Time-variant reliability of anchored slopes considering coupled corrosion and seismic effects

This study addresses the long-term performance degradation of slopes reinforced with early-stage tension-type prestressed anchors in seismic zones. It establishes a time-variant reliability analysis framework for anchored slopes that concurrently accounts for anchor corrosion and seismic action. Based on electrochemical corrosion theory, a predictive model for the uniform corrosion rate of the anchor tendon was developed, quantifying the influences of environmental temperature, relative humidity, and grout properties. Time-variant degradation models were established for the tensile yield resistance of the free segment and the bond resistance at the tendon-grout interface. Combining a case study of a rock slope with the First-Order Reliability Method (FORM), the failure probability at different service periods was calculated. The results show that: (1) A transition in the dominant failure control mechanism leads to accelerated decay of the anchoring force in the later service stage; (2) The combined effect of corrosion and seismic action induces a non-linear increase in the slope failure probability, with a significantly accelerated growth rate after 50 years; (3) Increasing the grout cover thickness to 50 mm can reduce the failure probability by 42%, while rises in temperature and humidity notably aggravate the degradation of reliability.