A geotechnical approach to compare different slope stabilization techniques for failed slope in the Darjeeling hills, India

Landslides are one of the extensive and destructive natural hazards in the mountainous areas and can cause loss of life and infrastructure. Slope stabilization methods can be adopted to minimize the losses due to landslides. The aim of this study is to investigate the failed slope due to landslides and suggest the site-specific ground improvement solutions capable to increase the factor of safety and reduce the displacement. In this study, a slope on a National Highway connecting the ridge to the foot hills in the Darjeeling Himalayas India is selected as the study site due to occurrence of landslides. The study site is investigated and the slope stability analyses are carried out by two-dimensional finite-element analyses. Comparisons of four different slope stabilization methods are introduced with the understanding of behavior of support system. Different slope stabilization methods along with or without ground improvement techniques like benching, retaining wall, soil nails, micropiles, shotcrete, and geogrid are attempted. Factors of safety along with displacements are computed for all the different combinations with and without rainfall effect. Parametric study is also carried out to investigate the optimum configuration for the suggested slope stabilization technique. After comparing and assessing different ground improvement techniques, the results suggest that the combination of soil nails with shotcrete and geogrid on stepped cut slope face along with retaining walls supported by micropiles and soil nails at the bottom has performed well and satisfies the stability conditions for the selected slope. The suggested combination provides an optimal solution and remediation option for stabilizing the slope.