Study On The Influence Of Concrete Segment Cracking On Service Performance And Its Control Measures

With the acceleration of urbanization and the expansion of urban scale,the contradiction between urban traffic demand and backward infrastructure is increasingly prominent.Because of its advantages of fast,efficient,energy-saving and punctual,Metro is undoubtedly the best tool to improve urban traffic.In order to promote the sustainable development of Metro and city,it is necessary to ensure the safe and stable performance and reliable quality of metro engineering,among which metro engineering is the one The concrete segment,an important structure to ensure the quality and safety of the project,not only bears the pressure of various vehicles and water and soil,but also resists the erosion of harmful substances.Once the segment cracks,it will affect the use function and service life of the segment,and even cause subway accidents.Therefore,it is necessary to control the cracks of the concrete segment.Based on the existing subway engineering,this paper Based on the theoretical research results and the project test,the paper puts forward the targeted control measures.The main research contents are as follows:(1)Combined with the field investigation of the subway segment project,through the means of test,observation and monitoring,and from the two aspects of load and concrete material components,this paper comprehensively analyzes the mechanism of cracks,summarizes the causes of cracks in the three stages of segment production,production,construction and assembly,and later operation,and analyzes that cracks are harmful to the stress,impermeability,durability and other performance of segments,and then The necessity of crack control and the pertinence of control measures are put forward.(2)In view of the cracks caused by the concrete components,theexpansion agent is usually added to the concrete mixture to inhibit the cracks,but the existing detection methods do not scientifically grasp the reaction process of calcium oxide type expansion agent.Therefore,a feasible detection method,strontium nitrate catalysis glycol ethanol benzoic acid solution titration method and TG-DSC thermal analysis method,is proposed The quantitative analysis of calcium oxide expansion agent is carried out in order to reasonably use calcium oxide expansion agent and control concrete cracks.(3)In view of the causes of cracks in the production process of segments,this paper studies the control measures from the components of concrete segment materials,so as to carry out the research on the internal maintenance of concrete,and uses silane coupling agent solution to modify the light aggregate to study the performance of segment concrete as the internal maintenance medium.By reasonably controlling the concentration of silane coupling agent solution,the mechanical properties and shrinkage reduction efficiency of internal curing concrete can be improved,the internal humidity of concrete can be adjusted and controlled to reduce the driving force of shrinkage,and the self resistance of concrete structure can be effectively improved,so as to improve the crack resistance of concrete.(4)In the production of concrete segments,the water cement ratio and slump are usually low,so as to meet the strength requirements.However,the rheological properties of high-strength concrete are affected.The measures of adding new chemical admixtures are taken to improve the rheological properties of concrete mixture.High molecular weight bio glue,a new rheological modifier prepared by natural starch biological fermentation,can effectively improve the cohesion and stability of the mixture,and make it have significant shear thinning and thixotropy,thus increasing the crack resistance and inhibiting the surface dry shrinkage cracks.(5)In order to study the effect of admixtures on the performance of concrete segments,it is necessary to carry out the application research in the actual engineering test section.Through the 100 ring segment comparative test,the improved test group and the control group without admixtures were carried out the anti-seepage and anti pulling of concrete segments The test results show that the test group is better than the control group in performance and has the feasibility of application.(6)The paper puts forward the restraining measures for the cracks of the concrete segment in the construction and assembly stage and the later operation stage,analyzes the calculation model,the stress and the assembly form of the concrete segment theoretically,uses the inversion analysis,the internal convergence displacement value is the variable,obtains the internal convergence displacement value and the crack width function through the finite element calculation,and puts forward the internal convergence displacement measurement value as the crack control The new index can control cracks more intuitively,and its effectiveness is verified by monitoring data.Through the above theoretical analysis and experimental research,it provides a certain theoretical basis and feasible measures for the crack control in the process of concrete segment manufacturing,assembly and operation.At the same time,the research of crack suppression has been applied to the tunnel of practical engineering and has been put into operation successfully,which has a certain guiding significance for similar projects in the later stage,and the research content has important practical significance and application value.