Research On The Optimization Of Components Dimension And Structural Mechanical Characteristics During Assembly Process Of Prefabricated Underground Garage

In recent years,the number of cars has shown a trend of rapid growth in China.In order to solve the problem of the serious shortage of parking Spaces,a new structure arises at the historic moment.Compared with the traditional cast-in-place garage,prefabricated underground garage has the advantages of short production cycle,high construction efficiency and saving labor.Based on the engineering test background of the underground garage in Worker Village,Qingshan District,Wuhan City,this paper studies the influence of the size of the prefabricated components on the mechanical properties of the structure through numerical simulation method,and analyzes the changes of the mechanical properties of the structure and the interface of joints and joints caused by the longitudinal splication of the prefabricated components in the construction process.The main work and results are as follows:(1)The disassembly design of the prefabricated underground garage structure includes the determination of the cast-in-place and prefabricated scope of the components,and the split location and location of the joint.In view of the two key points of prefabricated components and joints in the prefabricated structure,select the type of the prefabricated floor and joints suitable for this project.(2)The structural mechanical properties of the four partition schemes are analyzed,and the second scheme is finally determined as the component splitting scheme of the project from the perspective of waterproof performance of construction difficulty.Based on the two-dimensional load-structure model,the influence of the size and thickness of the roof plate、middle slab、side wall on the mechanical properties of the structure is analyzed,and the reinforcement of different sizes of components is calculated to determine the scope of the reasonable size parameters of the component.(3)Based on the HS constitutive relationship,a three-dimensional finite element model is established to analyze the influence of different dimensions of prefabricated components on the mechanical properties of the prefabricated underground garage structure and the change of the relative displacement values of joint interfaces.It is found that with the increase of the size of components,the maximum bending moment value of the garage structure continuously increases,and the maximum displacement value gradually decreases and finally stabilizes.When the size of the prefabricated components fails to meet the structural stiffness requirements,stress concentration will occur at the joint interface between the side wall and the roof,resulting in a large relative displacement,resulting and structure instability.The increase in component size makes the joint joints between the left and right top plates better,but it is not conducive to the mechanical properties of the side wall joints.(4)The overall construction scheme of prefabricated underground garage from foundation pit excavation to roof backfilling is determined.A three-dimensional numerical model is established to analyze the changes in the mechanical characteristics of the structure and joints of the garage structure during the longitudinal splicing of the components.During the assembly process,the maximum axial force value of the structure is transferred from the cast-in-place bottom plate to the position of the precast top plate close to the joint.The shear moment of the structure increases gradually in the splicing process within the third ring,and decreases slightly when the splicing process exceeds the third ring,but the variation is not large.The removal of the steel support in the foundation pit and the assembly of the precast ring will have different mechanical effects on the garage structure and joints.