Soil-structure interaction is an interdisciplinary field of endeavour which lies at the intersection of soil and structural mechanics and dynamics, earthquake engineering, geophysics, geomechanics, computational-numerical methods and technical disciplines. This is especially and significantly important for large and heavy structures such as nuclear power plants, dams, offshore platforms, bridges and high rise buildings built on soft soil. Excavation adjacent to buildings can intensify the soil-structure interaction effects. In this study, in addition to soil-structure interaction model and building-excavation interaction model, the fixed-based model was defined as well based on the finite difference method in FLAC. Modified mohr-coulomb model is used for soil medium and with the help of programming feature of the software, the stress-dependent stiffness and the material unloading behavior are applied. A fundamental stage in numerical modeling is the validation, verification and comparison of model results with field data. Validation of the numerical model is based on data extracted from tiltmeter installed on the column of a building adjacent to the excavation and some load cells placed on anchors against the excavated area wall. Analysis results studied in two separate parts of structural frame and retaining structure of excavation was studied, suggest that due to the high rigidity of retaining structure, the excavation practice does not affect the values of internal forces of adjacent structural frame. However, there was a significant difference in the values of the internal forces between the fixed-based model and the interactional models.