Numerical analyses for the bearing behavior and uplift potential of single pile in water-sensitive expansive soil

The swelling/shrinkage behavior of expansive soils in relation to water content may pose considerable threats to the infrastructures above them. While piles are commonly used to address this issue, the performance of pile-soil systems is usually elusive. In this context, the paper numerically studies the bearing behavior and uplift potential of a single pile in expansive soils. To this end, the stress-strain responses and shear strength variation of expansive soil specimens under different water contents are experimentally investigated through a series of consolidated undrained (CU) triaxial tests. Based on the dataset, threedimensional (3D) finite element analyses of a single pile in expansive soils are conducted using the thermo-mechanical module of ABAQUS. This approach utilizes the association between water-induced soil swelling/shrinkage behavior and that caused by temperature changes. The results reveal that as the water content within the effective depth increases, the ultimate bearing capacity of the pile initially rises and then declines, due to the competing mechanism between soil strength reduction induced by water infiltration and the upward soil-to-pile friction provided by soil swelling effects. Such a competing mechanism is shown to play a non-negligible role in affecting the interplay between the pile uplift potential and water content. In addition, the uplift potential is also influenced by the variation in pile self-weight due to the change of pile length or diameter.