Base friction test on the deformation and failure mechanisms of interbedded anti-inclined slopes with different cross joint angles

Toppling failure in interbedded anti-inclined slopes represents a critical geological hazard, threatening infrastructure and resident safety. This study proposes a base friction test method for analyzing interbedded anti-inclined slope models with varying cross joint angles. Using a non-contact measurement method combining Digital Image Correlation and Particle Image Velocimetry, nine physical model tests revealed the influence of different cross joint angles on the deformation and failure mechanisms. The results demonstrate that the cross joint angle has a greater impact on deformation depth than the slope angle and exhibits a distinct threshold effect on overall stability. As the cross joint angle shifts from inward to outward inclination, the failure plane transitions from a large-scale, deep-seated failure with a rough, stepped morphology to a small-scale, shallow feature with a smooth, linear geometry. Deformation is predominantly horizontal, increasing with slope height and maximizing at the crest, where the − 0.02 strain contour effectively delineates the boundary between stable and deformed rock masses. Furthermore, increasing the slope and cross joint angles shifts the temporal evolution of deformation from a creep-accelerated to a sudden-acceleration mode. The formation of multiple failure planes is attributed to the obstruction of deep-seated failure surfaces, prompting internal crack development and coalescence in the overlying rock mass. These findings provide valuable insights for determining the failure plane morphology and assessing the stability of interbedded anti-inclined slopes under similar conditions.