I. Overview of the Project:
Second, the construction preparation:
(1), remove sundries and tidy up the site; (2) Check and install main construction machines and tools; (3) Installation of water and electricity supply facilities at the construction site; (4) Reasonable organization of construction, clear responsibilities and reasonable division of labor; (5) Prepare enough construction materials.
Third, the construction scheme:
(a), channel and reinforced concrete slab culvert:
1), construction lofting. Carefully review the construction drawings and understand the design intent. According to the structural position and elevation determined in the drawings, the pile coordinates and axis direction in the structure are accurately calculated, and then the construction lofting is carried out according to the calculated specific position. In order to facilitate the inspection and recheck after excavation, the foundation axis control pile should be extended into the foundation pit to be fixed. After the lofting is completed, the boundary line of the structural foundation shall be set out according to the structural size of the foundation, and the application shall be made to the resident supervision engineer for review. After confirmation, the foundation pit can be excavated.
2), foundation pit excavation.
A, according to the site construction equipment conditions and construction environment, foundation excavation adopts excavator excavation and artificial repair; During excavation, special surveyors shall be sent to measure the elevation of basement in time to prevent over-excavation. For areas with groundwater, when excavating the foundation, drainage ditches should be dug around the foundation pit to maintain good drainage and ensure that it is not harmed by water during the whole construction period of excavation.
B, the culvert address is the foundation of Grade I gravity-free collapsible loess. After foundation excavation, it will be tamped with a heavy hammer, and the bearing capacity of the foundation will be tested on site with a light penetrometer. After it meets the design requirements, the foundation concrete can be poured. If the bearing capacity of foundation is insufficient, lime should be replaced as appropriate, and the thickness and width of cushion should be calculated by checking the bearing capacity of foundation. When replacing lime, the volume ratio of lime to soil is 3: 7, which is mixed in the mixing station. After the lime-soil mixture is mixed, it will be transported by car and leveled manually, and the paving thickness of each layer will be controlled at about 20cm. The compactness of lime soil is compacted by small pneumatic rammer, reaching the compactness approved by the supervision engineer. According to the actual situation, other measures can also be adopted for foundation treatment.
3), templates and supports:
A, foundation concrete template adopts standard size, smooth surface of bamboo veneer, template must ensure that its surface is smooth, do not leak slurry between plate joints.
B, template before installation, template surface besmear brushs release agent, shall not be used to stick to the concrete or make the concrete color oil.
C, in order to prevent the template from displacement and deformation when supporting, when supporting the foundation side form, support and fixation should be set on the outside of the template. The side formwork of the platform body shall be fixed with tie rods and concrete shall be poured. The pull rod should be designed according to the requirements of pulling out the pull rod, and the plastic pipe should be washed outside the pull rod. Formwork should be removed and pulled out for reuse.
D, template after the installation, in order to ensure the correct position, must self-check its plane position, flatness, verticality, top elevation, node connection and vertical and horizontal stability. Only after passing the inspection can it be reported to the supervision engineer for sampling inspection, and it can be poured only after the supervision engineer approves it. When pouring concrete, it is found that the template may exceed the allowable deviation value, and it shall be corrected in time.
4), concrete pouring and maintenance:
A. material selection. The laboratory is strictly controlled, and all raw materials must meet the needs of design and construction.
B. Culvert concrete shall be mixed centrally, transported by tank car and poured by crane. Strictly check the quality of various raw materials before mixing. Concrete is mixed centrally in the mixing station, transported by tank car, and put into the mould by bucket method. When pouring concrete, the concrete delivered to the construction site must be strictly inspected. Such as slump and workability of concrete.
C. Before pouring, check the supports, templates and embedded parts. Debris and water in the template should be cleaned up. If there are any gaps in the formwork, they must be pressed tightly.
D. In order to prevent segregation when concrete is poured into the mould from a height, when pouring the foundation, the dumping height of the crane shall not exceed 2m.
