Mechanical properties investigation and damage constitutive models of red sandstone subjected to freeze-thaw cycles

The mechanical properties of rock can be degraded by long-term freeze-thaw cycles (FTCs). However, the damage constitutive model of rock subjected to FTCs for simulating the whole deformation process is still lacking. In this paper, uniaxial compression tests for red sandstones were carried out under different numbers of FTCs, and the relationships between the mechanical parameters and the number of FTCs were established. The method for determining the fully compacted point was firstly proposed, and a random exponential function of strain difference during compaction stage and linear elastic stage was constructed. Then, a novel damage constitutive model simulating the whole deformation process of rock subjected to FTCs was proposed. The proposed model and three existing models were compared with experimental data, and their model performances were evaluated. The proposed model with the consideration of the initial compaction stage was found to be more consistent with the experimental data, while the two existing models can be improved to be more versatile. The finding enriches the research of rock in constitutive modelling in cold regions.