• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.360-366
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• 2004

This paper presents a method analyzing the motion of cylindrical buoy moored at 2 points and tensions action on each mooring line under the action of periodic waves. It was found that submersible buoy was more effective than floating one in the severe conditions considering its dynamic motions, wave forces, and mooring line tensions. The wave induced its dynamic responses and mooring line tensions peak when the ratio d/${\lambda}$ of the buoy length d to the waves length ${\lambda}$ was 0.66 due to its natural frequency. The results of this study were in agreement with the existing measurement ones, however, further verifications are needed considering resonance of cylindrical buoy and its displacements to wave height by a series of model tests.

• Geotechnical Engineering
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• v.9 no.2
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• pp.5-14
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• 1993

Weathered granite soil is the most representative as a surface soil in Korea. In this paper, the dynamic properties and settlement characteristics of Korea granite soil are studied through the dynamic triaxial compression tests. The dynamic characteristics are very important on the analysis of the foundations under dynamic loading such as machine vibration and earthquake. Soil samples having different grain sixtes were prepared at the relative densities between 80oA and 90oA and tested to measure shear moduli and damping ratios at each level of shear strain. The measured shear moduli of weathered granite soils showed large variations according to the grain sizes, confining pressures, relative densities and shear strains. Sandy weathered granite had a little larger dynamic properties than the average values of the sand studied by Seed and Idriss. Pot the well compacted granite soils, little residual settlements occured due to dynamic loading.

• Journal of the Korean Geotechnical Society
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• v.37 no.8
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• pp.15-24
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• 2021

Recently, cases for inevitable adjacent construction are increasing due to the limited spaces in urban area. When a new structure is constructed near an existing structure, interference effects induced by the pre-existing structure should be considered. Thus, numbers of studies have been conducted to investigate the effects of adjacent construction, while laboratory scales studies are not well reported. In this study, laboratory scale experiments have been conducted to investigate the bearing capacity and settlement variations with different adjacent construction cases. Results show an optimistic ground bearing capacity increase of the new foundation structure due to the existing foundation structure, while concerns on the increased settlement of the pre-existing structure. Thus, both bearing capacity of the new foundation structure and subsequent settlement of the existing foundation structure have to be considered when assessing the technical applicability of adjacent structure construction on site.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.485-502
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• 2021

In order to evaluate the impact of ground subsidence and superstructures that are inevitably caused by tunnel excavation, a total of seven major influencing factors of surface subsidence and structural soundness reduction were set, and a Parameter Study using numerical analysis was conducted. Stability analysis was performed using scheme of Boscardin and Cording method and the maximum subsidence amount and the angular displacement, and correlation analysis was performed for each major influencing factor. In addition, it was applied that used the mutual behavior of the ground and the structure by parameter analysis in the site of the 𐩒𐩒𐩒 tunnel located in Hwaseong-si, Gyeonggi-do, and the applicability of the site was analyzed. As a result, the error was found to be 1.0%, and it could be used as a basic material for determining the appropriate tunnel route under various conditions when evaluating the stability of the structure according to tunnel excavating at the design stage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.977-988
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• 1994

In this paper, the comparisons between field measurments and numerical results ware performed for the settlements, lateral displacement in Jinwol interchange works on the Honam express way whose site was improved by sand drain for the constructions of over bridges, piers and abutments. The computer program was developed by coupling Biot's equation with Sekiguchi's elasto-viscoplastic model under plane strain conditions. Steel pipe piles for piers were replaced into the equivalent steel sheet pile wall. The characteristics of behavior for both the soil foundations and the sheet piles wall were investigated with the variation of axial force on the wall, rigidity of the wall, supported condition of sheet pile into hard strata and the location of anchored point.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.25-37
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• 2023

Cellular Foundation Mattress made of new materials such as high density polyethylene, are not currently use for the foundation of small and medium-sized buildings in Korea. Therefore, they need to be developed and verified based on domestic ground and field conditions. This study presents the basic design and construction method of Cellular Foundation Mattress. Since the foundation reinforcement effect of Cellular Foundation Mattress should be evaluated and verified for soft ground, a performance comparison evaluation was conducted using the Soilbag method, which is commonly used for the foundation of small and medium-sized buildings in Korea. After the mattress reinforcement, the settlement amount decreased by 38.4% compared to the original ground and the bearing capacity increased by 159%, confirming the same ground reinforcement effect and ground stability as the Soilbag method.

