Dynamic response characteristics of moraine-soil slopes under the combined action of earthquakes and cryogenic freezing

Abstract

Freeze-thaw and earthquake are significant factors for the stability and failure of moraine soil slopes in high-altitude cold and strong earthquake area. The cryogenic freezing (CF) and heat thawing (HT) of moraine soil slopes were completed by using a self-designed constant-temperature test chamber, and several shaking table tests under different seismic intensity were carried out. In these tests, the displacement and acceleration responses were recorded by the non-contact measurement system and accelerometers, and the slope dynamic responses were clarified by the displacement, acceleration and energy. The results showed that: (1) the seismic responses of the CF slope are larger than that of the HT slope. (2) The failure process of the CF slope under earthquakes could be summarized into three phases: elastic deformation phase with seismic magnitude <0.4 g, brittle failure phase with seismic magnitude from 0.4 g to 0.8 g, and failure slip phase with seismic magnitude >0.8 g. (3) The failure mode of the HT slope is characterized by the overall collapse of loose moraine soil, and the particle size of the collapsed moraine soil redistributes during the sliding process. The failure mode of CF slope is a frozen block landslide with the soil-ice interface as the sliding surface. (4) The peak acceleration of the input wave, slope surface and elevation have amplification effect on the slope dynamic response, and the top of slope surface is the main deformation and failure area. (5) Reinforcement measures such as soil improvement of slope surface, weight reduction at slope top and backpressure at slope toe, heat pipes are recommended for moraine soil slopes in cold and strong earthquake area. Such findings may provide scientific basis for the damage state identification and seismic reinforcement of moraine soil slopes in alpine and strong earthquake areas.