Shaking table test and numerical simulation of shallow foundation structures in seasonal frozen soil regions

Abstract

Frozen soil layers can induce the formation of double or multilayers on the ground. Such formations change the dynamic characteristics and dominant period of soil, directly influencing the stability and safety of upper buildings. In this paper, the frozen soil-structure interaction system in cold region was taken as the research object. The frozen soil model was made artificially, and two kinds of structure models with different natural frequencies were designed. Through a series of shaking table tests and finite element numerical analysis, the influence of structural natural frequency, soil frozen depth and seismic load on the seismic response of structure were studied. The test results indicate that ground freezing could weaken the soil–structure interaction effect and the nonlinear development of the soil structure. The effect of peak acceleration amplification of the ground is significant close to the surface. The acceleration amplification coefficient of the ground surface decreased as the freezing depth increased, which indicates that the freezing of the ground suppressed the acceleration response of the ground surface. If the peak frequency of a seismic wave is close to the natural frequency of the structure, it can significantly amplify the seismic response of the structure. Owing to the interaction between the soil and the structure, the degree of liquefaction of the ground varied with different structures. Subsequently, a nonlinear finite element program was used to establish the dynamic calculation model of frozen soil-structure interaction system considering the gradient change of stiffness of frozen soil and the dependence of frozen soil on temperature. On the basis of validating the numerical model rationality, the seismic response of frozen soil-structure interaction system under horizontal seismic excitation was further explored. The analysis results show that the seismic response of the structure increased significantly with amplitude excitation; the greater was the freezing depth, the greater was the seismic response of the structure, The influence of the frozen ground on the seismic response of structures in the design of structures in frozen soil areas should be considered. In summary, the dominant period of the ground, the dynamic characteristics of a structure, the type of seismic wave, and the degree of liquefaction of the ground have a significant influence on the seismic response of the structure. Therefore, considerable attention should be paid to the influence of frozen soil on the dynamic characteristics of a structure in frozen soil regions.