Seismic stability of steep consequent rockslides with different lithology assemblies: a comparative Study

This paper aims to reveal the effect of lithology assembly on the seismic performance of steep consequent-layered slopes composed of strong and interbedded rock strata. These slopes exhibit failure during intense seismic events but typically remain stable under natural conditions. A large-scale centrifugal shaking table test is conducted with various seismic excitations to examine the dynamic response of these slopes. The test results comprise crack propagation observation, acceleration responses, and spectral characteristics. Additionally, a simplified analytical approach is introduced to determine the transient safety factors for the two slopes at any given time, considering the type of seismic failure the slope may experience. The failure mode of a steep consequent-layered slope closely associates with the lithology. Two distinct failure modes, namely buckling and rockfall, are identified and replicated through the centrifugal model test. In both slopes, there exists a critical height beyond which acceleration amplification significantly increases toward the slope surface. For a steep slope composed of strong rock, this critical height is situated near the upper-front slope surface, whereas for an interbedded steep slope with the same inclination, it is located at 1/4 of the slope height from the toe. Furthermore, the interpolated distribution of the transient safety factor field reveals that the most critical location varies with the seismic Peak Ground Acceleration (PGA) for assessing potential buckling failure, while it remains constant for evaluating potential rockfall failure.