摘 要 本研究針對黏土壓縮與壓密行為進行廣泛之研究，根據研究成果具體提出：(1)試驗方法對粘性土壤壓縮與壓密參數之影響、(2)尺寸效應對黏土壓縮與壓密行為之影響、(3)時間座標尺度對解釋次壓縮行為之影響、以及(4)超載預壓對黏土長期沉陷之影響等前人較少提及之研究結果。本研究亦規劃執行不同尺寸試體之壓密試驗，探究尺寸效應對黏土壓縮及壓密行為之影響，藉以驗證小尺寸試體之壓縮與壓密參數是否可反應現地土層之壓密沉陷行為。 此外，為掌握沉陷分析時施工作業對土層壓密行為之影響，本研究發展一套能考慮垂直向與徑向壓密、非線性土壤參數、軟弱土層大變形、荷載隨時間變化、不規則形狀荷載、樁-土複合地盤沉陷行為、點井抽水與解水、以及井阻抗與塗抹效應等現地施工狀況之多功能壓密沉陷數值程式，並透過實際之沉陷案例分析累積參數之選取經驗，而不同種類土壤壓縮與壓密參數之率定資料可供各界處理類似沉陷問題時之參考。 ABSTRACT Based on the results of this study we achieved several important conclusions such as the discrepancies of the compression and consolidation parameters under the different test conditions from the conventional consolidation test, the effect of size of specimens on the compression and consolidation parameters of clays, the effect of time scale on the interpretation of secondary compression for clays, and the effect of the amount and the duration of surcharge on the long-term settlement of clays. This study also carried out the consolidation tests for specimens of different size to investigate the size effect of compression and consolidation parameters. The results of the tests are not only to verify whether the compression and consolidation parameters of 2 cm specimen can be applied to predict the consolidation settlement of a thick soil layer in the field, but also to feedback the numerical model. Furthermore, the construction factors, such as nonlinear parameters, large strain, time-varying load, loading and unloading of arbitrary foundation shape, the settlement of the composite ground reinforced by piles, dewatering and recharging of ground water, and the smear effect and the well resistance of prefabricated vertical drains, are simulated to improve the abilities of the numerical program. The verification of the numerical model with other closed-form solutions or numerical results was performed. Furthermore, the statistical correlations of the compression and consolidation parameters with their physical indexes for many alluvial clays and the experiences of settlement analysis obtained from several engineering projects were also proposed.
