İnce Dane İçeriğinin Siltli Kum Zeminlerin Drenajsız Kayma Dayanımı Davranışı ve Durağan Durum Çizgisi Üzerindeki Etkisi

İnce dane içeren kum zeminlerin gerek drenajlı gerekse drenajsız yükleme koşulları altındaki kayma dayanımı davranışıları, konsolidasyon sonrası başlangıç koşulları yanısıra, ince dane içeriği, ince dane plastisitesi, iri ve ince danelerin şekli ve ortalama efektif gerilme düzeyinden etkilenmektedir. Dolayısı ile ince dane içeren zeminlerin davranışlarının değerlendirilmesi için temiz kuma göre daha fazla parametre ele alınmalıdır. Kritik durum zemin mekaniği (CSSM), tüm bu parametreleri göz önünde bulundurarak bu zemin türlerinin davranışını anlamak için uygun bir çerçevedir. Bu çalışmada %10, %20; %30, %40 ve %50 oranlarında düşük plastisiteli silt içeren kum-silt karışımı örnekleri üzerinde 50 kPa, 100 kPa ve 200 kPa efektif konsolidasiyon basınçları altına bir dizi konsolidasyonlu drenajsız statik üç eksenli basınç deneyi gerçekleştirilmiştir. Deneysel sonuçlar, örneklerin drenajsız kayma dayanımı davranışlanının ve durağan durum çizgisinin (SSL) ince dane içeriğinden önemli ölçüde etkilendiğini göstermektedir. Belirli bir eşik ince dane içeriğine kadar durağan durum çizgisi (SSL) konumunun temiz kum konumundan aşağıya doğru hareket ettiği ve bu değerin ötesinde, ince içeriğin artmasıyla yukarı doğru hareket ettiği görülmüştür. Bu da ince dane içeriğinin değişimi ile birlikte örneklerin drenajsız kayma dayanımı davranışının ve sıkışma eğiliminin değiştiğini göstermektedir. Bununla birlikte durağan durum parametre (Mss) ve durağan durumundaki mobilize sürtünme açısı (φss) değerlerinin de ince dane içeriğinden etkilendiği görülmüştür.

The Effect of Fine Content on Undrained Shear Strength Behavior and Steady State Line of Silty Sand Soils

Shear strength behavior of sand soils with fines under both drained and undrained loading conditions is affected by the initial conditions after consolidation as well as the fine grain content, fine grain plasticity, coarse and fine grain shapes and mean effective stress level. Therefore, in order to evaluate the behavior of soils containing fine grain, more parameters should be considered compared to clean sand. Critical state soil mechanics (CSSM) is an appropriate framework to understand the behavior of this soil types with considering all of the effective parameters. In this study a series of consolidated undrained static triaxial tests were carried out on sand-silt mixtures containing 10%, 20%, 30%, 40% and 50% low plasticity silt at an effective consolidation pressures of 50 kPa, 100 kPa and 200 kPa. The experimental results show that undrained shear strength behavior and steady state line (SSL) are significantly affected by the fine grain contents. It was observed that up to a threshold fine content the location of the SSL moves downward from the clean sand position and beyond that, it move upward with the increase of the fine content. This shows that undrained shear strength behavior and compression tendency of the samples change with the change of the fine grain content. However, it was observed that the steady state parameter (Mss) and the mobilized friction angle (φss) values in steady state were also affected by the fines content.

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