# Seismic Response and Mitigation Analysis of a Subway Station in the Site with Weak Interlayers
## 2 Seismic Response of the Subway Station in the Site with Weak Interlayers
### Computational Result
The next most affected condition is when the weak interlayer is located at the station's bottom, resulting in noticeable increases in tensile damage to the station's bottom slab, lower-level central column, and middle plate. When the weak interlayer is positioned at the station's top, the weak interlayer increases the tensile damage to the upper central column and top slab. The influence on the subway station structure is nearly negligible when the weak interlayer is situated at the top or bottom of the station. These patterns become even more conspicuous when the input acceleration is set to 0.4 g.  
Figure 8: Maximum displacement of the station lower column at different positions. (**a**) 0.2 g. (**b**) 0.4 g.  
Figure 9: _Cont._  
(2)  
Influence of the Influence of the thickness of weak interlayers  
Figures 11-13 present the maximum displacements of the structure's side wall and central column under various thicknesses of the weak interlayer, where \(H\) represents the interlayer's thickness. From these figures, it is evident that the maximum horizontal displacements of the station's side wall and central column in the weak interlayer site are greater than those in the layered soil site. This indicates that the weak interlayer has an adverse effect on structural horizontal deformations. It is important to note that the maximum horizontal displacement of the station's side wall and central column does not continuously increase with an increase in the thickness of the weak interlayer. Instead, it follows a pattern of decreasing and then increasing as the thickness reaches a certain level. Figure 10: Tensile damage of the station at different positions under a 0.4 g Chi-Chi earthquake. (**a**) Layered soil site. (**b**) Upper. (**c**) Top. (**d**) Middle. (**e**) Bottom. (**f**) Lower. Figure 9: Tensile damage of the station at different positions under a 0.2 g Chi-Chi earthquake. (**a**) Layered soil site. (**b**) Upper. (**c**) Top. (**d**) Middle. (**e**) Bottom. (**f**) Lower. When the thickness of the weak interlayer is 3 m, it has the most significant impact on the horizontal deformation of the structure. Figure 11: Maximum displacement of the station side wall. (**a**) Chi-Chi earthquake. (**b**) Dzuce earthquake. (**c**) Manjil earthquake. Figure 12: Maximum displacement of the station upper column. (**a**) Chi-Chi earthquake. (**b**) Dzuce earthquake. (**c**) Manjil earthquake. To further analyze the impact of the thickness of the weak interlayer on the seismic response of subway station structure, Figures 14-17 present the damaged nephograms of the station's main structure under varying weak interlayer thicknesses. Observing these figures reveals that under different levels of seismic intensity, station structures located within the weak interlayer experience significantly more severe damage compared to those on layered soil sites. This difference becomes more pronounced as the seismic intensity increases. When the seismic input acceleration is 0.05 g, the subway station structure experiences minimal damage. As the thickness of the weak interlayer increases, only minor damage occurs to the top and bottom slabs of the station. However, the damage to the structural column, side wall, and middle slab intensifies as the thickness of the weak interlayer increases when the input acceleration is set to 0.1 g. In the case of a 3 m thick weak interlayer during the Chi-Chi earthquake, seismic tensile damage almost permeates the entire lower part of the middle column. Under strong seismic activity (with peak input accelerations of 0.2 g and 0.4 g), the influence of the weak interlayer's thickness becomes more pronounced. In comparison to layered soil sites, structures within the weak interlayer experience severe tensile damage at the connections between the middle plates and side walls on both sides. As the thickness of the weak interlayer increases, the extent of damage to the middle column, side wall, top slab, and bottom slab intensifies.