Earthquake-induced displacements of slopes are often evaluated through decoupled approaches combined with empirical relationships accounting for the characteristics of the input motion and the dynamic properties of the sliding mass. As per the latter point, recent studies highlighted the key role played by the system modal properties on the slope performance. Notwithstanding, the natural periods of the slope are commonly evaluated through over-simplified expressions relating to homogenous soil deposit with horizontal ground level. With the aim to provide a more realistic and comprehensive dynamic identification, this study presents a numerical investigation on the modal features of slopes with planar slip surface, implemented in the analysis framework OpenSees. The consideration of several slope geometries and mechanical properties point out i) the influence of the soil incompressibility, of particular interest under saturated conditions, and ii) effective ranges for the multiaxial modal periods and participation masses as a function of the soil stiffness. The results of the parametric study are finally used to derive a practice-oriented identification procedure of the modal features of slopes, as starting information for calibrating simplified numerical tools devoted to their large-scale assessment.

Permanent seismic monitoring plays an essential role in the surveillance of embankment dams in seismically active regions. Weak-motion recordings collected from instruments located along the dam body and abutments provide valuable data sets to identify and characterize the dynamic response of the dam-foundation system at small strain levels. The objective of this work was to summarize the characterization and processing of the acceleration time histories recorded during the operation of an earth dam in Argentina, to identify the main features of its dynamic response. The paper first describes the seismic monitoring system of the dam; then, the records were attributed to seismic events pertaining to distinct seismogenic sources through catalogs of seismicity. It was shown that several seismogenic sources characterized by different types of faulting style, distance and magnitude may affect the dam during its operation. A number of selected records was processed in order to obtain a preliminary description of the dynamic response of the dam-foundation system at low-acceleration amplitudes. The analysis of peak acceleration ratios between the crest and mid-height recording stations revealed the significant influence of asynchronous motion. This aspect was confirmed by the analysis of Fourier’s and response spectral ratios, which yielded consistent estimates of the fundamental frequency of the dam-foundation system, notwithstanding the variability of the source mechanisms, and permitted to back-figure a realistic value of the average shear wave velocity of the gravelly soil.

We assess the seismic response of homogeneous slopes composed of sand using the outputs of two-dimensional (2D) dynamic nonlinear finite element analyses. The slope models are configured to have a range of static factor of safety (FS_static) by adjusting the slope geometry and soil shear strength. The Newmark displacements are numerically calculated from equivalent horizontal acceleration time histories, which are determined by integrating shear and normal stresses across the predefined failure surface. The Newmark displacements are correlated with a number of ground parameters, which include peak ground acceleration (PGA), peak ground velocity (PGV), arias intensity (Ia), and cumulative absolute velocity (CAV). It is demonstrated that PGV produces the strongest correlation with the Newmark displacement, whereas PGA yields a weak linkage with the numerically calculated displacement. Empirical functions that relate FS_static and ground motion parameters with the Newmark displacements are proposed.

Pseudo-static stability analysis is a widely used approach for assessing the seismic stability of slopes. It is a simple and efficient method that involves applying a static force to a designated facility to simulate acceleration in a model. When a structure is subjected to ground motions, the effect of shaking on the structure is equivalent to the force calculated by the seismic coefficient (kh). In this study, we investigated the stability of a laterally confined dip slope using a dynamic centrifugal model and the pseudo-static stability analysis. The experiment was conducted to examine the effects of various factors on the stability of the slope, including soil parameters, slope angle, and confining pressure. The results showed that the dip slope was highly susceptible to seismic loading and the pseudo-static stability analysis provided a reasonable prediction of slope stability. The findings offered valuable insights into the behavior of laterally confined dip slopes under seismic loading. The results can be used to inform slope design and guide engineering practices in areas prone to seismic activity. The use of dynamic centrifugal models in conjunction with pseudo-static stability analysis can improve our understanding of the behavior of laterally confined dip slope under seismic loading and enhance our ability to predict and mitigate the risks associated with seismic events.

River embankments are verified based on the amount of embankment settlement after an earthquake. Earthquakeverification is carried out using numerical analysis to predict the amount of river embankment settlement after earthquake. However, during earthquakes, not only settlement but also bank cracks may occur. The cracks are damaging to the inside of the river embankment and are thought to have an impact on osmosis and erosion during flood season, but this is not a verification item in the current design approach. Against this background, this study focuses on bank cracks that occur during earthquakes the analysis of damage cases caused by past earthquakes. From damage case analysis, the higher the embankment height, the more likely deep cracks are to occur, and that the smaller the embankment height, the more likely shallow cracks are to occur. Also, from an analysis focus on damage mechanisms, in cases of liquefaction of the embankment, the settlement tended to be large and the cracks shallow. On the other hand, in cases of liquefaction of the foundation ground, the settlement tended to be smaller and the cracks deeper. In some damage cases, embankment opening surveys were carried out after the earthquake. This has revealed not only information on cracks and settlement from outside the embankment, but also damage inside the embankment. The study analysis the results of the embankment opening survey, which confirmed that damage within the embankment tended to be more significant the fine fraction content was smaller.

In this paper, the effects of dominant period and duration of seismic motion on the seismic damage of river levees are numerically investigated. The results show that when the long-period component of the input seismic motion is dominant, not only liquefaction of sandy layers but also damage to clayey soil layers showed extensive seismic damage. In addition, since ground motions for design purposes are often specified by response spectra, the effect of duration is not strictly taken into account. Especially in the case of soft ground with strong elasto-plastic response, it is shown that the effect of duration of seismic motion is significant. Numerical analysis shows that it is important to take into account the seismic characteristics such as period and duration for detailed damage estimation.