A study of uniaxial compressive strength degradation model of soil-rock mixtures under freeze-thaw deterioration based on equivalent model characteristics of conductive paths

To further enhance our understanding of the microstructure of SRM and its intrinsic relationship with macroscopic properties, this paper conducted indoor freeze-thaw cycles, EIS and uniaxial compression tests. The results indicated that the number of freeze-thaw cycles has a significant exponential relationship with RCPP, RCPP1 and CDSRP. As the number of cycles increased, RCPP and RCPP1 exhibited a decreasing trend, whereas CDSRP showed an increasing pattern. The freeze-thaw cycles led to the expansion and connection of different pores, resulting in the widening or multiplication of channels in CPP, leading to a decrease in both RCPP and RCPP1. However, in DSRPP, the liquid-filled pores underwent radial expansion during freeze-thaw cycles, connecting with gas-filled pores around them. This transition led the conductive path to transform into CPP, reducing the accumulated thickness of non-continuous points. Consequently, CDSRP exhibited an increasing trend. Furthermore, the increase in porosity weakened the deformation resistance, increasing the compaction stage of pores and the peak strain, while reducing its peak strength and secant modulus. The peak strength, strain and secant modulus also exhibited significant exponential relationships with different cycles. There was a good exponential correlation between ∆RCPP of CPP and the uniaxial strength, and the freeze-thaw deterioration model constructed with it as an influence factor could better assess its peak mechanical strength after freezing and thawing. •An electrochemical circuit model for different conductive paths was proposed.•The microstructure was characterized by EIS parameters of the equivalent model.•The influence and mechanism of freeze-thaw cycles on EIS parameters were analyzed.•A degradation model for the uniaxial strength was established with EIS parameters.