Determination of Pile Base Resistance in Sands

Advances in the design of axially loaded piles are desirable because significant cost savings may result. Well-designed piles settle by amounts that are well tolerated by the superstructure and induce strains around the pile base that are far removed from failure. To investigate the development of base resistance for a given soil condition and increasing settlements, piles embedded in sand are modeled using the finite-element method with a nonlinear elastic-plastic model. Based on the load-settlement response obtained from the finite-element analysis and cone penetration resistance obtained from cavity expansion and stress rotation analyses, values of normalized base resistance, defined as base resistance divided by cone penetration resistance, are obtained. The relationship between base resistance and cone resistance is useful in the design of deep foundation using cone penetration test results. The effect of the initial coefficient of earth pressure at rest K0 on normalized base resistance values is also investigated. Several case histories, including both nondisplacement and displacement piles, are used for comparison with the theoretical results.