Refined Numerical Simulation And Research On Mechanical Properties Of Large Shake Table Foundation

As an important means of seismic research,shake table test is of great significance in studying the mechanism of structural failure under seismic action and ensuring the safety of major projects.As an important part of shake table test system,the geometric structure and quality layout of the foundation have a direct impact on the performance and test accuracy of the shake table.At present,the theory of large scale shake table foundation stress analysis is relatively lacking.The finite element simulation work mainly focuses on the influence of structural vibration on the surrounding environment,while the research focusing on the mechanical properties of the internal structure of the foundation is less.In this context,this paper takes the foundation of a large-scale shake table and an underwater shake table as the research object,takes the refined numerical simulation analysis as the main research means,uses ABAQUS finite element software to establish the three-dimensional numerical model of the foundation,and first carries out the time history analysis through the static analysis and the dynamic load generated by the shake table to explore the overall structural response of the foundation under different working conditions After that,the substructure method is introduced to analyze the stress mechanism of the key stress area,which realizes the comprehensive analysis from the overall structure stress to the internal force distribution of the components.The main contents of this paper are as follows:(1)From the perspective of high-precision reduction of internal structure of structure,a simplified method of solid soil element combining shell element and setting soil spring is proposed,which can effectively simulate the surrounding constraint conditions of foundation and improve the calculation efficiency.The feasibility of this method is verified by numerical simulation analysis of the shake table test of a subway station carried out by the Institute of engineering mechanics,China Seismological Bureau.The core of this method is to reduce the internal structure of the foundation,simplify the soil,refine internal structure maximize the allocation of calculation resources to the main analysis objectives,and greatly improve the accuracy of structural analysis.(2)Based on the modeling method proposed in this paper,the three-dimensional numerical model of the whole structure of the shake table foundation is established,and the static and dynamic analysis are carried out.The stress distribution of the shake table foundation under different water level conditions and the dynamic response of the shake table during operation are studied,and the time-varying laws of displacement,velocity and acceleration of the model under different working conditions are revealed.According to this law,the dynamic response characteristics of the foundation under the full load dynamic load of the shake table and the key components to be studied are determined.(3)The substructure analysis method is introduced to study the nonlinear depth of the foundation.The elastic-plastic numerical substructure method is used to model the members or regions with large stress and strain,and the internal force distribution and possible failure modes of key members are studied.The results show that the foundation meets the requirements of elastic design,and the risk of cracking is very small;the calculation results of substructure and overall structure are consistent,and the calculation accuracy of substructure is higher,and the results are more referential.