3D FE analysis of bored pile- pile cap interaction in sandy soils under axial compression- parametric study

Abstract

In this research study, a 3D elasto-plastic finite element was used to analyze the influence and the interaction between the bored concrete pile, pile cap, and surrounding ground under uniaxial compression load, using ABAQUS finite element software. Mohr-Coulomb plasticity model was used to simulate sand elements while the pile was modeled as elastic material with a modulus, Ep. The contact between pile and adjacent sand was simulated using contact pair with surface-to-surface type of interaction. Different sand properties and pile length / diameter (L/D) ratios were considered in the analysis. Pile cap bearing pressure (qcap), side shear stress (fside), tip bearing pressure (qtip), deformation, and stresses and strains around the pile were investigated. The results show that for the same soil, as L/D ratio increases qcap decreases. Moreover, the results show that for the same L/D ratio, qcap decreases as the soil modulus (Es) increases and qtip decreases slightly with the increase in Es whereas for the same Es, qtip increases with the increase in L/D ratio. The major contribution in the capacity of capped bored pile under compression loading is devoted to qtip. As L/D increases, the contribution of qtip increases. Furthermore, qtip increases as the relative stiffness, Es/Ep increases.