Stability analysis of geotextile-reinforced unsaturated slope under drawdown conditions

• Dual-role geotextiles enhance slope stability under drawdown conditions. • Drainage-enabled geotextile achieves a 24% higher FOS than non-drainage type. • Combined primary and secondary geotextiles prevent shallow failure surfaces. • Permeable geotextiles accelerate pore pressure dissipation, lowering phreatic line. • Sustainable geotextile solutions reduce slope failure risks amid climate uncertainty. Global warming has intensified erratic climatic events, such as increased rainfall, flooding, and rapid drawdown, often triggering slope failures. This study investigates the influence of primary and secondary geotextile reinforcements on the stability of unsaturated soil slopes under rapid and transient drawdown conditions. Seepage forces were analyzed using the effective stress B-bar method and finite element method (FEM), while slope stability was assessed using the limit equilibrium method (LEM) integrated with the unsaturated soil mechanics concepts. Results revealed that the combined use of the primary and secondary geotextile reinforcements significantly improves slope stability by mitigating shear stresses near the slope face, reducing shallow failure surfaces, and ensuring global stability. Drainage-enabled geotextiles were particularly effective, facilitating rapid dissipation of pore pressure, lowering the phreatic surface, and achieving a higher factor of safety (1.790) compared to non-drainage geotextiles (1.439). These findings highlight the dual role of geotextiles in providing reinforcement and drainage, confirming their potential as a sustainable solution for mitigating slope failures during rapid drawdown in the face of climate uncertainty.