Influence of presence of adjacent surface structure on seismic response of underground structure

A numerical study is made on the dynamic through-soil interaction between underground station and nearby pile supported surface structure on viscous-elastic soil layer, under vertically incident S wave. This paper, as a companion of another paper written by the authors [1], focuses on the influence of presence of adjacent surface structure on seismic response of underground structure, while the reference [1] centers on the influence of presence of adjacent underground structure on seismic response of surface structure. To this end, a commercial software product for finite element analysis, ANSYS, has been further developed and enhanced for calculation in frequency domain, in which hysteretic damping can be considered for both the soil and the structures, so that structure-soil-structure interaction (SSSI) can be investigated by via a direct methodology. A discussion is made on the influence of arrangement of structures, distances between structures, shaking direction of seismic wave, shear wave velocity and damping of soil, scale and burial depth of underground structure, storey number, stiffness, style and pile length of surface structure on SSSI, in terms of horizontal relative displacement of underground structure. Maximum relative displacement responses are also presented for 12 seismic inputs. Arrangement and shaking direction are two of the most important factors. The system response can be either amplified or attenuated according to the distance between adjacent structures, related to dynamic properties of the overall system. Those underground structures, surrounded by buildings with the fundamental frequency approximate to that of free field, are heavily affected.