In most engineering problems it is commonly practicaland convenient to use linear formulation. In studying theload-settlement behaviour of pile groups, homogeneous andlinear soil behaviour are usually used. However, if realisticresults are to be obtained, the nonlinear formulation shouldbe adopted especially in geotechnical problems.In this thesis, modeling soil nonlinearity is the maintask as the stress-strain relationship of soil is essentiallynonlinear. As soil nonhomogeneity is likely to prevail in mostsoil conditions, it is also accounted for in a consistentmanner.A group of piles connected with a rigid cap isconsidered to consist of two main parts. The rigid pile cap,triangular face, these patches are then combined to produce asurface with an overall et continuity.The necessary transformations, hidden-surfaces elimination,shades, and shadows are examined for completeness of the work.