Under-reamed pile-soil interaction in sand under lateral loading: A three-dimensional numerical study

The studies on the lateral response of under-reamed piles in sand are very limited. Therefore, a 3D numerical model is developed to study the behavior of under-reamed piles in sand under lateral loading. The present numerical model is validated with the results of numerical analyses, small scale model test, centrifuge test, field test, and existing closed-form solution. In the present study, the effects of embedment length of pile, bulb position, number of bulbs, bulb spacing, and soil friction angle are studied. At higher bulb positions, under-reamed piles give a stiffer load-deflection response, thereby producing higher load-carrying capacity and lesser deflection than pile without bulb. The deflection of the under-reamed pile further reduces with more bulbs and lesser spacing. For higher bulb positions, maximum negative (opposing) shear force and the bending moment in the shaft of under-reamed pile are lesser than the pile without bulb. The failure mechanism of soil around underreamed pile is also studied. From the present study, it is concluded that the provision of a bulb improves both pile capacity and structural response. The results of the present study are presented in non-dimensional form; hence, these will be helpful for the design purpose.

Automated summary

A 3D numerical model is developed to study the lateral response of under-reamed piles in sand under lateral loading. The study shows that under-reamed piles at higher bulb positions exhibit stiffer load-deflection response, better load-carrying capacity, lesser deflection, and lower negative shear force and bending moment in the shaft compared to piles without bulbs. The provision of a bulb improves both pile capacity and structural response.