E, pouring the concrete horizontally in layers according to a certain thickness order, and completing the pouring of the upper concrete before the initial setting of the lower concrete; When the upper and lower layers are poured at the same time, the pouring distance between the upper and lower layers should be kept above 1.5m, and the pouring thickness should not exceed 30cm.
F. Concrete shall be vibrated by plug-in, and the movement shall not exceed 1.5 times of the action radius of the vibrator, and it shall be 5 ~ 10cm away from the side formwork.
G. Concrete pouring shall be carried out continuously. If it is interrupted for some reason, the interruption time shall be less than the initial setting time of the previous layer of concrete.
H. After concrete pouring is completed, it should be cured as soon as possible after the slurry is collected. The concrete shall be cured by sprinkling water, and the curing time shall be no less than 7 days.
5) Treatment of construction joints:
Because the foundation platform and the bearing platform are poured separately, the construction joints should be carefully treated, and the construction joints should be treated by manual roughening. Within 1-2 days after pouring the concrete of the treatment layer, the cement mortar and loose layer on its surface should be roughened, and the roughened concrete surface should be washed with water. Before pouring the second layer of concrete, spread a layer of 1:2 cement mortar on the horizontal joints with a thickness of 1 ~ 20cm, and continuously pour the reinforced concrete, concrete arch ring and cover concrete on site to avoid construction joints.
6) Settlement joint treatment:
Settlement joints shall be set according to the design drawings, and a settlement joint shall be set every 4 ~ 6m in the tunnel. Settlement joint construction shall be carried out in strict accordance with the construction drawing. The setting of settlement joint must be connected into a vertical line from top to bottom, and the foundation wall should be poured in sections according to the design length of settlement joint. When pouring, use a wooden board as a stop at the settlement joint. When the concrete reaches a certain strength, remove the wooden block and stick foam plastic at the settlement joint.
7), the bottom of the cave paving:
The bottom surface of culvert and passage foundation is smooth and hardened, and the elevation of basement is controlled by surveyors, and concrete is poured according to the design label. If the slope in the culvert is too large, an inverse slope of 5% should be added to the bottom of the culvert to make the foundation step to ensure the stability of the foundation.
8) Prefabrication, transportation and installation of cover plate:
Precast cover plate. ① Processing and binding of steel bars: steel bars are uniformly cut, bent and manufactured in the steel bar workshop according to the drawing requirements, welded and bound in strict accordance with the specification requirements, and the dimensions are accurate during installation. (2) Formwork support: The formwork shall be made of bamboo glue with high hardness, and at the same time, it shall have sufficient rigidity to prevent obvious deflection when pouring concrete. Before the formwork is installed, the formwork surface shall be coated with release agent, and oil that is easy to stick to concrete or discolor concrete shall not be used. In the process of erection, we should pay attention to check whether the interior of the formwork is in contact with the steel bar to ensure that the structural members have enough protective layer thickness; Secondly, pay attention to check the up and down direction of formwork, pay attention to the direction of oblique culvert, and avoid reverse errors. (3) Mixing and pouring of concrete: The ingredients shall be prepared in strict accordance with the construction mixture ratio provided by the laboratory, and the forced mixer shall be used for centralized mixing, and the shortest mixing time shall meet the requirements of construction specifications. When mixing, a part of mixing water should be added before the cement and aggregate are put into the barrel, and all the water should be evenly injected into the mixing barrel within 15S before mixing. The mixed materials after mixing should be evenly distributed and have the same color visible to the naked eye. The mixture is transported by tank car and poured manually. The mixture delivered to the site must be inspected (including slump and workability of the mixture, etc. ). Before pouring, check the scaffold template and embedded parts, and remove the sundries and water in the template. If there are gaps in the template, it must be filled in. When pouring concrete, assign special personnel to check the stability of supports, templates, steel bars and embedded parts. If looseness, deformation and displacement are found, they should be handled in time. (4) Concrete curing: After concrete pouring is completed, the surface should be watered and cured manually as soon as possible after the slurry is collected, and the watering and curing time should be no less than 7 days. The structure should be kept moist continuously before formwork removal.
