Shear bands occur when inelastic shear deformation localize in narrow regions of the material. These structures can directly influence the properties of materials, in addition to affecting their integrity and contributing to the initiation of structural failures. This study presents a methodology for the characterization of shear bands in Indiana Limestone carbonate rock through numerical modeling using the finite element method (FEM). As it is known, the numerical modeling of strain localization phenomena using FEM has some drawbacks, such as loss of ellipticity of the governing equations, triggering convergence problems and results dependent on the mesh discretization. Some alternatives to overcome these problems are presented and discussed, giving a special emphasis to the viscous regularization technique used in the numerical modeling of biaxial and triaxial tests. Parametric and sensitivity studies were performed to identify the impact of the mechanical properties on the occurrence of shear bands. The results showed that strength properties, non associative flow rules and strain-softening are the factors with larger influence on the initiation and development of shear bands.