Failure characteristics and mechanism of a layered phyllite landslide triggered by foot excavation in the Qinba Mountains of China

China’s Qinba Mountains Area presents a fragmented terrain, diverse geomorphology, and adverse geological structure. It is frequently impacted by severe geological hazards, especially in the weak rock strata of this area. The Yaobai landslide occurred on a slope with strong-moderately weathered phyllite and intensive structural planes, and foot excavation by human engineering activities triggered it. Large-scale physical model tests were carried out to elucidate the landslide’s motion traits and damage mechanism by considering the influence of structural planes’ inclination and orientation, filling conditions, slope foot excavation, etc. The results elucidated that the strength of the structural plane affected the ultimate angle of the slope foot and the location of the sliding plane; variation of structural plane orientation induced block rotations and increased the failure complexity; the mode of foot excavation affected the block slide sequence, locus, and distance. The landslide’s deformation failure model can be summarized into three types: progressive sliding failure, monolithic sliding failure, and rotary sliding failure. The research results can provide a basis for preventing and controlling such landslides in the Qinba Mountains Area.