• The Journal of Engineering Geology
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• v.11 no.2
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• pp.175-190
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• 2001

This study investigates the existing theoretical backgrounds in order to examine the behavior of lateral flow according to the plasticity of soils when unsymmetrical surcharge is worked on polluted soft soils by comparing and analyzing the results measured through model tests. Model tests are canied out as follows soil tank, bearing frame and bearing plate are made. By increasing unsymmetrical surcharge to the ground soils with the consistent water content and with gradually increased polluted materials at intervals, the amounts of settlement, lateral displacement and upheaval were respectively observed. In conclusion, the value of critical surcharge was expressed as q$_{cr}$=2.78$_{cu}$ which was similar to those Tschebotarioff(q$_{cr}$=3.0$_{cu}$) and Meyerhof(q$_{cr}$=(B/2H+$\pi$/2)$_{cu}$) had been proposed. The value of ultimate capacity was expressed as q$_{ult}$=4.84$_{cu}$ which was similar to that of Prandtl. The lateral flow pressure is adeQuately calculated by the eQuation(P$_{max}$=K$_o$ r H) and the maximum value of lateral flow pressure is found near O.3H of layer thickness(H) and is higher to ground surface than the ones in composition pattern, Poulos distribution pattern and softclay soils (CL, CH) which is not polluted. The stability control method used in this research followed the management diagram of Tominaga.Hashimoto, Shibata.Sekiguchi, Matsuo.Kawamura who use the amounts of plasticity displacement by lateral flow. As a result, the ultimate capacity values in the diagram {S$_v$-(Y$_m$/S$_v$)} of Matsuo.Kawamura and in the diagram {(q/Y$_m$)-q} of Shibata. Sekiguchi were smaller than in the ones of load-settlement curve (q-S$_v$).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3548-3556
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• 2015

In order to fulfill the needs of reliable and economically feasible foundation, engineers should consider not only the working load that can endure extreme conditions but also apprehending precise behavior of continuous dynamic load while designing the foundation of offshore wind power generators. To actualize the foundation, a model pile was made in miniature. Also, calibration chamber was made and a 500mm height of sand-bed was made to perform "static lateral load experiment" and "repetitive loading experiment", total of two Lateral load tests. As a result, in Static Lateral load test, the bigger length/diameter of model pile led an increase in load displacement. However, when performing "Cyclic Lateral load test", the increase in number of under loading led the decrease in horizontal displacement from each repeated lateral load. While performing Static Lateral load test and repeated loading experiment, we could observe the decreasing in the rate of ultimate lateral load capacity increase of the pile. Also, it turned out that the higher relative density of the ground, the lower ultimate lateral load capacity by repeated horizontal loading.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.177-190
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• 1993

When soft soils are effected by unsymmetrical surcharge due to embankement and abutements of a bridge, large plastic sheraring deformations such as settlements, lateral displacements, upheavals and sliding shearing failure in the soils occurred and they have often damaged considerabily to the soils and structure. This study examines the existing theoretical background for the behavior of the displacement of soils by unsymmetrical surcharge on the soft soils and compares the analytical results to the actual measurements performed through the model test. The procedures of model test are that a model stock device is made and soft soils are filled in a container which fixes the soils. Then the displacements observed when surcharge load increa ses by regular interval at undrainage condition. It analyzes the relation of soil characteristics to displacement, critical surcharge and ultimate bearing capadty, condition of plastic flow and lateral flow pressure, comparing them with the existing theories. Understanding the causes of lateral displacement in soft soils due to unsymmetrical surchages will prevent a damage in advance.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.57-69
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• 1999

This study investigates the existing theoretical backgrounds for bearing capacity determination according to the plasticity of soils when unsymmetrical surcharge is loaded on polluted soft soils. It also investigates the behavior of the displacement and bearing capacity by unsymmetrical surcharge on the Polluted soft soils. by comparing the analytical results and the actual measurements performed through the model test. Model tests were carried out as follows : soil tank, bearing frame and bearing plate are made for the test ; the water content in soil tank was kept constant while the contaminants in natural soils and polluted material were gradually increased ; unsymmetrical surcharge is increased at regular intervals and then the amounts of settlement, lateral displacement and upheaval are observed. In conclusion, the value of critical surcharge was expressed as $q_{ cr}= 2.78_{Cu}$ which was similar to those $Tschebotarioff(q_{cr}=3.0_{Cu)$ and $Meyerhof(q_{cr}=(B/2H+\pi/2_{Cu})$ had proposed. The value of ultimate capacity was expressed as $q_{ult}=4.84_{Cu}$ which was similar to that of Prandtl.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.69-78
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• 2016

A suction bucket foundation has been considered to be a potential foundation type for offshore wind turbines. A suction bucket foundation is usually installed in soft soil, so the accumulated displacement of the foundation may occur under long-term cyclic loads. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The dry model ground was prepared to have two different soil densities by air-pluviation method. The model tests were performed varying the embedment depth of the suction bucket, the soil density, and the amplitude of cyclic load. A one-way horizontal cyclic load was applied over $10^4$ cycles. Test results showed that the accumulated rotation of the suction bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the suction bucket foundations in dry sandy ground under long-term cyclic horizontal loads.

