• Geomechanics and Engineering
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• 제7권6호
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• pp.589-612
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• 2014

This study includes determination of liquefaction potential in Erzincan city center. Erzincan Province is situated within first-degree earthquake zone on earthquake map of Turkey. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes (6.0, 6.5, 7.0) were determined. Liquefaction potential was investigated using Standard Penetration Test (SPT). Liquefaction potential analyses are determined in two steps: geotechnical investigations and calculations. In the first steps, boreholes were drilled to obtain disturbed and undisturbed soil samples and SPT values were obtained. Laboratory tests were made to identify geotechnical properties of soil samples. In the second step, liquefaction potential analyses were examined using two methods, namely Seed and Idriss (1971), Iwasaki et al. (1981). The liquefaction potential broadly classified into three categories, namely non-liquefiable, marginally liquefiable and liquefiable regions. Additionally, the liquefaction potential index classified into four categories, namely non-liquefiable, low, high and very high liquefiable regions. In order to liquefaction analysis complete within a short time, MATLAB program were prepared. Following the analyses, liquefaction potential index is investigated by Iwasaki et al. (1982) methods. At the final stage of this study, liquefaction potential maps and liquefaction potential index maps of the all study area by using IDW (inverse distance weighted) interpolation method in Geostatistical Analyst Module of ArcGIS 10.0 Software were prepared for different earthquake magnitudes and different depths. The results of soil liquefaction potential were evaluated in ArcGIS to map the distributions of drillings with liquefaction potential. The maps showed that there is a spatial variability in the results obtained which made it difficult to clearly separate between regional areas of high or low potential to liquefy. However, this study indicates that the presence of ground water and sandy-silty soils increases the liquefaction potential with the seismic features of the region.

• 한국재난정보학회 논문집
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• 제14권3호
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• pp.296-304
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• 2018

연구목적: 이 논문에서는 인천 해안 매립 지반에 대한 액상화 평가를 위하여 장주기의 Hachinohe 지진파와 단주기의 Ofunato 지진파에 대하여 ProShake 프로그램을 사용하여 지반응답해석을 수행하였다. 연구방법: 지반응답해석 결과와 수정 Seed and Idriss의 방법을 이용하여 액상화 평가를 수행하였다. 각 지점의 액상화 평가 결과를 대표할 수 있는 지표로 Iwasaki가 제시한 액상화 가능성 지수를 산정하였다. 또한, 액상화 구역도 작성을 위한 정량적인 지표로서 등가 액상화 안전율을 이용하였다. 연구결과: 이 논문에서는 액상화 가능지수와 등가 액상화 안전율을 이용하여 인천 해안 매립지역을 대상으로 액상화 구역도를 작성하였다. 결론: 구역도 작성 결과, 액상화 가능지수와 등가 액상화 안전율을 이용하여 작성된 구역도가 유사한 분포 형태를 보여 이 논문에서 제시한 액상화 구역도 작성 지표로 인천 해안 매립 지역의 액상화 구역도를 작성할 경우 이용에 편리할 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.431-438
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• 2002

Reclaimed coastal areas for the construction of ports and harbors are in general subjected to strong possibility of liquefaction. In this research, a new method for liquefaction hazard microzonation based on liquefaction settlements was developed. Severity of liquefaction hazard was defined by liquefaction settlements obtained from the method proposed by Tokimatsu and Seed. 10 coastal areas, representing typical geological and geotechnical characteristics of Korean ports and harbors, and 3 real earthquake records for site response analysis were selected. From this research, liquefaction settlement criteria is adapted as a new quantitative index for the liquefaction hazard microzonation. Liquefaction settlements were also compared with LPI (Liquefaction Potential Index), obtained from the assessment of liquefaction potential based on the modified Seed and Idriss's method. As an example, 2 and 3 dimensional liquefaction hazard microzonations of Pusan port and harbor area were mapped by overlapped liquefaction settlement contours.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.431-438
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• 1999

An assessment of liquefaction potential is made in principle by comparing the shear stress induced by earthquake to the liquefaction strength of the soil. In this study, a modified method based on Seed and Idriss theory is developed for evaluating liquefaction potential. The shear stress in the ground can be evaluated with seismic response analysis and the liquefaction strength of the soil can be investigated by using cyclic triaxial tests. The cyclic triaxial tests are conducted in two different conditions in order to investigate the factors affecting liquefaction strength such as cyclic shear stress amplitude and relative density. And performance of the modified method in practical examples is demonstrated by applying it to liquefaction analysis of artificial zones with dimensions and material properties similar to those in a typical field. From the result, the modified method for assessing liquefaction potential can successfully evaluate the safety factor under moderate magnitude(M=6.5) of earthquake.

