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Quality control of track engineering materials of Beijing Rail Transit Daxing Line?

What is the quality control of Beijing Rail Transit Daxing Line track engineering materials? Below, Zhongda Consulting will introduce relevant content for your reference.

1 Overview The main line of Beijing Rail Transit Daxing Line is 21-7km long, divided into underground, transitional and elevated sections. It adopts a variety of track bed forms. On the main line and auxiliary lines, underground lines are generally The short sleeper type integral track bed is used in the section. The vibration-absorbing section adopts type III shock absorber fastener type integral track bed, trapezoidal sleeper type integral track bed and steel spring floating plate type integral track bed according to different vibration reduction levels. The viaduct adopts bearing rails. Table-type integrated track bed; gravel track bed is used on the outside lines of the yard line and test line warehouse; and integrated track bed is used inside the warehouse. The various forms of track beds also result in the diversity of various engineering materials for the Daxing Line track project. Taking fasteners as an example, the general section of the main line and auxiliary line uses DTⅥ2 type elastic separate fasteners; the general section of the elevated line uses DTⅦ2 type elastic separate fasteners; the general vibration-absorbing section uses type III shock absorber fasteners; The trapezoidal sleeper section uses spring II-1 type fasteners; the 60kg/m rail section of the yard line test line uses DTVI1 type, and the 50kg/m rail section uses DTIV1 type fasteners; the overall track bed in the depot generally uses DJK5-1 type fasteners . The column-type inspection pit in the warehouse is specially equipped with buckle-type fasteners.

The incoming materials for the Daxing Line track project are divided into two categories according to the procurement method. The first category is purchased by Jia, with a total of 36 types from 8 units; the second category is materials purchased by the construction unit itself. ***A total of 16 units and 57 categories. 2 Material Management Measures 2-1 Supervise the construction unit to establish and improve the material quality management system. The quality control of engineering materials is an important part of the construction unit's project quality assurance system and is the first step in project quality control. The full play of the role of the construction unit's own quality assurance system plays a decisive role in ensuring the quality of the project. Therefore, in the supervision of the Daxing Line track project, the Superintendent's Office attaches great importance to the role of the construction unit's own quality assurance system, and urges the construction unit to establish and improve the material quality assurance system through various methods, so that the construction unit can ensure that the construction unit is equipped with personnel, system establishment and procedures, Strengthen investment and management in all aspects and links such as methods and means, so that the quality assurance system of the construction unit can operate healthily and fully play its role, playing a fundamental role in ensuring the quality of engineering materials. At the beginning of entering the site, the General Director's Office required the construction unit to report the personnel, division of labor and corresponding responsibilities of the material management department, and focused on checking the qualifications of the test personnel to ensure that personnel were in place, responsibilities were clear, the system was operating, and quality was controllable. 2-2 Establish and improve the material supervision management system and responsibility system of the general director's office. The supervision unit's random inspection, re-inspection and parallel inspection of project materials are an effective supplement and supervision of the self-inspection and self-control work of the construction unit, and are an important responsibility of the supervision unit. It plays an important role in the quality assurance of engineering materials. The construction unit must conduct sampling and testing work under the supervision (witness) of the supervisor. When the inspection results of the supervisor are inconsistent with the test results of the construction unit, the inspection results provided by the supervisor shall be used as the standard. In response to the actual situation of the Daxing Line track project, the Superintendent’s Office formulated detailed supervision rules and clarified the material supervision procedures and responsibilities. Detailed provisions are made on the responsibilities, powers, working methods, steps, means of directors, resident supervision team leaders, material supervision engineers and on-site supervisors in material supervision work, as well as the quality requirements for materials and measures to be taken to ensure quality. . The General Director's Office has established a ledger for testing and testing of incoming materials to keep abreast of the quality of materials at the construction site. Each resident supervision team leader is responsible for statistics and inspection of the incoming materials of the bidding section, and professional supervision engineers carry out their work in strict accordance with the relevant regulations on material supervision. 2-3 Laboratory management The test (inspection) of track engineering materials can be carried out by the construction unit on site (if there is a laboratory on site) under the supervision of the supervisor, or on-site sampling can be carried out under the supervision of the supervisor and by a third-party laboratory Experiment. According to the actual situation of the Daxing Line track project, all engineering tests and re-inspections are undertaken by third-party laboratories. Therefore, the qualifications of engineering laboratories and the accuracy and reliability of test data are crucial.

