AnÃlise de provas de carga realizadas em micro-estacas utilizadas no reforÃo das fundaÃÃes de uma ponte histÃrica do Recife-PE

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

This work was part of the recovery of the âSeis de MarÃoâ Bridge, at Santo AntÃnio, Recife-PE, Brazil, from where these studies were obtained. This work was developed in a partnership between the geotechnical engineering department â DEC/UFPE and private companies. The general objectives of this work are: (1) present concepts related to micropiles, (2) present the process and the importance of this bridge foundation recovery and (3) analyze the results of pile load tests realized in the newly constructed micropiles. The concepts related to micropiles that are presented in this work are: definition, classifying, main components, construction control and considerations about the influence of high pressure grouting. The recovery process employed in the Seis de MarÃo bridge foundation was based on its complete reconstruction, with the execution of 90 micropiles divided in 9 blocks of 10 piles. In the project, it was admitted that only the new piles would resist and transmit the loads to the ground. As a fundamental part of the project, it was executed 5 vertical pile load tests and 8 horizontal pile load tests. For the vertical pile load tests, are presented the load-displacement curves obtained in the piles top. Following, it is presented the obtaining of the value of the ultimate load based in methods that use the load-displacement curve (NBR 6122/96, VAN DER VEEN, 1953, modified by AOKI, 1976, and DÃCOURT, 1996b). These methods results were confronted with methods that estimates the ultimate load based in the SPT (DÃCOURT &QUARESMA, 1978, modified by DÃCOURT, 1996a; AOKI &VELLOSO, 1975, modified by MONTEIRO, 1997; a methodology used in this project, based in DÃCOURT QUARESMA, 1978, and a method based on the effective residual grouting pressure, DRINGENBERG, 1990a). Next, the toe and skin friction resistances were determined using the method of rigidity (DÃCOURT, 1996b, 2006), and the Two Lines Method (MASSAD &LAZZO). The results of the static horizontal pile load tests and a brief study for obtaining soil reaction modulus, nh, using the CINTRA &ALBIERO (1982) method, are presented. It is also presented a prediction of the load-horizontal displacement obtained by the software (demo version) FB-Multipier. 4 In general, it can be concluded that the methods used for obtaining the ultimate load based in the load-displacement curve presented good agreement between themselves. The NBR 6122/96 method presented values slightly conservatives. From the methods based in the SPT, the used in this project and the AOKI &VELLOSO (1975) modified by MONTEIRO (1007) presented good agreement between them and with the results of pile load tests. The method of DRINGENBERG (1990b) showed to be good, but, because it depends on the knowledge of the effective grouting pressures, it should be applied only after the piles construction. The study of the toe and skin friction resistances showed that the toe resistance obtained was superior to the waited for this kind of pile, and the skin friction resistance was lower.

ASSUNTO(S)

micropiles load-displacement micro-estacas injeÃÃo efetiva fundaÃÃo de ponte effective injection vertical load carga de ruptura engenharia civil

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