Abstract Background Stability of rock slope along the Dumre-Besisahar-Chame road of Nepal Himalaya in Udipur, Nepal is important to protect the infrastructure and human lives in the area nearby. This part of slope has been experiencing landslides every year during monsoon causing huge damage. The selected area also falls under seismically active zone. Generally, rock slope stability depends on the properties of rock mass along with discontinuities. Factors like slope geometry, groundwater level, rainfall infiltration, and seismic forces, when combined with a highly weathered and open jointed rock mass, complicate slope behavior and make analysis difficult. This study aims to analyze open jointed rock slope failure mechanism under both static (with groundwater) and dynamic conditions through field investigations, laboratory testing and numerical modelling techniques using FEM and LEM. Results The slope rock mass quality varied from poor to fair, consisting of highly weathered quartzite with three major joint sets. Kinematic analysis indicated potential for planar, wedge, and toppling failures. Numerical modelling through Finite Element Method indicates that the factor of safety obtained in static analysis is more realistic in when incorporating joint interfaces (SRF = 1.03) than those obtained by continuum approaches (SRF = 1.3), showing slope stability was controlled by joints and fractures dominance. Under groundwater analysis through Limit Equilibrium Method, the safety factor drops to 0.47 confirmed instability due to increase of pore water pressure. Dynamic analysis followed FEM approaches at seismic loading, k h = 0.1 reduces SRF/FoS to 0.79, with catastrophic failure occurring beyond k h = 0.6. Stress redistribution within jointed and intensely fractured rock masses retards displacement for a while but later, accelerates progressive failure. Conclusion FEM static analysis shows the slope is critically stable in natural conditions. But moderate infiltration or low seismic acceleration can destabilize structurally controlled slope, where brittle fracture propagation and joint resonance along pre-existing geological structures further amplify slope instability. The deformation behavior of cataclinal slope is influenced by open joints, groundwater level and weathering.
Khadka et al. (Mon,) studied this question.