Transportation and installation of cover plate: The finished concrete can be transported only after its strength reaches 70% of the design strength, transported to the site by trailer and hoisted by Y- 16T crane. Before installation, check the size of culvert abutment. During installation, before placing the cover plate, lay 1cm thick linoleum between the bottom of the floor and the cap. For culverts with longitudinal slope at the bottom of culvert ≥4%, after the cover plate is placed, both ends are reinforced and fixed with Ф18 studs, and the holes are filled with 10 cement mortar after the studs are installed. After the installation is completed, cut off the rings on both sides, fill one end of the plate end with linoleum and the other end with 20 # cement mortar.
9) Backfilling of abutment:
Backfilling of abutment must be carried out after the strength of culvert reaches more than 80% and the cover plate is lifted, that is, after the abutment back basement is 2.0m, 1: 1 lime soil shall be filled in the range from slope to culvert top. All backfill soil at the back of abutment must be filled in layers, rolled by small rollers, and compacted by small flat vibrators near walls, edges and dead corners. In the process of filling. When filling the top of culvert, the strength of cover plate must meet the design strength.
(2) Reinforced concrete circular culvert:
1) Excavation foundation:
A. Before foundation excavation, accurately set out the center line position, and control the precise position and elevation with the pile.
B. Excavators shall be used for foundation excavation with manual excavation. During excavation, surveyors shall release the elevation of basement in time, and overbreak is strictly prohibited. After foundation excavation, if the bearing capacity of foundation is not enough, lime shall be used for filling according to the specific situation, and the thickness and width of cushion shall be calculated by checking the bearing capacity of foundation. When replacing lime, the volume ratio of lime to soil is 3: 7, which is mixed in the mixing station. After the lime-soil mixture is mixed, it will be transported by car and leveled manually, and the paving thickness of each layer will be controlled at about 20cm. The compactness of lime soil is compacted by small pneumatic rammer, reaching the compactness approved by the supervision engineer. According to the actual situation, other measures can also be adopted for foundation treatment.
2) Foundation formwork and support:
A. The foundation concrete shall be shaped composite steel formwork with high strength, good rigidity, standard size and high turnover rate. Composite steel formwork must ensure smooth surface, accurate shape and no slurry leakage between plate joints.
B before the formwork is installed, the formwork surface shall be coated with release agent, and the oil that is easy to stick to concrete or discolor concrete shall not be used.
C. In order to prevent the formwork from protruding due to displacement during formwork erection, the lateral formwork shall be supported and fixed outside the formwork during formwork erection.
D after the formwork is installed, in order to ensure the accurate position, its plane position, flatness, verticality, top elevation, node connection and vertical and horizontal stability must be checked. Only after it is qualified can it be reported to the supervision engineer for sampling inspection, and concrete can be poured after it is approved by the supervision engineer. When casting, it is found that the template may exceed the allowable deviation value, and it should be corrected in time.
3) Pouring and curing of foundation concrete:
Culvert concrete is mixed centrally, transported by tank car and poured by crane. Strictly check the quality of various raw materials before mixing. Concrete is mixed centrally in the mixing station, transported by tank car, and put into the mould by bucket method. When pouring concrete, the concrete delivered to the construction site must be strictly inspected. Such as slump and workability of concrete.
Before pouring, the supports, templates and embedded parts shall be inspected. Debris and water in the template should be cleaned up. Template if there is a gap, must be packed tightly.
In order to prevent segregation when concrete is poured into the mould from a height, when pouring the foundation, the dumping height of the crane shall not exceed 2m, and it will fall through the string tube.
Concrete is poured horizontally in layers according to a certain thickness order, and the upper concrete is poured before the initial setting of the lower concrete; When the upper and lower layers are poured at the same time, the pouring distance between the upper and lower layers should be kept above 1.5m, and the pouring thickness should not exceed 30cm.
Concrete shall be vibrated by an internal vibrator, and the moving amount shall not exceed 1.5 times of the action radius of the vibrator, and it shall be 5 ~ 10cm away from the side formwork.
Concrete pouring is continuous, and if it is interrupted for some reason, the interruption time should be less than the initial setting time of the previous layer of concrete.
