A Variational Solution for Downdrag Force Analysis of Pile Groups

This article presents a variational approach for the analysis of downdrag forces of pile groups undergoing soil downward movement. The theoretical load-transfer curves are employed to describe the soil load-displacement relationship. A soil with stiffness varying with depth and with stiffer end-bearing stratum at the pile toe can be easily treated using the present method. The validity of the present method is demonstrated through comparison with existing theoretical solutions and field measurements.