Numerical and analytical study on uplift capacity of under-reamed piles in sand

In the present study, the uplift capacity of the under-reamed piles (also referred to as belled piles) in the sand was determined by following a finite element analysis. In this regard, the soil was assumed to obey Mohr-Coulomb's failure criteria, together with a non-associated flow rule. The pile geometry, soil, and pile properties were selected by following relevant literature. The friction angle (phi) of sand varied from 25 degrees-45 degrees, whereas the embedment ratio (L/D) of the pile was kept between 7.0-17.5. The computed uplift capacity was expressed in a non-dimensional manner. After comparison of uplift capacity with literature, an analytical equation to predict the uplift capacity of under-reamed\belled piles was developed using the generated failure patterns from numerical analysis. The proposed equation was validated using 300 datasets from literature which includes field and laboratory test both. The uplift capacity estimated with the developed equation correlates well with literature as the R-2 value in all the cases was greater than 0.99.

Automated summary

In this study, the uplift capacity of under-reamed piles in sand was determined using finite element analysis. An analytical equation was developed to predict the uplift capacity of these piles, which was validated using a large dataset from literature with a high degree of correlation. The proposed equation proved to be effective in predicting the uplift capacity of under-reamed/belled piles.