Abstract: To ensure the effective long-term operation of anchoring systems for large-scale water conservancy and hydropower projects, we conducted statistical analysis of anchoring systems monitoring data from six hydropower stations under the Three Gorges Group and clarified the time-history evolution law of anchor cable load and anchor bolt stress as well as the factors affecting these characteristic changes. Results demonstrate that the anchor cable loads and anchor bolt stresses of high slope and underground cavern are mainly within designed ranges, with significant changes occurring primarily during the construction period, gradually stabilizing after the completion of excavation and support. Anchor cable loads on slopes exhibit three distinct stages, rapid decline, followed by slow decline, and eventual stability or periodic change. Anchor cable loads in underground caverns exhibit similar characteristics, yet with more complex variation. Bolt stress demonstrates a significant negative correlation with temperature. Anchor cable load in underground cavern exhibits a diameter effect, with cavern size in direct proportion to the average cable load value and a more significant loss rate change range. Fully unloaded areas, such as intersection portals in the underground cavern group, blocks, and retained rock piers, display the largest anchor bolt stresses, and the loss rates in block section are generally higher than those in other engineering parts. Load loss rates of fractured anchor cables are relatively high. Rock mass quality negatively correlates with anchor cable load loss rates. Failure characteristics of anchor cable projects during construction include steel strand breaks, anchor cable breakage through anchor covers, and steel strand shrinkage. Long-term failures of anchor cable operation include anchor pier head corrosion and calcium carbonate precipitation.

Key words: water resources and hydropower engineering, anchoring system, anchor cable load, bolt stress, evolutionary features, influence factors