Investigation of the mechanical behavior and continuum damage model of sandstone after freezing-thawing cycle action under different immersion conditions

This study systematically investigated the influence of freezing-thawing (F-T) cycles on the physical and mechanical properties by using scanning electron microscope (SEM), acoustic emission (AE) equipment, and digital image correlation (DIC) techniques for the sandstone samples under different immersion condition. The SEM results showed that after 50 F-T cycles, the new cracks were created and the porosity was increased. The peak strength and elastic modulus decreased gradually as the F-T cycles increased, and the peak strain emerged an ascending trend. When the F-T cycles were from 10 to 50 under anhydrous immersion conditions, the high distinct AE counts distributed discretely after the initial crack closure stages, pre-peak stages, and post-peak stages. When the F-T cycles were from 0 to 50, high distinct AE counts distribute concentrated the pre-peak stages and post-peak stages. No AE counts discretely nearby crack closure stage and elastic deformation stage for the samples subjected to semi-immersion in water solution. The samples subjected to less F-T cycles action suddenly lose their bearing capacity and the failure mode was shear slipping. For the samples undergoing the more F-T cycles, the brittleness of the samples decreased and the ductility increased, the stress-strain curve exhibits a lower slope during the strain softening stage. A continuum damage model was proposed to quantitatively analyze and describe the damage evolution of the samples subjected to different F-T cycles under the different immersion conditions during uniaxial compression.

Automated summary

This study systematically investigated the influence of freezing-thawing (F-T) cycles on the physical and mechanical properties of sandstone samples under different immersion conditions. The results showed that F-T cycles led to the creation of new cracks and increased porosity. The peak strength and elastic modulus gradually decreased with increasing F-T cycles, while the peak strain showed an ascending trend. The distribution of distinct acoustic emission (AE) counts varied with the F-T cycles and immersion conditions. Samples with fewer F-T cycles suddenly lost their bearing capacity and exhibited shear slipping failure, while samples with more F-T cycles showed decreased brittleness and increased ductility. A continuum damage model was proposed to analyze and describe the damage evolution during uniaxial compression.