A deterministic-stochastic DFN-DEM numerical modeling method with application in stability of fractured rock slope in BDa Hydropower Station

Long-term geological processes have resulted in the formation of complex fracture networks within rock masses, posing significant safety risks to hydropower projects. One of the challenges in hydraulic geotechnics is constructing a discrete fracture network (DFN) model that accurately represents real geological conditions based on exploration data and to identify potential deformation and failure modes in fractured rock slopes. This study proposes a deterministic-stochastic DFN-DEM modeling framework for fractured rock slopes, aiming to achieve a realistic numerical representation of geological conditions and to identify potential deformation and failure mechanisms. The approach integrates multi-source geological data, including deterministic discontinuities derived from tunnel mapping and geological profiles, and stochastic fractures generated from dominant joint sets identified via stereographic projection and probability density functions and the elastic-plastic constitutive model is applied to both rock blocks and discontinuity, enabling the simulation of mechanical responses and failure modes identification under the coupled influence of rock block and discontinuity. Taking the right bank dam shoulder slope of the BDa Hydropower Station as a case study, a three-dimensional DFN-DEM model was developed to simulate slope behavior under natural state and strength reduction conditions. Results indicate that the analysis paradigm captures the spatial distribution of deformation and identifies critical failure modes induced by the interaction of bedding planes, steep fractures, and toppling faults. Targeted reinforcement strategies were implemented and evaluated, demonstrating their effectiveness in controlling excavation-induced deformation. The proposed method offers a practical and robust framework for slope stability analysis failure modes identification and support optimization in fractured rock slope.