粘土具非線性的力學性質，但傳統的壓密理論及現今的數值分析模式假設土壤的力學性質為線性。在小應變壓密時此一假設不致造成過大的誤差，但在大應變壓密時有必要在分析時考慮粘土滲透係數及體積壓縮係數隨孔隙比減少而變化之特性。 本文提出在 FLAC沉陷分析中考慮粘土非線性性質的方法，並以之分析實驗室壓密試驗及預測現地厚土層之主要壓密及二次壓縮沉陷。分析結果顯示本文提出的方法現有的方法精準，尤其本文提出的方法可計算長期二次壓縮沉陷。

　　　　　It is generally known that clays possess nonlinearmechanical properties. However, traditionaltheory of consolidation and numerical approachassume linear mechanical properties for clays. Incalculation of small strain consolidation, this assumptionwould not induce serious error. But it isnecessary to consider variations of permeabilityand compressibility with the decrease in void ratioduring large strain consolidation. This paperpresents an approach in using the FLAC computerprogram with non-linear soil proerties. Theapproach is used to analyze laboratory consolidationcurves and to predict in-situ settlement curve,including both the primary consolidation and thesecondary compression stages. Results of thisstudy show that the approach presented is moreaccurate than the conventional FLAC analysis.