Macro-micro investigation of catastrophic damage and durability degradation in anchorage structures under corrosion

To thoroughly investigate the damage evolution of anchorage structures under corrosive conditions, laboratory simulations of corrosive environments were conducted, including corrosion tests and mechanical performance evaluations on anchorage systems. Based on experimental results, relationships were analyzed between factors (prestress, pH value, and anti-corrosion methods) and the corrosion degree, macro-micro characteristics, and mechanical performance degradation patterns of specimens. The results of the test indicated that: (1) the corrosion of coal bodies increases over time, and lower pH environments correspond to lower uniaxial compressive strength of coal bodies; (2) the corrosion of the rock bolts increases over time, the maximum mechanical performance in the rock bolts loss occurs at pH ​= ​5.0, and higher prestress of the rock bolts leads to greater mechanical degradation, and galvanization effectively reduces corrosion in functional rock bolts; (3) the degree of corrosion in the anchorage bodies has increases over time, pH ​= ​5.0 causes maximum bond strength of the anchorage bodies property loss and increases the prestress in the anchorage bodies exacerbates bond strength degradation, and double anti-protected anchorage bodies show less bond strength loss than ordinary ones. The corrosion-induced structural deterioration of underground anchorage systems leads to significant mechanical performance degradation, potentially causing support failure, surrounding rock instability, and roof fall disasters. Greater attention therefore needs to be paid to this area.