With the development of highway construction to high grade, the investment proportion and route length of bridge engineering are increasing, and the construction quality of bridge engineering directly affects the construction quality of the whole highway. Engineering quality supervision is a strict, systematic and comprehensive supervision and management of all links and procedures in engineering construction according to contract terms, technical specifications and design documents, so as to ensure the engineering quality meets the requirements stipulated in the contract. In bridge engineering supervision, the focus of work is to seize the inspection of each working procedure, strictly implement the quality management procedures of each working procedure, and ensure that the engineering quality of each working procedure meets the standards and grade requirements stipulated in the contract.
A, supervision contractor's preparation work before construction
Examining and approving the contractor's construction organization design is mainly to inspect the people, machines and materials entering the construction site.
1. Check the allocation of management and technical personnel according to the bidding documents or contract documents, and ask for corresponding supporting materials (such as project manager's certificate, ID card, technical qualification certificate, etc.).
2. According to the construction equipment report submitted by the contractor, check the configuration of construction equipment item by item, and hire professionals to check the intact state of various construction equipment to ensure the construction progress and quality of the whole bridge.
3. Check the mixture ratio test of raw materials, mortar and concrete.
(1) The quality inspection of bridge engineering materials mainly includes steel, cement, stone and sand. In addition to the ex-factory inspection list, the purchased materials must be sampled and inspected in parallel to confirm their quality. Self-collected materials, after determining the yard, take representative samples for testing to determine whether they are qualified.
(2) On the basis of raw material inspection, try to match mortar and concrete, and confirm the construction mixture ratio, and confirm and approve the mixture ratio of mortar and concrete.
4. Check the construction scheme, focusing on: (1) whether the main basis of design, various materials and descriptions of site construction conditions are correct; Whether the construction sequence and method are technologically advanced, economical and reasonable, and the time is optimal, and whether the new technology has been repeatedly demonstrated by the expert group, and provide detailed construction drawings, construction instructions and construction points; (2) According to the technical standards, go to the site to check whether the drawings, bridge centerline and leveling points meet the design requirements, whether the pile protection of the centerline control pile is stable and easy to operate, whether the connection with the centerline of subgrade meets the requirements, and whether the setting of leveling points meets the requirements of construction quality control; (3) Construction quality assurance system inspection: check whether the contractor's self-inspection personnel, quality and test equipment are complete, meet the contract commitments and meet the requirements of construction quality control; (4) Check whether the construction site, living facilities, water source, warehouse, material storage yard, transportation sidewalk, water and electricity supply, rest and entertainment facilities arranged by the contractor can meet the needs of the project scale.
Second, do a good job of preparation before construction.
The supervision of the construction process can be divided into three stages: construction preparation stage, construction implementation stage and project completion acceptance stage. The key point of quality control in the construction preparation stage is to check the contractor's preparation work before construction according to the contract terms.
1. Improve the supervision organization and define the quality control objectives. According to the supervision contract signed with the construction unit, first establish and improve the supervision organization. For several key positions of quality control, personnel familiar with the business and with corresponding qualifications and titles shall be appointed as chief supervision engineer, resident supervision engineer, road professional engineer, bridge professional engineer, test professional engineer, survey professional engineer, etc. , so that supervisors can carry out supervision work in a targeted manner.
2. Supervise the construction unit to establish the project quality self-inspection guarantee system. Although the supervisor manages the whole construction process, the inspection carried out by the supervisor is random inspection, and the overall quality inspection of the construction process is first carried out by the construction unit. Therefore, it is very necessary to urge the construction unit to establish a perfect self-inspection system as soon as possible before the project starts. In addition to reviewing the quality assurance system block diagram of the construction unit, we should also check the quality of the test personnel and the work quality of the self-inspection personnel of the construction unit, because they play an important role in ensuring the engineering quality. At the same time, in order to detect in time in the project, check whether the quantity, model and specification of laboratory equipment can meet the requirements of relevant testing standards, and verify relevant equipment and instruments.
3. Quality points that must be strictly controlled before construction. Before the project officially starts, the supervisors mainly control the following quality: (1) Check the raw material certificate and retest report, and conduct sampling inspection; (2) Check the quantity, performance and integrity of construction machinery and equipment; (3) Check the construction pay-off to ensure that the line position is accurate and the leveling points are closed.
Through the control of the above quality points, it laid a foundation for quality control and guarantee in the construction process.
