Creep properties and acoustic emission characteristics of soft-hard interbedded rock masses with different initial damage

Abstract

To investigate the long-term stability of soft-hard interbedded rock masses with initial damage induced by earthquakes and periodic drying and wetting, this study prepared samples with different initial damage through cyclic loading and unloading (CLU) experiments followed by cyclic drying and wetting (CDW) experiments, and finally conducted creep experiments. The study analyzed the effects of initial damage on creep mechanical behavior, crack evolution, and explored failure precursor information, revealing the damage failure mechanisms. The results show that the structural characteristics of the rock mass control its macroscopic failure mode. Initial damage promotes microcrack development, influences the fracture mode, and increases the proportion of high-frequency (200–280 kHz) acoustic emission events during creep. Meanwhile, initial damage exacerbates creep characteristics, increasing the creep rate, shortening total creep failure time, and reducing long-term strength. The damage failure is attributed to: the generation of internal cracks and pores in the rock caused by CLU; mineral hydrolysis and expansion-contraction due to CDW, resulting in weakened intergranular cementation; and full development of cracks and pores under creep stress. Additionally, the deformation difference coefficient and the coefficient of variation of RA/AF values can serve as precursor indicators for creep failure.

Keywords

creep properties / initial damage / soft-hard interbedded rock mass / acoustic emission / failure precursors / damage failure mechanism

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