First of all, the supervision unit reviews the qualifications of the test and inspection unit. At the same time, when receiving the test report from the inspection unit, the supervision unit must not only check whether the material test data meets the standards, but also check whether the inspection standards used by the inspection unit are valid to ensure that the project is used Materials of high standard. 2-4 Management before materials enter the site. For all materials planned to enter the site, the material supplier or manufacturer must provide a complete set of material quality certificates, including factory certificate, quality commitment letter, third-party inspection report provided by the production unit, and factory Inspection reports, quality certificates, and raw material entry inspection reports will be reviewed by the general manager’s office together with the construction unit, otherwise they will not be allowed to enter the site. 2-5 Material Inspection and Engineering Test Management In view of the small subway construction site, it is difficult for the construction unit to purchase large quantities of materials. For each batch of materials entering the site, the General Director’s Office requires the construction unit to stack and store them separately according to product and model, and clarify whether Pass the re-inspection. In order to ensure the continuous progress of construction, the general manager's office divided the incoming materials into three categories based on the objective conditions of different materials for different levels of control and inspection. (1) For materials that cannot be replaced, use them only after passing the inspection (such as various steel materials used in track beds, etc.). (2) For materials that can be replaced, on the basis that the supplier can provide material self-inspection certificates and qualified third-party inspection reports, inspection and construction should be carried out at the same time (such as track connection parts, etc.), and each batch should be strictly recorded The parts used will be randomly inspected and retested. If the first sample does not meet the standard, a second double inspection can be carried out. If it still does not meet the standard, the batch of incoming materials will be withdrawn from the site and the used ones will be replaced. deal with. (3) For materials related to the function and safety of engineering use, physical tests should be done first. If the results are qualified and the technology is stable, they should be reported to the laboratory for inspection. The inspection and construction should be carried out at the same time, and self-inspection tests should be done regularly (such as the type of rail joint welding). testing and periodic inspection, etc.). 2-5-1 Steel For each batch of steel coming into the site, the construction unit is required to stack and store it in batches and categories, and fill in an inspection form to explain the origin, specifications, and usage parts of the steel. On this basis, the material supervision engineer will inspect Product certificate, quality guarantee and material test report, and conduct witness sampling tests. Materials that have not been inspected are not allowed to be used in projects; materials that do not meet the quality requirements will be removed from the site in a timely manner. For example, if the steel coming in from the construction unit is inspected as steel produced by Tangshan Iron and Steel Co., Ltd., and the supervisor comes to the site and finds that the steel entering the site does not have a nameplate, the supervisor immediately notifies the construction unit to prohibit its use and supervises the removal of all steel in this batch from the site. Most of the incoming steel bars must be processed on site before they can be used in projects. Before processing, the construction unit must first make welding test pieces and have them welded by professional welders. Only after passing the inspection can the steel be processed and welded. Insist on taking 1 set of samples for testing every 300 joints, and always insist on synchronizing random inspection with the progress of material processing. 2-5-2 The track component construction unit shall submit the material arrival plan in a timely manner based on the construction progress and site conditions. After the materials arrive at the site, the construction unit notifies the resident supervision team leader to confirm the completeness of the relevant quality certification documents, and check the consistency with the physical objects and quantities. Unloading will be carried out after the materials are correct. When stacking materials, fire-proof, moisture-proof, anti-corrosion and other measures shall be taken to ensure that the materials are in good condition before use. The material supervision engineer, together with the material technicians of the construction unit, will sample different batches of incoming materials based on the principle of one random inspection and double random inspection, and then send them to a third-party inspection unit for retesting. After passing the inspection, It is allowed to be used in engineering projects. If unqualified products are found, the construction unit shall be ordered to remove the products. 2-5-3 Commercial concrete Review the qualifications of commercial concrete manufacturers for supplying commercial concrete, review and approve the mix ratio of commercial concrete, test the slump at the pouring site, and strictly comply with the provisions of the "Concrete Structure Engineering Construction Quality Acceptance Code" (GB50204-2002), on-site retention Test blocks are used for witness testing to ensure the construction quality of track bed concrete. 2-5-4 Before the formal welding of rail welding joints, the construction unit is required to organize professionals with certificates to work, debug the rail welding machine at the rail welding base, and conduct rail welding tests. After the inspection by the flaw detector is qualified and the data is stable, the construction unit Organize a drop weight test and adjust the relevant parameters of the rail welding machine according to the test conditions.

When the construction unit passes the drop weight test for 3 batches, the supervisor will participate in 3 consecutive batches of tests. If the test fails, the relevant parameters of the rail welding machine will continue to be adjusted and retested. If all tests pass, the supervisor will be sent to a third-party inspection unit for the third batch. Three-party inspection, formal welding can be carried out only after passing the inspection. After welding the rails, the construction unit conducts rail flaw detection. When the flaw detection wavelength exceeds the specified value, the construction unit is required to saw off the welded joints and re-weld them. When the construction unit's self-inspection is 100% qualified, the supervision unit will organize professional flaw detectors to conduct quality inspections based on 10 of the total number of welding heads. Ensure the welding quality of rail welding joints and ensure driving safety. The testing units and testing items involved in the Daxing Line track project are shown in Table 3. 3 Conclusion For the quality control of track engineering materials, the initiative of the construction unit should be fully utilized, and different engineering materials should be managed separately according to the actual conditions of the project. In the process of material inspection, we adopt a combination of visual inspection and experimental inspection, and combine self-inspection of the construction unit with supervision sampling inspection and parallel inspection. We strictly follow the supervision procedures and strictly control the laboratory qualifications. We focus on supervision, supervise, help, and promote Only by combining them can we ensure the quality of track engineering materials and lay the foundation for effectively controlling the quality of track engineering.

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