Time-dependent system reliability analysis of anchor-reinforced slopes based on surrogate models

This study proposes a time-variant reliability calculation method for anchor-reinforced slope systems (ARSS) based on a surrogate model. By incorporating composite failure modes, the variability of geotechnical materials, and the effects of corrosion as uncertainty factors, the proposed method overcomes the limitations of traditional system reliability analysis approaches. The probability of system failure is defined as the sum of the product of the combined probabilities of local anchor failures and the conditional probabilities of slope failure under corresponding conditions. The time-variant system reliability of the anchor-reinforced capacity, which degrades over time due to corrosion effects, is also calculated. The results indicate that ARSS possesses a certain level of redundancy. However, owing to the stress redistribution effect, local anchor failures significantly increase the probability that the remaining anchors and the slope fail. The failure of adjacent anchors and those in the middle to lower portions of the slope has a more significant impact. While the probability of system failure is dominated primarily by non-anchor failure events, neglecting local anchor failures can lead to nonconservative results. Anchors initially exhibit strong corrosion resistance. However, over time, the corrosion effect significantly reduces their load-bearing capacity, resulting in a nearly fourfold increase in the probability of slope failure. This study highlights the importance of accounting for local anchor failures, geotechnical material variability, and corrosion effects in long-term reliability assessments of ARSS. Such considerations contribute to enhancing the safety and sustainability of geotechnical engineering practices.