Stability of bedded rock slopes subjected to hydro-fluctuation and associated strength deterioration

Abstract

Reservoir-induced earthquakes (RIEs) occur frequently in the Three Gorges Reservoir Area (TGRA) and the rock mass strength of the hydro-fluctuation belt (HFB) deteriorates severely due to the reservoir-induced seismic loads. Three models of typical bedded rock slopes (BRSs), i.e. gently (GIS), moderately (MIS), and steeply (SIS) inclined slopes, were proposed according to field investigations. The dynamic response mechanism and stability of the BRSs, affected by the rock mass deterioration of the HFB, were investigated by the shaking table test and the universal distinct element code (UDEC) simulation. Specifically, the amplification coefficient of the peak ground acceleration (PGA) of the slope was gradually attenuated under multiple seismic loads, and the acceleration response showed obvious “surface effect” and “elevation effect” in the horizontal and vertical directions, respectively. The “S-type” cubic function and “steep-rise type” exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves (low seismic waves) and high seismic waves, respectively. According to the dynamic responses of the acceleration, cumulative displacement, rock pressure, pore water pressure, damping ratio, natural frequency, stability coefficient, and sliding velocity of the slope, the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized, and the numerical and experimental results were compared. Considering the dynamic effects of the slope height (SH), slope angle (SA), bedding plane thickness (BPT), dip angle of the bedding plane (DABP), dynamic load amplitude (DLA), dynamic load frequency (DLF), height of water level of the hydro-fluctuation belt (HWLHFB), degradation range of the hydro-fluctuation belt (DRHFB), and degradation shape of the hydro-fluctuation belt (DSHFB), the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method (OAM) was DLA > DRHFB > SA > SH > DLF > HWLHFB > DSHFB > DABP > BPT.