Page 291 - Analysis and Design of Energy Geostructures

266 Analysis and Design of Energy Geostructures

y. The cyclic mechanical degradation of the interface shear stress induced by the
thermoelastic expansion and contraction of the structural material at the inter-
face with the soil should be considered in the analysis and design of energy
geostructures, in all cases and irrespective of the magnitude of the applied
loads:
i. True
ii. False

Solutions
a. Gravity forces dominate interactions between phases in fine-grained
soils:
i. True
ii. False
b. Coarse-grained soils are generally more sensitive to temperature varia-
tions than fine-grained soils:
i. True
ii. False
c. The overconsolidation ratio, OCR [ ], is defined as the ratio between
0
the preconsolidation stress, σ ½PaŠ, and the overburden vertical effective
p
0
stress, σ ½PaŠ. soils are considered NC if the 1 # OCR # 2, while they are
z
considered OC if OCR . 2.
d. Under NC conditions, fine-grained soils contract when heated and a sig-
nificant part of this deformation is not recovered upon cooling. Under
highly OC conditions, fine-grained soils expand when heated and this
deformation is entirely recovered upon cooling. Under slightly OC con-
ditions, fine-grained soils show an initial expansion and subsequent con-
traction when heated, followed by a tendency towards contraction upon
cooling.
e. The apparent preconsolidation pressure decreases at constant void ratio
with increasing temperature:
i. True
ii. False
f. Fine-grained soils under NC conditions expand upon heating:
i. True
ii. False
g. The phenomenon of plastic accommodation involves a decrease of plas-
tic volumetric strain over subsequent heating cooling cycles applied to
NC soils.