Dynamic centrifuge experiments using equivalent shear beam (ESB) model containers are widely utilized in geotechnical earthquake engineering to quantitatively assess the responses of soils or soil-structure systems subjected to seismic loads. This study presents the dynamic centrifuge test results on the boundary effect in an ESB model container in the KAIST Geo-Centrifuge Center. Two dynamic centrifuge tests, one with the empty container and the other with the container filled with dry sand, were conducted to identify the natural frequency of the container and to compare the responses at different horizontal locations and depths within the container. The results evaluated that the response at a location 13 cm horizontally distant from the wall still showed a minimal boundary effect. Moreover, the response spectrum results from 1D equivalent linear analysis using DEEPSOIL agreed well with the acquired from the tested container. The presented results validate the use of the ESB container for dynamic centrifuge tests with a minimal boundary effect.

The conventional design procedures for seismic stability evaluation of the reinforced soil retaining walls are based on the pseudo-static approaches. The accuracy of the pseudo-static analyses relies on adopting an appropriate seismic acceleration coefficient (Kh). Most of the proposed methods for calculating Kh are based on theoretical assumptions and the validation of this vital parameter has not been evaluated based on an experimental approach. In this study, a new method is introduced to estimate Kh for reinforced-soil walls adjacent to the rock slopes using the results of shaking table and push-back pressure tests. The results presented herein consider the acceptable seismic performance of the retaining wall and are compared with the other proposed coefficients in the literature. The proposed method of this study can be developed for all types of retaining systems.

This paper presents a series of centrifugal shaking table model tests conducted to examine the characteristics of arch action within an embankment subjected to basal settlement and water infiltration. The tests were performed on a flexible and impervious base to simulate the presence of non-liquefiable soft ground and resulting basal settlement, leading to arch action above the basal subsidence. A liquid supply system was utilized to deliver Metolose inside the embankment during centrifugal loading to investigate the effect of water infiltration and saturated condition on arch action. Additionally, dynamic loading was employed to induce soil liquefaction and the relationship between arch action and soil liquefaction was observed. The paper focuses on the arch action throughout the process of initial stress formation, saturation, liquefaction, and post-liquefaction. The experimental results demonstrated that basal settlement underneath an embankment can lead to the development of arch action, and soil liquefaction can occur in the loosened ground caused by basal settlement, which is influenced by saturation and dynamic loading. The analyses of the earth pressure distribution on the bottom of the embankment model provide insights into the mechanism of arching action and its implication for soil liquefaction. Furthermore, the study also investigated the onset of liquefaction and the collapse mechanisms of embankments. The findings suggest that the arching effect plays an important role in the seismic stability of an embankment and can aid in developing more effective design and reinforcement techniques for embankments and levees.

Buried pipelines, especially segmented ones in the water networks, face natural hazard events like earthquakes or landslides. Vulnerabilities in connections between pipe segments are a concern. While new connection joints are emerging, the performance of these systems, especially for large-diameter joints, remains inadequately evaluated. The study conducts a 4-point bending test on a 24-inch NS-type ductile iron pipe manufactured by Kubota Corporation that are extensively instrumented with distributed fiber optic sensors. These sensors measure the continuous strain development of the pipelines in the longitudinal and circumferential directions to capture the actual behavior of the pipes. Overall, this study provides insights into the behavior of large-diameter ductile iron pipes under transverse loading conditions and can inform future improvements to pipeline design, which can ultimately reduce the risk of damage to pipelines from seismic events.

This project aims to determine the Coefficient of Variation (CV) and Correlation Length (CL) of the soil at site. The methodology involves data acquisition through seismometers, analysis of horizontal to vertical spectral ratios (HVSR), inversion analyses to obtain shear wave velocity (V_S) profiles, and subsequent calculations of CV and CL. The site consists of a dense array of 14 seismometers, complemented by additional borehole tests. HVSR were computed for both surface and subsurface recordings, and the resulting inversed V_S profiles were utilized to derive a representative profile for the site. CV was computed for each layer of the representative profile, and CL was determined from spatial autocorrelation coefficients. The analysis revealed that CV varies with depth, with higher values in shallow layers and a decrease with depth. The CL also exhibited depth-dependent behavior, increasing up to 150 m and decreasing beyond that depth. This comprehensive investigation provides valuable insights into the soil properties at site, which are essential for seismic hazard assessments and engineering considerations.

In this study, we first conducted permeability tests in the laboratory under different conditions of compaction and moisture. From the test results, we clarified that the permeability of soils is strongly influenced by the initial degree of saturation during compaction. Based on these results, we made a model embankment possessing a layer with a large difference in hydraulic conductivity. After simulating rainfall by applying a certain amount of water, we confirmed the occurrence of “perched groundwater” within the embankment. In addition, seepage flow analysis of the model embankment suggested that spring water on the slope leads to early detection of “perched groundwater”.

The main purpose of this paper is to investigate the effects of the position of pipes buried in sloped ground on their responses to landslides. To achieve this purpose, a 1-g shake table test was conducted. Similitude laws were employed to construct the physical modeling. Four aluminum pipes were installed at different positions but at identical depths of the model ground. All the pipes had a direction angle of 70 degrees relative to the landslide direction. They were heavily instrumented with pair strain gauges to measure pure bending strain. Besides, two strain gauges were installed on each pipe to measure axial strain. The model was fully instrumented with acceleration and displacement transducers. These sensors were located at adequate distances from container walls to minimize the effects of boundary conditions on the results. Input shaking consisted of 25 sinusoidal cycles of loading with an amplitude of 0.32 g and frequency of 5 Hz. The input shaking was representative of an earthquake with M_w of 8.25. The shaking was applied parallel to the ground slope. The results showed that the lower part of the slope was the most critical location for buried pipes. On the contrary, the toe of the sloped ground was the safest location for the pipes against landslide hazards.