Effective Stress Capacity Model for Piles in Clay

Several rigorous, theoretical methods, using effective stress concepts, have been developed in the last five years to predict the ultimate shaft friction on piles supported in clays. The latest generation of these methods, which were developed as part of an industry sponsored project administered by Amoco, is described and critiqued. Computed results for four effective stress models and two conventional methods are compared with values measured on 10 piles at two field and one laboratory test sites. Predicted and measured values are in good agreement. The development of effective stress approaches to compute shaft friction provides for an improved understanding of factors that affect shaft friction and should lead in the future to improved techniques.