Above the end-bearing strata, there is a soil layer that is in the process of settling due to consolidation
or collapse.
• Above the end-bearing strata, the original groundwater table is permanently lowered causing an
increase in effective stress and resulting in settlement of the soil strata.
• A fill layer is placed at ground surface that causes settlement of the soil strata, such as shown in
Fig. 4.17.
The following equations can be used to calculate the downdrag load QD for a single isolated pile
or pier