Dynamic Research On Numerical Model Experiment Of Prefabricated Underground Structural Components

At present,the construction method of subway stations is mostly cast-in-place structure in the open excavation pit.This method is greatly affected by the construction environment,and the construction speed is slow,which also has a huge impact on the urban environment.In recent years,a fully prefabricated subway station structure equipped with grounting mortise and tenon joints has been proposed and used in the construction of Changchun subway,which effectively solves the above problems.Prior to this,many scholars have conducted systematic theoretical and experimental studies on the static mechanical properties of grounting mortise and tenon joint components,but the research on the dynamic performance of the joint components is still very limited.Based on this background,this article takes the prefabricated subway station structure as the research object.Starting from the existing statics research results of the joint member,the dynamic experimental model is established by numerical methods to study the deformation characteristics and failure laws of the joint member under the action of resonance load.The main research content and conclusions of the thesis are summarized as follows:1.Based on the existing static experiment results,by simulating the experimental components and loading conditions,a numerical model of the static loading experiment considering the nonlinear deformation of the concrete components and the simulation of the joint grouting interface is established,and the calculation results are compared with the experimental results.The verification results show that the model can accurately simulate the deformation characteristics of single-tenon and double-tenon grouting joints under static force(axial bending).2.The top arch structural components and the slab structural components of the station are selected as the research objects,and the dynamic amplification factor DIF is used to consider the strain rate effect of the concrete under dynamic load in the concrete material constitutive model.A numerical experimental model of dynamic loading is established.The modal analysis of the base plate component model is carried out,and the dynamic load of this model experiment is constructed based on the characteristics of the frequency composition of each order.3.The calculation results of the dynamic loading numerical test of the top arch and the bottom plate are analyzed.Based on the deterioration of the concrete material stiffness during the loading process of the three members,the failure process of the concrete bearing capacity is divided into four stages: emergence-expansion-spread-failure;The overall deformation law of the component after the failure of the concrete bearing capacity,combined with the existing research experience,uses the dynamic load limit,the joint deformation(opening,compression,deflection),and the joint deflection to evaluate the dynamic performance of the two components;The calculation results show that the dynamic load limits of the roof and bottom plate members are 0.85 g,0.9g,0.7g respectively.4.Designed multiple sets of calculation conditions for different joint forms(joint stiffness),presence or absence of closed cavities,and different constraint conditions,and analyzed the dynamic calculation results of the roof members and bottom members of the station;comparison of the calculation results of the various conditions can be obtained :The joint form(stiffness)has little effect on the modal frequency of the bottom plate(top arch)component,the dynamic load limit,and the deformation of the component after the concrete structure fails,and it has a small effect on the vertical deflection of the joint between the three components;The presence or absence of a closed cavity has a greater impact on the dynamic load limit of the three members and the joint deformation and deflection of the top arch member,and has a certain impact on the modal frequency of the three members,but has little effect on the joint deformation of the bottom plate member;member constraints;The conditions have a significant impact on the dynamic load limit,deformation,joint deflection,and joint deformation of the three members.