Soil-water characteristics and dynamic responses of compacted clay under different moisture and temperature paths

The microstructure, soil-water characteristics, accumulative plastic strain (ε_p) and resilient modulus (M_R) of a compacted Heilongjiang clay are compared. The specimens are imposed with three different moisture (wetting-drying, WD) and temperature (freeze-thaw, FT) paths (i.e., WD-FT, FT-WD and interlaced FTWD histories). The experimental results show that: (1) After moisture-temperature (M-T) actions, the structural pores develop while the textural ones shrink, which leads to reduction in the water retention capacity and increase in the desaturation rate. After M-T effects are stabilized, the microstructure and soil-water characteristics of the specimens with different M-T paths become similar. (2) Under at high moisture content (w), ε_p and M_R are more sensitive to moisture changes (including w and suction s). After FT cycles, ε_p becomes more sensitive while M_R becomes less sensitive to moisture changes. (3) After M-T effects, the M_R-s relationships are nonlinear while the M_R-w relationships are linear. The different M-T paths do not generate differences in ε_p and M_R when the M-T effects are stabilized. (4) A model based on the mechanics of unsaturated soils is used to rationally predict the variation of M_R with w and s for the specimens with different M-T paths.