• Journal of the Korean Geotechnical Society
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• v.26 no.8
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• pp.39-47
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• 2010

In recent days, the foundations of huge structures in general and mega foundations of grand bridges and high-rise buildings in particular are required in geotechnical engineering. This study described 3 dimensional behavior of mat foundation on soft rock based on a numerical study using 3D finite element method. A series of numerical analyses were performed for various soil conditions and mat rigidities under vertical loading. Based on the results of the parametric study, it is shown that the prediction of the settlement, cross sectional tensile stress and bending moments in the mat is overestimated in the analysis without considering interface behavior in comparison with the analysis considering interface between mat and rock mass.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.5-12
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• 2004

Soft foundation is extensively distributed in coastal areas including our local regions. Embankment load on such soft foundation causes displacement due to lack of base ground supports. Long-term consolidation can result in settlement and destruction of shear failure and structure. Therefore, a variety of vertical drain methods are applied to construction sites to prevent base from breaking and changing for secure construction. This study analyzed the patterns of changes displacement to determine efficient range of improvement since range of vertical drain material determines vertical and horizontal changes based on the width range of under ground improvement. Changes of intensity with distance from embankment edge were also analyzed in the field study of embankment slope.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.308-308
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• 2017

국내 하천에 설치된 횡단구조물은 2009년을 기준으로 약 20,753개로 알려져 있으며 수위 유지, 하상고 유지 등의 목적을 가지고 설치된다. 그러나 낙차를 가진 빠른 유속의 흐름을 형성시켜, 하류 하상에서 국소 세굴을 발생시킨다. 이를 방지하기 위해 횡단구조물 하류에 굴요성 구조(flexible structure)인 돌망태, 블록공, 사석 등으로 이루어진 바닥보호공(bed protection)이 설치되나 유실, 침하 등의 문제가 빈번히 발생되고 있어, 문제를 해결하기 위한 연구가 필요하다. 본 연구는 이러한 피복 대책에서 일어날 수 있는 파괴 기구인 전단파괴, 흡출 파괴, 경계 파괴, 하상 형태 변화에 따른 하부 침식 중 흡출 파괴(winnowing failure)를 유발하는 흐름을 검토하기 위한 수치모의를 수행하였다. 이때 흡출 파괴는 바닥보호공의 공극으로 미세한 하상 재료가 난류와 침투류의 작용에 의해 침식되어 바닥보호공이 침하되는 것을 말한다. 수치모의는 전산유체동역학(Computational Fluid Dynamics, CFD) 모형인 FLOW-3D 모형을 이용하였으며, 난류 모형으로 LES 모형을 적용하고 조밀한 격자를 부여하여 바닥보호공의 공극에서 발생되는 비교적 작은 척도의 와(vortex)를 해상할 수 있도록 하였다. 수치모의에 적용된 횡단구조물은 보, 물받이공, 바닥보호공으로 구성하였으며 특히, 바닥보호공의 형상은 구체(sphere)로 가정하여 다층으로 배치하였다. 바닥보호공의 공극 또는 구체 사이에서 발생되는 유속, 압력 등의 흐름특성을 분석한 결과, 바닥보호공 두께가 두꺼울수록 흡출 파괴에 대해 안정적인 것으로 나타났다. 이는 바닥보호공 설계를 위한 기초자료로 활용될 수 있으며, 향후 입자영상유속계(Particle Image Velocimeter, PIV)와 같이 공극에서 흐름을 측정할 수 있는 방법과 병행한 연구를 수행할 수 있을 것이다.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.711-719
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• 2006

A series of geotechnical centrifuge model tests and numerical modelling have been performed to study engineering characteristics of the composite ground reinforced by both the Sand Compaction Piles(SCPs) and the deformation-reducing sheet piles. The research has covered several key issues such as the load-settlement relation, the stress concentration ratio and the final water content of the ground Totally three centrifuge tests have been conducted by changing configuration of the sheet piles, i.e., a test without the sheet pile, a test with the sheet pile at a single side and a test with the sheet piles at the both sides. In the model tests, a vertical load was applied in-flight on the ground surface. On the other hand, class-C type numerical modelling has been performed by using the SAGE-CRISP to compare the centrifuge test results using an elasto-plastic model for SCPs and the Modified Cam Clay model for the soft clay. It has been found that the sheet piles can restraint failure of foundation, thereby increasing yield stress of the ground. The stress concentration ratio was in the range of $2{\sim}4$. In addition, numerical analysis results showed reductions both in the ground heave($20{\sim}30%$) and in the horizontal movement($28{\sim}43%$), demonstrating the deformation-reducing effect of the sheet piles.