After the concrete pouring is completed, it should be cured as soon as possible after the slurry is collected. The concrete shall be cured by sprinkling water, and the curing time shall be no less than 7 days.
After the foundation is completed, place the reinforced concrete circular pipe firmly on the concrete foundation with a crane, and require each pipe joint to be straight, with the adjacent height difference in the pipe not greater than 5mm, and the joints of the pipe joints shall be filled with asphalt hemp. In order to ensure that there is no water leakage between the pipe joints, the outside of the pipe joints is wrapped and sealed with linoleum, asphalt and reinforcement materials with a width of 15cm, and then a layer of asphalt is brushed outside to ensure that the external water does not leak into the culvert.
4) Culvert splayed wall construction:
After the completion of the culvert, let the surveyor set out the positions of the splayed walls of the openings on both sides.
Accurate positioning, and control the elevation, began to set up the template.
The formwork shall be made of bamboo plywood with standard size and smooth surface. The formwork must ensure that its surface is smooth and there is no slurry leakage between joints. Before the formwork is installed, the formwork surface shall be coated with release agent, and oil that is easy to stick to concrete or discolor concrete shall not be used.
When erecting formwork, in order to prevent displacement and deformation of formwork, when erecting foundation side formwork, support and fixation should be set on the outside of formwork. The side formwork of the platform body is fixed by tie rods, and concrete is poured. The pull rod is designed according to the pull-out requirements of the pull rod, and a plastic pipe is sleeved on the pull rod. After removing the templates, pull them out for reuse.
After template installation, in order to ensure the correct position, it is necessary to self-check its plane position, flatness, verticality, top elevation, node connection and vertical and horizontal stability. Only after it is qualified can it be reported to the supervision engineer for sampling inspection, and it can only be poured after it is approved by the supervision engineer. When pouring concrete, it is found that the template may exceed the allowable deviation value, and it shall be corrected in time.
The process of pouring splayed wall concrete is the same as that of pouring foundation concrete.
Backfilling of abutment:
When the concrete strength of the splayed wall reaches more than 80%, the abutment back can be backfilled. Backfill shall be made of natural gravel with good gradation and constructed symmetrically. Because the construction face is small, it is crushed by a small roller. For places close to walls, edges and dead corners, compact them with a small flat vibrator. When filling, the two sides of the culvert abutment must be compacted symmetrically in layers, and the degree of compaction must reach more than 95%. Backfill to the height of construction subgrade (exceeding the top surface of culvert), and then combine with subgrade.
Construction Scheme of Circular Pipe Culvert (2)
First, the number of projects.
There are 52.5m/2 285×250 double-hole box culverts, 60m/2 285×250 double-hole box culverts,101.4m1300 450 box culverts.
Second, the team and schedule
It is planned to arrange three culvert teams for construction, each with 42 people, totaling 126 people. After the construction, if there is not enough manpower, we will recruit from the local area. The first culvert team built 52.5m /2 285×250 double-hole box culvert and 60m /2 285×250 double-hole box culvert; The second culvert team will construct 300×250 box culverts101.4m1,reinforced concrete circular culverts182m/2; The third culvert team has completed 450×300 box culverts 2 10.4m/ 1.
Time schedule: 30 days for construction preparation from October 28th, 65438 to October 26th, 2004; 165438 2004 +70 days construction period 2005127 October to 4 February.
Third, the construction method
1, reinforced concrete circular tube culvert
1. 1 foundation engineering
The excavation of foundation pit adopts manual cooperation with mechanical excavation. After the foundation pit is accepted, compact macadam cushion will be paved in layers with small vibratory roller, and the degree of compaction will reach over 95%. The foundation concrete is poured twice before and after the installation of the pipe joint, focusing on controlling the combination of new and old concrete and the combination of pipe foundation concrete and pipe wall, and maintaining it in time.
