# Influence Analysis of Liquefiable Interlayer on Seismic Response of Underground Station Structure
###### Abstract  
To study the influence law of the seismic response of underground station structures at liquifiable interlayer sites, a two-dimensional numerical model of the interaction between the soil and station structure was established based on the finite difference software FLAC\({}^{\rm{3D}}\). The nonlinear dynamic response of the station structure located at the liquifiable interlayer site was analyzed considering the location distribution, relative density, and thickness of the liquifiable interlayer. The results show that the deformation of the structure is greatest when the liquifiable interlayer is distributed on both sides of the station side walls, while the interlayer has an energy-dissipating and damping effect on the upper station structure when it is located at the bottom of the structure. The lower the relative density of the liquifiable interlayer is, the stronger the internal dynamic response of the structure will be, and the more unfavorable it will be to the seismic resistance of the structure. When the liquefiable interlayer is only present in the lateral foundation of the station, an increase in its thickness results in a stronger shear effect on the structure and a higher probability of damage. However, when the thickness of the liquifiable interlayer reaches a point where the entire station is placed within it, the lateral force and deformation of the structure are significantly reduced. liquidiable interlayer; underground station structure; dynamic response; numerical simulation +
Footnote †: journal: [PERSON]  
et al. [11] revealed the seismic response characteristics of underground station structures in slightly inclined liquefiable foundations through shaking table tests and further compared and analyzed the effect of ground inclination changes on station structures in liquefiable sites. [PERSON] et al. [12] conducted a series of shaking table tests to reveal the effect of groundwater level changes on the degree of soil liquefaction and the seismic response pattern of underground structures. In addition to the methods employed through model tests, many scholars have used numerical simulations to investigate the dynamic response characteristics of subsurface structures at liquefiable sites [13; 14; 15; 16; 17; 18]. [PERSON] et al. [13] interpreted the seismic performance and uplift mechanism of large subway station structures in liquefiable soils considering the excavation process during the construction of the structure. [PERSON] et al. [14; 15] used the numerical analysis method coupled with the finite element and finite difference method to analyze the dynamics of rectangular structures in saturated sandy soil sites and explored the influences of different relative densities of sandy soils on the seismic response and uplift effect of underground structures. [PERSON] et al. [16] explored the force and deformation mechanism of an underground corridor structure at a non-homogeneous liquefiable site and further investigated the effect of burial depth on the dynamic response of the structure. In the above studies, the foundations were mostly considered as homogeneous liquefiable sites, or the station structures were wholly placed in liquefiable layers. The seismic response characteristics of station structures in non-homogeneous layered liquefiable sites need to be investigated further. [PERSON] et al. [17] and [PERSON] et al. [18] showed that underground structures undergo much more seismic damage at laminated liquefiable sites than at homogeneous liquefiable sites. In engineering practice, liquefiable foundations are mostly present in the form of liquefiable interlayers. The existing research is not explicit with respect to the influence law of liquefiable interlayers on the seismic response of underground station structures.