Abstract: It is of great practical significance to study the cumulative damage of slope under repeated seismic loads for long-term stability analysis of rock slope in reservoir area. In this paper, shaking table test and theoretical analysis were used to study the cumulative damage and failure mode of horizontal layered rock slope under repeated seismic loads. Results show that the fatigue crack propagation of concrete double K criterion explains the change tendency of the slope of the cumulative damage curve well. The complete cumulative damage evolution curve shows three stages, i.e., the initial damage stage, mesoscopic crack extension stage and macroscopic crack extension stage. The well fitted cubic polynomial and power exponent are adopted to establish the cumulative damage evolution model of slope rock mass under the action of micro-small earthquakes and strong earthquakes respectively. The cumulative damage curve of slope rock mass shows slight dip in the early stage, linear growth in the middle stage and moderate growth in the last stage under the action of micro-small earthquakes, which has the features of the positive "S" type. And the cumulative damage of slope rock mass under the action of strong earthquakes has a relatively rapid growth compared with that under the action of micro-small earthquakes, and the increase rate of which is accelerated before the slope failure. Under the action of frequent micro earthquake, stepped failure surfaces on the upper part of the horizontal layered rock slope are formed and exposed to the slope surface, while straight shear failure surface if formed on the lower part of the slope. The final failure surface of the slope is a stepped one.

Key words: seismic loads, rock slope, shaking table test, cumulative damage, failure mode