<p>This paper introduces the Modified Diaphragm Wall Top-down Method (MDWTM) and the Modified Iranian Top-down Method (MITM) for executing deep excavation. The horizontal and vertical deformations were compared with those of the traditional Diaphragm Wall Top-down Method (DWTM) and the Iranian Top-down Method (ITM) to evaluate this method. The studied variables in this research include the thickness impact, the story number of the structures adjacent to the excavation, the distance of the adjacent structure to the excavation, column spacing, and soil type. 3D modeling was carried out using the finite element software MIDAS GTS NX. The multi-level Niayesh parking project with a 29-m excavation depth was selected as the case study. The results indicate that the proposed method of this study (MITM) exhibits the minimum deformation, and reduces deformations by about 10%, 20%, and 30% compared to the ITM, MDWTM, and DWTM methods, respectively. This new approach demonstrates that the diaphragm wall construction in multiple stages can decrease deep excavation deformations by about 10%. Additionally, the findings of this study show that a 15% increase in wall thickness in top-down methods reduces deep excavation deformations by about 20 to 30%. In all scenarios, where buildings are adjacent to the excavation, and in both coarse-grained and fine-grained soils, the MITM method exhibits the minimum deformation compared to other methods.</p>