First, the construction technology
The construction of concrete culvert is: survey and lofting → foundation excavation → basement acceptance treatment → foundation construction → abutment construction → protective layer construction → settlement joint and waterproof layer construction → ancillary works construction.
Second, the main working procedure construction method
(a), construction lofting before construction, organization survey lofting, retest the center line and elevation, accurately release the foundation position, and timely review in the construction. If the location, direction, length, aperture, entrance elevation and connection of irrigation and drainage system of the culvert determined by the design are different from the actual terrain, contact the design and supervision in time, and change the design if necessary.
(2) Foundation excavation
1. Position and pay-off according to the survey data shown in the drawings, notify the supervision engineer to recheck the plane position of the survey foundation and the existing ground elevation, and then excavate the foundation, and reserve 20cm thick artificial bottom cleaning. Ensure that the foundation excavation meets the requirements of relevant provisions of drawings and specifications.
2, strictly control the plane size and elevation, it is forbidden to disturb the basement. The slope of soil foundation pit excavation is 1: 0.5, and bulldozers and excavators are used for excavation, with manual cooperation. Leave a layer of soil with appropriate thickness at the bottom of the foundation trench, and reach the design elevation after compaction; Small-scale loose blasting is used for stone foundation pit, and excavator cooperates with manual excavation. Abandoned earth and stone, materials and tools shall be stacked at a distance of 1.0~2.0m from the top edge of the pit, and not less than the depth of the foundation pit, so as to reduce pressure vibration and ensure the stability of the foundation pit slope.
3. When the foundation pit is excavated to the design elevation, carry out foundation detection on the basement. If the actual basement does not conform to the design, contact the design unit and supervisor in time, take appropriate measures to deal with it, and proceed to the next process after meeting the design and specification requirements.
(3), foundation construction
1. After the foundation trench is accepted, the eluvial soil shall be removed first. If there is overbreak, fill it with gravel and tamp it. The allowable bearing capacity of foundation should not be less than the design value. Do not meet the requirements, should be promptly reflected, and take corresponding measures. After the foundation pit has passed the inspection, the construction of the next procedure will be carried out in time with the visa of the supervision engineer.
2. The concrete foundation shall be constructed according to specifications, and when formwork is needed, the standardized composite steel formwork shall be adopted, which shall be installed according to the requirements of design drawings and reinforced with square timber support. The culvert foundation and culvert body shall be provided with 1 settlement joints every 4 ~ 6m according to the drawing requirements. Concrete is mixed centrally by the mixing station, transported to the construction site by the concrete truck, slid into the mold by the chute, poured in layers according to the requirements of concrete construction operation specifications, and vibrated by the internal vibrator. When pouring the top surface of the foundation, the elevation of the running water surface and the smoothness of the bedding face should be well controlled, and the joint surface between the top surface of the foundation and the wall should be treated according to the requirements of the Technical Specification for Construction of Highway Bridges and Culverts, except those that are brushed or chiseled.
(4), culvert construction
1. Template Culvert template adopts standardized template. Before formwork erection, measure and set out, pull up the construction line according to the measuring axis and design elevation, erect formwork on both sides of the platform according to the design size, and strictly control the verticality and flatness of the formwork during formwork erection. The formwork of the platform body is fixed by internal pull and external support. The internal tie rod is φ 10 round steel, arranged in a quincunx shape, with a spacing of1.5m×1.5m. The bottom of the formwork is supported and fixed by the outside 15cm× 15cm square timber, and φ80 steel pipes are supported and fixed on both sides of the formwork, with a spacing of/kloc. When shuttering, according to the requirements of design drawings, 1 settlement joints shall be set every 4 ~ 6m, and they shall correspond to the foundation settlement joints one by one. In order to ensure the appearance quality of concrete, the release agent on the formwork should be evenly coated, and sponge double-sided tape should be pasted between the joints of the formwork to prevent slurry leakage. In order to prevent the formwork from shifting or deviating, and ensure the straightness and smoothness of abutment wall, the ground anchor is embedded outside the formwork, and wood support is set to fix it. After the formwork is completed and inspected by the supervision engineer, the concrete of the bottom plate shall be poured.
2. Concrete shall be mixed in a concrete mixing station and transported by a concrete truck. When the height exceeds 2m, the concrete shall be sent into the mold by a string of barrels. The abutment wall shall be poured in layers, and the thickness of layers shall not be more than 30cm, and it shall be tamped with internal vibrating rod. Vibrating rods should be inserted into the lower concrete by 5cm, and the insertion interval should be less than the action radius of vibrating rods, and vibration leakage and heavy tamping are not allowed. When vibrating, observe that the concrete no longer sinks and the surface is flooded. When the level is shiny, you can slowly pull out the vibrator. Pulling out too fast will lead to voids in concrete. When pouring concrete, attention should be paid to embedding anchor bolts for reinforcement.
Third, quality inspection.
1, the bearing capacity of culvert foundation must meet the design requirements.
2, settlement joint, waterproof layer, abutment back fill should be carried out in accordance with the requirements of construction specifications and drawings.
3. Appearance appraisal
(1), the culvert body is straight, and the culvert bottom is paved densely and smoothly.
(2) The water inlet and outlet are connected with the upstream and downstream grooves smoothly, with smooth running water and no residue.
(3), hat stone and straight wall or figure-eight wall, no warping phenomenon.
For more information about bid writing and improving the winning rate, click on the bottom customer service for free consultation.