• 한국지반공학회논문집
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• 제36권4호
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• pp.17-30
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• 2020

본 연구의 목적은 2017년 포항지진 시 액상화가 관측되었거나 액상화 가능성이 높은 부지 5곳에 대하여, 국내에서 통상적으로 적용해 왔던 액상화 평가 기준과 최근 개정된 평가 기준을 적용하여 액상화 평가를 실시하고, 이러한 이론적인 액상화 평가 결과와 대상 부지에서의 실제 액상화 발현여부를 비교·검토함으로써, 개정된 액상화 평가 기준의 타당성을 검토하는 데에 있다. 액상화 평가를 위한 해석지진은 기존 국내에서 통상적으로 사용해 온 지진파와 포항 실지진파를 사용하였고, 해석지진의 최대지반가속도 크기는 0.097g~0.2713g 범위의 값을 적용하였다. 해석결과로부터, 기존 국내에서 통상적으로 적용해 왔던 구조물기초설계기준(2016)에 제시된 액상화 평가 기준의 개선점을 제시하고, 2018년에 개정된 내진설계일반에 제시된 액상화평가 기준의 기존 기준대비 개정 사항의 상대적 타당성을 평가해 보았다.

• 한국지진공학회논문집
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• 제24권5호
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• pp.197-209
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• 2020

Evidence of liquefaction during the 2017 Pohang earthquake has highlighted the urgent need to evaluate the current seismic design standard for liquefaction in Korea, particularly the liquefaction triggering standard. With the simplified method, which is the most popular method for evaluating liquefaction triggering, the factor of safety for liquefaction triggering is calculated via the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR). The parameters in the CSR and CRR have undergone changes over time based on new research findings and lessons learned from liquefaction case-histories. Hence, the current design standard for liquefaction triggering evaluation in Korea should also reflect these changes to achieve seismic safety during future earthquakes. In this study, liquefaction susceptibility criteria were discussed initially and this was followed by a review of the current liquefaction triggering codes/guidelines in other countries and Korea. Next, the parameters associated with the CSR such as the maximum ground acceleration, stress reduction factor, magnitude scaling factor, and overburden correction factor were discussed in detail. Then, the evaluation of the CRR using the SPT N-value and CPT qc-value was elaborated along with overburden and clean-sand correction factors. Based on this review of liquefaction triggering evaluation standards, recommendations are made for improving the current seismic design standard related to liquefaction triggering in Korea.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.477-484
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• 2001

In this paper shows the evaluation of the liquefaction potential of soils using in situ test. There are different types of in situ test used in the evaluation the liquefaction potential. In the particular study the Standard penetration test(SPT), Cone penetration test(CPT), ad Seismic cone penetration test (SCPT) were used. The SPT N value has been used all over for a very long time. The evaluation of the liquefaction of soil was preformed using the worldwide renowned CPT and SCPT. Shake 91 program was used to evaluate the results obtained by different in situ test and were later analyzed.

• 지질공학
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• 제33권1호
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• pp.151-167
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• 2023

본 연구는 LNG저장탱크가 설치될 느슨한 포화사질지반을 대상으로 개정된 액상화 평가법과 UBC3D-PLM 모델을 이용한 1차원 유효응력해석에 의한 액상화 평가법을 비교한 것이다. 이를 위해 여러가지 실내 및 현장시험을 실시하여 필요한 Parameter를 산정하였다. 검토결과, 지진응답해석결과와 SPT N 값을 이용하는 개정 액상화 평가법은 액상화 발생 가능성을 높게 평가하였지만, 다양한 액상화 저항인자를 고려할 수 있는 유효응력해석법은 액상화에 다소 안정한 것으로 분석되었다. UBC3D-PLM 모델을 이용한 1차원 유한요소해석을 할 경우 보다 간편하게 액상화 안정성 검토가 가능하였고, 액상화 보강 영역을 최소화 할 수 있었다. 또한, LNG저장탱크의 기초를 고려한 2·3차원 수치해석 시에는 액상화 발생 시 내진설계 및 거동특성을 규명하는 것에 활용될 수 있을 것으로 기대된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.443-450
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• 2001

