It is generally known that clays possess nonlinear mechanical properties. However, traditional theory of consolidation and numerical approach assume linear mechanical properties for clays. In calculation of small strain consolidation, this assumption would not induce serious error. But it is necessary to consider variations of permeability and compressibility with the decrease in void ratio during large strain consolidation. This paper presents an approach in using the FLAC computer program with non-linear soil properties. The approach is used to analyze laboratory consolidation curves and to predict in-situ settlement curve, including both the primary consolidation and the secondary compression stages. Results of this study show that the approach presented is more accurate than the conventional FLAC analysis.