<p>Civil engineers recommend the under-reamed pile foundation for constructing structures such as bridges, industrial sheds, overhead water tanks, and boundary and compound walls in areas with expansive soil. The traditional foundation system may fail due to the effects of swelling and shrinkage of expansive soil. The under-reamed pile resists upward pressure, which occurs due to changes in seasonal moisture within the soil. In the present investigation, the under-reamed pile embedded in black cotton soil has been simulated through the Finite Element application, Plaxis 2D. In the study, black cotton soil has been modelled using the soft soil model, and a prescribed upward displacement is considered at the top of the pile. The mechanisms are assessed through the shear strain formation and development of excess pore water pressure. In the investigation, the influence of various geotechnical and geometrical parameters, specifically cohesion, groundwater level, spacing between the bulbs, and bulb diameter, is evaluated by altering magnitudes on the developed mechanism. Furthermore, the uplift capacity of the pile is also assessed for variations in these geotechnical and geometrical parameters. It is concluded that the connection of the shear strain contour between the bulbs weakens beyond the critical spacing (<i>S</i>_<i>b</i>)_<i>cr</i> of 3<i>D</i>_<i>p</i>, and bulbs act as individual units.</p>