Experimental Comparison of Statically and Cyclically Loaded Non-Slender Piles in Sand

Søren Peder Hyldal Sørensen, Lars Bo Ibsen

Research output: Contribution to conference without publisher/journalConference abstract for conferenceResearchpeer-review

Abstract

The monopile foundation concept is often employed as foundation for offshore wind energy converters. Typically, monopiles are hollow piles made of steel with outer diameters, D, in the range of four to six meters and length to diameter ratios, L/D, around five. Hence, the piles exhibit a rather rigid form of motion. The Winkler model approach, employing p-y curves to describe the soil-pile interaction, is often employed as the design method for laterally loaded piles. The p-y curve formulation, currently recommended by the American Petroleum Institute and Det Norske Veritas, is based on tests on slender piles with length to diameter ratios larger than ten and outer pile diameters less than two meters. Hence, the pile tests that form the basis of the currently recommended p-y curve formulation are conducted with use of piles that exhibits a flexible behaviour, which is in contrast to the piles used as foundation for modern offshore wind energy converters. The aim of the present work is to investigate the pile behaviour for non-slender piles by means of small-scale testing. The pile behaviour is investigated and compared for both static and cyclic loading. When conducting small-scale tests the effective stresses in the soil will be low and vary linearly with depth. As a consequence of this the soil parameters will vary greatly with depth and the determination of soil parameters is subject to great uncertainties. To overcome these uncertainties an overburden pressure, P0, has been applied and hence the effective stresses in the soil have been increased homogeneously. The tests have been conducted in a pressure tank at Aalborg University. A total of 29 quasi-static tests and 14 cyclic tests have been conducted on laterally loaded piles situated in sand. Aluminium pipe piles instrumented with strain gauges have been used for the test series. The outer pile diameter has been varied between 40 and 100 mm, the length to diameter ration is between three and six and the overburden pressure is between 0 and 100 kPa.
Original languageEnglish
Publication date17 Jun 2012
Number of pages1
Publication statusPublished - 17 Jun 2012
EventInternational Ocean and Polar Engineering Conference 2012 - Ixia, Rhodes, Greece
Duration: 17 Jun 201223 Jun 2012
Conference number: 22

Conference

ConferenceInternational Ocean and Polar Engineering Conference 2012
Number22
CountryGreece
CityIxia, Rhodes
Period17/06/201223/06/2012

Keywords

  • Piles
  • Experimental Testing
  • Lateral Loading
  • Offshore Wind Turbine
  • Pressure Tank
  • Static Loading
  • Cyclic Loading

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