Mechanistic insights into corrosion-induced strength deterioration grouting anchor cable in deep coal mines: an integrated model for enhanced prediction

The corrosive environments of deep coal mines in saline-alkali regions accelerates the anchor cable corrosion and induces the strength degradation in grouting anchor cable. An accurate corrosion prediction model is essential to evaluate the long-term stability of roadway support systems under such harsh conditions. To overcome the limitation of traditional diffusion-only models, this study developed a time-dependent predictive model integrating chloride ion (Cl-) diffusion and temperature effects to predict the corrosion thickness, corrosion-driven strength loss, energy absorption decay, and seismic resistance attenuation. Field data from Zhaolou Coal Mine revealed highly corrosive groundwater, accelerating anchor cable corrosion. The proposed model combines Fick’s diffusion law with electrochemical kinetics, incorporating temperature-dependent Cl- diffusion coefficients and corrosion current density. Numerical simulations COMSOL tracked corrosion progression over 1500 days under varying Cl- concentrations 200-350 mg/L. The simulation results show that higher Cl- concentrations increase corrosion current density, reducing effective cable cross-sections. At Cl- concentration of 302 mg/L after 1500 day- service, the corrosion thickness of the anchor cable was predicted to increase to 1.24 mm while anchor strength and energy absorption attenuation was expected to decrease by 35.01 KN and 0.7 KJ, respectively. The maximum seismic resistance magnitude reduced from 2.075 to 1.691. Field validation confirmed the model accuracy with prediction error only 3%-12%. The study translates corrosion mechanisms into a practical model for predicting long-term anchor cable performance in corrosive deep-mining environments, enabling early risk detection and optimizing anchor cable replacement cycles to prevent roof-collapse disasters.