Corrosion Investigation of Rock Anchors Served over 10 Years in Underground Powerhouse of a Hydropower Station

With the wide application of prestressed anchors in high slopes, underground structures, and bridge projects, the corrosion problems of the anchor structure during the long-term service have demanded more attention. Because of the environmental impact and structural characteristics, anchor cable corrosion is almost inevitable. To obtain the corrosion status of the anchors that have served over 10 years in the underground chambers of a power station, a field investigation was performed. The environment aggressivity was evaluated, and the anchor corrosion was inspected during the investigation. The results show that the effect of groundwater and stray current on anchor corrosion is slight. The main cause of the severe corrosion of the anchor heads is the high temperature and humidity in the chamber. To better evaluate the corrosion tendency and corrosion degree of the anchor head, a corrosion rating method was proposed based on the principles of existing investigation methods and the actual corrosion situation of anchors observed on-site. It was proved that the rating method can effectively reflect the corrosion characteristics and determine the areas prone to corrosion. This field investigation suggests that a regularly scheduled investigation is of great significance and meaning for accurately obtaining the corrosion status, assessing the failure risk, and issuing an early warning.