The Failure Modes and Geometric Morphology of Soil Slope Under Random Earthquake Ground Motions

Generally, there are many potential slip surfaces for a soil slope, and each of them can lead to the slope failure. Some studies have shown the failure modes are different under static state when considering the variability of soil parameters. However, little research was carried out on the failure modes and geometric morphology under random earthquake ground motions. In engineering practice, the time history analysis pays more attention on slope dynamic stability. However, the factors of safety (FOS) are not enough to represent the overall behaviour of the slope under the uncertain dynamic loading. Thus, this paper carried out a series of earthquake tests on soil slopes, in order to research (1) what are the effects of seismic loading on the slope FOS and the critical sliding surface? (2) how the slope stability relates to the intensity-frequency characteristic of ground motion? And (3) how the failure models and geometric morphology evolution under random earthquake ground motions? Firstly, the sine waves and chirp waves are input to a slope model. After that, a series of intensity-frequency nonstationary random earthquake ground motions are used for computational simulation. It found that the failure model and geometric morphology (position, radius, and volume) are different under different seismic waves. When the acceleration is lower (< 0.15 g), the critical sliding surfaces are same with the static state condition. When the acceleration become higher (> 0.15 g), the critical sliding surfaces trend to have a straight surface (the radius increase), and the landslide volume will also change. In addition, when near the resonance frequency, the FOS of slope decreased rapidly. In addition, although the critical sliding surfaces are changed under random earthquake ground motions, the variation range are limited and can be obtained.