The Loss of Pile Axial Capacities due to Scour: Vertical Stress Distribution

Abstract

Pile axial capacities can be decreased as a result of scouring around the pile foundations. This phenomenon is particularly evident for friction piles subjected to large scour depths. As part of study of the loss of pile axial capacities due to scour, this study investigates vertical soil stress at the pile under different scour-hole dimension conditions. An analytical solution based on Boussinesq’s theory is developed for the stress distribution. Comparisons are made between the present method and the other existing methods such as US FHWA manuals for driven piles and drill shafts. The effects of scour-hole dimensions including scour depth, width, and slope angles on the vertical soil stress distribution are discussed. As the scour depth or width increases, the vertical soil stress decreases and the stress distribution curves extend to a greater depth before converging at the constant line. The effect of scour-hole slope angle on vertical stress distribution depends on both scour depth and width. There exists a minimum scour width and a corresponding minimum scour depth at which the effect of scour-hole slope angle can be ignored.