# Study on Seismic Reduction Measures of a Diaphrag Wall--Underground Structure System
###### Abstract  
In this paper, the seismic reduction and isolation measures are first proposed by setting a segmented isolation layer between the diaphragm wall and the side wall of the station structure. Although the segmented isolation layer can effectively improve the stress state of the side wall and slabs, the seismic reduction effect of the middle column is not obvious. In order to improve the overall seismic performance of the station structure, the reduction measures by combining the segmented isolation layer and new type bearing of the middle column are then proposed. At the same time of inserting the isolation layer between the diaphragm wall and the structure, the sliding bearing at the top of the column is set up to reduce the vibration. The results show that the segmented isolation layer can significantly reduce the internal force and damage at the top, bottom and side wall joints. In addition, the combined measures of segmented isolation layer and sliding bearing at the top of the column can effectively reduce the seismic damage of the middle column. The damage of the connection between the top plate, the middle plate and the middle column can be significantly decreased. finite element analysis; diaphragm wall; segmented isolation layer; underground structure; seismic reduction measures +
Footnote †: journal: Applied sciences  
To explore effective measures for seismic reduction and isolation and enhance the seismic performance of underground structures, researchers have conducted a series of scientific research by using theoretical analysis [6; 7], numerical simulation [8; 9; 10; 11; 12], and a model test [13]. These measures can be broadly divided into two categories. The first category involves modifying the characteristics of the structure itself, such as installing isolation devices at the ends of intermediate columns or other components. The second category involves incorporating an \"energy dissipation\" layer between the structure and soil to absorb a portion of seismic energy and mitigate the impact of ground motion on the structure. Some researchers believe that improving the stress conditions and deformation characteristics of the central column is one of the effective methods to improve the seismic performance of an underground structure. The installation of a shear plate damper and lead rubber bearing at the top of the structural column has an obvious seismic reduction effect. The self-centering energy dissipation column can reduce the internal force of the central column and the interstory displacement of the structure under the earthquake [14; 15; 16]. Based on the seismic damage mechanism of the Daikai underground subway station during the Kobe earthquake, [PERSON] et al. [17] found that the installation of sliding isolation bearings between the central column and the longitudinal beam can reduce the lateral deformation of the central column. Compared with the prototype structure, the overall lateral stiffness of the structure is significantly reduced after the friction swing bearing is set at the top of the middle column, while the truncated swing column can effectively improve the deformation and recovery capacity of the middle column [18]. [PERSON] et al. [19] further proposed a circular groove roller bearing suitable for high axial pressure of underground station structure, and its effectiveness was verified through numerical analysis. Another group of researchers focused on the isolation layer of underground structures and its effect on improving the seismic performance. [PERSON] et al. [20] carried out the research on seismic reduction technology for underground tunnels and found that the use of seismic isolation materials with lower shear modulus can significantly enhance the overall seismic performance of the tunnel. For station structure, [PERSON] et al. [21] found that inserting an \"isolation wall\" made of polymer material between the soil and the side wall of the structure can reduce the bending moment at the bottom of the side wall.