Effects of the construction method on pile performance: evaluation by instrumentation - part 1: experimental site at the University of Campinas

Abstract

This paper reviews the behavior of three types of piles (bored, CFA and Omega piles), installed in the experimental site of Unicamp (State University of Campinas). Unicamp subsoil is characterized by non-saturated diabasic soil, lateritic in its surface layer. Extensive data from geotechnical investigation is presented, expressed in parameters derived both from in situ and laboratory tests. Static load tests with electrical extensometers were performed along the depth of instrumented piles. It was observed that most of the loads applied were transferred by lateral friction. An analysis of load transfer functions was made, which displayed a very good definition of both shaft friction and tip interaction, namely the ultimate resistance. The average maximum unit shaft friction resistance of the piles was 41 kPa, 58 kPa and 86 kPa for bored, CFA and Omega piles, respectively. Maximum tip reaction was 87 kPa, 491 kPa and 1665 kPa, for bored, CFA and Omega piles, respectively. This paper also emphasizes the relevance of extracting each pile after completion of the test in order to inspect the pile facies and characteristics. This enabled checking the shape of tips and size of shafts. Part 2 of this paper will review the tests performed at the Experimental Field of FEUP (Faculty of Engineering of the University of Porto/Portugal).