Abstract: During construction of anchorages for a high rock slope, whether the anchorage force can be maintained is the key to the slope anchorage engineering, and thus it is essential to understand time-dependent variation mechanisms of the anchoring force. Firstly, we discussed the high slope anchorage engineering projects which had significant sustained loss of anchoring prestress, analyzed the occurrence mechanism of such rapid variation of the anchoring prestress, and found that it is inevitable to consider the effect of high slope strong unloading on the initial anchoring prestress loss process during the calculation. Then, based on an improved visco-elastoplastic model, a new model was established by introducing conversion time K and a prestressed anchor cable in parallel. Finally, through the anchored cable’s prestress monitoring data of LE1915 drainage hole and L2J connect hole 0 + 126 m on the left bank of Jinping I hydropower station, the newly developed model is verified to be suitable to be applied in high slope anchoring engineering, and also confirm its accuracy and broad application by comparing with the original model. Not only the newly developed model provides theoretical guidance and technical means for the control and compensation of anchor cable’s anchorage force, but also has an important significance to the long-term safe operation and early warning of high slope anchoring project.

Key words: anchoring loss, unloading effect, secular distortion, coupling effect