A hybrid cohesive phase-field numerical method for the stability analysis of rock slopes with discontinuities

The stability of rock slope is predominantly controlled by the fracture behavior of structural discontinuities, such as joints, faults, and bedding planes. Landslides of rock slopes usually involve concurrent tensile and shear fracture evolution within a continuous–discontinuous medium, occurring along the discontinuities and within rock mass, which poses challenges for accurately and efficiently predicting landslides and determining the factor of safety (FS). To address this issue, a hybrid cohesive phase-field numerical method based on the gravity increase method is developed. This approach integrates the cohesive joint model and the unified fracture phase-field method, effectively bridging the scale gap between discontinuity and rock mass. Numerical simulations indicate that the developed hybrid method is validated through physical tests on both discontinuities and rock mass, and achieves computational efficiency comparable to continuum methods. It is worth noting that the critical energy release rate has a more significant effect on the stability of rock slopes than the shear strength. Furthermore, the developed hybrid method accurately captures sliding surfaces and highlights the role of rock bridges in resisting landslides, enabling reliable predictions of FS of rock slopes with persistent discontinuities and non-persistent discontinuities. This study lays a foundation for the hybrid cohesive phase-field numerical method, and provides novel insights into the landslide mechanisms of rock slopes with discontinuities.