Experimental study on dynamic response law of bedding rock slopes under deterioration of rock mass in hydro-fluctuation belt
摘要
The deterioration of rock mass in hydro-fluctuation belt and the reservoir-induced earthquake, which are caused by the impoundment in the area of Three Gorges Reservoir, have a great impact on the stability of the bank slopes. The shaking table model tests are conducted to investigate the cumulative damage mechanism and dynamic stability of bedding rock slopes subjected to continuous seismic loads under the deterioration of rock mass in hydro-fluctuation belt. The results indicate that: (1) The acceleration response of slopes is significantly characterized by "elevation effect" and "surface effect", and the PGA amplification factor weakens obviously after several times of seismic loads. The cumulative displacement, pore water pressure and earth pressure of slopes show the trend of increasing, increasing and decreasing, respectively, with the continuous action of seismic loads. (2) The damping ratio, natural frequency and damage degree of slopes show the trend of increasing, decreasing and increasing gradually, respectively, with the continuous action of seismic loads. The nonlinear cumulative damage mechanical model for slopes under the action of micro-earthquake and strong earthquake can be characterized by "S-typed" cubic function and "steep rise" exponential function, respectively. (3) The evolution process of cumulative damage and instability failure of slopes can be summarized as: the initiation, propagation and penetration of the back edge of slope top (secondary joints and planes), the overall sliding of rock mass along the composite sliding surface, and the accumulation of the multi-scale broken blocks of rock mass at the foot of slopes after complete failure. Moreover, the rock mass in hydro- fluctuation belt is seriously broken by the coupling action of vibration, dissolution and erosion, and nearly slips as a whole to form a significant "cavity".