Keywords

Uplift, Bored pile, Drilled shaft, Shrink-swell soils, Full scale test, Load test, Tension, Fine grain soils, Expansive clays

Abstract

The swelling and shrinking of high plasticity clays can induce significant loads in otherwise stress-free piles such as bored piles right after construction. The seasonal weather fluctuations through rainfall and sunshine induce changes in water content and thus vertical movements, which lead to uplift by swelling or downdrag due to shrinking in the bored piles over time. This article describes three case histories in three different locations where measurements of load distributions in bored piles constructed in high plasticity clays were conducted along with associated undrained shear strength laboratory tests. The maximum friction generated due to swelling and due to shrinking is back-calculated from the measured loads, and recommendations are proposed to estimate the maximum friction using the undrained shear strength of the clay.

DOI