Loess slopes are susceptible to rainfall due to the water sensitivity and collapsibility of loess. The aim of this study is to investigate the instability mode, failure mechanism and control effect of homogeneous loess landslide under rainfall by using physical model experiments and numerical simulation, combined with a new anchor cable with negative Poisson ratio (NPR) structural effect. The findings indicated that the loess slope's failure under heavy rainfall is characterized by progressive shallow flow-slip instability, encompassing three deformation modes and seven deformation characteristics. Water content, pore water pressure and earth pressure monitoring instruments capture the dynamic response of internal hydromechanical properties within the loess slope during intermittent heavy rainfall, clarifying its failure mechanism. Rainfall leads to soil softening and a reduction in strength. The effective stress of shallow soil and potential sliding surfaces diminishes due to decreased matrix suction and increased pore water pressure. The accumulation of internal and external deformation eventually leads to the disintegration of the shallow layer of the loess slope. Numerical simulation results indicated that rainfall significantly affects the shallow layer of the loess slope, with greater subsidence deformation observed at the slope's crest. Indoor and field monitoring findings revealed the pattern of Newton force on the loess slope in response to rainfall and demonstrated its seasonal dynamics, characterized by an increase during the thaw-collapse and flood periods, followed by a decrease in the frost-heave period.

Geological disasters occur frequently in the Loess Plateau due to the joint fissures in the strata and human engineering activities. Against this background, the deformation and failure mode of the loess slope with the structural plane under excavation and the extension mechanism of the structural plane are analyzed and summarized. The results showed that: (1) Through the physical model test, the deformation failure mode of the slope is summarized as the tension-splitting, pressure-sliding shallow failure. The collapse failure process is defined as four stages: Compression deformation, creep deformation, slip deformation and slip failure. (2) Slope displacement is concentrated beneath the pressure plate, increasing linearly under load conditions but becoming nonlinear after excavation conditions. As the excavation angle rises, the displacement range along the structural plane gradually extends toward the slope toe. The displacement time-history curve shows three stages: The lifting load stage, the cumulating deformation stage, and the sliding failure stage. (3) The stress redistribution caused by excavation, prompting deformation and potential failure. As internal stress nears the soil strength limit, human-induced disturbances exacerbate stress redistribution, leading to accumulated stress. Finally released through deformation and cracking. Each excavation condition modifies the original loading transfer path, driving stress redistribution at the slope surface and at the structural plane's tip. (4) The sudden drop in stress level and sudden rise of accumulated settlement are the characteristics of slope sliding failure. The position of the structural plane determines the position of the slope sliding surface. (5) According to the external characterization of the structural plane, the extension process of the structural plane can be defined as four stages: Initiation of crack extension, classification deformation, sub extension and compression sealing. According to the extension of the structural plane, the spreading cracks of the slope's internal structural plane are defined as two types: Fractured cracks and shear cracks.