In most research, 2D models based on plane strain theory are applied for design, analysis and parametric studies of soil nailed walls and the 3D effects of trench geometry is disregarded in many cases and 2D results are generalized for 3D conditions which may lead to either unsafe design or conservative and uneconomical design. In the current study, The restrictive effects of adjacent walls in corner of nailed soil trench that are perpendicular to the main nailed wall are studied on its behavior. a soil nailed rectangular trench is modeled, full scale, in PLAXIS 3D Foundation software and  the results of the critical section are compared with the results of PLAXIS 2D. In other word, the adjacent walls behave such as lateral supports and restrict the soil nailed wall deformations. The results show that the deformations of 2D analysis are always greater than those of 3D analysis. The results also show that if the length of soil nailed wall (L) is less than 10H, amount of restrictive effects are more and if L is greater than 10H the result of 2D analysis can be generalized to 3D conditions.