本研究先以乾燥土壤施作不同加勁材長度在不同圍壓下之拉拔試驗，再根據 Huang (2014)所推導之拉出強度-拉出位移雙曲線理論建立預測拉拔試驗之模型，並得到模型之控制參數KT、nT、RT，在建立模型的過程中，摩擦角的決定十分重要，與模型的準確性密切相關，本研究採取兩種方式來決定摩擦角，分別為試驗條件為最短長度加勁材與最低圍壓之拉拔試驗所得之摩擦角，與施作加勁材之界面直剪試驗所得之加勁材與試驗土壤之表面摩擦角，比較兩者後以較準確之方式建立預測模型。
確立了模型建立的流程之後，改變試驗土樣之乾濕度，以飽和土樣進行試驗並建立拉出強度預測模型，並且也進行了飽和砂之界面直剪試驗求得摩擦角，台灣地區降雨量大，雨量豐沛，且現地容易遭遇地下水層之影響，所以藉由飽和濕土來模擬現地土壤之極端狀況，並觀測飽和砂拉拔試驗施作時，試體內孔隙水壓之變化情形。
試驗結果顯示在建立模型時，排除掉拉斷破壞之拉拔試驗可以得到較準確之有效長度，而拉拔試驗在飽和土壤中所得到之極限拉拔力比起乾燥土壤是下降的，與加勁材料與試驗土壤界面直剪試驗有相同的趨勢。乾砂拉拔試驗中所得之模型參數KT、nT、RT，與飽和拉拔試驗中之參數隨著加勁材長度的上升，有著相同的變化趨勢。

A heat-bonded nonwoven geotextile with different lengths was used to perform pull-out tests to investigate possible different behavior of pull-out of reinforcement embedded in dry and saturated sands. Hyperbolic pull-out resistance vs. displacement relationships are established to facilitate the prediction of reinforcement pull-out resistance. Three model constants were back-calculated from the pull-out stress-displacement curves.
It was found that these three constants have good relationships with the embedment length of reinforcement. The established hyperbolic pull-out model generates curves of pull-out stress-displacement well agreed with the experimental ones.
To facilitate the establishment of the hyperbolic pull-out model, four series of direct shear tests using a medium-scale direct shear apparatus were performed. The direct shear tests include sand-sand and sand-reinforcement interface tests using dry and saturated sands. Significant different friction behavior was found between dry and saturated conditions. This is also true between sand-sand and sand-reinforcement interface tests.
The peak friction angles obtained from the sand-reinforcement interface direct shear tests facilitate the establishment of an accurate model of ‘effective pull-out length’ which is a crucial element in the hyperbolic pull-out model.

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