Construction scheme
According to the design and actual terrain of the culvert, the road change and construction survey should be done well before construction, and the culvert should be divided into the left half and the right half, with the center line of the line as the boundary. The culvert foundation is excavated by excavator, and 20cm of artificial foundation clearing is reserved to keep the undisturbed soil of the foundation pit; When there is water in the foundation pit, pump water in time to keep the foundation trench dry. The reinforcement of culvert foundation and cover plate is processed centrally and installed on site; The mortar for masonry of culvert wall mortar is now mixed and used in strict accordance with the design mixture ratio, and samples are taken at any time; The concrete of culvert foundation, bearing platform and cover plate is mixed centrally by mixing station, and transported to the site by concrete truck for pouring.
Fourth, the construction technology
See Figure 4- 1 for the construction technology of reinforced concrete box culvert with capping beam.
Verb (abbreviation for verb) raw materials
1, stone
(1), the stone should be firm, dense, firm and durable, with suitable and meticulous texture, uniform color and no weathering, peeling, cracks and structural defects. Stone strength is not less than 40, which meets the design requirements.
(2) Stone materials shall not contain sludge, oil pollution or other harmful substances that hinder the normal bonding of mortar or damage the appearance of exposed surfaces.
(3) The thickness of flaky should not be less than 150㎜ (oval and flaky shapes are not allowed). The size of facing stone should be slightly larger, the surface should be flat, slightly thicker and chiseled. Use larger stones in the corner, roughly square.
(4) Stone materials should be roughly square, and the upper and lower parts should be roughly parallel. The thickness of the stone is 200 ~ 300mm, and the width and length of the stone should be 1 ~ 1.5 times and 1.5 ~ 3 times of the stone thickness, respectively. The sharp corners of the stone should be chiseled away. The depression depth of all facing stone surfaces perpendicular to the exposed surface shall not exceed 20mm. The corner stone or face stone at the pier tip shall be chiseled into the required shape as required.
2. Mortars
Mortar strength grade should meet the design requirements and supervision engineer requirements. Mortar strength grade refers to a standard cube specimen of 70.7㎜×70.7㎜×70.7㎜, which is cured for 28 days at a temperature of 20℃ 3℃ and a relative humidity of not less than 90%. The ultimate compressive strength obtained from the compressive test is expressed in Mpa. Medium sand or coarse sand should be used in mortar, and the maximum particle size of sand should not be greater than 5 ㎜ when used for masonry flaky; When used for masonry stone, coarse stone should not be greater than 2.5㎜.
3. Other main materials
Use sand, stone, cement and steel that have passed quality inspection.
Six, the main working procedure construction method
(a), construction lofting
Before construction, organize survey and lofting, retest the center line and elevation, accurately set out the foundation position, and recheck it in time during construction. Measure the position, direction, length, aperture of culvert and the position and elevation of the entrance and exit splayed walls according to the design drawings. If the connection between rural roads and irrigation and drainage system is different from the actual terrain, contact the design unit and supervision unit in time and change the design if necessary.
(2) Foundation excavation
When excavating, strictly control the plane position, section size and elevation, and 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. The reserved 20cm thick foundation pit is cleaned manually by small loose blasting and excavated manually by excavator. Abandoned earth and stone, materials and tools shall be stacked at a distance of 1.0~2.0m ~ 2.0m from the pit top edge, 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. . Ensure that the foundation excavation meets the requirements of relevant provisions of design drawings and specifications.
When the foundation pit is excavated to the design elevation, the foundation of the basement shall be tested. If the actual basement is not in conformity with the design, contact the design unit and the supervisor in time, take appropriate measures to deal with it, and then proceed to the next working procedure after it meets the design and specification requirements.
(2), foundation construction
The processing and production of foundation reinforcement are concentrated in the workshop, and the layout and blanking are carried out according to the design drawings, and the reinforcement is bent in strict accordance with the number, size and shape of reinforcement in the design drawings. Steel welding adopts double-sided welding, the weld length is not less than 5d, and the weld is full. Other technical requirements shall be strictly implemented. The processed steel bars are transported to the site for installation by car.
