Abstract: On the basis of classical peridynamics, the nonlocal force density is re-derived using deformation equivalence. Combined with the theory of nonlocal differential operators, this approach reduces the calculation error at the boundary. A stress-strain solution model is constructed to address the limitations of traditional theories in stress analysis. Meanwhile, the strain energy density stiffness reduction theory is introduced to establish the correlation between the mechanical parameters of the medium at the crack and the residual strain energy. The proposed method is used to simulate the stress distribution in layered rock mass with prefabricated interval fractures. The results are compared with previous findings to verify its effectiveness and applicability. Furthermore, the evolution process of strip interval fractures in the middle weak layer of complete layered rock mass is studied. The results show that the ratio of crack spacing to thickness significantly affects the mechanical state of the layered rock mass. As the ratio increases, the stress between existing cracks transitions from compressive to tensile stress. The equidistant fracture phenomenon in the weak layer includes processes such as microcrack propagation, the formation of interval fractures, and gradual crack saturation. Continuous loading causes damage between the weak layer and the base layer, as well as overall failure of the rock formation. This method effectively describes the interval fracture process of layered rock mass and demonstrates good application prospects.

Key words: layered rock mass, peridynamics, crack propagation, interval fracture