Different Dynamic Behavior of Potentially Sliding Blocks in Near and Far Field Earthquakes

Worldwide experience repeatedly shows that damages in different kind of slopes caused by earthquakes are highly dependent on site condition and epicentral distance. In this paper, a potentially sliding slope in Alborz region was selected as an example to investigate these two effects. In order to verify the analysis software, a hemicycle valley was first modeled and its amplification response to the Ricker wavelet was compared with the results of previous studies. The numerical model of the well-known Shafarood landslide located in the Reservoir of Shafarood dam was prepared and dynamic analysis of the model was performed. Eight far and near field acceleration time histories of different earthquakes in Iran was selected as input motion. Then, the average acceleration time history of the sliding block to each input excitation was calculated and the permanent Newmark displacement was evaluated using MATLAB software. The results demonstrate that the permanent displacement of the potentially sliding block in near field earthquakes is less than that for far field ones. Besides, it was concluded that the frequency content of the records has more influence on the Newmark displacement than the epicenter distance.