• Geomechanics and Engineering
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• 제10권3호
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• pp.269-284
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• 2016

Simplified techniques based on in situ testing methods are commonly used to assess seismic liquefaction potential. Many of these simplified methods were developed by analyzing liquefaction case histories from which the liquefaction boundary (limit state) separating two categories (the occurrence or non-occurrence of liquefaction) is determined. As the liquefaction classification problem is highly nonlinear in nature, it is difficult to develop a comprehensive model using conventional modeling techniques that take into consideration all the independent variables, such as the seismic and soil properties. In this study, a modification of the Multivariate Adaptive Regression Splines (MARS) approach based on Logistic Regression (LR) LR_MARS is used to evaluate seismic liquefaction potential based on actual field records. Three different LR_MARS models were used to analyze three different field liquefaction databases and the results are compared with the neural network approaches. The developed spline functions and the limit state functions obtained reveal that the LR_MARS models can capture and describe the intrinsic, complex relationship between seismic parameters, soil parameters, and the liquefaction potential without having to make any assumptions about the underlying relationship between the various variables. Considering its computational efficiency, simplicity of interpretation, predictive accuracy, its data-driven and adaptive nature and its ability to map the interaction between variables, the use of LR_MARS model in assessing seismic liquefaction potential is promising.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.141-150
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• 2000

In this study liquefaction hazard potential was assessed by modified Seed and Idriss method and maps of liquefaction hazard potential utilized by LPI(Liquefaction Potential Index) and FE(Equivalent Liquefaction Factor of Safety) were constructed in two dimensional space, Comparisons of liquefaction hazard maps assessed by LPI and FE are represented to verify the FE method proposed in this study. Based on the results of comparing liquefaction hazard map using LPI and FE there is similar distribution trend of zonation indices. from the result of comparison of liquefaction hazard maps of FE base using Hachinohe and ofunato PGA(Peak ground Acceleration) data at one site of port and harbor in Korea the values of FE in liquefaction hazard map using Hachinohe data are underestimated. And in the view of quantitative analysis FE is more convenient than LPI because types of results from FE are factor of safety that widely used in geotechnical practice and aseismic design standard for port and harbor in Korea.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1246-1249
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• 2009

Liquefaction hazard caused by earthquake is the damage in a wide range. Until now, liquefaction hazard potential at a small area or most structure in Korea was assessed by modified Seed & Idriss method. However, it has been known that this method is not proper for metropolitan area due to a lot of time and data to perform the related ground response analyses such as Shake program. For these reasons, the current method has been used facilities or structures, not metropolitan area. In this study, several contents in seismic design of Eurocode and Korean seismic design standard for Port and Harbor were introduced and applied for assessing the liquefaction potential and mapping the liquefaction hazard by LPI(Liquefaction Potential Index). Finally, Ulsan metropolitan city was practically drawn in two dimensional space.

• Geomechanics and Engineering
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• 제9권1호
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• pp.1-14
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• 2015

Piezovibrocones have been developed to evaluate the liquefaction potential of onshore soils, but have not yet been utilized to evaluate the in-situ liquefaction behavior of offshore marine and volcanoclastic sediments. Two static and vibratory CPTu (Cone Penetration Tests) were performed at Tauranga Harbor, New Zealand. The lithology is known from nearby drillholes and the influence of vibration on different types of marine soils is evaluated using the reduction ratio (RR) calculated from static and vibratory CPTu. A sediment layer with high potential for liquefaction and one with a slight reaction to cyclic loading are identified. In addition to the reduction ratio, the liquefaction potential of sediment is analyzed using classic correlations for static CPTu data, but no liquefaction potential was determined. This points to an underestimation of liquefaction potential with the classic static CPTu correlations in marine soil. Results show that piezovibrocone tests are a sensitive tool for liquefaction analysis in offshore marine and volcanoclastic soil.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1446-1453
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• 2008

This paper presents the mapping of liquefaction for the Incheon Song-do reclamation area using both the liquefaction potential index(LPI) and the equivalent liquefaction factor of safety(FE). As a result, the mapping of liquefaction based on LPI and FE shows similar distribution pattern. Therefore, the mapping of liquefaction presented in this study will be a convenient index for use when the mapping of liquefaction for the Incheon Song-do reclamation area is drawn up. It will make selection of area that needs specific estimation and areas with adaptation of liquefaction counteraction construction methods for the future reclaimed land with the economical soil investigation.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.77-84
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• 1999

An assessment of liquefaction potential is made in principle by comparing earthquake induced shear stress to the liquefaction strength of the soil. In this research a modified method based on Seed and Idriss theory is developed for evaluating liquefaction strength of Jumunjon sand(Korean standard sand). Also the factors affecting liquefaction strenght such as cyclic shear stress amplitude and relative density are investigated and verified by using cyclic triaxial test. From the result the new relationships between cyclic shear stress ratio and number of load cycles are proposed for evaluating liquefaction strength under moderated magnitude(M=6.5) of earthquake.