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International Journal of Soil Science

Year: 2016 | Volume: 11 | Issue: 2 | Page No.: 49-60
DOI: 10.3923/ijss.2016.49.60
Effects of Variable Angular Velocities and Soil Moisture Contents on Undrained Shear Strength in a Sandy Loam Soil (Eutric Leptosol)
David Lomeling, Juma L.L. Yieb, Modi A. Lodiong, Mandlena C. Kenyi, Moti S. Kenyi and George M. Silvestro

Abstract: The study discusses the empirical derivation of undrained shear strength Sund from vane tests and compared this to those derived from predictions under the influence of both angular velocity (ω) and Soil Moisture Content (SMC) percentage. The study conducted on partially and fully saturated samples of sandy loam soil (Eutric leptosol) evaluated the effects of three different angular velocities and Soil Moisture Contents (SMCs) on the Sund, using a pocket vane tester. The angular velocities used in this study were 7.2, 3.6 and 1.8° sec–1, which corresponded to rotation rates of 5, 10 and 20 sec per 0.1 kg cm-2, respectively. The results showed that Sund positively correlated with time to failure (tf) irrespective of change in the angular velocity and negatively correlated with both (ω) and SMC, which both were best described using a power function: Sund = Λθ. The Sund was constant at any given SMC regardless of variations in angular velocity however, the Sund decreased with increase in SMC suggesting that Sund was largely controlled by SMC and less by w. Decoupling the torque into the cylindrical and horizontal shear components showed that the shear resistance generated by the cylindrical or vertical torque (Tv) was more or less constant around 0.1 kg cm-2 till failure, whereas the shear resistance generated by the horizontal torque (Th) was variable at about 0.3 kg cm-2. On average, the Th was three times the Tv, while the measured Sund was overestimated by about 40% higher than the predicted Sund.

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How to cite this article
David Lomeling, Juma L.L. Yieb, Modi A. Lodiong, Mandlena C. Kenyi, Moti S. Kenyi and George M. Silvestro, 2016. Effects of Variable Angular Velocities and Soil Moisture Contents on Undrained Shear Strength in a Sandy Loam Soil (Eutric Leptosol). International Journal of Soil Science, 11: 49-60.

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