Progressive failure mechanisms of anti-dip rock slopes near reservoir banks considering rock mass deterioration in the hydro-fluctuation belt

The construction of high dams and large hydropower projects significantly alters the hydrodynamic environment of reservoir shorelines, inducing periodic water level fluctuations. These fluctuations trigger complex hydro-mechanical interactions within the surrounding rock mass, leading to the development of transient seepage fields, cyclic changes in pore water pressure, and progressive degradation of rock structure. Consequently, the risk of slope failures in hydro-fluctuation belts is substantially increased. In this study, a typical anti-dip rock slope near Huangdeng hydropower station was selected to study the fluid–solid coupling mechanism of slope instability under hydro-fluctuation belt. A series of physical model tests were conducted under controlled hydrodynamic conditions to simulate the weakening of rock mass due to seepage. The coupled evolution of displacement and strain was recorded throughout the failure process. The primary findings of this research are as follows: The toppling failure process of the anti-dip rock slope model near the reservoir bank can be categorized into six distinct stages: compaction, creep, crack initiation, crack propagation, crack penetration, and instability failure. Under hydro-fluctuation belt rock mass degradation, the reservoir bank slope model exhibited increased crack generation, with the displacement field, strain field, and Newton forces all reaching critical warning thresholds, ultimately leading to large-scale slope instability. The results demonstrated that displacement changes lagged behind Newton force variations by 90–100 s, confirming that Newton force monitoring represents an effective approach for pre-sliding landslide warning.