Analysis of the bearing capacity of continuous flight auger piles in terms of their excavation energy and of rainfall data

Abstract

Continuous flight auger piles (CFAs) are among the most common types of foundation executed in the tropical residual soil of Brasília, DF, Brazil. The bearing capacity of CFAs can be controlled according to the energy required to excavate each pile but is also influenced by seasonal conditions that affect the unsaturated soil profile. In the present article, a database of controlled execution of CFAs carried out at Brasília-DF was evaluated. The execution methodology enabled the full control of the drilling energy. Load tests were also performed and the pile bearing capacity was estimated by extrapolating the load-settlement curve using the van Der Veen method. As the site was excavated before the foundation was built, the morphology of the site was also considered in the analyses. Furthermore, by comparing the execution energies and climatological information, a relation between the moisture indexes and the execution energies was investigated. From these analyses, discussions regarding the relation between the bearing capacity of the piles tested and the rainfall regime they have been subjected to are presented. The changes observed in bearing capacity due to climatological effects may lead to economical savings and offer enhanced reliability in the design of CFAs.