Scaling effects on the centrifuge modelling of energy piles in saturated sand

Abstract

Although various researchers have reported that scaling effects should be considered carefully when modelling the mechanical behaviour of pile in sand by a geotechnical centrifuge, scaling effects on the coupled thermo-mechanical behaviour of the energy pile have not been reported. In this study, the scaling effects on the centrifuge modelling of floating energy piles are assessed by the so-called ‘modelling of models’ technique. Two centrifuge models of energy piles were tested at the 28 and 56 g-levels to simulate the same prototype in saturated medium dense sand. The ratio of pile diameter to mean sand particle size (D/d50) ranged from 92 to 184. Identical working load was applied to the two piles with a factor of safety of 2·5 and each pile was subjected to seven heating–cooling cycles. After the tests, measured thermally induced settlements of both energy piles were similar (1·3%D). Furthermore, a good agreement was obtained between the two piles in the distribution of the axial load along each energy pile. It is evident that the scaling effects due to particle size on the centrifuge modelling of floating energy piles with a ratio of D/d50 larger than 92 can be ignored.