After the foundation reinforcement is installed and inspected by the supervision engineer, the foundation concrete operation shall be carried out in time. The concrete foundation shall be constructed in strict accordance with the design and specification requirements. When the formwork needs to be erected, the standardized composite steel formwork shall be adopted, which shall be installed according to the number of inches in the design drawing, 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.
(3) Abutment body masonry and abutment cap construction
1, abutment masonry
Rinse the brushed masonry position with water, spread a layer of high-grade mortar, and then lay it in blocks and rows, which is roughly horizontal. Decorative stones should be laid in a suitable way or in a suitable way, and stones at any level should overlap adjacent stones by at least 80㎜. The vertical joints of lining stone and abdomen stone should be staggered, the width of mortar masonry flat joint should not be greater than 30㎜, and the width of vertical joint should not be greater than 40㎜.
Masonry jointing adopts convex joint or flat joint according to design or regulations. 10 cement mortar shall be used for jointing, and the mortar strength shall meet the design requirements. The jointing of wet masonry should be embedded in the joint about 20mm deep. If the joint depth is not enough, it should be chiseled to a sufficient depth before the joint. Mortar masonry should be watered and cured 7~ 14 days after the initial setting of mortar, and collision, vibration or bearing should be avoided during curing.
2, pile cap construction
No.7.5 mortar stone abutment shall be constructed to the design elevation, and abutment cap shall be constructed after it is accepted by the supervision engineer. Template adopts standardized composite steel template. The structure of the table cap is divided into left and right parts. 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 the method of "pulling inside and supporting outside". The internal tie rod is φ 10 round steel, arranged in a quincunx shape, with a spacing of1.5m×1.5m. The settlement joints correspond to the settlement joints of the foundation and abutment one by one, and the whole joints are filled with hemp fiber impregnated asphalt.
The concrete is mixed in the mixing station, transported by the concrete truck, and hoisted into the mold by the truck crane. When the height is more than 2m, the concrete will be sent into the mould with 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. At the same time, the specialist is responsible for observing the changes of the template and checking the support at any time to prevent accidents.
When pouring concrete, attention should be paid to embedding anchor bolts for reinforcement.
When the concrete stress of the pile cap reaches more than 5Mpa, the formwork shall be removed with the consent of the supervision engineer, covered with straw bags in time after removal, and watered by special personnel for health preservation.
(4), reinforced concrete cover plate
1, steel processing and installation
The processing and production of protective layer steel bars are concentrated in the workshop, and the layout and blanking are carried out according to the design drawings, and the steel bars are bent in strict accordance with the number, size and shape of the design drawings. The steel skeleton is made according to the design and welded on both sides. The weld length is not less than 5d, and the weld is full. Other technical requirements shall be strictly implemented. The processed skeleton and bent steel bars are transported to the site for installation by car.
After the bottom formwork of culvert cover plate is laid and accepted by the supervision engineer, the reinforcement of cover plate shall be bound. When binding, the spacing between steel bars shall be correct and even, and the thickness of protective layer of steel bars shall be ensured. Welded joints of steel bars should be staggered, and the distance between two joints should not be less than 50cm. The intersection of steel bars shall be securely bound with iron wire. Spot welding can be done if necessary. The reinforcement of the cover plate is made of concrete trapezoidal cushion blocks of 5cm×5cm×5cm, which are arranged in a quincunx shape with the spacing of1m×1m.. Block and steel binding closely, and staggered.
