In a growing metropolis, vital infrastructure is crucial for supporting developing cities, prompting a demand for enhanced underground development to improve livability and ensure environmental protection. These structures, used in civil and mining engineering, face dynamic loading challenges, including static, impact, and blast loads. The numerical study was performed on twin tunnel models using geosynthetic materials (GM1, GM2, and GM3). Impact was done on the center of the surface of the model, and deformation was measured at the crown along the tunnel length. Because of the symmetry, both tunnels have the same deformation profiles. In all cases, the cover depth, pillar width, and tunnel diameter are constant. Different material layering schemes (GM1, GM2, and GM3) were considered. This study explores the dynamic behavior of unlined parallel twin tunnels in two and three horizontal-layered rock masses, synthetically created with strengths ranging from 0.7 to 2.91 MPa. Findings show that three-layered models undergo greater deformation than two-layered ones, with increasing impact loads causing more pronounced deformations and cracks.