Abstract: The problem of surface slope instability induced by underground mining in the Yellow River Basin occurs frequently. Among the controlling factors, cohesive slip zone soils serve as one of the dominant factors controlling slope deformation. However, their mechanical response mechanisms under dynamically evolving mining-induced stress fields remain unclear. To investigate the mechanical behavior and failure mechanisms of shallow clayey mudstone under different stress paths, this study, based on the stress characteristics of overburden strata in goaf, designed four typical stress paths, including loading, constant axial stress with decreasing confining pressure, increasing axial stress with decreasing confining pressure, and proportional unloading of axial and confining pressures. Triaxial shear tests under multi-stage confining pressure conditions were conducted to systematically analyze the stress-strain relationships, shear strength characteristics, and failure mode evolution of clayey mudstone. In addition, X-ray diffraction and scanning electron microscopy techniques were employed to analyze the correlation between the microstructural characteristics of clay minerals and their macroscopic mechanical behavior from a microscale perspective. The results show that expansive clay minerals, such as kaolinite, can enhance the shear strength and residual strength of specimens under certain conditions. However, unloading paths exert a deteriorative effect on the shear strength parameters of the rock mass, as evidenced by the reduction in internal friction angle with unloading, and the positive correlation between cohesion and axial stress, indicating the evolution of self-stabilization capacity of weak interlayers during stress adjustment. The failure mode of the rock mass gradually shifts from shear failure under loading conditions to combined shear-tensile failure under unloading. The contact mode between particles changes from face-to-face to edge-to-edge and edge-to-corner, and the structural loosening trend becomes more pronounced, serving as a key microscale indicator of strength degradation. With increasing confining pressure, the rock mass exhibits a transition from brittle fracture to soil-like plastic slip, and the deformation mechanism shifts from dilation-dominated to contraction-dominated, reflecting a significant structural compaction effect which further demonstrate the synergistic regulatory role of confining pressure and clay mineral structure in stress redistribution during unloading. The intrinsic mechanisms governing the strength evolution and deformation-failure behavior of clayey mudstone under mining disturbance conditions, and provides a theoretical basis for the investigation of slope instability mechanisms and disaster prevention in goaf.