Abstract: Under the combined action of water-rock, the physical and mechanical properties of the rock mass at the toe of a anticline rock slope in the Three Gorges Reservoir area are prone to deteriorate, which might affect the stability of the slope. It is particularly important to accurately understand the failure mechanism of the anticline rock slope under the condition of deterioration of the rock mass at the toe of slope. In this paper, the sandstone anticline rock slope in the Three Gorges Reservoir area is presented as a case history. The slope models with different slope angle, rock dip angle and layer thickness are established by using GDEM numerical analysis software. For slopes without toppling deformation before and after toe deterioration, the variation of the maximum principal stress before and after toe deterioration is analyzed. For slopes that are stable before slope deterioration and have toppling deformation after slope deterioration, the deformation evolution process of anticline slope under the condition of the slope deterioration is summarized. Its response characteristics to the slope deterioration are clarified. In addition, the influence of the slope angle, dip angle and layer thickness on the slope deformation is analyzed, and the shape and location characteristics of the fracture surface of the sandstone anticline slope are proved. The angle between the main fracture surface and the plane of the sandstone slope is 20~26, and the boundary between the deteriorated rock mass at the toe of slope and the deformed rock mass at the upper part is taken as the boundary, and the fracture surface is in a near-straight shape upward from the cut-off point. The main failure mode in the anticline slope of sandstone is spalling, toppling and fracture.

Key words: GDEM Software, Three Gorges Reservoir Area, Anticline Sandstone Slope, Slope Toe Degradation, Failure Mechanism