1. A method for upscaling geomechanical properties, comprising: mapping fine cells from a geological model to a coarse cell; assigning mechanical properties to each of the fine cells based, at least in part, on the geological model; simulating material response characteristics of the coarse cell to various boundary conditions based on the mechanical properties assigned to each of the fine cells; and computing upscaled mechanical properties of the coarse cell based on the material response characteristics of the coarse cell.