At present, the widely used bishop stability analysis method does not consider the unsaturated effective stress, and the effective stress theory is unclear. To address these questions, this study initially explores a novel methodology for determining pore water pressure via the phreatic line. Subsequently, this study integrates the unified effective stress equation for both saturated and unsaturated soils, known for its clear physical significance, to propose an enhanced Bishop method(EBM) that accounts for effective stress in unsaturated soils. This EBM features a comprehensive theoretical framework, enabling direct stability analysis based on the phreatic line and demonstrating significant value for engineering applications. The reliability of the computational procedure of the EBM is validated through a saturated slope case study. Building upon this validation, the study further investigates the impact of incorporating unsaturated effective stress on slope stability. The results show that the deeper most dangerous sliding surface corresponds to an increase in the factor of safety(FOS) from 1.01% to 20.51% when considering the unsaturated effective stress. Overall, the integration of unsaturated effective stress exerts a positive influence on slope stability, underscoring the significance of this method for stability analysis and engineering design applications.

Narmada valley development authority proposed a scheme under, which 12.6 cumecs of water from the Hathani River (Tributary of Narmada) will be lifted to irrigate the command area. At the pumping station lies near Alirajpur, Madhya Pradesh, India. There was a need to protect the slope on both sides as water thrust from the upstream side may lead to failure of the slope. This paper presents the stability analysis of the slope using the GEO5 software. It was observed that the terrain at the site was a mixture of soil and rocks. The unit weight of the rock and backfill soil observed was 21 kN/m3 and 18 kN/m3. Using numerous techniques factor of safety was calculated for the particular slope, and it was observed that a suitable mitigation measure needs to be provided to prevent the failure of the slope. The inclusion of a gabion retaining wall increased the slope's safety factor significantly. The proposed mitigation measure was executed at the site, and the completed wall has not shown any damage till date. The analysis of the slope's stability results, as well as its construction of the gabion retaining wall recommended as a protective measure, are presented in this work.