• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1512-1519
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• 2005

In this study, the potential for liquefaction in the Incheon international airport was calculated by appling the standard penetration test data and laboratory test data to the modified Seed & Idriss(2001) method. The analysis was performed on the non-plastic silty layer and silty sand layer which within the depth of 20m, below 20 of the standard penetration value(N), and the ground water level. Also, each set of data was mapped by using GIS(geographic information systems) and the factor of safety for the potential for liquefaction was obtained by overlapping those layers. As a result, it was found that there exist potential hazard zone for the liquefaction partially. So, the additional detailed assessments for those are thought to be necessary.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.3
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• pp.171-180
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• 2016

Earthquake event keeps increasing every year, and the recent cases of earthquake hazards invoke the necessity of seismic study in Korea, as geotechnical earthquake hazards, such as strong ground motion, liquefaction and landslides, are a significant threat to structures in industrial hub areas including coastal facilities. In this study, systemized framework of integrated assessment of earthquake-induced geotechnical hazard was established using advanced geospatial database. And a visible simulation of the framework was specifically conducted at two coastal facility areas in Incheon. First, the geospatial-grid information in the 3D domain were constructed with geostatistical interpolation method composed of multiple geospatial coverage mapping and 3D integration of geo-layer construction considering spatial outliers and geotechnical uncertainty. Second, the behavior of site-specific seismic responses were assessed by incorporating the depth to bedrock, mean shear wave velocity of the upper 30 m, and characteristic site period based on the geospatial-grid. Third, the normalized correlations between rock-outcrop accelerations and the maximum accelerations of each grid were determined considering the site-specific seismic response characteristics. Fourth, the potential damage due to liquefaction was estimated by combining the geospatial-grid and accelerations correlation grid based on the simplified liquefaction potential index evaluation method.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.13-24
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• 2009

This paper introduces various kinds of applications of the scenario-based seismic risk assessment in Taiwan. Seismic scenario simulation (SSS) is a GIS-based technique to assess distribution of ground shaking intensity, soil liquefaction probability, building damages and associated casualties, interruption of lifeline systems, economic losses, etc. given source parameters of an earthquake. The SSS may integrate with rapid earthquake information release system to obtain valuable information and to assist in decision-making processes to dispatch rescue and medical resources efficiently. The SSS may also integrate with probabilistic seismic hazard analysis to evaluate various kinds of risk estimates, such as average annual loss and probable maximum loss in one event, in a probabilistic sense and to help proposing feasible countermeasures.

• Journal of the Korean GEO-environmental Society
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• v.6 no.2
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• pp.5-14
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• 2005

In the present study, the liquefaction potential in the area of the Incheon international airport was assessed by applying the data of both standard penetration tests and laboratory tests to the modified Seed & Idriss method. The analysis was performed against the non-plastic silty soil layer and silty sand soil layer existing within the depth of 20m and under the ground water level, having the standard penetration value(N) of below 20. Also, each set of data was mapped using the GIS(Geographic Information System) and the safety factor against the liquefaction potential ($FS_{liquefaction}$) was obtained by overlapping those layers. Throughout the analysis, it was found that there exists a potential hazard zone for the liquefaction, showing partially that the safety factor against the liquefaction potential is 1.0 to 1.5 below the standard safety factor criterion. It is further thought to be necessary that the liquefaction potential for the corresponding hazard zone be additionally assessed in detail.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5C
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• pp.313-322
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• 2006

Liquefaction of soil foundation is one of the major seismic damage types for infrastructures. In this paper, deterministic and probabilistic approaches for the evaluation of liquefaction potential are briefly summarized and the risk assessment method is newly proposed using seismic fragility and seismic hazard analyses. Currently the deterministic approach is widely used to evaluate the liquefaction potential in Korea. However, it is very difficult to handle a certain degree of uncertainties in the soil properties such as elastic modulus and resistant capacity by deterministic approach, and the probabilistic approaches are known as more promising. Two types of probabilistic approaches are introduced including (1) the reliability analysis (to obtain probability of failure) for a given design earthquake and (2) the seismic risk analysis of liquefaction for a specific soil for a given service life. The results from different methods show a similar trend, and the liquefaction potential can be more quantitatively evaluated using the new risk analysis method.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.127-140
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• 2004

Conventional methods for the assessment of liquefaction potential were primarily for areas of severe earthquake zones (M=7.5) such as North America and Japan. Detailed earthquake related researches in Korea started in 1997, including development of the seismic design standards for port and harbour structures, which was later completed in 1999. Because most contents in the guidelines were quoted through literature reviews from North America and Japan, which are located in strong earthquake region, those are not proper in Korea, a moderate earthquake region. This requires further improvement of the present guidelines. Considering earthquake hazard data in Korea, use of laboratory tests based on irregular earthquake motion appears to be effective to reflect the dynamic characteristics of soil more realistically than those using simplified regular loading. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. Effects of these components on dynamic behavior of soils are discussed as well. From the test results, screening limits and magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.4
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• pp.1-13
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• 2009

Liquefaction is a significant threat to structures on loose saturated sandy soil deposits in the event of an earthquake, and can often cause catastrophic damage, economic loss, and loss of life. Nevertheless, the Korean peninsula has for a long time been recognized as a safe region with respect to the hazard of liquefaction, as the peninsula is located in a moderate seismicity region, and there have been no reports of liquefaction, with the exception of references in some historical documents. However, some earthquakes that have recently occurred in different parts of the world have led to liquefaction in non-plastic silty soils, a soil type that can be found in many of the western coastal areas of Korea. In this study, we first present procedures for evaluating the liquefaction potential, and calculate the liquefaction potential index (LPI) distribution at two western coastal sites using both piezocone penetration test (CPTu) data and standard penetration test (SPT) data. The LPI is computed by integrating liquefaction potential over a depth of 20m, and provides an estimate of liquefaction-related surface damage. In addition, we compared the LPI values obtained from CPTu and SPT, respectively. Our research found that the CRR values from CPTu were lower than those from the SPT, particularly in the range between 40 and 120 for the corrected tip resistance, (qc1N)CS, from the CPTu, or in the range of CRR less than 0.23, resulting in relatively high LPI values. Moreover, it was observed that the differences in the CRR between the two methods were relatively higher for soils with high fine contents.

• Geomechanics and Engineering
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• v.8 no.5
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• pp.663-674
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• 2015

Many seismically vulnerable regions in India and worldwide are located on deep soil deposits which extend to several hundred meters of depth. It has been well recognized that the earthquake shaking is altered by geological conditions at the location of building. As seismic waves propagates through uppermost layers of soil and rock, these layers serve as filter and they can increase the duration and amplitude of earthquake motion within narrow frequency bands. The amplification of these waves is largely controlled by mechanical properties of these layers, which are function of their stiffness and damping. Stiffness and damping are further influenced by soil type and thickness. In the current study, an attempt has been made to study the seismic site response of deep soils. Three hypothetical homogeneous soil models (e.g., soft soil, medium soil and hard soil) lying on bedrock are considered. Depth of half space is varied from 30 m to 2,000 m in this study. Controlled synthetic motions are used as input base motion. One dimensional equivalent linear ground response analyses are carried out using a computer package DEEPSOIL. Conventional approach of analysing up to 30 m depth has been found to be inadequate for deep soil sites. PGA values are observed to be higher for deeper soil profiles as compared to shallow soil profiles indicating that deeper soil profiles are more prone to liquefaction and other related seismic hazards under earthquake ground shaking. The study recommends to deal the deeper soil sections more carefully for estimating the amplification factors for seismic hazard assessment at the surface.