本研究根據Terzaghi (1925) 及Biot (1941) 所提出之飽和土壤壓密理論，在假設單層土壤於固定以及正弦週期性載重下，且土壤表面及底層皆為透水層與大氣接觸，探討兩者之理論僅能單向度排水時之差異，和土壤在受到正弦週期性載重壓密時，土壤質地、週期性載重之週期及時間對超額孔隙水壓之影響。另一方面，本研究根據Schiffman and Stein (1970) 之層狀土壤壓密理論，在假設土壤間之交界面滿足超額孔隙水壓連續及流速連續之條件下，且土壤表面及底層皆為透水層與大氣接觸，將單層土壤壓密沉陷問題延伸至多層土壤，探討地層由三種不同質地之土壤 (砂土、壤土及黏土) 所組成時，其在地層中不同的排列順序對無因次超額孔隙水壓、土壤總沉陷量、各層土壤沉陷量及各層土壤沉陷量貢獻百分比之影響。
在假設土壤僅能單向度排水之條件下，Terzaghi與Biot理論間之差異僅為是否考慮土壤顆粒及水之壓縮性，由於土壤顆粒及水之統體模數極大，壓縮性極低，因此兩者之理論在一維度時無法顯現出差異。當土壤受正弦週期性載重作用壓密時，超額孔隙水壓不會完全消散，但會隨著時間趨於一動態平衡，達到動態平衡所需之時間與土壤質地及載重之週期有關
三層土壤受到固定載重作用而壓密時，不同的排列順序會影響到整層土壤的排水速率，上下層土壤排水特性之良窳對整層土壤之排水速率有很大的影響；在初始時 (10秒)，層與層間土壤之排水速率則須同時考慮飽和水力傳導度之大小及距排水邊界之距離。達壓密沉陷穩定時，土壤總沉陷量不因土壤排列而異，各層土壤之沉陷量，則與統體模數呈負相關；整層土壤達壓密沉陷穩定所需時間與整層土壤之排水速率有關；在初始時，各層土壤間之沉陷量及沉陷量貢獻百分比與層與層間土壤之排水速率有關。

Soil consolidation plays an important role in practical applications of engineering, such as soil improvement by using the precompression method and disaster prevention of land subsidence. However, the stratum is usually composed of different types of soil and the surface load varied with time. In this study, the analytical solution for a one-dimensional problem was derived based on the consolidation theories respectively proposed by Terzaghi (1925) and Biot (1941). We derived the analytical solution for the excess pore pressure of the single-layered case and the three-layered case as well as soil settlement for the situation of free drainage surface on its top and base. This thesis explored the differences between these two theories on the assumption of one-dimensional drainage only. In addition, we discussed the consolidation process of saturated soils under constant or periodic loading on a single-layered soil and constant loading on a three-layered soil. The result shows that it has no differences in these two theories under the one-dimensional assumption. Our numerical results also show that the excess pore water pressure for a saturated soil layer subject to periodic loading does not dissipate completely, but it reached dynamic equilibrium. The time required to achieve dynamic equilibrium is sensitive to soil texture and the period of loading. In addition, for a three-layered soil subject to constant loading, the drainage rate of excess pore water pressure is affected by soil arrangement in the stratum. The drainage rate of the soil at the first layer and the third layer has a great impact on the whole stratum.

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