Análise de prova de carga estática em estaca hélice contínua e comparação com previsões semi-empíricas

Abstract

The foundations reliability is hand in hand with economy and, in that sense, the foundations elements are designed so that to bear the applied load as long as they are not oversized. In Brazilian practice it is common to use semi-empirical formulations for design of foundations piles as to load-bearing capacity, which can bring approximate values or not of the real behavior of these structures. In fact there is not always full knowledge regarding the safety of foundations and, in many cases, the sizing is restricted to SPT reports. However, it is the methodology available and widely explored in the geotechnical practice. In this sense, the research seeks to analyze a Static Loading Test (SLT) carried out on a continuous flight auger pile located in the region of Itaboraí-RJ and compare it with semi-empirical load capacity estimates to determine the methodology that most approached the extrapolated value from the load-settlement curve. The estimate is based on the use of three SPT reports from the region of interest, classified as SP-81, SP-82 and SP-83, and also on the influence of the survey group (GS). SP-82 is the nearest to the tested pile. The SLT data were analyzed and it was verified the need to use reliable methodology for the extrapolation of the load-settlement curve, as there was no clear failure. Van der Veen (1953) was used to extrapolate the SLT for physical failure, obtaining a load of 1.227 KN. Conventional failure methodologies required the use of the Van der Veen curve (1953), as the SLT settlement data were not of the magnitude required for the analysis, and the graphical intersections of the methodologies occurred in stretches where settlement variations did not influence the value of failure. Due to the lack of development of the settlements, the methodology of Décourt’s Rigidity (1996) brought a debatable conventional failure value, therefore, the physical failure of Van der Veen (1953) was adopted as an analysis parameter. The methodologies that came closest to the failure value were those of Aoki-Velloso (1975) and Décourt-Quaresma (1982).