• 산업기술연구
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• 제25권B호
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• pp.55-62
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• 2005

This paper is the results of experimental and numerical works on analyzing the geotechnical engineering behavior and characteristics of excavated clay slope formed by the method of excavated replacement which is one of treatments in soft soil ground. For the centrifuge model tests, models of excavated clay slope were prepared by remolding the marine clayey soil sampled from the field. Tests were performed with changing the slope to investigate the behavior of them. On the other hand, numerical analyses were carried out to analyze the change of safety factor against instability of slope with time. Changes of pore water pressure, shear strength and displacement were also investigated. As results of centrifuge model tests with slopes of 1:1.5 and 1:3 using the confining body of simulating the effect of excavation, for the case of 1:1.5, slope failure occurred right after remove the confining body whereas relatively small displacements within the range of 3.2mm, implying to maintain the stability of slope, were observed for the case of 1:3 slope. From the results of numerical analyses using the software of PLAXIS to investigate the stability of slope after excavation, the minimum safety factor against slope failure was 1.28 for the case of 1:3 slope. The further researches in the future are required with considerations of build up of static pore water pressures during acceleration of centrifuge, depth of excavation influencing the behavior of the slope and permeability of the slope since excavation of the slope was not simulated well resulted from the limitations of apparatus at the stage of excavation during the centrifuge tests.

• Smart Structures and Systems
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• 제24권6호
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• pp.793-802
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• 2019

The centrifuge model test is usually used for two-dimensional deformation and instability study of the soil slopes. As a typical loose slope, the municipal solid waste (MSW) landfill is easy to slide with large deformation, under high water levels or large earthquakes. A series of centrifuge model tests of landfill slide induced by rising water level and earthquake were carried out. The particle image velocimetry (PIV), laser displacement transducer (LDT) and marker tracer (MT) methods were used to measure the deformation of the landfill under different centrifugal accelerations, water levels and earthquake magnitudes. The PIV method realized the observation of continuous deformation of the landfill model, and its results were consistent with those by LDT, which had higher precision than the MT method. The deformation of the landfill was mainly vertically downward and increased linearly with the rising centrifugal acceleration. When the water level rose, the horizontal deformation of the landfill developed gradually due to the seepage, and a global slide surface formed when the critical water level was reached. The seismic deformation of the landfill was mainly vertical at a low water level, but significant horizontal deformation occurred under a high water level. The results of the tests and analyses verified the applicability of PIV in the two-dimensional deformation measurement in the centrifuge model tests of the MSW landfill, and provide an important basis for revealing the instability mechanism of landfills under extreme hydraulic and seismic conditions.

• 한국지반공학회논문집
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• 제23권10호
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• pp.109-119
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• 2007

CFRD 형식의 댐 건설이 증가함에 따라 CFRD 거동에 대한 보다 정확한 분석 및 평가가 필요하게 되었다. 수위 변화에 따른 댐 거동은 댐 설계자와 관리자의 주요 관심사이지만, 국내의 경우 관련 연구가 충분히 진행되지 않아 아직도 많은 경우 국외 사례에 의존하고 있는 실정이다. 본 연구에서는 콘크리트 차수벽 강성이 서로 다른 세 가지 원심모형실험을 통해 수위변화에 따른 CFRD 거동을 정량적으로 평가하였다. 원심모형실험은 국내에서 운영 중인 D댐의 1/2크기의 원형으로 수행되었으며, 모형 준비, 설계, 모형 구축, 계측기 설치, 실험 절차를 상세히 제시하였다. 콘크리트 차수벽은 3 종류의 유리섬유판을 통해 모사하였으며, 비행 중 수위조절을 위한 특별히 장치를 고안하였다. 국내 외 댐 계측사례를 수집 정리하여 본 원심모형실험 결과와 비교하였으며, 그 결과 본 원심모형실험은 실제 댐 거동을 비교적 높은 정확도로 모사하였음을 확인하였다.

