Summary of bridge builder's work

Introduction: In order to carry out the work better in the future, make a summary of the main points of the bridge construction in this project at this stage. I will summarize the work of bridge builders for you, hoping to help you! Summary of bridge builder's work:

1. Key points of pile foundation engineering quality control

1. Bored pile drilling:

(1) In order to prevent pile foundation deviation, we should attach great importance to the pile position control work from the opening of bored pile to the completion of pile, and the survey and setting-out must be "once released, twice reported for inspection", and cross-shaped piles must be buried to strengthen daily inspection and calibration.

(2) In order to grasp the drilling situation in time, the drilling records should be standardized and complete to fully reflect the actual working conditions and geological changes. Drilling operations should be carried out continuously in shifts, and samples should be kept for verification at any time. The original record sheet must be recorded on site by pile and machine, and the relevant information such as stopping drilling, changing rods, maintenance, accidents, footage and geological changes should be truly recorded.

(3) When the geological conditions are seriously inconsistent with the geological profile, and in case of abnormal geological conditions such as karst caves and quicksand, the design unit should be informed in time to improve the design, so as to avoid affecting the overall progress of the substructure due to changes.

2. hole cleaning of bored piles:

(1) it is not allowed to replace hole cleaning by deepening the drilling depth. After the final hole, the hole must be cleaned twice before pouring concrete, and the sediment thickness and mud index at the bottom of the hole should be taken as the main control indexes of hole cleaning.

(2) The first hole cleaning should basically remove the ballast before tripping out, and the second hole cleaning should last until the concrete arrives. After the second hole cleaning before concrete pouring, the mud specific gravity should not be lower than 1.3, but not higher than 1.1, and the thickness of sediment at the bottom of the hole should meet the design or specification requirements.

(3) In order to improve the hole cleaning efficiency, a screen can be used to intercept some fine sand carried by mud in the (reverse circulation) mud return tank or around the (positive circulation) mud pump.

3. Before the foundation pile reinforcement cage is lowered, in addition to the reinforced protective layer adopted in the design, small crushed stone concrete rollers with strength not lower than C25 should be installed on it to ensure the thickness of the reinforced protective layer.

4. In addition to the construction in strict accordance with the specification requirements, the following main items should be noted:

(1) The concrete mixing plant and concrete pouring site must be equipped with standby power supply;

(2) The concrete mixing production and transportation speed should meet the requirement that the pile hole is poured within the specified time. The pouring time shall not be longer than the initial setting time of the initial plate of concrete. The grouting speed should be appropriately slowed down in the easy-to-collapse stratum and the junction of soft and hard geology.

(3) aggregate gradation and construction mixture ratio should be strictly controlled to ensure the workability of concrete. The material receiving port of concrete transport vehicle should be equipped with a screen to effectively remove the super-large particle size aggregate and cement caking in concrete.

(4) The slump of concrete before entering the funnel should be strictly controlled at 18-22cm.

(5) The initial concrete quantity shall ensure that the initial buried depth is not less than 1m, and the elevation of concrete surface shall be measured every time the conduit is lifted, so as to ensure that the buried depth of the conduit is not less than 2m and not more than 6m. Check the situation inside the catheter every time you pull out the tube;

(6) near the end of grouting, it is advisable to adopt the method of increasing the height of funnel or pumping mud to prevent the pipe from being blocked due to insufficient concrete pressure difference and unsmooth boiling;

5. Before concrete pouring of pile foundation, the following measures should be taken to prevent the reinforcing cage from floating:

(1) Before concrete pouring, effective measures should be taken to make the reinforcing cage and the casing firmly fixed.

(2) In the process of pouring concrete, the conduit should be properly lifted to minimize the buoyancy of the reinforcing cage caused by concrete pouring.

(3) When the reinforcing cage shows signs of floating, the pouring should be stopped immediately to find out the reason, and appropriate pressure can be applied to prevent further floating.

6, according to the construction experience, pile foundation construction should be carried out as soon as possible without damage detection, so as to help find problems in time, sum up experience, improve technology, avoid sick piles and improve the quality of subsequent piles.

2. Key points of pier column and abutment construction:

1. Before construction, a special construction scheme and the checking calculation of formwork support structure shall be formulated and submitted to the supervisor for approval.

2. Strengthen the control of pier alignment, use integral formwork, and minimize joints. When joints are made, pad sponge strips or rubber strip and tighten the seal. After each template is installed, the elevation, center and plane size of the top surface of the template should be detected.