Third, the quality supervision in the construction stage
Quality control is the core of supervision work. In addition to the supervision work in the construction preparation stage, we must also attach great importance to the quality of concealed works. The quality of concealed engineering has a great influence on the quality of the whole project.
1. Strictly control concealed works, especially the inspection of foundation works: (1) Foundation excavation and inspection shall be carried out in strict accordance with construction procedures and supervision procedures. The focus of foundation pit excavation is the cleaning and drainage of the basement, and the inspection of the bearing capacity of the basement, including the size, elevation, soil uniformity, foundation stability and bearing capacity, construction diary and related test data. (2) The key points of supervision of bored pile foundation process are: site cleaning; The manufacture, burying or sinking of the liner shall meet the requirements; Mud can generally be made of cohesive soil with plasticity index greater than 25, particle size less than 0.074mm and clay content greater than 50%; Drilling should be completed at one time, without stopping halfway, and records should be filled in carefully. After the drilling reaches the design depth, it shall be inspected in time and signed by the supervision engineer. The actual preparation label of underwater concrete should be higher than the design10% ~15%; After drilling, hole cleaning, reinforcing cage hoisting and concrete pouring, inspection shall be made, cement concrete pouring records shall be filled in and submitted to the supervision engineer for filing. When the supervision engineer thinks it is necessary, the static load test can be carried out on the cast-in-place pile.
2. Quality control of pier and abutment: (1) When pouring the pier and abutment foundation and the first layer of concrete, water in the concrete should be prevented from being sucked away or the water in the foundation seeps into the concrete to reduce the strength of the concrete; (2) When the slipform is used to pour the pier and abutment, the following provisions shall be observed: 1) The concrete shall be of low fluidity or semi-dry; 2) When pouring, it shall be carried out symmetrically in layers and sections, and the same layer of concrete shall be poured at the same time, and each section shall be poured to a position not less than 10 ~ 15 cm away from the upper edge of the formwork; 3) Adopt mechanical vibration, and the vibrator shall not be inserted into the lower layer more than 5cm4) Early strength agent can be added to accelerate the lifting of the formwork; 5) Pay attention to prevent the hydraulic jack or tubing joint from leaking oil to the concrete or steel bar during sliding; 6) Casting shall be carried out continuously. Stop halfway for some reason, according to the construction joints.
3. Inspection of hoisting ropeway: (1) Installation quality; (2) no-load operation; (3) Static load operation; (4) Carry out trial operation.
4. Inspection of support, formwork and steel bar layout: (1) Formwork and support are correct in shape and size, can reliably bear all allowable loads that may occur during construction, and ensure no deformation, convenient disassembly and assembly, repeated turnover, tight joints and no leakage of slurry; (2) The fabrication and installation of steel bars meet the requirements of design drawings.
5. Inspection of anchorage and tensioning equipment: (1) Anchorage: The materials shall be used according to the design regulations, the configuration shall be complete, and the strength inspection meets the requirements; (2) Tension equipment: inspection of steel strand bundle and tension operation.
6. Inspection of prefabricated members: (1) The site is smooth and solid, and drainage can be done well; (2) each precast member is poured at one time; (3) The reinforcement in the block should be firmly supported; (4) vibrating should be dense; (5) The installation shall meet the requirements.
7. Inspection of auxiliary works of bridge deck: (1) Expansion joints and settlement joints meet the requirements; (2) the waterproof layer material quality should be checked before construction; (3) The position and quantity of drainage pipes shall be implemented according to the design requirements; (4) When installing seat belts, kerbs, sidewalks and railings, check the size and installation position, and pay attention to construction safety.
8. Inspection of filling soil at the bridge approach and abutment back: (1) The filler shall be made of permeable materials, which shall be filled and compacted in layers under the optimum water content, with the thickness less than 20cm and the compactness meeting the design requirements; (2) When filling symmetrically, backfill can be carried out after the concrete strength of abutment reaches 70%; (3) The approach road filling shall be carried out in coordination with subgrade filling.
Four. conclusion
In supervision practice, corresponding measures should be taken according to the actual situation in view of different problems in actual construction. The supervision procedure of bridge engineering construction should be carefully formulated and divided, the inspection of each specific component should be detailed, and different supervision schemes should be formulated for different bridge types. In short, the supervision of bridge engineering construction should be carried out in strict accordance with the design documents and relevant specifications, and the supervision engineer must have a sense of responsibility, earnestly follow the supervision policy of 16 "strict supervision, enthusiastic service and meticulous justice", and truly play the role and function of a supervision engineer.
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