Study on water-heat-deformation interaction process of soil-rock mixture exposed to freeze-thaw cycles
Freeze-thaw cycles significantly affect the water-heat-deformation interaction process of the soil-rock mixture.Therefore,this paper carried out the water-heat-deformation interaction and unconfined compressive strength test of the soil-rock mixture under unidirectional freeze-thaw cycles.Utilizing a unidirectional freeze-thaw cycling device,the soil-rock mixture sample with a rock content of 30%was prepared,and four freeze-thaw cycles were conducted according to the preset temperature change curve,with each cycle lasting 168 hours.Simultaneously,the mechanical properties of the sample both before and after freeze-thaw cycles were conducted,and the microstructural deterioration mechanism of the soil-rock mixture exposed to freeze-thaw cy-cles was investigated.The results show that the unidirectional freeze-thaw cycle has a significant effect on the temperature,moisture,and deformation variations in the treated sample.In the process of unidirectional freeze-thaw cycles,the melting rate of the soil-rock mixture is greater than the freezing rate.Meanwhile,the frost depth changes continuously during the freeze-thaw cycles and does not reach a stable state within the limited number of freeze-thaw cycles.The migration and redistribution of volumetric unfrozen water in soil samples oc-curred during the freeze-thaw processes.At the onset of the experiments,the volumetric unfrozen water content changes under the influence of temperature gradients,causing the liquid water to infiltrate downwards and lead-ing to the accumulation of unfrozen water at the middle location of the sample,while the volumetric unfrozen water content at the top does not undergo drastic changes.Additionally,the first freeze-thaw cycle has a signifi-cant influence on the vertical deformation of the soil-rock mixture,and the net deformation of the sample increas-es first and then tends to be stable with the freeze-thaw cycles raised.Furthermore,the pore structure and inter-nal arrangement of the soil-rock mixture are restructured during the unidirectional freeze-thaw cycles.The repeat-ed expansion and contraction of soils accelerate the destruction of the skeletal structure,gradually reducing the attraction among soil particles and leading to the formation of new fractures.The unconfined compressive strength test shows that the compressive strength and deformation modulus of the sample decrease by 45.31%and 60.92%,respectively.
soil-rock mixturefreeze-thaw cycletemperatureunfrozen water contentdeformation
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