A hybrid approach to road-cut slope stability assessment: integrating empirical and numerical modelling

Landslides along Himalayan Road corridors pose persistent threats to infrastructure due to steep terrain, intensely jointed rock masses, and continuous road-widening activities. This study develops an integrated assessment framework to evaluate the stability of three representative road-cut slopes in Mussoorie, India, through combined field investigations, empirical rock mass classifications, and numerical analysis. Kinematic assessment and RMR–SMR–GSI classifications were performed to characterise failure mechanisms and rock mass conditions. Subsequently, stability was quantified using Limit Equilibrium Analysis (LEA) and Finite Element Analysis (FEA) with the Generalised Hoek–Brown and Barton–Bandis models. LEA results indicate marginal stability with FOS ≈ 1.0, whereas joint-controlled FEA shows a 20–40% decrease in strength reduction factor (SRF ≈ 0.60–0.80), consistent with observed field deformation patterns. The study demonstrates that integrating discontinuity stiffness significantly improves reliability over single-method approaches, providing a realistic basis for mechanism-specific stabilisation of Himalayan road-cut slopes.