Friction Piles in Clay with Recent Fill.
The lower right diagram in Fig. 8.17 shows the condition of piles embedded in clay with the recent placement of a fill layer at ground surface.
In this case, the piles will be subjected to a downdrag load due to placement of the fill layer.
Section 6.3.4 presents a discussion and the equations needed to determine downdrag loads for single piles and pile groups.