue), 20 14 (06): 28 ~ 29.
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