Liquefaction damage enhanced by interference between the body wave and surface wave induced from the inclined bedrock

Nakai, Kentaro; Asaoka, Akira; Sawada, Yoshihiro

doi:10.3208/jgssp.jpn-118

Cited by 6 publications

(5 citation statements)

References 4 publications

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“…Pender et al (2016) used V s = 400 m/s for the elastic half-space to investigate the effect of permeability on the cyclic generation and dissipation of pore pressures in saturated gravel layers in Christchurch, New Zealand. Fukutake and Jang (2013) and Nakai et al (2016) used a V s of 430 m/s and 400 m/s for liquefaction potential studies in Urayasu, Japan. Mase et al (2022) used V s = 400 m/s as elastic half-space for liquefaction analysis in Osaka, Japan.…”

Section: Priors and Likelihoods Of Site Amplificationsmentioning

confidence: 99%

Updating proxy-based site amplification map with in-situ data in Osaka, Japan: A Bayesian scheme based on uncertainty projected mapping

Chakraborty,

Goto,

Sawada

2023

Earthquake Spectra

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Site amplification maps are mostly proxy-based. Often due to the absence of in-situ data at the regional or local scale, a high level of confidence cannot be assigned to the site amplifications. It has often been observed that the in-situ amplifications differ from proxy-based estimates. So, whenever new in-situ data are made available, it is necessary to update the proxy-based estimates. Bayesian frameworks are recently gaining attention as model updating schemes. This study proposes a Bayesian scheme for updating proxy-based maps with in-situ data. This scheme is based on uncertainty projected mapping (UPM), where the significance of local in-situ data variability determines the posterior estimates. The study area is in Osaka, Japan, where discrepancies in proxy-based estimates and observed ground motions were documented during the 2018 Northern Osaka earthquake. Dense borehole data from the Kansai Geo-informatics Network are available in this area. Peak ground velocity (PGV) site amplification evaluations from this dense borehole network are used as likelihoods to update the prior proxy-based Japan seismic hazard information system (J-SHIS) site amplification map. As a result, the posterior map shows updated site amplification estimates which better represent the in-situ data. The updated site amplification map is then used to investigate the role of site amplification in explaining the building damage during the 2018 Northern Osaka earthquake.

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Section: Priors and Likelihoods Of Site Amplificationsmentioning

confidence: 99%

Updating proxy-based site amplification map with in-situ data in Osaka, Japan: A Bayesian scheme based on uncertainty projected mapping

Chakraborty,

Goto,

Sawada

2023

Earthquake Spectra

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“…However, the report was limited to the study of resonance in high-rise buildings and oil tank sloshing damage, and did not mention any effects on ground damage at all. Regarding these matters, the authors conducted a 2D elasto-plastic seismic response analysis considering stratum irregularities, and numerically confirmed that complex wave propagation due to stratum irregularities causes severe and nonuniform liquefaction damage (Nakai et al, 2016). Although the authors suggested that surface waves excited at the base of the irregularity near the ground surface were the important cause, validation of the numerically represented surface waves including the effect of analytical region and finite element mesh division, etc., was not sufficient because of the narrow analytical model region.…”

Section: Introductionmentioning

confidence: 97%

Severe and nonuniform liquefaction damage of reclaimed ground contributed by interference between body waves and stratigraphic irregularity-induced surface waves

Nakai,

Noda,

Asaoka

2024

Earthquake Spectra

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The 2011 off the Pacific Coast of Tohoku earthquake caused extensive liquefaction damage to reclaimed land along the Tokyo Bay coast, even though it was approximately 400 km from the epicenter. The characteristics of the liquefaction damage include the fact that liquefaction occurred in soils with a high percentage of fine particles and that the distribution of liquefied and nonliquefied areas was nonuniform. The factors contributing to such nonuniform liquefaction damage included the heterogeneity of the ground materials and their depositional conditions, and the effects of the long earthquake duration. Although these points are certainly valid as reasons for the occurrence of severe liquefaction damage, they do not fully explain the mechanisms of the liquefaction of the fine-grained soils, or the localized extent of the liquefaction. To elucidate the severe and nonuniform damage, seismic response analyses of a multi-layered ground were conducted focusing on the stratigraphic irregularities in the ground beneath Urayasu city. The results showed that the thicker and softer sedimentary layers amplify the slightly long-period component of the seismic motion and increase the shaking at the ground surface. Moreover, the wave propagation in the ground became very complicated owing to the focal effect caused by the refractions and reflections of body waves at the stratum boundary, surface wave excitation at the base of the slope, and amplified interference between body and surface waves. This complex wave propagation contributed to nonuniform surface ground shaking and severe liquefaction damage. In addition, surface waves, which consist primarily of slightly long-period components, can propagate far and wide; as such, they triggered extensive damage owing to delayed shaking phenomena that continue even after the earthquake. The analysis results suggested that multidimensional elasto-plastic seismic response analyses considering stratigraphic irregularities are important for detailed seismic evaluation.

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“…Using numerical techniques, Nakai et al [6] showed that ground deformation was strongly affected by the spatial distribution geological layer structures. However, they focused on the distribution of non-liquefiable layers or its inclination under the liquefiable layer.…”

Section: Introductionmentioning

confidence: 99%

<b>Prediction Method of Damage of Ground Induced by Liquefaction Based on Geological Structure of Surface Ground</b>

2018

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When ground liquefaction occurs, settlement is often caused by shear deformation during and consolidation after an earthquake. However, settlement does not occur regularly but usually varies in space. In order to clarify the mechanisms underlying non-uniform settlement caused by liquefaction, 2-dimensional effective stress analyses were performed on a field damaged in the 2011 off-the-Pacific-coast-of-Tohoku earthquake. Distributions of the thickness and resistance of the liquefiable layer obtained from field surveys were considered in the numerical models. Simulated results confirmed that the non-uniform settlement was caused by the spatial distribution of the thickness and resistance of the liquefiable layer.

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Liquefaction damage enhanced by interference between the body wave and surface wave induced from the inclined bedrock

Cited by 6 publications

References 4 publications

Updating proxy-based site amplification map with in-situ data in Osaka, Japan: A Bayesian scheme based on uncertainty projected mapping

Updating proxy-based site amplification map with in-situ data in Osaka, Japan: A Bayesian scheme based on uncertainty projected mapping

Severe and nonuniform liquefaction damage of reclaimed ground contributed by interference between body waves and stratigraphic irregularity-induced surface waves

<b>Prediction Method of Damage of Ground Induced by Liquefaction Based on Geological Structure of Surface Ground</b>

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