Study of micro-mesoscopic creep damage on mudstone based on stress corrosion model

To study the creep minor damage evolution process and creep damage mechanism of mudstone, this paper establishes a numerical model of a two-media triple cementation particle flow procedure of mudstone, reproduces the tender damage destruction process of mudstone under creep based on a parallel bonded stress corrosion model, and explores the macroscopic creep characteristics and minor damage mechanism of mudstone specimens under different stress levels and surrounding pressure conditions. The results show that the intrinsic driving force for creep damage in mudstone is the micro-tensile force generated between non-homogeneous particles of mudstone, and the inter-particle cementation is continuously damaged and deteriorated with increasing time; the stable creep rate of mudstone specimens increases with increasing stress level and decreases with increasing surrounding pressure; high-stress levels diffuse microscopic damage in mudstone by increasing the magnitude of inter-particle microtension and the number of particles generating microtension, manifesting as multiple extensions of microcracks; the enclosing pressure dramatically reduces the creep characteristics by limiting the development of inter-particle micro-tensile forces; the microcrack distribution is more uniform and dispersed under the enclosing pressure conditions. The amount of mutual slip between particles increases.