Thermal Effects on Saturated Sand: Experimental and Numerical Study

In geo-energy and geo-environmental engineering, soils in many earth structures, including energy piles and landfill covers, are subjected to heating and cooling cycles. The thermally induced soil volume changes can have dramatic consequences for the serviceability of these structures. For example, thermally induced volume change of soils surrounding an energy pile would affect the normal stress acting on the pile and hence the pile settlement (Ng et al., 2015). Up to date, the behaviour of clay and silt under thermal loads has been widely studied (Zhou et al., 2015). Relatively little research has been reported on the volume changes of sand under thermal loads, although energy piles may be constructed in sands. In the first part of this paper, a newly developed temperature-controlled triaxial apparatus is described. This apparatus is intended to investigate thermally induced volume changes of soil skeleton of saturated Toyoura sand. Soil specimens with different initial densities were isotropically compressed and then subjected to heating from 23 to 50℃. In the second part of the paper, two-dimensional DEM simulations using PFC2D are reported with the intention to provide quantitative interpretation of the response of loose and dense specimen under heating. After sand specimens were prepared and consolidated to target isotropic stress value in DEM analyses, heating effects are simulated by increasing the radius of individual particle following the law of thermal expansion.