Page 263 - Analysis and Design of Energy Geostructures

238 Analysis and Design of Energy Geostructures

Table 5.2 Compressibility parameters of fine-grained soils at different temperatures.
T [ C] C r [ ] C c [ ] C s [ ]

Sample S3 20 0.01 0.04 0.02
40 0.01 0.05 0.02
60 0.01 0.04 0.01
Sample S4 20 0.01 0.04 0.01
40 0.01 0.04 0.02
60 0.01 0.05 0.02
Source: 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.

Figure 5.23 Effect of temperature on (A) the plastic rigidity index and (B) the elastic moduli of
fine-grained soils. Redrawn after Di Donna, A., Laloui, L., 2015. Response of soil subjected to thermal
cyclic loading: experimental and constitutive study. Eng. Geol. 190 (1), 65 76.

grained soils slightly decreases with temperature, while the bulk modulus slightly
increases with temperature. Supporting data are presented in Fig. 5.23. The shear
modulus at the reference mean effective stress is plotted for completeness (a Poisson’s
ratio of υ 5 0.25 is assumed for its calculation). While considering the variation of the
plastic rigidity index and bulk modulus of the soil with temperature in analyses of
energy geostructures may improve the accuracy of the obtained results, neglecting the
considered variation is considered acceptable for practical design purposes.
Along with the previous results, the soil Young’s modulus, E, appears to be insensi-
tive to temperature for coarse-grained soils (Recordon, 1993; Saix et al., 2000), while
characterised by potential variations for fine-grained soils. A slight increase of the
Young’s modulus with temperature is often considered for fine-grained soils under NC
conditions due to the influence of the thermal collapse (Di Donna and Laloui, 2015).