Earth retaining wall systems are used for stabilizing deep excavations. Present research aims to understand the behavior of a retaining wall system with tieback and soldier pile under static loading conditions and dynamic excitation as well. It is necessary to use appropriate constitutive model which is capable of prediction the behavior of soil on different stress states. Hence, the first objective of this research was to model the tieback retaining wall systems using a unified bi-surface elasto-plastic model constitutive model for the matrix soil[1]. This model have been already implemented in a finite difference code, FLAC 3D [35]. Model parameters were obtained based on the results of a triaxial test. Lateral earth pressure behind wall was compared with the existing empirical earth pressure envelop. Furthermore, results were compared with the numerical results using Cam-Clay and Mohr-Coulomb models. Having better perception of wall performance, a parametric study was conducted in which the results give more information regarding influence of different affecting parameters including the location of first tendon from the ground surface, magnitude of anchor forces, embedded depth of the soldier pile, relative stiffness of the piles and soil, piles spacing and tendon bonded length on the wall behavior. Due to importance of earthquake excitation followed by destructive effects on retaining structures such as tieback walls, investigation on dynamic behavior of this type of anchored walls is essential. A suitable model for dynamic soil/structure interaction should capture the hysteretic behavior and energy-absorbing characteristics of real soils. The second objective of this research was to implement a newly introduced plasticity model developed for simulation of monotonic and cyclic loading of sandy soils to the commercial finite-difference code FLAC 3D , using its User-Defined-Model (UDM) capability. The model is developed[2] based on the general two-surface plasticity concept and the bounding surface plasticity theory and is capable to simulate accurately volumetric and stress-strain behavior of soils under monotonic and cyclic loading; hence the related observations like accumulation of pore pressure, cyclic mobility and cyclic liquefaction could be modeled utilizing this model in any numerical method. The plasticity model was implemented with an integration scheme based on the cutting plane method. Throughout a calibration process, a single set of model constants can be used to simulate stress-strain response under different initial void ratios and variably confined pressures.