1.2 culvert construction
Culverts are prefabricated by designated manufacturers, and transported to the construction site after passing the inspection. The total length of culverts, the configuration of pipe joints and the exact position of end walls are accurately calculated, and they are installed from the downstream, so that the joints are installed in the upstream, and each culvert is closely attached to the paved base, so that the stress of culverts is uniform.
Anti-collision measures should be taken in the process of loading, unloading, transportation and installation of pipe joints to avoid damage or cracking of pipe joints; Culvert loading and unloading, machine installation and storage sites must be approved by the supervision engineer and installed in strict accordance with the specifications.
1.3 connector
According to the design requirements, install the rubber ring of the interface and fill the joint with M 10 mortar. The joint width should not be greater than 1cm, and the joint should be smooth. It is forbidden to increase the joint width to meet the requirements of culvert length.
1.4 abutment back and culvert top fill
After the culvert is completed, construction can be started when the strength of mortar or concrete for culvert masonry reaches 70% of the design strength.
Backfill should be carried out, and the backfill should meet the quality requirements. The gap of the embankment at the culvert should be filled from both sides of the culvert body within the range of not less than 2 times the aperture, filled horizontally and symmetrically, and compacted (flattened). When mechanical earth filling is used, in addition to the above provisions, only when the thickness of earth filling at the top of culvert is greater than 1m can the machinery pass through, and it is forbidden to start the vibration source when the vibratory roller is used for rolling.
Strictly control the thickness and compactness of layers, and assign special personnel to be responsible for supervision and inspection. The inspection frequency is every 50m 2 1 point, and at least 1 point when it is less than 50m2. Every point must be qualified and compacted by small machinery. The layered thickness of backfill soil is 0. 1 ~ 0.2m ... and the degree of compaction should reach 95%.
2. Reinforced concrete box culvert
2. 1 basic treatment
Adopt manual and mechanical excavation, pay attention to waterproof and drainage facilities before excavation, set up job-hopping excavation according to deformation joints, and do temporary support work when necessary.
The basement shall be leveled and tamped, and the bearing capacity of the basement shall be tested. If it fails to reach 150Kpa, replace the gravel or crushed stone.
After the bearing capacity of the basement meets the design requirements, the formwork shall be set up as the concrete cushion according to the design requirements.
2.2 floor and side wall steel binding
Measure the setting-out on the cushion, draw the layout details of the steel bar and the edge of the formwork, then tie the steel bar on the bottom plate and side wall, and set temporary support on the outside with steel pipe to prevent the deformation of the steel cage. Main reinforcement protective layer 3㎝ (wall reinforcement is tied with double-peak pad near the internal model), reinforced protective layer 4㎝ at the lower part of the bottom plate, the anchorage length of reinforcement is 35d, the lap length is 42d, and the lap percentage of reinforcement is not more than 25%.
2.3 Internal Support and Internal Formwork Construction
The internal support is erected with φ50 steel pipe, and the vertical and horizontal spacing is not more than 1m, and the vertical spacing is not more than1.2m. The longitudinal beam is supported by adjustable diagonal braces at the top, and the cross beam is located on the longitudinal beam, and the cross beam is the top formwork. The transverse steel pipe of internal support should be connected with the internal formwork by steel pipe clips at the joint of transverse and vertical belts (both transverse and vertical belts of internal and external formwork adopt double steel pipes) to play the role of transverse internal support. The internal model adopts 1.5㎡ large plane template, and the surface is required to be flat and free from faults, and sealing strips are affixed at the joints of the template.
2.4 binding roof reinforcement and external formwork.
In strict accordance with the specification and design requirements, bind the double-peak cushion block of steel bars at the bottom of the roof, and spot weld the supporting stirrups to ensure that the upper steel mesh is not deformed.
The external formwork is assembled by ordinary steel formwork, which is fixed by φ 16 tie rod and supported by logs or steel pipes.
2.5 concrete pouring
The concrete adopts commercial concrete. Use a crane with a feeding funnel to pour into the warehouse, and use an internal vibrating rod to vibrate.
