Análise da previsão da capacidade de carga à tração de estacas hélice contínua em solo granular e proposta de alternativas

Abstract

Construction projects must be structures with appropriate safety, similarly, the foundations of these structures must present as safety concerning the structural element rupture and to soil-structure system rupture, as safety concerning acceptable displacements. In general, foundations are susceptible to compressive loads only, however, in many buildings, the foundations are submitted to other efforts such as bending and traction, security need to be verified for these cases. Wind turbines, power lines, bridges, and anti-flotation slab anchors are examples where piles are submitted to traction. This research investigates the behavior of continuous flight auger piles in granular soils submitted to uplift effort. For this, 4 sites with granular subsoils were selected, 3 sites in Ceará and 1 in Bahia. In total 20 piles were evaluated, of which 3 tensile tested, 5 compression tested and 12 are reaction piles monitored in compressive load tests. In addition, this research used 101 standard penetration test (SPT) distributed across the 4 sites. Initially, the subsoils were characterized using the standard penetration test (SPT). Subsequently, the bearing capacities of the piles were determined by load testing using the methods of Van der Veen (1953) and NBR 6122 (ABNT, 2019). Then, the bearing capacity of the piles analyzed were estimated using specific and non-specific methods found in the literature. Thus, these estimates were compared with the experimental values. In addition, 3 methodologies were developed to estimate the ultimate bearing capacity in continuous flight auger piles in granular soils. Then, the developed methods were evaluated and compared with the experimental values and with the estimates of the most concordant methods used and available in the literature. According to literature methods, the most agreement specific method was Meyerhof and Adams (1968), and the non-specific method was Meyehof (1956), both with approximately 65% higher values, on average, than reference values and with high dispersion. The developed methods presented more agreement estimates and slight dispersion, representing as alternatives to the determination of the bearing capacity in continuous flight auger piles in granular soils