• 대한토목학회논문집
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• 제28권4C호
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• pp.221-230
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• 2008

캐나다 서부 밴쿠버 지역의 Fraser강 바닥의 사질토 지반에 위치한 George Massey 침매터널이 지진 시에 어떻게 거동하는 지를 연구하였다. 지진으로 발생하는 간극수압을 계산할 수 있는 유효응력모델인 UBCSAND모델을 이용하여 지진하중으로 인한 지반의 변위와 침매터널의 거동을 예측하였으며, 이를 미국 Rensselaer Polytechnic Institute(RPI)에서 실시한 원심모형실험 결과와 비교하였다. 본 연구에서 해석한 George Massey 침매터널의 원심모형실험은 2개의 모델로 구성되었으며, Model 1은 기본 모델로서 원상태 지반을, Model 2는 다짐공법으로 지반개량을 실시한 지반을 모델링하였다. 원심모형실험 Model 1에서 설계지진으로 인한 주변 지반의 액상화로 모형터널의 변위가 크게 발생하였다. Model 2에서 다짐공법으로 터널 주변 지반을 개량하였을 때 모형터널의 수직 및 수평 변위는 Model 1보다 50% 정도 감소하였다. UBCSAND모델은 원심모형실험에서 계측된 과잉간극수압, 가속도, 변위를 비교적 잘 예측할 수 있었다. 이와 같이 검증된 수치해석방법은 유사한 지반에 설치된 침매터널의 지진 시 변위와 거동을 예측할 수 있으며, 액상화에 대한 지반개량공법과 개량범위를 체적화할 수 있을 것으로 판단된다.

• 산업기술연구
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• 제17권
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• pp.111-118
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• 1997

This thesis is an experimental research of investigating behavior of single pile, subjected to the vertical compression loads, using the centrifuge facility located in the geotechnical engineering laboratory in Kangwon National University. Centrifugal model experiments of model pile were carried out changing diameter of model pile, relative density of sandy ground and the gravitational level applied in the centrifuge. Thus, their effects on the load-settlement behavior and the ultimate bearing capacity of pile were investigated. Experimental results obtained from centrifuge model tests were compared with the theoretical or semi-empirical equations to analyze values of ultimate bearing capacity of model pile. When we compare the ultimate bearing capacity of experimental results with the ultimate bearing capacity of theorical results, the experimental results appear more higher in the De Beer method and Meyerhof. Expecially, Terzaghi method is very same as the experimental results normally.

• 한국지반공학회논문집
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• 제21권2호
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• pp.121-126
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• 2005

건축구조물이나 합 등의 구조물이 부등침하의 영향으로 기울어지게 되는 것은 그리 드문 현상이 아니다. 그동안 구조물의 기울기를 감소시키기 위한 다양한 공학적인 해결방안이 시도되어 왔는데, 그 가운데는 soil extraction 공법도 포함되어 없다. 본 논문에서는 최신의 로보트 굴착장비를 이용한 2개의 원심모형실험을 실시하여 soil extraction공법을 이용하여 기울어진 건물의 경사를 감소시키는 데 있어서의 주된 요소에 대한 연구를 실시하였다. 원심모형실험에서는 모형토조가 고속으로 회전하는 가운데 로보트를 이용하여 기울어진 건물의 주변에 구명을 천공하였다. 지반에 구멍을 천공함으로 지중응력의 감소를 유도하여 건물의 기울기를 성공적으로 감소시킬 수 있었다. 원심모형실험을 통해서 분석된 천공의 순서, 지반의 밀도 및 배열 등이 건물의 기울기를 감소시키는 정도에 대하여 심도 있는 연구를 실시하였다.

• Geomechanics and Engineering
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• 제33권4호
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• pp.415-425
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• 2023

Pile-supported wharves, port structures that support the upper deck, are installed on sloping ground. The sloping ground should be covered with a rubble mound or artificial blocks to protect the interior material from erosion caused by wave force. The behavior of the pile may vary during an earthquake if a rubble mound is installed on the slope. However, studies evaluating the effect of rubble mound on the pile during an earthquake are limited. Here, we performed dynamic centrifuge model tests to evaluate the dynamic behavior of piles installed in a slope reinforced with rubble mound. In the structure, some sections (single-pile, 2×2 group-pile) were selected for the experiment. The moment of the group-pile decreased by up to 26% upon installation of the rubble mound, whereas the moment of the single-pile increased by up to 41%, thus demonstrating conflicting results.

