Slope stability is one of the fundamental issues in geotechnical engineering, holding particular significance in civil, mining, an‎d road construction projects. Slope instability can lead to irreparable financial an‎d human losses. Therefore, precise analysis of slope behavior an‎d prediction of failure time are essential as key criteria in the safe design of geotechnical structures. In this study, numerical modeling using Plaxis software was employed to analyze the stability of soil an‎d rock slopes an‎d predict their failure time. Initially, theoretical foundations an‎d previous studies were reviewed to introduce the creep behavior of materials an‎d conventional failure prediction approaches. Subsequently, a baseline model was developed in the Plaxis environment an‎d validated against available field data. Among various constitutive models, the Soft soil creep model demonstrated superior accuracy in reproducing real-world data due to its ability to simulate time-dependent behavior of soft soils. Following validation, time-dependent analyses were conducted, an‎d displacement-time an‎d velocity-time diagrams were extracted at critical points. Using analytical methods based on inverse velocity-time plots, the approximate failure time was determined. A parametric study was then carried out to investigate the influence of key parameters on failure time an‎d slope stability. Results indicated that the internal friction angle (φ) has the greatest impact on increasing failure time. An increase in cohesion (c) also improved stability, albeit to a lesser extent than the friction angle. Moreover, increasing the creep coefficient (Cα) significantly reduced failure time. Additionally, rising groundwater levels were found to decrease the factor of safety an‎d accelerate failure. Overall, the findings of this study demonstrate that using time-dependent constitutive models such as Soft soil creep within Plaxis constitutes a powerful tool for long-term slope stability analysis an‎d failure time prediction. These findings can be applied to safer slope design, risk management, an‎d the development of monitoring an‎d control methods in geotechnical projects. The main innovation of this research lies in its focus on time-dependent stability analysis combined with parametric investigation, enabling identification of sensitive parameters an‎d quantification of their individual contributions to deformation progression an‎d failure occurrence. Accordingly, the results can assist geotechnical engineers in selec‎ting appropriate stabilization methods, designing efficient drainage systems, an‎d defining early-warning indicators. Furthermore, the findings lay the groundwork for developing practical guidelines for risk management in large-scale civil an‎d mining projects. Additionally, integrating numerical modeling with field monitoring data an‎d modern remote sensing technologies such as InSAR in the future can enhance prediction accuracy an‎d enable timely interventions to prevent accidents. In summary, this research, by providing a comprehensive framework for time-dependent stability analysis, can serve as a scientific an‎d practical foundation for the safe an‎d sustainable design of geotechnical projects.

محمدرضا خان محمدي , محمود بهنيا

محمدعلي روشن ضمير , امين ازهري