• Journal of the Korean Geotechnical Society
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• v.34 no.4
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• pp.49-55
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• 2018

A pre-load of bracing was imposed to prevent the horizontal displacement on the strut of the braced wall adjacent to the building during the ground excavation. For this purpose, large scale model tests were conducted, without and with pre-load on braced wall. Adjacent building load was also imposed in different locations, that were 0 m, 1D, 2D on ground surface. In this study, model tests in 1:10 scale were performed in real construction sequences, and adjacent building was 12 m in width and the size of model test pit was 2 m in width, 6 m in height, and 4 m in length. As a result, it was found that the stability of the existing building adjacent to the braced wall within Rankine's active zone could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load. which was larger than the designated axial force on the strut of the braced wall.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.3
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• pp.100-107
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• 1982

최근 철근 콘크리트 구조물의 지진하중 및 이와 유사한 진동하중에 대한 내진안전성 문제가 대두되어 이에 관한 모형공식체의 진동실험 및 실존구조물의 동적구조특성의 해석 등에 의한 내진성 향상을 위한 보강방법이 강구되고 있다. 본 연구에서는 진동하중에 파괴되기 쉬룬 철근 콘크리트 보와 기둥이 상호 교차되는 죠인트 구역의 동적파괴거동을 확인하기 위하여 "L"형 철근 콘크리트 죠인트와 부재를 제작, 모의지진하중 조건하에서의 동적 응답특성을 구명하고자 반복하중에 따른 joint구역과 보 및 기둥의 동적파괴거동을 고찰하였다. 특히 내진구조물 설계에 주요 요소인 연성(m)이 0.5, 1.0, 3.0일 때 각각 3회씩 그리고 m=5.0일 때 부재가 완전히 파괴될 때까지 4회 반복하여 반복하중을 작용시키면서 이때의 부재의 극한강도 및 그 변형성능을 LVDT System을 사용하여 조사분석하였으며, 파괴성상은 물론 배근효과에 대하여도 이를 구명하고자 노력하였다. 본 연구 결과 무엇보다도 부재의 강성과 내력의 향상 및 신축만곡, 전단변형 등의 변형성능의 개선 그리고 보의 휨파괴에 대한 보강 및 joint구역의 전단보강은 내진구조물 설계를 위하여 중요 사항임을 확인하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.1
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• pp.77-85
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• 2001

본 연구에서는 차량하중에 의한 상시진동기록을 이용한 교량의 손상추정기법을 연구하였다. 즉, 차량진행 중 측정된 신호로부터 구조물의 모드특성을 구하고, 이를 이용하여 손상위치 및 손상정도를 추정하는 알고리즘을 제안하였다. 제안기법의 검증을 위하여 차량하중을 재하할 수 있는 모형교량을 제작하여 손상실험을 수행하였다. 차량진행 중 교량의 수직가속도를 계측하였으며, 측정된 가속도시계열로부터 random decrement(RD) 기법을 사용하여 자유진동신호를 구한 후, 이로부터 구조물의 모드특성을 추정하였다. 추정된 모드특성을 기초로 신경망기법을 적용하여 손상위치 및 손상정도를 추정하였으며, 추정된 결과는 실제 손상과 비교적 잘 일치하였다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.136-143
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• 1997

본 연구에서는 철골구조물을 대상으로 지진격리(Base-Isolation)를 사용하였을 때의 진동감소 효과를 분석하기 위하여 지진하중에 대한 진동대 실험을 수행하였다. 실험 대상구조물은 $\frac{1}{4}$축소모형의 3층 철골구조물이며, 입력지진은 여러 계측기록과 UBC 설계스펙트럼으로부터 3가지 지반조건에 대하여 작성한 인공지진기록을 사용하였다. 축소 실험모형은 기초가 고정된 일반적인 철골구조물과 적층고무받침(Laminated Rubber Bearing) 형식의 지진격리장치(Base Isolator)를 사용한 구조물을 동시에 설치하여 그 지진응답을 비교 관찰하였다. 대부분의 하중하에서 지진격리장치가 사용된 철골구조물의 경우에 지진응답이 현저히 감소하는 것을 알 수 있으나, 장주기파의 성분이 강한 지반운동에 대해서는 오히려 지진응답이 증가하였다. 그러나 여러 지반조건에 대하여 UBC 시방서에서 규정한 설계하중에 대하여는 진동감소효과가 우수함을 보인다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.1
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• pp.38-51
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• 1984

Mononobe-Okabe에 의해서 옹벽에 대한 동적 토압계산법이 개발된 이래 본론두중 옹벽의 과동에 의한 변위에 대해서는 많은 연구가 이루어졌으나 Mononobe-Okabe식이 원래 옹벽 자체의 관성을 고려치 아니하였고 또 동적 하중의 작용점을 제시하지 않으므로서 전도모멘트를 계산할 수 없게 하므로서 옹벽의 전도에 의한 변위에 대해서는 연구가 되지 아니하였다. 본 연구의 목적은 해석적 방법과 모형실험을 통해서 지진 및 폭파 등의 동적 하중에 의한 옹벽의 전도에 의한 변위를 고찰하고자 하는 바 그 결과를 요약하면 다음과 같다. 1. 활동에 대한 항복가속도가 있는 것과 마찬가지로 전도에 대한 항복가속도가 있다. 이 항복가속도는 옹벽의 안전율이 증가함에 따라 증가한다. 2. 이론치와 실험치는 경향으로 보아 일치한다. 실험치가 이론치보다 작은 것은 모형실험에서 옹벽측면과 컨테이너 사이의 마찰에 기인한 것으로 보아지며 마찰을 줄임으로써 이론치에 더 접근시킬 수 있을 것이다. 3. 옹벽의 회전각도의 크기는 지반가속도가 클수록, 옹벽저면이 작을수록 그리고 흙의 내부마찰각이 작을수록 크게 증가한다. 4. 실용적인 규격의 옹벽의 변위는 활동에 의한 것보다 전도에 의한 것이 훨씬 크며 전체 변위의 대부분을 차지한다. 5. 옹벽 상단의 횡적 변위는 옹벽 설계를 결정짓는 중요한 요소가 될 수 있다.