This paper presents finite element analyses of negative skin friction on a short single pile, long pile and superlong pile under various conditions. Negative skin friction is a most common problem in designed and construction of pile in a highly compressible soft soil. In this paper, a 3D-dimensional axisymmetric model is built in the finite element program, ABAQUS6.14. The model first is verified with a centrifuge test results. The study concluded that the neutral plane is located closer to the end of the pile as the end bearing increases. Based on the analyses, it is found that the location of the neutral plane is significantly influenced by the pile tip location from bearing layer. the normalized neutral plane decreases with the increase of the pile length embedded in the clay layer. Closed form equations of Shong, 2002, predict the numerical results in well agreement.

An end bearing stone column is one of the most common types of stone columns, which completely penetrates through a layer of soft clay soils, resting on much stiffer soils. This article presents a numerical model (analyses) of the stone column used to strengthen the soft clay soil. The analyses were performed using a three-dimensional model in FLAC3D. To investigate the effect of the stone column on strengthening soft clay soils, a dimensionless parameter called the settlement improvement ratio (Ks) is used. The results show that, the settlement improvement ratio (Ks) increases with an increasing diameter of the stone column. The lateral deformation of the stone column decreases with the increasing stone column diameter, and the maximum lateral deformation was occurred at approximately (1.0 to 1.5) diameter from the top of the surface.

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The third author's name is incorrect. It should read D. A. K. Sayed.The original article has been corrected.