Análise do comportamento de estacas strauss submetidas a carregamento horizontal no solo da região de Londrina - PR

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In Londrina city, Strauss piles are frequently used as retaining structure for building basement excavation, being submitted to horizontal load. However, the projects of such retaining structures are usually conducted using design methods that do not take the concrete cracking of pile transversal section and the properties of lateritic tropical soil into account. This work aimed to study the behavior of Strauss piles under horizontal loads by means of horizontal bearing capacity tests, carried out on Geotechnical Experimental Site (CEEG) of Londrina State University. Nine Strauss piles were tested. They were 12 meters long and had 32 cm in diameter. Six piles were reinforced with three steel bars and three piles were reinforced with seven steel bars, along their entire lengths. The geotechnical profile of experimental field is typical of Londrina city and can be defined as a basaltic residual soil, with a superficial layer of a porous and collapsible silty-clay soil. This soil presents a lateritic behavior, what means that its geotechnical field behavior is similar to a sandy soil, despite the fact that it has almost 80% of clay grains. The horizontal load tests results were performed on two piles at each same time, and the results were presented in load x horizontal displacement curves under two soil conditions: non-saturated and pre-wetted during 36 and 12 hours. Under no wetted moisture conditions, the less structural rigid piles presented an average horizontal bearing capacity of 20 kN, whereas that, for the most rigid piles, the rupture occurred with 30 kN of horizontal load. The collapse loads for the two pile types were 15 kN and 27 kN, to the pre-flood times of 36 and 12 hours, respectively. The Gabr &Borden (1989) and Robertson et al. (1989) methods were used to check the correlation between experimental and computed the p-y curves. It was found that the first method gives good agreement with the results obtained in field, and the second method, using expression for non-cohesive soils, only showed good results if a correction in Fs factor is considered. From the horizontal load tests results, it was found an average soil coefficient, nh, equal to 5 MN/m³, that is very close to that achieved by other researches in the same experimental site. Due the consideration of concrete cracking for the rupture loads of piles, it was observed an increase in average displacements of 39% for piles reinforced with 3 steel bars and 28% for piles with 7 steel bars, at the ground surface.

ASSUNTO(S)

estacas - fundações - engenharia estacas strauss - engenharia geotécnica estacas - fundações - engenharia engenharia geológica - estacas engenharia geológica - estacas piling strauss piling strauss engineering engineering strauss piling strauss piling foundation(engineering) foundation(engineering)

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