Research On Causes And Control Measures Of Concrete Cracks In Frame Structures Of Metro Station

As the main travel mode of people in urban rail transit,the subway project plays an important role in people’s daily life and work.The subway station frame structure is an important part of the construction of the subway project.During the construction process,the subway station frame structure is affected by the shrinkage of the concrete and the heat of hydration.Part of the concrete structure has cracks to varying degrees,affecting the subway.Normal use.Based on a large amount of information and previous experts’ conclusions,this paper conducts theoretical analysis and finite element simulation,discusses the causes of cracks in the side walls,beams and other components of subway stations,and gives certain solutions.Get better crack prevention measures.Theoretical derivation of heat transfer of concrete was introduced.The theoretical basis of hydration heat and concrete parameters were introduced.Based on this basis,the influence of beams,slabs and walls of subway station frame structures on concrete hydration heat was also studied.The influence of concrete components on the cracks of beams,slabs and walls in different convection coefficients,different ambient temperatures,different pouring temperatures,different pouring sizes,etc.is simulated by finite element software and combined with theoretical analysis to obtain the distribution of temperature stress law.The shrinkage mechanism and prediction mode of concrete and the effect of early shrinkage of concrete on the cracks in the frame structure of subway stations are introduced.At the same time,the theoretical analysis of the beams,slabs and walls of the subway station structure under the influence of concrete shrinkage and the changes in the conditions of different humidity,different constraints,different continuous pouring lengths,and different reinforcement ratios were passed through the finite element software The simulation is performed and compared with the theoretical analysis to obtain the evolution law of shrinkage stress.Relying on a station of Shijiazhuang Subway Line 2 as a project,the crack distribution of each frame structure of the subway station frame was obtained on the site,and the combined effects of hydration heat and shrinkage were combined to analyze the overall component and change the construction method and thermodynamic parameters.Keep all components within the range of safe use,and finally analyze other reasons that affect concrete cracks,and put forward measures to reduce shrinkage stress and temperature stress based on the effects of concrete shrinkage and hydration heat,and then reduce concrete cracks to ensure subway stations At the end of the normal use,based on the above analysis results,the deficiencies and some prospects of this article are put forward.