Numerical and Analytical Study on Axial Ultimate Bearing Capacity of Fixed-Head Energy Piles in Different Soils

In this paper, the axial ultimate bearing capacity of fixed-head concrete energy piles is studied considering various soils and thermomechanical loads, through numerical and analytical models. Accordingly, an axisymmetric numerical approach was adopted using the finite-element method by considering temperature-dependent soil and pile–soil interface parameters, and the results were validated using experimental datasets. Quantitative and statistical comparisons showed an acceptable agreement between the numerical predictions and experimental observations. Then, a vast numerical parametric study was carried out on various soil strength parameters and different thermomechanical conditions to evaluate the changes in compressive/tensile ultimate bearing capacity of the fixed-head energy piles in dry and saturated soils. The results showed that temperature changes and environmental conditions have significant effects on the ultimate load capacity of energy piles. Thereafter, different analytical approaches were developed for various soil types and thermomechanical loading conditions to assess the soil–structure and thermomechanical interactions between the examined energy piles and the surrounding soil. Accordingly, by comparing the obtained results from the analytical and numerical solutions, the best analytical approach for each soil type and load condition was proposed. Finally, by performing an analytical sensitivity study on the geometrical aspects of the examined energy piles, the remarkable effects of the pile diameter and pile length on the ultimate load capacity of energy piles were revealed.