Suction and reloading effects on pile behaviour in tropical soil

ABSTRACT The design of foundations for buildings subjected to unload–reload cycles generate the need to understand the reloading effects in piles. Commonly, such foundations are found in unsaturated soils, which also requires considering the effects of matric suction. This paper investigates the effects of soil suction and reloading on the behaviour of piles from an experimental and numerical approach. A bored pile built on a tropical soil profile was subjected to a sequence of load tests, performed at different climate seasons. An average 85% decrease in soil suction was measured from the pile load test in the dry season to the test in the rainy one, which contributed to a reduction in the pile’s ultimate axial load capacity and stiffness of around 50%. The unload–reload cycles caused an increase on the pile’s ultimate load capacity between 7% and 9% and on the pile stiffness between 13% and 24%.