Research On Optimizing Of The Construction Scheme About Cast-in-Place Simply Supported Girder Bridge Overpass Existing Railway Line Based On Value Engineering

With the railway transport services, especially the rapid development of construction of high-speed railway in our nation, the situation that the newly-built or rebuilt railway intersects with the existing railway during the construction of railway often encountered, One of the most common is the existing line in beam construction?Because its big risk for construction, tense construction period and quality requirement is high. which prompted the railways builders set of ideas, innovation to speed up the technology research and exploration on bridge construction, At the same time adopt a scientific and rational theory method to various alternative construction scheme optimization, to achieve the purpose that safety, high-quality and high-efficient completion of the construction of the bridge engineering.So this paper take one cast-in-place simply supported beam bridge which crossing Shi-Wu passenger dedicated line in ZhengZhou airport intercity railway as the research object. And Study on the value engineering principle to carry on the scheme optimization, from study obtained following conclusions:(1)Through the analysis of overhead existing railway line simply-supported beam bridge construction characteristics, applicability and advantages and disadvantages of the conventional construction method such as Adjust the longitudinal slope method, Side a precast moving beam method,Covers all the scaffolding method,movIing formwork method were analyzed. combining with the actual situation of the project, by the careful research and analysis calculation of experts and constructive technicians put forward a new construction method for overhead existing railway line simply supported beam bridge cast-in-place.”pier top longitudinal support scaffolding method”.(2)According to the pursuit of consistency of simpiy-supported beam bridge construction scheme optimization in overhead existing railway line and value engineering,that is at the lowest cost make products to meet the function need of the user. the result shown that using the value engineering principle to carry on the scheme optimization is feasible.(3)From five aspects, safety(safety of existing lines, safety of scaffold erection,security of beam concrete pouring, safety of scaffold remove), quality reliability(quality reliability of scaffold erection,quality reliability of beam concrete pouring,quality reliability of beam appearance),rationality of construction time(rationality of scaffold erection construction time, rationality of beam concrete pouring construction time,rationality of scaffold remove construction time),feasibility of construction(operationa complexity for constructors,whether meet the material equipment limits,whether meet the site space limits)and environmental protection(legitimacy of the construction waste emissions, controllability of noise pollution, controllability of dust pollution) to define its function and analysis of the construction scheme of construction scheme for simply supported beam bridge in overhead existing line. and then using multi scale evaluation method to take theoretically feasible construction scheme as a whole to consider.summarize and proposes one function evaluation system for construction scheme,using this system to carry out the function evaluate for the alternatives scheme,and then calculate the function coefficient,cost coefficient, value coefficient of each scheme,finally choose the scheme with the maximum value coefficient as the implementation construction scheme.finally introduction of one cast-in-place simply supported beam bridge which crossing Shi-Wu passenger dedicated line in ZhengZhou airport intercity railway to verify this method,the result shown that this method is scientific,reasonable and feasible.