عنوان مقاله [English]
The study of the effect of underground cavities on site seismic response have been mainly carried out by analytical methods. The main weakness of these methods are extra simplification in terms of geometry and material properties. Therefore, the need to comprehensive studies in this field, using numerical modeling and experimental methods, particularly considering the real case underground cavities is essential. In the present study, a real case of a subway tunnel, belong the underconstruction subway network of the Karaj city (Iran) was considered. 4 sites along the line 2 of this subway, for which experimatal measurment of ambiant noise have been perfomed, were selected and for them numerical modeling by finite element method were carried out. Results of the numerical modeling are compared with the experimental spectral ratios obtained by Kazemeini et al (2014). The result show that the presence of underground cavities, affect the site seismic response significantly and leeds to apperance of amplification in low and high frequency ranges that increase with increment of tunnel dimention and decrement of the distance to the tunnel axis.