• Geomechanics and Engineering
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• 제27권5호
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• pp.447-463
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• 2021

Caisson-type structures are widely used as quay walls in coastal areas. In Korea, for a long time, many caisson-type quay walls have been constructed with a low front water depth. These facilities can no longer meet the requirements of current development. This study developed a new technology for deepening existing caisson-type quay walls using grouting and rubble mound excavation to economically reuse them. With this technology, quay walls could be renovated by injecting grout into the rubble mound beneath the front toe of the caisson to secure its structure. Subsequently, a portion of the rubble mound was excavated to increase the front water depth. This paper reports the results of an investigation of the seismic behavior of a renovated quay wall in comparison to that of an existing quay wall using centrifuge tests and numerical simulations. Two centrifuge model tests at a scale of 1/120 were conducted on the quay walls before and after renovation. During the experiments, the displacements, accelerations, and earth pressures were measured under five consecutive earthquake input motions with increasing magnitudes. In addition, systematic numerical analyses of the centrifuge model tests were also conducted with the PLAXIS 2D finite element (FE) program using a nonlinear elastoplastic constitutive model. The displacements of the caisson, response accelerations, deformed shape of the quay wall, and earth pressures were investigated in detail based on a comparison of the numerical and experimental results. The results demonstrated that the motion of the caisson changed after renovation, and its displacement decreased significantly. The comparison between the FE models and centrifuge test results showed good agreement. This indicated that renovation was technically feasible, and it could be considered to study further by testbed before applying in practice.

• 한국지반공학회논문집
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• 제22권5호
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• pp.59-67
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• 2006

동일한 흙으로 조성된 모형지반에 대하여 1-g 모형실험과 원심모형실험을 수행하고 그 결과를 비교하였다. 원형지반은 10m 두께의 수평하고 느슨한 포화 사질토 지반으로 가정하였다. 1-g 모형실험은 1/20 축소모형, 원심모형실험은 1/40 축소모형을 이용하였다. 원심모형실험의 경우 점성유체를 사용하여 동적시간에 대한 상사비와 과잉간극수압소산시간에 대한 상사비가 동일하도록 하였다. 원심모형실험의 계측결과는 원형지반의 거동으로 가정하였다. 그리고, 1-g모형실험에 정상상태개념 및 두 가지 시간상사비 등을 적용하여 원형지반의 거동을 모사하고자 하였다. 동일한 위치에서의 과잉간극수압, 지반가속도 그리고 지표 침하량 등을 계측하여 비교하였다. 실험결과 지반의 투수계수가 작아서 진동 중 과잉간극수압 소산의 영향이 작고, 소산시간상사비를 적절하게 결정하면 1-g 모형실험으로부터 원형지반의 과잉간극수압 거동을 모사할 수 있는 것으로 나타났다.

• 산업기술연구
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• 제26권A호
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• pp.101-108
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• 2006

This study is the results of experimental and numerical study on the consolidational behavior of multi-layered soft soil ground installed with plastic board drains (PBD). Centrifuge model tests with a marine clay sampled from field were performed to investigate the consolidational behavior of multi-layered ground where a dredged soil was placed on the soft clay ground and PBDs were installed. Test results were compared with those of numerical analyses, using the 2-D equivalent model previously proposed. From test results, it was found that the amount of consolidation settlement occurred in the original ground due to embankment surcharge loads was in the range of 38% of total settlement in the whole ground. From the results of cone penetration tests executed after finishing the centrifuge model tests, the cone resistance was found to increase with depth. The measured water contents inbetween PBDs were in the ranges of 38~50% and their values tended to increase with increasing the distance between PBDs.