SEISMIC SITE RESPONSE INDUCED BY A SEDIMENTARY BASIN: 1D AND 2D NUMERICAL ANALYSIS

Nowadays, the influence of the site and geological conditions, especially in the sedimentary basins, is quite obvious on the characteristics of the input motion and the distribution of their damage. The existence of various effective factors in calculating the seismic response of sedimentary basins such as topography features and the characteristics of sedimentary layers and the combination of these factors together will create uncertainties in this subject, which can be explained only by an accurate evaluation of specific site study (Singh et al., 1981). These effects are mostly evaluated using one-dimensional analysis. However, one-dimensional analysis is not able to predict the site responses and their wave amplification. In this paper, the seismic behavior of the Persian Gulf Bridge’s basin as case study has been evaluated, using FLAC 2D program based on the finite difference method. In this regard, a 1D modeling for soil profile at each pier position of bridge and a 2D modeling for all piers located on sedimentary basin are performed. In order to verify the results of the numerical modeling, the 1D responses obtained from the FLAC 2D and DEEPSOIL 1D software have been compared using the Viscoelastic soil behavior. In this study, the 2D modeling process includes introducing soil layers characteristics and determining the lateral free-field boundaries and quiet boundary as the bottom boundary, are subjected to the 18 earthquake excitations. In the following, as shown in Figure 1, a two-dimensional model of the sedimentary basin is constructed using the FLAC 2D program, that its net length of 2500 meters in the sea, with an overall length of 3000 meters and a depth of 120 meters.

کلیدواژه ها:

Sedimentary basin ، Numerical modeling ، Seismic amplification ، Response spectra