Mountains and rivers are thousands of miles away, and the steps are non-stop. At 10:00 am on March 16th, the MCC17 Highway Engineering Technology Company successfully completed the pouring of the massive concrete bearing platform of the left No.1 pier of the Shichuan Yellow River Bridge of the Lanzhou Qingzhong Section of the G30 Lianyungang-Horgos Highway after 20 hours of continuous hard work. So far, Shichuan Yellow River Bridge has completed all the construction tasks of the bearing platform, marking that the construction of the main pier of the whole bridge has changed from "underground" to "above ground", and has entered the construction stage of the double-limb solid pier of the substructure.
The Shichuan Yellow River Bridge connects the Daheping Tunnel and the Shangheping Tunnel, which is one of the key projects of the expansion and reconstruction project of Lanzhou Qingzhong Section of Lianhuo Expressway, one of the highlights of the whole line, and one of the 30 key projects of MCC17. Its main span is 160 meters across the Yellow River. The bridge type is (90 + 160 + 90) meters three-span prestressed concrete corrugated steel web continuous rigid frame. The left bridge is 350 meters long and the right bridge is 349 meters long. The main girder of the bridge is a single-box and single-cell prestressed concrete continuous box girder with variable cross-section and corrugated steel webs, the main pier is a double-limb solid pier, and the lower foundation is a pile cap connected pile group foundation. Among them, there are four mass concrete bearing platforms, with a single size of (13.20 × 13.20 × 4.50) m, 71.9 tons of reinforcement and 784 cubic meters of C30 concrete design. Up to now, 36 pile foundations and 4 mass concrete bearing platforms of the main pier have been completed, and the double-limb solid pier of the substructure is advancing section by section.
As the final project of the last mass concrete bearing platform of the whole bridge, in order to ensure the smooth completion of pouring, the project department strictly controls each process. In terms of technical management, seminars and disclosure meetings on construction technical schemes and emergency safeguard measures for pile caps were organized for many times before construction to optimize various construction processes and refine various process measures. One hour before the start of pouring, the safety, technology, test management personnel and supervision engineers of the project department once again carried out detailed safety and technical construction disclosure to the site construction personnel on the concrete mixing, moulding, vibrating and temperature control links, so as to ensure that each operator can master the standard construction essentials and safety protection measures of each process; In the aspect of material selection, low-heat and micro-expansion cement is used, and a proper amount of ground fly ash is added to reasonably optimize the concrete mix proportion and reduce the cement consumption. The incoming floor materials shall be inspected layer by layer, and the unqualified products shall be removed from the site in strict accordance with the regulations. In the current situation that large vehicles can not enter the construction site of the super-large bridge, the whole process uses water transport to prepare enough materials for the mixing station; In terms of quality control, there are 5 layers of cooling pipes and 10 temperature measuring lines inside the reinforcement framework of the bearing platform. The cooling water is controlled by 24-hour circulation in a single-in and double-out way. The water temperature difference between the inlet and outlet pipes is between 5 and 10 degrees. The bearing platform is continuously injected for half a month from pouring to pouring; In the aspect of sample guide, the binding of steel bars, the installation of embedded parts and formwork, the mix proportion of concrete, the pouring speed and the vibration process are strictly debugged and controlled during the construction process, which provides a strong guarantee for the successful completion of the pouring of the bearing platform. Through the scientific management and control of the project department and many measures taken simultaneously, the one-time continuous pouring of the last mass concrete bearing platform was successfully completed, which effectively reduced the internal temperature of the bearing platform concrete and ensured that there would be no quality problems caused by the hydration heat of cement in the process of pouring and curing. The successful pouring of the
last bearing platform is a demonstration of the spirit of the project management personnel to "work together to defend their posts and fight on the front line all night long". It is also a major node achievement of the project and lays a solid foundation for the subsequent construction. Faced with such difficulties as tight construction period, heavy tasks, complex geology and difficult construction since the commencement of construction, the Project Department has always closely focused on the MCC Group's goal of "creating two top five", implemented the requirements of the "Three-year Action for Basic Management Promotion", adhered to the enterprise spirit of "not delaying for a day, not slacking for a day", and actively practiced the MCC17's "24-hour working method". On the premise of ensuring safety, quality and construction period, we should carry out all kinds of objectives in a down-to-earth manner, take the initiative to attack and constantly overcome difficulties, regardless of difficulties and conditions. Next, the project department will, as always, maintain a good construction situation, concentrate its efforts, strive for excellence, further accelerate the construction progress, and strive to complete all construction and production tasks safely and efficiently with the attitude of "decisive battle at the beginning, sprint at the beginning".
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