International Journal of Soil Science1816-4978xxxx-xxxxAcademic Journals Inc.10.3923/ijss.2016.49.60LomelingDavidYiebJuma L.L.LodiongModi A.KenyiMandlena C.KenyiMoti S.SilvestroGeorge M.22016112The study discusses the empirical derivation of undrained shear strength S_{und} 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 S_{und}, 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 S_{und} positively correlated with time to failure (t_{f}) irrespective of change in the angular velocity and negatively correlated with both (ω) and SMC, which both were best described using a power function: S_{und} = Λθ^{-β}. The S_{und} was constant at any given SMC regardless of variations in angular velocity however, the S_{und} decreased with increase in SMC suggesting that S_{und} 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 (T_{v}) was more or less constant around 0.1 kg cm^{-2} till failure, whereas the shear resistance generated by the horizontal torque (T_{h}) was variable at about 0.3 kg cm^{-2}. On average, the T_{h} was three times the T_{v}, while the measured S_{und} was overestimated by about 40% higher than the predicted S_{und}.]]>De Alencar, J.A., D.H. Chan and N.R. Morgenstern,1988Bjerrum, L.,1972Bjerrum, L.,1973O'Kelly, B.C.,2013Chandler, R.J.,1988In-situ Measurement of the Undrained Shear Strength of Clays Using the Field Vane.]]>Biscontin, G. and J.M. Pestana,1999He, J., J. Chu and H. Liu,2014Kamata, T., Y. Tsukamoto and K. Ishihara,2009Keentok, M., J.F. Milthorpe and E. O'Donovan,1985Kim, D. and S. Ha,2014Kimura, T. and K. Saitoh,1983Kirkpatrick, W.M. and A.J. Khan,1984Komamura, F. and R.J. Huang,1974Koumoto, T. and G.T. Houlsby,2001Kulhawy, F.H., C.H. Trautmann, J.F. Beech, T.D. O'Rourke, W. McGuire, W.A. Wood and C. Capano,1983Lerouiel, S. and M.E.S. Marques,1996Mayne, P., M. Coop, S. Springman, A. Huang and J. Zornberg,2009Menzies, B.K. and C.M. Merrifield,1980Perez-Foguet, A., A. Ledesma and A. Huerta,1999Robinson, R.G., T.S. Tan and F.H. Lee,2003Schlue, B.F., T. Morz and S. Kreiter,2007Schlue, B., T. Moerz and S. Kreiter,2010Silvestri, V. and M. Aubertin,1988In-situ Vane Tests.]]>Silvestri, V., M. Aubertin and R.P. Chapuis,1993Terzaghi, K., R.B. Peck and G. Mesri,1996Tortensson, B.A.,1977Tsukamoto, Y., K. Ishihara, H. Nakazawa, K. Kamada and Y. Huang,2002Tsukamoto, Y., K. Ishihara and T. Shibayama,2004Wiesel, C.E.,1973in situ vane test results.]]>Donald, I.B., D.O. Jordan, R.J. Parker and C.T. Toh,1977