Dynamic response characteristics and instability criteria of a slope with a middle locked segment

Stability prediction of rock slopes under seismic loads is important for landslide hazard assessment. For this work we designed and built a model of a slope with a middle locked segment. To investigate its dynamic response characteristics and instability criteria under the influence of an earthquake, comparative experiments on a largescale shaking table were performed. The results show that the acceleration amplification factor within the model slope is clearly amplified by elevation and surface proximity. There are large differences in the acceleration response for a slope experiencing different types of input wave. The acceleration amplification factor first increases then decreases with the increase of input wave frequency, reaching a maximum value when the frequency is 20 Hz. A similar trend is observed with increasing input wave amplitude; the acceleration amplification factor of the slope generally increases then decreases as the amplitude increases. During the experiments, several cracks form and propagate in the locked segment between the prefabricated crack at the top and the weak interlayer at the bottom. These cracks develop continuously, coalescence into X-shapes, and finally form three sliding surfaces inside the slope. Under continuous vibration, the slope will slide along the three sliding surfaces. Based on cusp catastrophe theory and the experimental data, the relevant instability criteria are established. The critical acceleration amplitude of the dynamic instability of the slope is quantitatively determined to be 0.5 g.