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.
