Some forty years ago, when geotechnical centrifuge modelling had been rediscovered and was being developed once more after the early work of Phillips (1869), only a few studies were devoted to the questions and concerns about scaling laws and similitude conditions. During the first decades, it was relatively easy for researchers to keep themselves informed about the main outcomes of these studies and to take them into account when designing new centrifuge model tests. This is obviously not true today following the welcome growth in terms of the large number of centrifuge facilities now in operation around the world. It is increasingly difficult, but yet absolutely essential, to know about the relevant developments concerning studies into the scaling laws and, furthermore, into the limits of the domains of the use of centrifuge modelling. On the other hand, new media offers a significant opportunity to provide this resource to the physical modelling community. New topics are investigated by many researchers as they become more inventive in the ways in which geotechnical centrifuge modelling is applied to solve pressing problems within geotechnical engineering, and across other disciplines too. Innovative work presenting comparisons between centrifuge model tests and true scale tests are providing original data on the validity of the scaling factors. During the TC2 meeting at St John’s (Canada) in July 2002, the first author, J. Garnier (LCPC), suggested making an inventory of the scaling laws and similitude questions relating to centrifuge modelling. The aim of this catalogue is to present the questions already solved (with inclusion of the references of the papers where the results have been presented) and the unsolved problems (on which research should continue). The first draft of this catalogue is now available and it is hoped that it will become a useful tool for scientists and researchers involved in centrifuge modelling. Of course, this catalogue will be regularly updated, every four years during the International Conferences on Physical Modelling in Geotechnics. The latest version of the catalogue is available on the TC2 website ( www.tc2.civil.uwa.edu.au ).

The present study was conducted to examine the behaviour of instrumented ‰exible piles in dry sand under lateral cyclic loading using centrifuged models. Considering load service conditions, the in‰uence of the number of cycles of their amplitude and of the soil density on the pile cap displacement and the maximum bending moment of the pile is examined. An empirical law to evaluate pile head displacements at application point is proposed. From the bending moment proˆle recorded during loading, P-y reaction curves are identiˆed. A reduction coe‹cient r (P-multiplier) is introduced to quantify the eŠects of cyclic loads on P-y curves.

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The uplift capacity of helical anchors normally increases with the number of helical plates. The rate of capacity gain is variable, considering that the disturbance caused by the anchor installation is generally more pronounced in the soil mass above the upper plates than above the lower plates, because the upper soil layers are penetrated more times. The present investigation examines the effect of the number of helices on the performance of helical anchors in sand, based on the results of centrifuge model tests. Uplift loading tests were performed on 12 different types of piles installed in two containers of dry sand prepared with different densities. The measured fractions of the uplift capacity related to each individual helical plate of multi-helix anchors were compared with the fractions predicted by the individual bearing method. The results of this investigation indicate that in double- and triple-helix anchors, the contributions of the second and third plate to the total anchor uplift capacity decreased with the increase of sand relative density and plate diameter. In addition, these experiments demonstrated that the variation of the anchor load–displacement behavior with the number of helices also depends on these parameters.

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An experimental study has been carried out to investigate the effects of soil partial saturation on the behaviour of laterally loaded piles. The proposed study has been conducted by means of centrifuge tests at 100×g, where a single vertical pile has been subjected to a combination of static horizontal load and bending moment. The study has been conducted on a silty soil characterized with laboratory testing under saturated and unsaturated conditions. During flight, two different positions of water table have been explored. The influence of density has been investigated compacting the sample with two different void ratio. Finally, the effects of a variation of saturation degree on the pile response under loading have been studied rising the water table to ground surface. Data interpretation allows drawing different considerations on the effects of partial saturation on the behaviour of laterally loaded piles. As expected, compared to saturated soils, partial saturation leads always to a stiffer and resistant response of the system. However, the depth of the maximum bending moment is related to the position of water table and the bounding effects induced by partial saturation appears to be more important for loose soils.