The behaviour of ‘non-displacement’ piles installed in dense Fontainebleau sand and subject to both static and cyclic vertical loads is investigated in a geotechnical centrifuge at a scale of 1:23. Different loading sequences with several combinations (one- and two-way) have been applied. The influences of the cyclic load amplitude and mean amplitude are analysed.

1. Introduction

Numerous types of structure experience significant cyclic loading. Cyclic loads may be essentially environmental (e.g. wave, wind) or operational in origin. The oil and gas industry has developed procedures for considering the effects of large wave cyclic loads on foundations for offshore structures (e.g. American Petroleum Institute (API), 2011). Comparatively, the effects of cyclic loading on foundations are largely ignored in most civil engineering and building activities. The French national programme, SOLCYP (Puech et al., 2012), aims to investigate the effects of cyclic loadings on piles. The experimental part of the project includes both large-scale and model pile testing, which will be performed in calibration chambers and in the centrifuge. The main objective of the centrifuge tests is to study the stability of piles in sands and clays subject to a large variety of cyclic loading histories. Centrifuge testing has proved its efficiency in conducting extensive series of tests, as it allows a large range of parameters to be varied while keeping associated costs relatively low, when compared to in situ testing (e.g. Craig, 1988). This paper focuses on the results of the first series of tests conducted at the IFSTTAR (formerly LCPC) centrifuge facility in Nantes, France. The mode of installation of the model piles is intended to simulate soil-pile interactions relevant for cast-in-place piles. The tests, conducted in dense Fontainebleau sand, covered the full range of loading modes (monotonic versus cyclic; compressive versus tensile; and oneway versus two-way).

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