Catastrophe instability analysis of rock slopes with locked segments in open-pit mine due to freeze–thaw weathering

Slope rock mass containing locked segments is susceptible to freeze–thaw (F-T) weathering. It can result in slope instability and serious geological hazards. This paper conducts mechanical analysis and F-T tests to investigate the failure mechanism of the rock slope with locked segment subjected to F-T cycles. Using theoretical analysis, the cusp catastrophe prediction model for the failure of locked slope in cold regions is established, and the catastrophe eigenvalues are derived. The results show that the stability of the locked slope is related to the stiffness ratio considering the F-T treatment. As the F-T cycles increase, the damage variable increases in the form of a power function. In addition, a threshold of the number of F-T cycles exists for the degradation of locked slope caused by F-T weathering. By substituting the damage variables of the F-T cycles obtained from the experiment into the developed cusp catastrophe model, it can be deduced that the locked slope with 45° creep-slipping segment is the most sensitive to the effects of F-T degradation, and the most prone to landslides. Finally, the frost resistance is the strongest for the locked slope with 15° creep-slipping segment.