| In the past 20 years,the rapid development of China’s high-speed railway industry has greatly changed people’s lifestyle,promoted the social development and the exchange and integration of urban culture.With the steady development of China’s high-speed railway construction,the design scheme of laying Turnouts on bridges is favored by designers.Therefore,the elevated turnout beam has become a key consideration in the design and construction.In order to meet the structural stress requirements,continuous variable crosssection box girder is often used for turnout beam.Its section width is changeable,the span is large,the technical content is high,and the construction difficulty is also increased.The support method is the most commonly used construction method of turnout beam at present.In the process of turnout beam construction with bracket method,the bracket is a temporary load-bearing structure which bears the load of bridge beam and other ancillary structures,construction personnel and equipment,and plays a very important role.Serious safety accidents often occur due to unqualified support design and erection quality.Therefore,it is an important research topic to design and study the high formwork support system of turnout beam,so as to reduce the possibility of accidents caused by support problems in construction.This paper starts with the high formwork support system,searches for the relevant literature at home and abroad,and combs the relevant theories.According to the actual case,through introducing the background of the case,analyzing the hydrogeological conditions,elaborating the design scheme of the formwork,analyzing the stress of the foundation,and selecting the existing support scheme.After doing a good job in the preliminary work,the finite element model of various support design schemes is constructed,and then the stress analysis of the main components is carried out,and then the economic comparison and selection of each support scheme is carried out,so as to obtain the optimal support scheme from two aspects of technology and economy.Finally,the preloading monitoring in construction is analyzed.The main conclusions are as follows:(1)Through the analysis of the engineering characteristics and hydrogeological characteristics,and the stress calculation of the support foundation,it is considered that the foundation performance is good.(2)The finite element model of various support design schemes was constructed(1)In the aspect of beam component strength,the strength of steel pipe column Bailey beam component is greater than that of steel pipe column military beam component;in terms of vertical pole strength,the safety factors of vertical pole strength of four schemes are 2.44,2.25,2.57 and 2.46 respectively,and the safety factors of each scheme are not different,and they are all greater than 1.0,meeting the requirements of the code.(2)In terms of stability,the safety factor of stability of the four schemes is greater than 1.0.The smallest is the steel pipe column military beam support,which is 2.08,and the maximum is the fastener type full hall support,which is 2.85.(3)In terms of stiffness,the safety factors of steel pipe column Bailey beam support and steel pipe column military beam support are 2.65 and 1.46 respectively,which meet the requirements of the specification.(4)The four kinds of support schemes are safe and reliable.The minimum safety factor of strength is 1.64,the minimum safety factor of stability is 2.08,and the safety factor of stiffness of beam type member of beam support is the minimum,which is 1.46,which is greater than 1.0,which meets the requirements of the specification.(3)From the economic point of view,the steel tube column Bailey beam type support needs the least material,the lowest erection cost and the best economy.Therefore,this scheme is the optimal support design scheme.(4)In this paper,the erection,installation,preloading and dismantling of steel pipe column Bailey beam support are monitored and analyzed,and the preloading is tested on site.According to the preloading results,the pre camber value calculated in the early stage is compared and analyzed,which provides the basis for the actual camber adjustment after preloading.The research in this paper provides a reference for the design and construction of the support system of related projects,enriches the research on the support system of high-speed railway turnout,and provides assistance for the research of the support system. |
