Rock Mass Classification and Slope Stability Analysis of Road Cuts in Anambra State

Steep road cut slopes developed through the friable Nanka Sands and Ameki Formation in Anambra State, South East Nigeria, are prone to mass failure and erosional undercutting, posing recurring safety risks to road users and requiring engineering geological characterisation to guide remediation. This study performs rock mass classification and slope stability analysis along selected cut slopes on two road corridors in Anambra State. Field discontinuity surveys were conducted using the scan-line mapping method, recording spacing, orientation, persistence, roughness, weathering grade, and aperture of identified discontinuity sets in exposed rock faces. The Rock Mass Rating and Slope Mass Rating classification systems were applied to evaluate overall rock mass quality. Kinematic analysis using stereographic projection was performed to identify potential failure modes including planar sliding, wedge sliding, and toppling. Factor of safety calculations for critical failure planes were undertaken using the limit equilibrium method with appropriate shear strength parameters derived from tilt tests and literature values. Stabilisation measures appropriate for identified failure mechanisms, including rock bolting, drainage improvement, and vegetative cover, are recommended based on economic feasibility. Results are submitted to the Anambra State Ministry of Works and the Federal Roads Maintenance Agency. This study provides a practical framework for undergraduate slope stability assessment in Nigeria's erosion-prone sedimentary terrain. Keywords: slope stability, rock mass classification, road cuts, Anambra State, kinematic analysis.