The consolidation behavior of mixed in place cement and lime/cement columns is studied. Consolidation of this composite foundation is modeled as a three-dimensional axi-symmetric problem. By use of the method of finite difference, the arbitrary pore pressure variation with time is obtained at any location below the surface. Using a computer program developed by the first author, some interesting conclusions about consolidation behavior of cement- and lime-mixed pile foundations can be drawn. Finally, a combined model, including the permeability coefficients of cement-mixed piles and soil, is studied and its feasibility is evaluated.