DEM Simulations on the Volume Change of Sand during Heating-Cooling Cycle

Shuhua Wang

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: FUNDAMENTALS - VII Soil & Rock Mechanics

ABSTRACT: The volume changes of sand under thermal loading can greatly affect the serviceability of many earth structures in geo-energy and geo-environmental engineering. Up to date, this thermal volume change behaviour has not been fully understood. In this paper, the measured volume changes of saturated Toyoura sand with different densities during heating and cooling cycles are reported and discussed. In addition, DEM analyses are also carried out to investigate the mechanisms of thermally induced volume changes of sand, from particle-level microscopic point of view. It is found that after the first thermal cycle, loose and medium dense sand would exhibit irreversible volumetric contractions, with larger contraction at lower density. This thermally induced contraction is attributed to the fact that thermal expansion of individual particles can destroy large pores and induce particle rearrangements. On the contrary, dense sand only shows elastic response during heating and cooling cycles due to its highly interlocked microstructure. Résumé Les changements de volume de sable -énergétique et géo-environnement. Jusqu'à ce jour, ce changement thermique du volume n'a pas été totalement compris. Dans cet article, les variations de volume du sable saturé de Toyoura, mesurées avec des densités différentes pendant les cycles de chauffage et de refroidissement sont présentées et discutées. De plus, des analyses DEM sont également menées pour étudier les mécanismes de irréversibles, avec une plus grande contraction à faible densité. Cette contraction induite par la chaleur est due au fait que l'expansion thermique des particules individuelles peuvent détruire les gros pores et induire des réarrangements de particules. En outrde refroidissement en raison de sa microstructure fortement agrafée.

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