Damage evolution mechanism and constitutive model of freeze- thaw yellow sandstone in acidic environment

• Published in: Cold regions science and technology 2018-11, Vol.155, p.174-183
• Main Authors: Qu, Dengxing, Li, Dengke, Li, Xinping, LUO, Yi, Xu, Kun
• Format: Article
• Language: English
• Subjects: Acidic environment; Constitutive model; Damage mechanism; Freeze-thaw of rock; Statistical strength
• ISSN: 0165-232X; 1872-7441
• DOI: 10.1016/j.coldregions.2018.07.012

The study on the damage evolution mechanism of freeze-thaw of rock sample in acidic environment is of great theoretical and practical significance to the analysis and prevention of freeze-thaw disasters in cold area. Taking the yellow sandstone as the research object, the freeze-thaw cycle experiments, the NMR system experiments, the chemical composition analysis experiments and the uniaxial compression experiments under acidic environments with different pH are carried out to analyze the physical and chemical characteristics of the yellow sandstone. The damage evolution equation and constitutive model of rock are studied based on statistical strength theory, Lemaitre strain equivalent assumption and damage mechanics. In this paper, the damage evolution equation of chemical freeze-thaw sandstone under load is established. The damage correction coefficient is introduced to modify the total damage of chemical freeze-thaw sandstone under load. The constitutive model is deduced and the model parameters are deduced by the combination of theoretical derivation and experiment. The results show that the rock damage is the result of the coupling of freeze-thaw cycles and acid erosion, and the freeze-thaw cycle is the main reason and acidic erosion is the secondary reason. The experimental parameters are brought into the constitutive model, and the reliability of the model under uniaxial stress is verified by comparing with the experimental curve. •On the one hand, it destroys the cementation structure and filling form of the sample and reduces the cohesion of the sample.•On the other hand, it increases the porosity of the yellow sandstone sample, and provides a channel for the flow of water in the sample, which is conducive to hydration and the freeze-thaw action of the acid solution to migrate inside the sample.•The effects of chemical erosion and freeze-thaw cycles are mutually promoting, which together cause the damage of yellow sandstone.•Based on the statistical strength theory and the damage mechanics principle, the damage evolution equation of chemical freeze-thaw sandstone under load is constructed.•Considering that the initial damage of the sample is obvious, the damage correction coefficient is introduced to modify the total damage of chemical freeze-thaw sandstone under load, and the constitutive model is deduced.•Compared the theoretical curve fitted by the constitutive model with the stress-strain curve obtained by the uniaxial compression experiment,