Multi-scale analysis of mudstone freeze–thaw damage mechanism

Freeze–thaw (F–T) cycle-induced mechanical deterioration of mudstone layers in slopes is a critical challenge for the stability of slopes located in cold-regions open pit mines. Indoor F–T cycle experiments were initially conducted on mudstone samples obtained from the North Slope of the Fushun West Open Pit Mine. Furthermore, a constitutive model for F–T damage was developed using Weibull distribution fracture mechanics. After that, a Voronoi tessellation-generating program and a program for inserting cohesive elements between tessellations were developed to establish a multi-scale thermo-mechanical coupling analysis platform in ABAQUS software. Finally, the damage constitutive model was integrated into Voronoi tessellations to simulate the mineral matrix. The research findings revealed that F–T cycles induced substantial damage to mudstone. Moreover, with an increase in the number of F–T cycles, the damage factors associated with each parameter significantly increased. Multi-scale analysis results indicated that for higher numbers of F–T cycles, samples may not necessarily develop cracks along initial flaws, but could instead be cracked in the matrix phase due to F–T damage. The F–T cycle exhibited a destructive effect on the stability of slopes in cold regions. Therefore, it is essential to consider the effect of F–T damage in the stability analysis and protection design of open-pit mine slopes in cold regions.