I general provisions 1. Compilation basis: Gan is based on Construction Drawing Design Document of Sifangshan Reservoir Project in Nanxian County, Bidding Document, Implementation Rules for Supplementary Supervision of Concrete Pavement on Dam Top of Sifangshan Reservoir in gannan county (2009), Organizational Design and Technical Measures of Construction Unit, etc. 2. Scope of application: These supervision rules are applicable to the concrete road at the dam top of Sifangshan Reservoir reinforcement project. 3. All technical standards, codes and regulations used within the scope of the project are applicable, including:-Specification for construction supervision of water conservancy construction projects (SL 288-2003)- Specification for hydraulic concrete construction (SDJ 207-82)- Technical specification for highway subgrade construction (JTJ 033-95)- Technical specification for highway cement concrete pavement construction (JTG F30-2003)- Foundation excavation 1. 1 earthwork excavation shall be carried out from top to bottom according to the design drawings and the earthwork excavation section approved by the supervision engineer. After the topsoil and turf are cleared, they should be dumped in the designated place for stacking. After excavation, the slope shall remain stable and shall not cause damage or interference to adjacent structures or facilities. 1.2 subgrade compaction: determine the compaction thickness, compaction times and the best compaction machinery combination through the test road. After the subgrade works are completed one after another, all structures have been completed, and the soil foundation is compacted and shaped when the optimum water content is 2%. For the loose soil after paving, use light vibratory roller to carry out static pressure, and after the subgrade is reshaped and backfilled 1.3, carry out subgrade reshaping, cut off the overfilled parts on both sides of subgrade, carry out slope reshaping and leveling, and strictly level the top surface of subgrade with bulldozer until the indexes such as road arch, elevation, width and flatness meet the requirements of technical specifications. 2. Cement stabilized gravel at the base of pavement. (1) The thickness is 20 cm, the cement content is 6%, and the degree of compaction is K > 95%. The "factory mixing method" is adopted. Before construction, the mixture of this layer shall be subjected to heavy compaction test according to the designed mixture ratio to obtain the maximum dry bulk density and the best water content, and the test data and information shall be submitted to the supervision engineer for approval. Before large-scale paving, the test section should be filled according to the specification requirements, and the required loose paving coefficient and construction technology should be determined according to the design mixture ratio and layer thickness. ⑵ The upgraded macadam should be graded well, the nominal maximum particle size of cement stabilized macadam and graded macadam is 19.0mm, the fine particle content less than 0.075 should not be greater than 5%, the particle content less than 4.75mm should not be greater than 5%, the liquid limit of fine grained soil should be less than 25%, and the plasticity index should be less than 6. The water content and particle composition of the mixture meet the specified requirements, and the mixed 6% cement stabilized macadam shall be transported to the paving site as soon as possible. When the transportation distance is far away and the temperature is high, the transportation vehicles should be covered with tarpaulins to avoid excessive evaporation of water. Paving should be done with a paver, and a special person should be assigned behind the paver to eliminate the segregation of coarse and fine aggregates, especially the local "nests" of coarse aggregates should be removed immediately and filled with new mixture. Paving shall be carried out in strict accordance with the laid elevation lines (the laid imaginary square elevation). Rake flat by hand. After initial leveling, the elevation of each section point (left, middle and right) shall be measured. Remove the bulldozer of MIG line, stabilize the pressure and measure again. After manual leveling is qualified, it can be rolled. The daily work seam is made into a transverse seam. Longitudinal joints must be connected vertically, and oblique joints are strictly prohibited. According to the rolling machinery and rolling times of the test section, the tester will check the compaction degree at any time until it meets the requirements. If there are wheel tracks, they can be eliminated by static pressure. The straight section is rolled by staggered wheels from the shoulders on both sides to the center of the road, and the flat curve section is rolled by staggered wheels from the inner shoulder to the outer road. Cement must be rolled before initial setting. Where the roller can't work, it should be tamped with machines and tools, and it should always be moist during the rolling process. The water content of the mixture should be controlled at the optimum water content. It is forbidden for the roller to turn around or brake suddenly on the completed or rolling section. Any mixture left for more than 2 hours or raining should be discarded. In the two sections of construction on the same day, the joints overlap and mix, and in the two sections of construction on the next day, after the last section is rolled every day, a