2. Model of cover plate
The vertical formwork of side formwork and bottom formwork adopts standard combined steel formwork, which is supported by full bowl buckle. The splicing interval of the support is 1.2×0.9× 1.2m (length× width× height), and the whole support is connected into a whole by diagonal tie rods. Before installing the support, carefully check the stow-wood on the bottom die, accurately adjust the top elevation of the support stow-wood, and reserve a certain pre-camber according to the specification requirements when necessary. After the bracket is installed, its plane position, top elevation, node connection and vertical and horizontal stability shall be comprehensively inspected. After confirmation, install the standard steel template, evenly coat the release agent on the template, and seal the template joints. Adjacent template height difference is not more than 2mm, template flatness control under 5 mm.. The template size is correct, and its error is controlled within the range allowed by the specification. After the acceptance of the supervision engineer, install the protective layer reinforcement.
3. Concrete pouring of cover plate
Concrete is mixed centrally in the mixing station and transported by concrete truck. The truck crane is hoisted into the mould, and the plug-in vibrating rod is used for tamping. When vibrating, insert quickly and pull slowly. The insertion depth of the vibrator is 5cm away from the bottom die, and the insertion distance is less than the action radius of the vibrator. Vibration leakage and heavy tamping are not allowed. Vibrating time should not be too long. When the concrete stops sinking, bubbles no longer appear, and the surface is smooth and pulpy, the vibrator can be pulled out slowly, and the pulling speed should not be too fast, otherwise it will lead to cavities in the concrete.
After the initial setting of concrete, cover it with straw bags in time, and water it by special personnel according to the temperature change.
4. Demolition
When the concrete strength of the cover plate reaches 2.5Mpa, the side formwork can be removed. When the concrete strength reaches more than 85% of the design strength, the bottom die can be removed. Form removal shall be carried out symmetrically from top to bottom and from left to right. Attention should be paid to safety during form removal, with special personnel in charge and unified command. After the supervision engineer passes the inspection, the back of abutment shall be backfilled and maintained.
(5), settlement joint
Settlement joints shall be constructed according to design drawings. The settlement joint in the abutment wall is filled with 10 cement mortar 15cm, and the settlement joint on the outer wall surface is treated with a layer of asphalt impregnated linen and a second layer of gypsum asphalt, with a width of 50cm. The joints are filled with 5cm asphalt impregnated hemp reinforcement, and the middle is filled with clay.
(6), waterproof layer
The cover plate support shall be leveled with 7.5 mortar, and the top of the cover plate and the waterproof layer of abutment shall be painted with hot asphalt twice, with the thickness of 1- 1.5mm per degree, and a layer of linoleum paper shall be laid between two times. Other technical requirements shall be carried out in accordance with the specifications and the instructions of the supervision engineer.
(7), splayed wall construction
The splayed wall foundation is made of 15 concrete, which will be carried out together with the abutment wall foundation during construction. The wall is cast-in-place 15 concrete, and the construction method is the same as that of abutment wall.
(8), ancillary works
The ancillary works shall be set out according to the size and elevation of the design drawings, and then the construction shall be organized, and the requirements of relevant construction specifications shall be strictly implemented to ensure the engineering quality.
(9) Backfilling of abutment
1. Backfilling can only be carried out after the concrete strength of culvert reaches 80% of the design strength.
2. Use backfill materials approved by the supervision engineer that can be fully compacted, and turf soil, garbage and organic soil are strictly prohibited.
3, backfill should be two culvert abutment symmetrical filling at the same time, layered filling, layered compaction, the thickness of each layer is +05 ~ 20 cm, in order to prevent severe impact, using a small roller or flat vibration rammer compaction, in order to achieve the required degree of compaction. Strictly control the water content of backfill filler. Backfilling of abutment requires more than 95% density.
(10), rainy season construction
Combined with the actual terrain around the culvert, improve the waterproof and drainage facilities in rainy season. Site layout, stacking position of materials and machinery should be reasonable and scientific. Waste canals should be repaired and utilized in time, and the "three ditches" should be unblocked according to the principle of "dredging, guiding and intercepting".
Seven, quality assurance measures and quality inspection standards
(a), quality assurance measures
The quality assurance system is shown in Figure 7- 1- 1, and the quality assurance measures are as follows:
1, carry out total quality management.
