On June 3, the steel beam erection construction site of the Zhujiang Jicheng Jinhai bridge of China Railway Bridge Bureau was in full swing. More than 500 workers gave up their rest and spent the holidays on the construction site to speed up the project construction with hard work.
For the first time, the cantilever steel beam of No. 28 pier of Jinhai bridge was erected asynchronously. On June 1, the D3 standard section steel beam of 28 pier was erected. On June 2, the E3 standard section steel beam of 28 pier was erected. On June 3, the fine adjustment of the d3/e3 standard section steel beams of 28 pier was completed and the construction of high-strength bolts was started. So far, more than half of the cantilever steel beams of pier 28 of Jinhai bridge have been erected asynchronously.
The steel beam of d3/e3 standard section of 28 pier has a unit weight of about 684t, and a 750t walking beam erecting crane is used for asynchronous erection. During the erection of steel girder, the operators overcome the difficulties of positioning the ship transporting steel girder due to the strong wind and waves at sea, the rapid rise and fall of the tide; The steel beam is heavy, with a single section weighing about 684 tons, and the hoisting safety risk is high; In addition, the double cantilever asymmetric hoisting scheme is adopted for the first time for the erection of the steel beam of pier 28, i.e. hoisting on one side, adding water to the counterweight on the other side synchronously, and the synchronous and symmetrical loading on both sides requires high precision control; The installation accuracy of steel beam shall be high, and the deviation of steel beam axis shall be controlled within ± 2mm. In addition, No. 28 pier is between the access channel and CNOOC pipeline. During the erection of steel beams, transport ships will occupy the channel, so it is necessary to communicate and coordinate with maritime and other relevant departments in advance. The CNOOC pipeline is laid on the seabed where the sea area is erected, which has high requirements on ship anchoring and other aspects.
The main bridge of Jinhai bridge consists of 4 steel main towers, 8 large section steel box girders and 39 standard steel box girders (including 3 closure blocks). At present, China Railway Bridge Bureau has completed the erection of 4 steel main towers and 8 large section steel girders of the main bridge, and all 18 standard section steel box girders of piers 26 and 27 have been erected in place. In the second round of 18 steel box girders, 2 standard steel box girders for Pier 29 and 6 standard steel box girders for Pier 28 have been erected. It is expected that the side span steel girder of the bridge will be closed in mid June this year, and the main bridge will be closed in August this year.
The Zhuhai Airport intercity rail transit project and the Jinhai highway bridge construction project are key projects integrated into the national strategy of Guangdong, Hong Kong and Macao Great Bay area. After completion, they will become an important passenger channel connecting the mainland and the Pearl River Delta with Macao and Hong Kong and the most important transportation hub of Zhuhai Hengqin new area.
What are the requirements for steel beam processing?
1) The variety, specification, chemical composition and mechanical properties of steel and welding materials used for steel beam processing must meet the requirements of design and relevant technical specifications, and have complete ex factory quality certificate. They can be used only after they are rechecked and qualified by the manufacturer and the supervising engineer.
2) The processing dimensions of steel beam processing elements, lifting points and rail lifting points and the pre assembly accuracy of steel beam shall meet the requirements of relevant technical specifications, and shall be signed and approved by the supervising engineer after inspection and acceptance.
3) Welding procedure qualification must be carried out before steel beam processing and fabrication, and the evaluation results shall meet the requirements of technical specifications and be signed by the supervising engineer for approval. Welding personnel must have corresponding welding qualification certificates and work licenses. The steel beam weld at the same position shall not be repaired more than twice, and the repaired weld shall be rechecked according to the original quality standard.
4) Before assembling the steel beam, check whether the web plate and flange plate need to be corrected. Assembly and welding can be carried out only after they are qualified. (semi) automatic welding machine is mainly used for welding, combined with manual arc welding.
5) Before welding, the welder shall recheck the quality of the weldment joint and the treatment of the welding area. When the H-section steel does not meet the requirements, it shall be repaired and qualified before welding. Damp flux and rusty welding wire shall not be used. The anti slip coefficient of high-strength bolts shall be inspected, and the inspection results must meet the requirements of design specifications.
6) After welding, the welder shall clean the slag on the weld surface, check the appearance quality of the weld, and the overall dimension of the weld shall comply with the provisions of the current national standard “overall dimension of steel structure weld”. The T-shaped connection weld between the upper and lower flange plates of the H-shaped steel beam and the web shall be fully welded.
7) The steel beam processing must be subject to trial assembly and acceptance according to the design and relevant technical specifications. Site installation and construction personnel shall participate in trial assembly and acceptance. After passing the acceptance, the beam section product certificate shall be filled in and issued before delivery and installation.
Basic requirements for steel beam processing and fabrication
8) Steel beam processing elements and steel beams shall be stored to prevent deformation, collision damage and paint damage, and unqualified elements shall not be used.
9) The embedded parts of drainage facilities, lamp holders, guardrails, curbs and railing posts shall be installed according to the design drawings without omission and in accurate positions.