Time-Dependent Reliability Analysis of Anchored Soil Slopes Considering Anchor Prestress Attenuation

Abstract The long-term stability of prestressed anchored soil slopes (ASSs) is significantly affected by the time-dependent attenuation of anchor prestress. However, systematic research on the prestress attenuation law of anchors and its influence on the time-dependent reliability of ASSs remains unexplored. This study proposes a time-dependent reliability analysis method for ASSs that accounts for anchor prestress attenuation. First, based on the assumption of axial deformation compatibility between the anchor and the surrounding soil, a prestress attenuation model coupled with soil consolidation-creep behavior is established, and an analytical solution for the time-dependent prestress attenuation is derived, with the unknown model parameters calibrated using FLAC3D numerical simulations. Subsequently, based on the obtained time-dependent prestress attenuation law, the strength reduction method is employed to analyze the time-dependent variation of the slope stability coefficient. Finally, considering the uncertainty of soil parameters, a response surface surrogate model is developed and integrated with Monte Carlo simulation to evaluate the time-dependent reliability of ASSs. The results show that both the prestress and the slope reliability decrease over time, and their degradation rates gradually diminish with time. Furthermore, increasing the anchor diameter and the bearing-plate area can mitigate this degradation trend, with the anchor diameter exhibiting a more significant effect. The proposed method provides a theoretical basis for the nondestructive safety evaluation of existing ASSs, assisting engineers in inspecting ASSs under the condition of lacking long-term monitoring data.