Deformation–failure mechanism of saturated fill slopes due to resonance phenomena based on 1gshaking-table tests

Abstract

Earthquake motions include waves of various frequency bands ranging from low to high frequency. Notably, the dominant frequency affects the seismic stability of fill slopes. Hence, to analyze the deformation–failure mechanism during an earthquake, 1g shaking-table tests were conducted in this study on saturated fill slopes considering the resonance phenomenon. Results show that the deformation–failure mechanism of a fill slope cannot be defined by only one sliding surface. Multiple sliding surfaces are formed progressively depending on the ground and external conditions. Moreover, evaluating the seismic stability of fill slopes depends not only on the magnitude of the acceleration, but also on the relationship between the natural frequency of the fill slope and the input frequency. These phenomena cannot be considered in the seismic-intensity method nor in the Newmark’s method used in conventional design. When implementing seismic countermeasures, it is important to determine the frequency characteristics of fill slopes and design the countermeasures considering the predominant frequency of the seismic wave anticipated at the site.

Progressive Failure of Unsaturated Fill Slope Caused by Cumulative Damage Under Seepage Surface

“…The term "foundation" refers to the bedrock underlying the embankment or model slope, and "embankment" refers to the material atop the foundation. About the similitude rules under 1g field, refer the previous research [4]. The water tanks at the front and rear of the soil tank were used to create the seepage surface in the model slope.…”

“…The water tanks at the front and rear of the soil tank were used to create the seepage surface in the model slope. The soil samples and method of preparing the model slope were the same as in the previous research [4], except for the seepage surface position. As shown in Fig.…”

“…The excitation method employed in this study was the same as that employed in the previous research [4]. A sine wave frequency sweep was performed in advance with a constant acceleration amplitude of 0.2 m/s 2 .…”

“…The authors previously conducted a series of shaking-table tests to evaluate saturated hillside embankment, to identify the failure and deformation mechanisms of hillside embankments during earthquakes [4]. It was found that the input frequency affected how the model slope moved and the magnitude of acceleration leading to collapse.…”

“…Therefore, it would be beneficial to accumulate model test results for the purpose of understanding the effect of seepage surface position of the hillside embankments on their seismic behavior. This study conducted a series of shakingtable tests on embankments in the unsaturated state and compared with previous results in the fully saturated condition [4] to determine the effects of seepage surface position on the stability, deformation modes, and failure mechanisms of hillside embankments during earthquakes.…”