3. During concrete pouring, displacement observation should be carried out, and observation records should be made. The verticality or inclination of pier shaft should be strictly controlled, and the deviation should be corrected immediately to avoid formwork expansion. The thickness of layered pouring and vibrating is generally one layer every 3cm. When vibrating, the vibrating rod should be about 5cm deep into the lower layer, not too thick, otherwise the vibrating effect is not good. Concrete should be poured continuously, and the interval between two layers should not be too long.

4, bearing cushion stone construction should be measured and laid out one by one, and steel formwork should be adopted; After casting, it is necessary to retest one by one, strictly control the elevation and flatness of the top surface, and rework the unqualified ones.

3. Key points of beam and slab prefabrication

1. Beam and slab prefabrication should be centralized, and the number and location of bridge prefabrication plants should be determined according to the specific conditions of the project before implementation. In principle, it is not allowed to set the bridge prefabrication yard within the red line of subgrade. If necessary, it should be set in the subgrade section that has reached the elevation and must be reported to the superior for approval.

2. All kinds of production and living facilities in the prefabrication plant should be arranged reasonably, all kinds of machines and equipment should be placed in order, the waterproof and drainage system should be perfect, and the roads in the site must be hardened to ensure smooth roads. The prefabrication factory shall set up the project introduction board, the layout plan of the construction site, the safety and civilized construction slogan, etc.

3. The storage site of beam body should be leveled and compacted, and drainage ditches should be excavated around to ensure that there is no water in the site. Do a good job in the layout of the beam storage site first. The beam storage site requires leveling and compaction, and the drainage is smooth to prevent the beam and slab from breaking due to foundation settlement.

4. Precautions for precast beam:

(1) The foundation at both ends of the reused' prestressed beam pedestal shall be enlarged and deepened according to the concentrated load calculation after the precast beam is tensioned; T-beam and box girder pedestal should be reinforced with reinforcement.

(2) The beam yard should be provided with a perfect drainage system to avoid soaking of pedestal foundation and uneven settlement and cracking.

(3) The anti-arch should be set reasonably according to the camber value of prestressed beam.

(4) During the construction, the bottom die shall be inspected regularly, and any abnormality found shall be handled in time.

(5) we should strengthen the inspection of template quality and template installation quality, and replace deformed templates in time, especially to prevent slurry leakage caused by lax flat-fell seam and loose sealing of various reserved holes, which will affect the quality of concrete pouring.

(6) The following measures should be taken to solve the problems of leakage or inaccurate orientation of reinforcement embedded in some bridge crash walls and expansion joints.

when prefabricating side beams and end beams, the embedded steel bars should be accurately positioned according to the design position, and fixed with the beam

body steel bars by spot welding, so as to prevent the embedded steel bars from being offset during concrete pouring, so as to ensure the accurate and effective connection between the collision wall steel bars, expansion joint steel bars and embedded steel bars.

the reinforcement of the collision wall should be embedded in place as soon as possible.

when the position of some steel bars in beam and slab conflicts, they shall not be cut at will, and the avoidance of steel bars shall follow the principle that ordinary steel bars give way to prestressed steel bars and secondary steel bars give way to main steel bars. When it is impossible to avoid, the processing shape of steel bars at the conflict can be appropriately changed.

(7) It is advisable to accurately mark the position of structural reinforcement on the prefabricated pedestal or binding pedestal of beam and slab, so as to effectively ensure the accurate installation position of reinforcement and avoid the lack of reinforcement.

(8) It is not advisable to remove the back pressure device to prevent the internal model from floating immediately after the roof is poured in the prefabrication of small box girder, so as to prevent the internal model reaction force from causing cracks at the chamfer of the top plate of the box girder inner hole before the concrete strength is formed. Countermeasures 1: It is advisable to remove the back pressure device step by step after the concrete pouring of the bottom and web plates is completed and before the pouring of the top plate; Measure 2: Remove the back pressure device after removing the internal mold.

(9) When the concrete of beam body is poured, the concrete at the anchorage zone of beam end, the concrete at the end of diaphragm and the horseshoe of T-beam are easy to leak, which leads to exposed honeycomb. The following measures should be taken to improve the prefabrication quality of beam and slab:

Special attention should be paid to vibrating the concrete under the prestressed anchor pad, and a vibrating rod as thin as possible should be selected, or steel plates should be installed on the vibrating rod for insertion and vibration; Strengthen the attached vibration force of this part; In the construction as far as possible reasonable reinforcement; Adopt high-grade fine stone concrete.

(1) in order to prevent slurry leakage at the bottom of the beam, the following methods can be used: when setting the pedestal, use channel steel or angle steel as the pedestal to wrap the notch outward, fill it with a high-strength rubber tube with a diameter slightly larger than the size of the notch, and use the side formwork to push the rubber tube tightly to effectively stop slurry.