Study On The Effect Of Seismic Responses Of Structure With Different Soft Soil Foundation Treatment Scheme

Pile foundation and CFG pile composite foundation are two common methods for soft soil foundation treatment, They both have gained wide popularity in engineering due to the good performance in soft soil reinforcement. However, relevant theoretical research cannot meet the demands of engineering practice, The research on seismic response of structure located on the treated foundation is especially scarce.The background of the presented research is a nuclear power plant which is to be built on complex multi-layered soft soil. To improve the performance of the soil foundation, two potential treatment methods are proposed, i.e., pile foundation and CFG pile composite foundation. The two schemes have been analyzed via soil-structure interaction analysis. Dynamic time history analysis based on the Finite Element Method (FEM) has been performed, and the response of the structure and foundation for the two schemes has been studied. The following points are covered:(1) The Viscous-spring artificial boundary model is introduced in the direct FEM analysis to simulate the effect of soil-structure dynamic interaction. Meanwhile some relevant issues encountered in the analysis are discussed.(2) Two different ways were used to solve the free-field responses of the homogeneous soil foundation subjected to SV wave or P wave incitation. Through a comparison of the results, the proposed procedure for introducing the three-dimensional viscous-spring boundary is verified.(3) The modal analysis of nuclear power plant was carried out to study the self-vibration characteristics of superstructures. Then the free-field responses of the two treated foundations were analyzed.(4) Dynamic time-history analyses of the nuclear power station-pile foundation system and nuclear power station-CFG pile foundation system were performed. The response of the two systems, in terms of response spectra of the structure and internal forces of the piles, was investigated and compared. A comparison between the two foundation treatment schemes concerning seismic response was provided.