Thermal Gradient-Dependent Strain Behavior of Contacted Soil Specimens Subjected to Freeze-Thaw

摘要

Soil specimens were initially prepared by freezing with a thermal gradient (F-nonuni) and then thawing under uniform temperature (T-uni), then the strain behaviors of which using digital processing technique (DPT)-aided unconfined compression on contacted specimens were investigated. Although the specimen treated under F-nonuni - T-uni exbihted a strength over 1.8 times higher and a specimen scale-based (S-) lateral strain over 0.3 times smaller than that treated under freeze-thaw with uniform temperatures F-uni - T-uni, it exhibited a relatively greater local scale-based (L-) strain level under identical S-axial strain, and dominated the deformation process of the specimen assembly. The characteristic of L-strain relationship between top and bottom specimens under F-nonuni - T-uni and specimens under F-uni - T-uni approached identical when S-axial strain exceeded a threshold corresponding to the peak strength. Further, an asymmetric L-strain gradient at two sides of the fractured surface in specimens was observed, and it was more evident in specimens treated under F-nonuni - T-uni. These test data and observations obtained have been validated by detailed comparisons with previous studies, and contribute to build a constitutive model considering nonlocal variable and thus improve the settlement prediction precision of the thawed soils.