This paper shows the reduction effect of tile earthquake-induced liquefaction potential of soils that improved by Vibro-Replacement Stone Columns. The Vibro-Replacement Stone Columns method transforms soft cohesive soils into a composite mass of compacted granular or crushed stone columns by using vibrating equipment and water jets. This study investigated and analyzed the behavior of the stone columns and composite ground using the results of in situ test and measurement at the job-site. This paper shows the evaluation of the earthquake-induced liquefaction potential of soils using in situ test. There are different types of in situ test used in the evaluation the liquefaction potential. In the particular study the Standard penetration test, and Cone penetration test were used. The N value of Standard Penetration test has been used all over for a very long time. The evaluation of the liquefaction of soil was performed using the worldwide renewed Cone penetration test

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 학술발표집 지반진동 영향평가
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• pp.1-14
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• 1993

Ground reinforcements is the essential method to prevent the liquefaction of loose sand deposit, However, in the construction of the life lines, it is impossible to treat the whole loose deposit against liquefaction. As an countmeasure for the life lines against the liquefaction, a monitorning system can be considered for an immediate judgement of the liquefaction occurrence during an earthquake. Through shaking table tests on model grounds, pore presure developments were investigated in terms of the surface spectral velocity, which was verified as a tool for the immediate judgement of the liquefaction occurrence.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.28-35
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• 2001

Liquefaction potential on the specific site of nuclear power plant is analyzed and reviewed. The layered site fur this study consists of silt and sand. Based on the limited available soil data, maximum shear strength at critical locations using Seed & Idriss method and computer program SHAKE is calculated, and liquefaction potential is reviewed. Seismic input motion used fur the assessment of liquefaction is the artificial time history compatible with the US NRC regulatory Guider .60. Assessment results of the liquefaction are validated by analyzing to the other typical soil fecundations which can show the effects of foundation depth and soil data.

• 한국지반공학회논문집
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• 제35권3호
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• pp.37-46
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• 2019

최근 다른 현장시험에 비하여 비교적 정확성이 높은 CPT 기반 액상화 평가법의 사용이 증가하고 있다. CPT 기반 액상화 평가는 다양한 흙의 특성을 예측하고 이를 액상화 평가에 활용할 수 있다. 특히, 세립분 함량은 CPT 기반 액상화 평가에서 중요한 입력 변수 중 하나로 이에 대한 정확한 예측식의 사용 및 예측 변동성을 정량적으로 파악하는 것은 매우 중요하다. 본 연구에서는 2017년 포항지진 시 액상화 현상이 관측된 지점에서 수행된 CPT 자료를 이용하여 기존 세립분 함량 예측식들의 오차를 분석하고 포항지역에 적합한 세립분 함량 예측식을 선정하였다. 또한, 지반의 고유한 변동성을 분석하고 CPT의 측정오차, 선정된 예측식에 대한 변환 불확실성을 고려한 세립분 함량의 예측 변동성을 정량적으로 평가하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.105-111
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• 2000

If a saturate sand is subjected to ground vibrations it tends to compact and decrease in volume. if drainage is unable to occur the tendency to decrease in volume results in an increase in pore water pressure and if the pore water pressure build up to the point at which it is equal to the overburden pressure the effective stress becomes zero the sand loses its strength completely. This phenomenon is called "Liquefaction" It is associated primarily but not exclusively with saturated cohesion soils. The attention and study on liquefaction have been growing since the earthquake in Niigita Japan in 1964. Many researchers on liquefaction effect have been carried out in many countries under the potential influence of earthquake including Japan. However little research on liquefaction has been reported in Korea because Korea has been considered to be safe from earthquake. The term "liquefaction" is only known among geotechnical engineers,. In this paper overview of liquefaction and the evaluation on the applicability of vibrated crushed-stone pile as a liquefaction prevention method are presented.ethod are presented.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.590-599
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• 2006

In this study, Liquefaction characteristics of saturated sand under various dynamic loadings such as sinusoidal loading, increasing wedge loading, and real earthquake loading were investigated focusing on the dissipated energy. From the results of cyclic triaxial test, liquefaction resistance strength was calculated by the concept of energy according to the type of input loading. Liquefaction resistance strength was expressed in accumulated dissipated energy calculated from stress-strain curve(hysteresis loop). The dissipated energy according to loading type was compared and the energy-based evaluation was proposed. The procedures are presented in terms of normalized energy demand(NED), normalized energy capacity(NEC), and factor of safely, where NED is the load imparted to the soil by the loading(both amplitude and duration), NEC is the demand required to induce liquefaction, and factor of safely is defined as the ratio of NEC and NED.