Keywords: channel; Lining works; Construction method
1 construction preparation
Fully do a good job in the layout of construction sites such as material yard and mixing station, as well as the preparation of electricity, water, roads, machines and equipment for construction. Testing and commissioning of testing and construction equipment shall be carried out. If it does not meet the requirements, it shall be replaced or adjusted. Permanent and necessary temporary drainage facilities should also be made to ensure that the lining channel meets the construction requirements.
2 channel lining engineering construction method
2. 1 measuring unreeling
Before excavation, survey and setting-out, the machinery shall be marked with sideline piles and leveling points every 50m, and the sideline shall be clearly marked with lime and bamboo poles. Manual excavation shall be marked with sideline piles and leveling points every 20m, and the sideline shall be clearly marked with lime and bamboo poles.
2.2 Earthwork excavation
Trench excavation adopts backhoe excavator combined with manual trimming. For areas with water, water retaining cofferdams should be laid first. For shallow buried section, one-time excavation can be used to the design elevation, and then the bottom can be cleaned manually. According to the trend of each channel, the excavation point is excavated from the downstream to the upstream of the channel, and according to the geological conditions and water seepage, water collection wells are set at regular intervals to drain water with submersible pumps. When digging to the design elevation, personnel shall be arranged in time to remove the residual soil and dredge the accumulated water in the ditch to facilitate drainage and elimination. For channels with poor geological conditions, appropriate baffles should be used for expansion and reinforcement to prevent collapse.
2.3 earthwork backfill compaction
(1) Before compaction, the roots, silt, sapropelic mud, garbage and hidden underground masonry in the channel bed should be removed first.
(2) The compaction thickness of the canal slope from the bottom of the canal to the inner side of the dike is 1.5m, and the compaction size from the top of the dike is 1m, showing an inclined trapezoid shape.
(3) Backfill compaction adopts the method of layered pedal compaction, and the thickness of each layer of soil shall be ≤30cm, and the soil shall be evenly spread. If the soil is dry, water should be sprayed to adjust the soil water content. If the soil water content is large, drainage, drying and soil replacement should be adopted to control the water content within a suitable range.
(4) The rammer is a frog rammer or other machinery that can meet the same quality requirements, and the column stone rammer shall not be used. The times of layered compaction shall not be less than 4 times, so as to prevent the phenomenon that pressure leakage, virtual soil layer and rubber soil do not meet the quality requirements. The dry bulk density of compacted soil samples shall not be less than 1.55t/m3. A backfilled and compacted working face shall not be less than 100m, and a slope cutting amount of 20-30cm shall be reserved in the ditch.
2.4 River bed formation
In order to avoid dust and damage caused by dry surface, trampling by human factors, rain erosion, etc., the slope of the groove should be cut the day before the concrete is poured in place. When cutting slope, the elevation and surface smoothness should be strictly controlled. Hand thread hanging and fine cutting. If the slope is cut too much, it shall not be backfilled with floating soil, and it shall be filled with concrete with the same label as cast-in-place. The allowable deviation of groove bottom and inner slope flatness is 0.5cm.
2.5 sand cushion construction
After the slope flatness meets the requirements, sand cushion shall be laid.
2.6 expansion joint fixation
The expansion joints are made of wood boards with good materials and meet the requirements in size and specifications, and are dipped in clear oil to play an anti-corrosion role. Before construction, measure and set out according to the construction drawings, and install, fix and correct according to the measuring points and lines. During the construction period, adequate temporary fixing facilities shall be provided to prevent deformation and inclination. Expansion joint construction should be carried out in strict accordance with the operating procedures to protect the plate and prevent the plate from being damaged. When the plates are installed and spliced on site, attention should be paid to the splicing quality, and the joints should be smooth and tight to prevent the wrong platform and ensure that the template installation meets the specifications and technical requirements.
2.7 steel binding
Before construction, lofting and blanking processing should be carried out according to the requirements of construction specifications and design requirements, including straightening, derusting, stretching, blanking, shearing and bending. Steel binding adopts 22# lead wire twisted into four strands as binding wire. Binding is firm and accurate. The binding joint is in tension, and the compression zone should be regarded as the joint in tension zone.
2.8 concrete pouring
2.8. 1 Building materials (1) Cement shall be inspected before leaving the factory, and the factory certificate and re-inspection data shall be attached to the invoice. Transportation and storage should meet the requirements of the specification. After being transported to the construction site, samples shall be taken for inspection. If the test fails, it is forbidden to use it.
(2) All potable water can be used for concrete mixing. River water or groundwater should be used, and its water content substances should meet the specification requirements, and should not affect the increase of workability and strength of concrete, and cause corrosion of steel bars and concrete.
(3) The stone with good texture, reasonable gradation, cleanliness and no impurities shall be used on site. Yellow sand adopts Yihe high-quality sand, which ensures excellent texture, and its gradation, density, fineness modulus and impurity content meet the requirements of the specification. Aggregates purchased on site shall be tested for mud content, specific gravity and other indicators according to the specification requirements, and different aggregates shall be stacked separately. It is forbidden to mix and mix with soil.
2.8.2 The mix proportion of concrete should be designed according to the different construction sites and concrete strength. The dosage of cement and water and the dosage of fine aggregate and fine aggregate should be determined by gravimetric method, and the mixture ratio test should be carried out. Three groups of tests shall be conducted for each kind of concrete. Each group should prepare three (20 * 20 * 20 cm) concrete strength specimens for 7 days and 28 days, and send them to the laboratory for compressive test.
2.8.3 Concrete mixing According to the distance between the construction site and the concrete mixing station and the volume of concrete, js500 forced mixer, electronic batching and mechanical feeding are adopted respectively. When mixing concrete, the ingredients shall be made in strict accordance with the specified ingredient list. If any discrepancy is found, the reason shall be found out immediately and corrected. Unqualified concrete shall be scrapped and prohibited from storage.
2.8.4 Concrete transportation Concrete transportation is assisted by dump trucks, rickshaws and manual lifting. The transportation distance shall not exceed 200 meters to prevent the concrete from being subjected to strong vibration during transportation. It is required that the transportation road surface or driveway surface should be kept flat and clean at any time. During the whole transportation process, the following basic requirements shall be met:
(1) Prevent concrete mixture from segregation, otherwise it will lose uniformity and it will be difficult to compact by vibrating.
(2) In order to prevent the loss of cement mortar, it is forbidden to leak slurry or absorb water when transporting concrete tools.
(3) Prevent the plasticity of concrete from decreasing after initial setting, which will affect the combination of upper and lower layers and make it impossible to vibrate and compact.
2.8.5 Concrete pouring shall be transported to the basement by sliding chute, and compacted by vibrating rammer to ensure even mixing and compact vibrating.
2.9 maintenance
After the initial setting of concrete is achieved after pouring, water should be sprayed in time to maintain its surface moist, so as to ensure the temperature and humidity in the process of cement hydration and create good hardening conditions for concrete. Ordinary portland cement is adopted in this project, and its curing time shall not be less than 14 days.
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