vertical facade is dug horizontally at the end of cement gravel layer by hand to remove loose materials. During the construction on the second day, sprinkling water can be directly connected with the first day. Curing: Cure immediately after rolling, and cover the surface with water (geotextile or sacks, etc.). ) to keep moisture. Sprinkling should be carried out 2-3 hours after the completion of rolling (depending on the temperature), and the curing time should be no less than 7 days. The surface of water-stabilized gravel must be kept wet continuously, and all vehicles are prohibited from passing except sprinklers. The driving speed shall not exceed 15km/h, and it shall be carried out immediately after the construction. Attention should be paid to the construction when the temperature is below 5℃ or it snows; Be careful not to construct in rainy days, and the mixture should be mixed intensively and meet the requirements of the test before it can be transported; Pay attention to the influence of temperature and transportation. Generally, the water content required for ex-factory materials is about 2% higher than the optimal water content. 3. Concrete Pavement Construction The concrete dam crest pavement is 20 cm thick and 5.73m wide. The strength of concrete is C30F200. Formwork support: after the grass-roots units pass the inspection and report to the supervision engineer for approval, the steel formwork will be set out for construction, and the gaps will be filled with mortar to prevent slurry leakage. After the formwork is supported, it shall be submitted to the supervision engineer for approval. Set a control pile every 10M to accurately control the elevation. The template must be firm. Mixing: Use a forced electronic metering mixer. Before mixing, accurately adjust the dosage of cement, coarse and fine aggregate, water and other aggregates according to the requirements of mixing ratio, so as to ensure mixing production. The mixture is uniform and stable, with good workability and cohesiveness. Proportioning accuracy is: water and cement 3%, admixture 2%. Check the accuracy of ingredients at least twice per shift, and check the slump twice a day. Transportation: The transportation equipment and capacity of concrete should be adapted to the mixing and pouring capacity, the concrete situation on the warehouse surface and the needs of formwork, so as to ensure the transportation quality of concrete and avoid segregation, slurry leakage, serious bleeding and excessive slump loss during transportation. The longest allowable time for the mixture to be discharged from the mixer and poured shall be determined according to the initial setting time of cement and the construction temperature. Segregation shall be prevented during transportation, and the unloading height during unloading and paving shall not exceed1.5m. Paving and vibrating: After the concrete is transported to the paving site, it shall be directly poured into the installed road groove and filled evenly manually. In the process of paving, when it comes to the installation of steel bars, a layer of concrete mixture should be paved at the bottom first, and the paving height should be pre-added with a certain sinking height according to the design position of steel bars. Vibrate the paved concrete quickly and evenly with flat vibrator and plug-in vibrator. The effective depth of vibrator shall not be less than 18cm, and the same position shall not be less than 20S. The moving distance of internal vibrator should not be greater than 1.5 times of its action radius, and the distance from formwork should not be greater than 0.5 times of its action radius, and collision between formwork and steel bars should be avoided. When vibrating at the same position, there will be no bubbles and cement slurry. Further vibration leveling with paver, the vibrating beam travels back and forth for 2 ~ 3 times, so that the surface is submerged and bubbles are expelled. 4. Before the initial setting period of napping, napping should be carried out without sticking hands or solidification. Should be uniform and beautiful, perpendicular to the direction of the route, and the depth is appropriate. Check the flatness in time after galling, and deal with individual unevenness. 5. After the concrete construction is completed and the temperature reaches 250 hours, the joints shall be cut. Don't trim the edges, master the successful experience, and someone will take care of it. 6. After health-keeping sewing, enter the health-keeping stage, cover it with sacks and straw bags, fill it with water with sprinklers for 28 days, close the traffic to prevent human and animal injuries, and assign special personnel to be responsible. 7. Before the joint filling is opened to traffic, it is necessary to send someone to fill the joint filling material thoroughly, so that it is full and dense, and it is not allowed to leak slurry or run slurry, which will affect the appearance, and someone will be in charge. 8. Precast concrete is used for kerb construction. The structural dimension is 12×50×75cm, and the kerbs are flush with the road surface at the dam top. After the pavement concrete and water-stabilized macadam reach a certain strength, the kerb shall be manually chiseled to bury the groove, the line shall be hung, and the joint shall be filled with 1: 3 cement mortar, so that the groove wall will be firmly bonded with kerb and kerb.
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