• Journal of the Korean GEO-environmental Society
• /
• v.23 no.5
• /
• pp.5-13
• /
• 2022

In this study, dynamic characteristics and liquefaction resistance characteristics of silica sand which is used to simulate sandy layer were conducted using the cyclic triaxial test according to the relative density difference. The difference in liquefaction resistance with the relative density was confirmed through the test results, which the relative density conditions were changed to 40%, 60%, and 80%, and the cyclic resistance ratio (CRR) curve of the silica sand was obtained. In addition, in order to examine the validity of the liquefaction resistance ratio (CRR) curve, artificial silica sand ground was created, and liquefaction potential was evaluated through the simple assessment method and the detailed assessment method, and the safety factors of each were compared.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.3
• /
• pp.35-51
• /
• 2008

In this paper, the application of the DSC model to the analysis of liquefaction potential is examined through experimental and analytical investigations. For more realistic description of dynamic responses of saturated sands, the DSC model was modified based on the dynamic effective stress path and excess pore pressure development. Both static and cyclic undrained triaxial tests were performed for sands with different relative densities and confining stresses. Based on test results, a classification of liquefaction phases in terms of the dynamic effective stress path and the excess pore pressure development was proposed and adopted into the modified DSC model. The proposed methods using the original and modified DSC models were compared with examples with different relative densities and confining stresses. Based on the comparisons between the predicted results using the original and modified DSC models and experimental data, the parameters required to define the model were simplified. It was also found that modified model more accurately simulate initial liquefaction and dynamic responses of soil under cyclic undrained triaxial tests.

• Journal of Korean Society for Geospatial Information Science
• /
• v.22 no.4
• /
• pp.31-38
• /
• 2014

Seismic of the Korean Peninsula is terrible about 1,900 times. Lately, because of a world-occurring seismic, investment of seismic design about ground & structures come to the force as means to protect national life and property. This study evaluated having seismic performance above design criteria among the existing port structures not applied seismic design. Based on the results, classified apprehensive area of liquefaction from seismic performance evaluation and made hazards according to liquefaction risk & structural performance using the analysis of seismic performance and GIS method. After Establishing quantitative & detailed input database through liquefaction evaluation and seismic performance, analysed all seismic data are used directly valuation data on repair reinforcement for apprehensive area of earthquakes.

• The Journal of Engineering Geology
• /
• v.30 no.4
• /
• pp.589-602
• /
• 2020

As can be seen in many earthquakes, liquefaction causes differential settlement, which sometimes produces serious damages such as building destruction and ground subsidence. There are many possible active faults near the Busan city and the Yangsan, Dongrae, and Ilgwang faults among them pass through the city. The Busan city is also located within the influence of recent earthquakes, which occurred in the Gyeongju, Pohang, and Kumamoto (Japan). Along the wide fault valleys in the city, the Quaternary unconsolidated alluvial sediments are thickly accumulated, and the reclaimed lands with beach sediments are widely distributed in the coastal area. A large earthquake near or in the Busan city is thus expected to cause major damage due to liquefaction in urban areas. This study conducted an assessment of the liquefaction hazard according to seismic recurrence intervals across the Busan city. As a result, although there are slight differences in degree depending on seismic recurrence intervals, it is predicted that the liquefaction potential is very high in the areas of the Nakdonggang Estuary, Busan Bay, Suyeong Bay, and Songjeong Station. In addition, it is shown that the shorter the seismic recurrence interval, the greater difference the liquefaction potential depending on site periods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.7
• /
• pp.133-143
• /
• 2018

Liquefaction is one of secondary damages after earthquake and has been rarely reported until earthquake except Mw = 5.4 15 November 2017 Pohang earthquake in Korea. In recent years, Mw = 5.8 12 September 2016 Gyeongju earthquake and Mw = 5.4 15 November 2017 Pohang earthquake, which induced liquefaction, occurred in fault zone of Yangsan City located at south-eastern part of Korea. This explains that Korea is not safe against liquefaction induced by earthquake. In this study, the distance between the centroid of administrative district and the epicenter located at Yangsan fault, peak ground velocity (PGA) induced by both Mw = 5.0 and 6.5, and liquefaction potential index (LPI), which is calculated by using groundwater level and standard penetration test results of 274 in the area of Gimhae city located in adjacent to Nakdong river and across Yangsan fault, have been estimated and then kriging method using geographical information systems has been used to evaluate liquefaction effects on the damage of facilities. This study presents that Mw = 5.0 earthquake induces a small and low level of liquefaction resulting in slight damage of facilities but Mw = 6.5 earthquake induces a large and high level of liquefaction resulting in severe damage of facilities.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.6
• /
• pp.25-36
• /
• 2018

Soil liquefaction is one of the types of major seismic damage. Soil liquefaction is a phenomenon that can cause enormous human and economic damages, and it must be examined before designing geotechnical structures. In this study, we proposed a practical method of developing a multi-hazard fragility surface for liquefaction of levee considering earthquake magnitude and water level. Limit state for liquefaction of levee was defined by liquefaction potential index (LPI), which is frequently used to assess the liquefaction susceptibility of soils. In order to consider the uncertainty of soil properties, Monte Carlo Simulation based probabilistic analysis was performed. Based on the analysis results, a 3D fragility surface representing the probability of failure by soil liquefaction as a function of the ground motion and water level has been established. The prepared multi-hazard fragility surface can be used to evaluate the safety of levees against liquefaction and to assess the risk in earthquake and flood prone areas.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.5
• /
• pp.129-136
• /
• 2001

본 논문에서는 석탄회 매립지반의 액상화 가능성을 평가하기 위해 순수 모래시료와 더불어서 모래시료와 석탄회가 혼합된 모래시료에 대한 일련의 진동삼축실험을 변형률제어 방법으로 수행하였다. 실험결과 진동하중에 의해서 시료 내에 발생하는 간극수압의 크기는 작용하는 전단변형률의 크기에 심각하게 영향을 받고, 작용하는 전단변형률이 지반의 한계전단변형률 보다 작은 경우에는 진동수가 높은 조건에서도 간극수압이 발생하지 않음을 알았다. 또한 전단변형률이 약 0.1%보다 작고 한계전단변형률에 가까운 경우에는 순수 모래시료와 비교하여 본 논문에서 조사한 석탄회 함유율 범위 (10%~30%)의 시료에서 간극수압이 더 크게 발생하였다. 반면에, 전단변형률이 큰 경우에는 순수 모래시료에서 간극수압이 크게 발생하는 추세를 보였다. 반복 전단에 따른 간극수압의 발생량은 전반적으로 석탄회 함유율이 증가할수록 커지는 경향을 보였다. 이러한 결과를 근거로 해안이나 하천에 인접한 한계지 개발에 있어서 사질토에 석탄회를 혼합 매립하여 지반을 조성하는 경우에 액상화에 대해서 불안정한 지반이 될 가능성이 있는 것으로 판단되었다.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.129-139
• /
• 2000

The liquefaction of reclaimed land generally caused the harbor facilities to hazards. In Korea, the major harbor quay walls are gravity type and the gravity quay wall is not a good earthquake resistant structure. Recently, various earthquake resistant quay walls have been suggested, but the study on the efficiency of reinforced quay wall was not much performed. In this study, numerical analysis is carried out for performance evaluation of easily adoptable earthquake resistant quay walls. The results of numerical analysis are compared with shaking table test that is performed at the same cross-section.

• Geotechnical Engineering
• /
• v.30 no.6
• /
• pp.8-22
• /
• 2014

• Geotechnical Engineering
• /
• v.39 no.2
• /
• pp.35-50
• /
• 2023