| The ground motion amplification is significant in seismic design and safety assessment of engineering structures. This research investigates the ground motion amplification characteristics in soft alluvial deposits where the amplification is often observed during earthquakes. Because of insufficient earthquake data and corresponding geotechnical parameters, analytical methods are used to provide the database for statistical modeling. The one-dimensional wave propagation program SHAKE and two-dimensional finite element program FLUSH are selected for the analyses.These analytical procedures are validated by estimating the ground motions from two previous earthquakes. It is proven that both 1-D and 2-D analyses can well estimate the surface and downhole ground motions during these two events. The analytical results reveal that the amplification of accelerations essentially occurs in the surficial clay layer. It also demonstrates the advantage of 2-D analysis which accounts for the edge boundary effect on the surface ground motions.Three amplification variables, AR, SR, and fThis research demonstrates that appropriate analytical approach is an effective alternative to provide a ground motion database for statistical modeling. The proposed regression models account for the simple nonlinear relationships between independent and dependent variables. These models involve a limited number of parameters which can be easily obtained. This research also concludes that a 2-D model is needed to predict the amplification involving the edge boundary effect. For the amplification at sites away from the edge of basin, the use of 1-D model is appropriate. |
