Abstract: The stability of perilous rock bank slopes in the fluctuation belt of the Three Gorges Reservoir Area is greatly affected by the deterioration of the rock mass caused by periodic water level fluctuations. A study was conducted using field research, geological survey data, and numerical simulation with the universal distinct element code (UDEC) to investigate the impact of degradation zone morphology on the stability of nearly horizontal layered high steep perilous rock bank slopes. The research findings indicate that the rock mass in the fluctuation belt of the Wushan section of the Three Gorges Reservoir Area exhibits severe degradation in nearly horizontal layered perilous rock bank slopes. Different degradation zones exhibit distinct degradation morphologies, including tightly layered, loosely fragmented, dissolution cavity, and compression fractured zones. Perilous rock bank slopes with the first type of degradation zone morphology demonstrate good stability, with minimal displacement and sliding failure as the primary instability mode. The second type of degradation zone morphology causes the perilous rock body of the bank slope to shift inward and then collapse outward as the support strength of the rock mass weakens. The third type of degradation zone morphology leads to significant displacement towards the outside of the slope, with toppling failure as the instability mode. The stability of perilous rock bank slopes with the fourth type of degradation zone morphology is primarily influenced by the mechanical properties of the compressive fracture zone, which is prone to rotational sliding failure along the cutting surface of the fracture zone. By implementing prevention and reinforcement measures on the perilous rock bank slopes in the different types of deterioration zones mentioned above, the deformation and displacement of the perilous rock masses have been effectively controlled to varying degrees.

Key words: k bank slope, morphology of deterioration zone of the fluctuation belt, field research, universal distinct element code (UDEC), numerical simulation, deterioration characteristics, stability