Creep damage characteristics and slip law of weak-layer mudstone in an open mining slope

To study the creep damage mechanism and slip characteristics of the weak layers on the south slope of the Fushun West Open-Pit Mine, the full stress-strain and creep curves of the weak-layer mudstone under different confining pressures were obtained via laboratory experiments. The relationship between the softening modulus and the viscoplastic parameters of the mudstone with confining pressure was obtained via a fitting method. A nonlinear creep damage model of the weak-layer mudstone was established based on the Mohr-Coulomb strain-softening and Burgers models. A numerical calculation program was developed using the discrete element method to verify the reliability of the model. On the basis of the creep damage numerical model, the large deformation and the slip law of the weak-layer slope of the West Open-Pit Mine were studied. The results indicate that both the softening modulus and the viscoplastic creep parameters of weak-layer mudstone have a nonlinear exponential relationship with the confining pressure. The creep damage model can characterize both the pre-peak creep damage characteristics and the post-peak strength attenuation characteristics of the mudstone. The numerical results are in good agreement with the laboratory experimental data. The creep slip characteristics of the weak-layer slope of the West Open-Pit Mine analyzed based on the creep damage model are basically consistent with the actual slip, and the displacement calculation results are also close to the field monitoring data. The research results provide scientific basis for the prevention and control of landslide in West Open-Pit Mine.