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244 Analysis and Design of Energy Geostructures

Figure 5.31 Effect of temperature on the secondary compression index of fine-grained soils. Data
from Di Donna, A., Laloui, L., 2015. Response of soil subjected to thermal cyclic loading: experimental
and constitutive study. Eng. Geol. 190 (1), 65 76.

normalised with respect to the value of the considered parameter measured at 20 C,

kðT 5 T 0 Þ, for two clays tested by Towhata et al. (1993). As the hydraulic conductivity
governs the primary consolidation, the drainage conditions and the significance of poten-
tial groundwater flow, its variation with temperature may be considered in the analysis
and design of energy geostructures.
Concerning the secondary compression index, C α (alternatively defined as the sec-
ondary compression ratio, C αε ), experimental data support an increase of this parame-
ter with temperature (Mitchell and Campanella, 1963; Meschyan and Galstyan, 1972;
Eriksson, 1989), while others support an insensitivity with temperature (through the
consideration of the coefficient C A 5 C α =C c )(Laloui et al., 2008; Marques et al.,
2004; Boudali et al., 1994; Towhata et al., 1993). Further results that corroborate the
last observation, which may be accounted for the analysis of energy geostructures, are
reported in Fig. 5.31 with reference to the work of Di Donna and Laloui (2015).

5.7 Characterisation of soil structure interfaces
5.7.1 General
Soil structure interfaces represent a critical setting for the transfer of loads from struc-
tural elements to the ground. Soil structure interfaces are typically defined as the thin