Research On Key Construction Techniques For Bridge-building Integrated System In Railway Stations

With the rapid development of modern railway in our country, national railway mileage reached110000kilometers, of which the passenger railway and intercity railway run13000km long by2012. According to the principle of point-line capacity matching, more than1000new railway stations will start construction in our country, so the tasks of railway stations constructions are very arduous. In accordance with the principle of "functionality, systematicness, advancement, culture, economy" formulated by former ministry of railways, the construction of railway station presents many new trends in our country:comprehensive three-dimensional transportation hub, simple and transparent space, both advanced and economical efficiency. So the " bridge-building integrated structure" arise at the historic moment, which is adopted by the new Wuhan station. This new type of structural system gives people a refreshing sense of shock, though brings a lot of problems to the structural construction.The thesis regarded the construction of bridge-building integrated system in Wuhan station as the object of research, and studied the key technology in this new structure. The main research achievement is as follows:(1) Through the technical and economic analysis and comparison between the whole bridge construction project and the separate poured integral tensioning construction project, found that the latter project can ensure the construction quality and time limit for the project of three span rigid frame arch bridge, which reduced the input of template, and provided a good traffic environment for the scene. On this basis, the construction project of the three span rigid frame arch bridge in Wuhan station was confirmed, which established the foundation of smoothly construction and completed on schedule for this project.(2) Take advantage of the time-varying mechanics theory and ANSYS software, the numerical simulation and analysis of the whole construction process that separate poured integral tensioning of three span rigid frame arch bridge in Wuhan station was carried out.The simulation calculation results and analysis conclusions provided a scientific grounding for formulating safety measures in the construction process targeted and improving the efficiency of construction, played an important role in ensuring the safety of the Wuhan station three span rigid frame arch bridge construction and completion on schedule.(3) Contraposing the complexity and importance of the three span rigid frame arch bridge’s template system in the Wuhan station, the template system was designed according to the related specification of both Chinese and English contrast analysis, the British standard was used to confirm the rule of horizontal load value in formwork system design,and the SAP2000and ANSYS11.0software was used to review and optimize the template system design scheme, all of these was for the sake to ensure the design optimization and safe use of complex template system.(4) Contraposing composition of non-developable surface in the three span rigid frame arch bridge of Wuhan station, in order to meet the stencil palette’s high precision requirement of fair-faced concrete, the paper presented the design principle and method of high precision stencil system with complicated structure, and established the template layout, blanking, spellers process and acceptance criteria, which can be a reference of other similar projects system template design.(5) Contraposing the problem that the conventional moveable formwork in conventional bridge construction can’t be used, the paper invented the multi-fulcrum lateral movement formwork with the function of whole demoulding, overall folding, whole lift, overall direction to walk, self-adjustment, free of preloading, which could form the multi-fulcrum technology, no settlement sand box technology, the whole demoulding technology, the overall folding technology, the overall folding technology, the moveable formwork location adjustment technology of the multi-fulcrum lateral movement formwork."Multi-fulcrum lateral movement formwork in the bridge construction"(ZL200910147109.7) and "Adjustable interface template installation structure"(ZL200910157420.X) were granted the invention patent by the state intellectual property office."Preloading sandbox"(ZL201020552516.4) was granted the patent for utility model by the state intellectual property office, which have been successful applied in the construction of three span rigid frame arch bridge of the Wuhan station. The series of achievements meet the requirements of the template system in the group of bridge construction, save the time limit for a project, implement fast turn around of the template, and achieve good technical and economic benefits and social benefits.(6) Because of the complex shape, dense steel bar distribution (327kg/m3), and high concrete gap (up to11m) of three span rigid frame arch bridge of Wuhan station, and the apparent mass should meet with quality requirements of the original veneer of fair-faced concrete, the paper researched the mixing ratio of self-compacting fair-faced concrete and corresponding technology, which has been successfully applied in Wuhan station project. In the case of large earthwork quantity of the self-compacting fair-faced concrete (6600m3), the long construction duration (almost24months), the paper implemented the concrete apparent of complex special-shaped concrete within the same visual space structure to achieve the requirement and standard of the fair-faced concrete veneer. This perfectly showed the natural texture of fair-faced concrete, and reduced the decorative surface of about145500m2, obtained considerable economic benefit and social benefit.(7) Combining the requirements of working performance of concrete in the floor filling layer of Wuhan station, the working performance of lightweight aggregate concrete was improved by reasonable selection of raw materials, adjusting the concrete mixing process, adding air-entraining agent and homemade tackifier in concrete,and replacing partly light sand by river sand moderate. At the same time, a new technologyof concret has been developed which has a low apparent density (1160kg/m3) and pumping characteristics."A kind of lightweight aggregate concrete which contains zeolite powder and natural river sand and its preparation method"(ZL200910177544.4) was granted the invention patent by the state intellectual property office. This technique successfully applied in Wuhan station project, improved work efficiency, significantly reduced the weight of the structure, achieved the comprehensive utilization of resources, obtained good technical and economic benefits and social benefits.