Influence Of Groundwater Level Change On Seismic Dynamic Response Of Subway Station

Earthquake damage investigations show that underground structures are more likely to be damaged in earthquakes when they are in a non-uniform site.With the increase of domestic and industrial water consumption and rainfall,the groundwater level is constantly changing.However,there are relatively few studies on the impact of groundwater level changes on the seismic dynamic response of underground structures.The reason is that the existing research methods have changed the soil around the structure.Simplified to the study of isotropic single-phase medium,the influence of groundwater level cannot be considered,Therefore,based on the Biot fluid two-phase saturated porous medium theory,this paper establishes a multi-medium coupling site analysis model of gas-saturated soil layer-water-saturated soil layer-bedrock layer to study the influence of water level changes on the seismic dynamic response of the station structure.The design provides theoretical and technical support.The specific research content and research results are as follows:(1)A numerical simulation model for seismic response analysis of subway station structures considering the influence of groundwater level changes is established.The soil layers above and below the groundwater level are regarded as gas-saturated and water-saturated media respectively,and the gas-saturated medium-water-saturated medium-single-phase medium is derived.The dynamic explicit finite element expression of the interface node when the three media are coupled,and the finite element overall analysis method for the seismic response analysis of the subway station structure considering the influence of the groundwater level change is established.(2)Extending the existing one-dimensional time-domain finite element algorithm for calculating free-field response to two-dimensional space,combined with multiple transmission artificial boundaries,established a ground motion input method considering water level changes under oblique incidence of seismic waves.(3)When seismic waves are incident vertically,the influence of groundwater level changes under different porosity sites on the dynamic response of subway station structures is studied.The results show that with the increase of soil porosity,the seismic dynamic response of the structure is significantly affected by changes in groundwater level.(4)When seismic waves are incident obliquely,the impact of water level changes on the dynamic response of subway station structures under different incident wave frequencies and incident angles is studied.The results show that the impact of groundwater level changes on the seismic dynamic response of the structure is obvious.Related.