Investigation of Sheetpile’s Behaivior Under Seismic and Dynamic Loading Using the Bounding Surface plasticity Model Behnaz Kolahdooz Rahimi Behnaz.k.rahim@gmail.com Department of Civil Engineering Isfahan University of Technology, Isfahan 84156-83111, Iran Degree: M.Sc Language: Farsi Supervisor’s H.Hashemalhosseini, ( hamidh@cc.iut.ac.ir ) Supervisor’s M.N.Moghim, ( moghim@cc.iut.ac.ir ) Sheet pile wall is a typical retaining structure with advantage of safety, reliability and low cost which is widely used in road engineering and coastal engineering. This type of structures due to their small thickness, deform Substantially due to lateral soil pressure. The amount of the deformation is depend on implement length, the soil characteristics behind the sheet pile and so on. In order to investigate sheet pile behavior under dynamic and seismic loading, it is necessary to use appropriate software and constitutive model that can predict soil and structure behavior. In this research FLAC 3D software, which is an explicit finite difference program and has the ability to simulate Soil and sheet piles, has been used and Soil has been simulated using Bounding Surface constitutive model. First, the accuracy of the constitutive model has been investigated by comparing the result with moher-coulomb constitutive model and then, in order to study the sheet pile behavior, soil and structure components has been modeled in the form of the existing conditions in reality, and the effect of dynamic loading has been analyzed by changing the loading frequency and loading Amplitude. In this study, various factors such as excess pore pressure created in different parts, bending moment and displacement in different part of the sheet pile are investigate in two condition witch sheet pile is next to sea water or not. The results indicated that the Bounding Surface constitutive model has the potential to predict soil behavior. Studies show The hydrodynamic pressure (positive and negative) have a minor effect on the wall performance (of the order of 5% or less) and also the effect of the dynamic loading is mostly similar to seismic loading. Key Words Anchored Sheet pile, Seismic loading, Dynamic loading, Bounding Surface, hydrodynamic pressure.