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Thermohydromechanical behaviour of soils and soil structure interfaces 225

Figure 5.12 Volumetric behaviour of coarse-grained soils subjected to temperature variations.
Redrawn after Ng, C.W.W., Wang, S.H., Zhou, C., 2016. Volume change behaviour of saturated sand
under thermal cycles. Géotech. Lett. 6 (2), 124 131.

Results are depicted in terms of the relationship between thermally induced volumet-
ric strain, ε v , and applied temperature variation, ΔT. The volumetric strain purely due
to the thermal expansion of the particles characterising the tested coarse-grained soil,
that is Toyoura sand, is also plotted for reference [calculated by Ng et al. (2016) with
reference to the work of Agar (1984)]. The considered values of relative density refer
to the condition prior to thermal loading (not to the initial conditions).
Very dense coarse-grained soils expand when heated. The amount of thermal
expansion is almost the same as that of the individual soil particles (Ng et al., 2016).
Thermally induced volumetric strains of up to 20.1% (for temperature variations of

up to approximately ΔT 5 30 C) can be observed.
In contrast, dense to loose coarse-grained soils show an initial contraction and a
subsequent expansion when heated. Thermally induced volumetric strains ranging
from 0.05% to 0.15% can characterise dense to loose coarse-grained soils upon heating

(for temperature variations of ΔT 5 12 C, e.g. from a temperature T 5 23 C 35 C).
A further heating of these materials leads to thermally induced volumetric strains of
up to 20.05% (for temperature variations of ΔT 5 15 C, from a temperature

T 5 35 C 50 C). For the same temperature variation, the observed thermal collapse
of dense to loose coarse-grained soils is approximately ten times smaller than that