Effect of Near- Field Ground Motions on the Stability of Embankment Dams

In the past two decades, near-field problems became an important topic for civil engineers. The two characteristics of near-field ground motions, i.e., the forward directivity effect and permanent displacement effect, result in long period and large velocity pulse in the velocity time history and large step pulse in the displacement time history. As a result, many aspects related to civil engineering will be influenced by changes of the type of load in the nearfield ground motions. Some effects of near- field ground motions on buildings and bridges have been studied and considered in few building design codes but there is not any fundamental study in this regard for embankment dams. In this paper, the "Masjed Soleyman embankment dam" with height of 177.0 m and 3km far from the "Andica fault" is chosen for investigation of effects of near and far-field time histories on embankment dams. For this propose a numerical method is chosen and several near- field and far-field time histories are applied for carrying out nonlinear analysis. The results indicate to the influence of near- field ground motions on stability of embankment dams that create larger permanent displacement and decrease slope satiability safety factor than farfield ground motions and can affect on excess pore pressure. So, it should be considered in analyses and designof embankment dams.

کلیدواژه ها:

near-field ، far-field ، characteristics of ground motions ، embankment dams