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Thermohydromechanical behaviour of soils and soil structure interfaces 217

Figure 5.3 Influence of the overconsolidation ratio on the thermally induced volumetric strain of
fine-grained soils. Modified after Cekerevac, C., Laloui, L., 2004. Experimental study of thermal effects
on the mechanical behaviour of a clay. Int. J. Numer. Anal. Methods Geomech. 28 (3), 209 228.

The traditional approach employed for describing from a phenomenological per-
spective the volumetric behaviour of fine-grained soils subjected to temperature varia-
tions is in terms of the stress history, which can be assessed in terms of the OCR. This
approach is illustrated in Fig. 5.3, in which the influence of the OCR, on the ther-
mally induced volumetric strain, ε v , of different soils tested by Plum and Esrig (1969),
Demars and Charles (1982), Kuntiwattanakul (1991), Baldi et al. (1991) and
Cekerevac and Laloui (2004) is shown. The thermal contraction of slightly OC to NC
soils upon heating increases for a decrease in OCR, while the thermal expansion of
OC soils upon heating increases for an increase in OCR (Cekerevac and Laloui,
2004).
A further interpretation of the volumetric behaviour of fine-grained soils resorting
to the stress history can be carried out with reference to the relationship between the
‘apparent’ preconsolidation stress and the temperature. The word ‘apparent’ is used to
remark that the mechanical load that is actually applied to the material does not
change, so that the maximum load historically applied is always the same (Di Donna
and Laloui, 2013). Extensive experimental evidence shows that the apparent preconso-
lidation pressure decreases at constant void ratio with increasing temperature (see, e.g.
Eriksson, 1989; Tidfors and Sällfors, 1989; Boudali et al., 1994; Moritz, 1995; Laloui
and Cekerevac, 2003). According to Boudali et al. (1994), this phenomenon is inde-
pendent of viscous effects. Results that corroborate the variation of apparent preconso-
lidation pressure with temperature are summarised in Fig. 5.4, drawing from the
investigations of Eriksson (1989), Tidfors and Sällfors (1989), Boudali et al. (1994) and
Moritz (1995). Various analytical expressions have been formulated to capture the pre-
vious evidence (see, e.g. Hueckel and Baldi, 1990; Boudali et al., 1994; Moritz, 1995;