2.6 deformation joint treatment
The box culvert body is provided with a deformation joint every10 ~18m (including foundation), and the deformation joint is set at the junction of foundation soil change and foundation filling and excavation, and the joint width is 2 ~ 3 ㎝. Rubber waterstop of deformation joint adopts QZ5—400 rubber waterstop.
At the location where deformation joints are set, the concrete around the box culvert should be thickened by one circle, and the thickening size is 25㎝. 3㎝ thick oil-immersed cork board is embedded in the inner side of deformation joint, and water-stopping paste is embedded in the outer side. In order to ensure that the whole deformation is vertical and on the same section, two separate templates (clip-type water stop) must be set up at the plug of the vertical formwork, and connected with the internal and external templates by screws, and oil-impregnated wood boards must be stuck on the steel templates corresponding to the plug of the hollow pipe.
2.7 Filling of abutment back and culvert top on both sides of box culvert
Backfilling is the same as circular culvert.
Fourth, quality and safety assurance measures
1, quality assurance measures
1. 1 When the culvert is excavated mechanically, 20cm shall be reserved for manual excavation and cleaning. After reaching the design elevation, check whether the section size and bearing capacity meet the design requirements, and then enter the next working procedure after being checked and signed by the supervisor.
1.2 rebar shall be inspected for factory certificate and spot-checked. It can only be used after inspection. Steel bars shall be straightened, derusted and descaled before use. Welders must hold relevant certificates, and welding heads must pass the examination before they can be officially operated.
1.3 rebar must be used for spacing during rebar installation. Steel bars should be crossed before binding. Vertical main reinforcement and horizontal distribution reinforcement shall be firmly bound according to the design position to form standardized construction, and the thickness of protective layer of reinforcement shall be strictly guaranteed.
1.4 scaffolding and supports for concrete construction shall be firmly erected, and the formwork shall be horizontal and vertical to prevent formwork from running away. Tamping shall be carried out by special personnel, and the thickness of layers shall be strictly vibrated in layers to prevent honeycomb pits.
1.5 During the masonry construction of culvert engineering, the stones should be carefully selected, mortar should be mixed in strict accordance with the mixture ratio, and the masonry should be built by extrusion method, and the interlaminar joint should meet the requirements of masonry specifications. Masonry should be down, vertical masonry is prohibited. Mortar is full, mortar joint adopts concave joint.
1.6 settlement joint and waterproof layer shall be constructed in strict accordance with the requirements of design and construction specifications, so as not to leak. If water seepage is found, it should be repaired as soon as possible.
1.7 The back backfill of culvert abutment shall be constructed in strict accordance with the specification requirements, and both sides shall be compacted symmetrically. When the thickness of culvert top fill is greater than 1m, construction machinery can be allowed to pass through to prevent concrete cracking and other man-made damage.
2, safety assurance measures
2. 1 A distribution box must be set up on the construction site, and the incoming and outgoing cables should be sheathed to ensure that the incoming and outgoing cables are not disorderly. It is forbidden to use flower thread or plastic thread, and the conductor shall not be dragged or tied to the scaffold anywhere.
2.2 Operate the site machinery and equipment in strict accordance with the safety technical operation procedures to prevent illegal operation, and it is forbidden to operate machinery and equipment after drinking.
2.3 When excavating the foundation pit, excavation shall be carried out according to the designed slope, and temporary support shall be provided to prevent landslide. Equipped with pumping equipment to prevent slope collapse and leakage caused by flooding.
2.4 template installation, internal and external support is firm, tamping personnel should wear insulating anti-electric gloves; When dismantling the formwork, it shall be carried out according to the prescribed procedures, and the formwork, materials and tools shall not be thrown down directly.
2.5 When working high above the ground, you must fasten your seat belt and set up protective fences around. People should be careful when walking. People suffering from acrophobia, heart disease and myopia are prohibited from working at heights.
2.6 Strengthen on-site public security protection, and the layout of the construction site meets the requirements of fire prevention, flood control, explosion prevention, lightning protection and other safety regulations.
2.7 Lighting lamps, guardrails, fences and warning signs set on site should be maintained frequently to maintain their normal functions, and specified safety warning signs should be hung in dangerous places.