Do a good job in quality education, strengthen the quality awareness of all staff, and firmly establish the concept of "quality first, quality first". From material procurement and supply, quality inspection and acceptance to the construction production process and completion acceptance and delivery of each working procedure, the whole process management is implemented, and the working procedure quality is guaranteed with good working quality, and the ideas and methods of total quality management are truly applied to the whole construction process of this bid section.
2. Improve quality inspection institutions and strengthen quality supervision and inspection.
Project intends to set up a safety and quality department, full-time quality inspection engineer to conduct a comprehensive construction inspection of the whole project. At the same time, quality inspectors are set up at the team level, and the team has full-time and part-time quality inspectors. Adhere to the system of self-inspection, mutual inspection and handover inspection in the construction process, so that the project quality is under control in the whole construction process.
3. Strict quality standards
The project is carried out in strict accordance with standardized operations, so that the process has standards, inspections have inspections, and all inspections have conclusions (according to the reward and punishment regulations). The main working procedures of each project are operated in strict accordance with the operation standards, and new technologies, new processes and new methods are applied in various construction and production to ensure the quality of standardized operations.
4. Strictly control the quality procedures.
Strictly implement the supervision engineer visa system. If the previous process fails, the next process is not allowed.
5, strict reward and punishment system
Clear quality responsibility, the implementation of wages, bonuses and project quality rewards and punishments.
6. Strictly control materials.
The purchased materials must have three certificates (ex-factory certificate, certificate of conformity and inspection certificate), and must be sampled according to regulations after entering the site, and can only be used after passing the inspection. Materials must be ordered by manufacturers with good quality and high reputation.
(2), quality inspection standards
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.
4. See Table 7-2- 1 for inspection items of reinforced concrete capping box culvert.
According to the concrete box culvert inspection items table 7-2- 1
Inspection method of specified value or allowable deviation of project inspection
1 concrete strength (Mpa) is in accordance with the inspection standard in Appendix D of the Standard for Quality Inspection and Evaluation of Highway Engineering (JTJ07 1-98).
2 Height (mm)-10, +5 Check three sections with a ruler.
3 Width (mm) 30
4. The position of the settlement joint and the settlement joint of the waterproof layer shall meet the requirements of the drawings and be controlled at the site.
5. Roof thickness+10, -0 feet. Quantity: check 3 ~ 5 places.
Cover culvert shall not be less than the design value. Quantity: check 3 ~ 5 places.
6 Smoothness (mm) 5 2m ruler: check 2 places ×3 feet every 10m.
7 The thickness of side plates and bottom plates shall not be less than the design value. Gauge: Check 3 ~ 5 places.
Eight, safety assurance measures
The safety guarantee system is shown in Figure 8- 1- 1, and the safety guarantee measures are as follows:
1, safety management system
(1), all construction-related personnel must hold relevant certificates and wear safety helmets at the construction site, or they will be fined above 50 yuan 10 yuan.
(2) The construction team shall conduct construction safety inspection every day and make detailed records, propose maintenance or improvement measures and implement them.
(3) Adhere to the principle of giving priority to self-examination, supplemented by mutual inspection, and making changes while checking; Mainly check the thought, system, discipline, leadership, hidden dangers and accident handling. Combined with the seasonal characteristics, we will focus on implementing measures to prevent electric shock, falling from high altitude, mechanical vehicle accidents, fire prevention and lightning strike.
2, culvert construction safety assurance measures
(1) When installing the steel formwork of the platform, the full-time safety officer shall be under unified command, adjust and reinforce the steel formwork in time, and set cables and wind ropes for the platform reinforcement and formwork.
2, concrete pouring, construction personnel clear division of labor, unified command, continuous construction, in case of accidents.
Nine. Environmental protection
Environmental protection is an important event related to human survival and development and maintaining ecological balance. It is the basic duty of construction enterprises and the problems that must be paid attention to, not only to do a good job in engineering construction, but also to reduce the damage to the environment caused by construction.