• Journal of the Korean Geotechnical Society
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• v.29 no.5
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• pp.5-17
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• 2013

This study investigates the effect of thermal stress on axial load and pile settlement of PHC energy piles. A series of numerical analyses were performed by controlling major influencing parameters such as pile arrangement, pile spacing, end-bearing condition, soil condition and pile cap stiffness. It is found that the characteristics of pile-load transfer are significantly affected by seasonal operation mode (i.e., cooling and heating) throughout the year. Also, the axial load under thermal loading increases with increasing the pile spacing. The settlement of the pile in sand is larger than that in clay because of the thermal stress generated. It is also found that thermal stress highly influences on the end-bearing pile, corner pile and rigidity of pile cap.

• Computational Structural Engineering
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• v.10 no.1
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• pp.193-200
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• 1997

Even though there are many analysis methods of circular tanks on elastic foundation, the finite element method is widely used for that purpose. But the finite element method requires a number of memory spaces, computation time to solve large stiffness equations. In this study many the simplified methods(Analogy of Beam on Elastic Foundation, Foundation Stiffness Matrix, Finite Element Method and Transfer Matrix Method) are applied to analyze a circular tank on elastic foundation. By the given analysis methods, BEF analogy and foundation matrix method, the circular tank was transformed into the skeletonized frame structure. The frame structure was divided into several finite elements. The stiffness matrix of a finite element is related with the transfer matrix of the element. Thus, the transfer matrix of each finite element utilized the transfer matrix method to simplify the analysis of the tank. There were no significant difference in the results of two methods, the finite element method and the transfer matrix method. The transfer method applied to a circular tank on elastic foundation resulted in four simultaneous equations to solve completely.

• Geotechnical Engineering
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• v.1 no.2
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• pp.7-16
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• 1985

The behaviour of buried rigid pipe under embankment is analysed by a linear finite element program to study the influence of variation of the geometry of soil-conduit pipe system and elastic modulus of soil on the pipe response. The geometry of the system considered includes the thickness of pipe, the height of embankment, and the width arid the depth of trench. The normal contact pressure distribution around the pipe and the vertical load on the pipe are modelled by a multiple linear regression. And the vertical load on the pipe computed by Marston-Spangles Theory Is generally larger than that by finite element analysis. The settiement ratio in Marston-Spangler Theory is found to be variable for various for various of all factors mentioned above.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.183-186
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• 2010

교각에서의 기초세굴 단계 및 상부구조물의 영향에 따른 진동특성을 파악하기 위해 교각 시험체를 이용하여 충격진동실험과 Midas FEA ver.2.0를 이용한 유한요소해석을 수행하였다. 기초세굴 모의는 교각시험체 기초 주위의 지반을 단계별로 굴착하였으며, 상부구조물의 영향은 철근콘크리트 블록을 제작하여 교각 시험체 위에 재하하였다. 충격진동실험과 수치해석결과, 강성이 작아지거나 질량이 커질수록 1차 모드 고유진동수도 작아지는 등 유사한 경향을 나타내었다. 대체적으로 충격진동실험으로 구한 1차모드 고유진동수는 수치해석으로 구한 값보다 작은 경향을 나타내었으며, 이는 지반의 강성변화를 수치해석 모델에서 연속적으로 반영하지 못하는 한계로 인해 발생한 오차로 판단된다. 따라서 1차 모드 고유진동수의 변화를 이용한 교각 세굴 건전성 평가를 위한 유한요소해석을 위해서는 지반물성을 보다 잘 모의할 수 있는 기법의 개발이 필요하였다.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.157-168
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• 2000

토류구조물의 안정문제로는 장단기적으로 정적인 경우와 동적인 경우, 그리고 지반의 동적 거동특성, 흙의 강도저하 등을 미리 파악하여 기술적인 대처를 할 필요가 있을 것이다. 본 연구에서는 실내 모형 실험을 통하여 구조물의 배면에 토성이 다른 일반모래, 표준모래, 점성토를 뒷채움하여 다짐없이 강사만 하고, 룰러다짐, 진동다짐을 하여 토피의 수평 진동거리를 길게, 짧게 그리고 중간으로 하여 강성벽체에 작요？는 수평토압에 대한 정적, 동적 특성을 규명하는 것이다. 모형 실험장치로는 실험대, 토조, 토압측정장치, 진동하중 발생장치, 진동측정장치, 강사기, 롤러 등을 설치하여 거리에 따른 병진운동으로 가속도와 수평토압, 수평토압계수, 전체토압, 토압의 작용점, 지진토압증분 증을 구하여, 실험결과와 기존 이론결과, 그리고 유한요소 해석결과와 비교 고찰하였다.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.153-162
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• 2007

For the reinforced earth wall constructed on a soft ground in parallel with replacing soft soils, the behavior of the wall according to variations of thickness and stiffness of soft layer, replacement depth, and wall height is investigated using a finite element method, in which incremental construction steps including consolidation of soft soil layer are considered. The behavior of wall is characterized by investigating displacements and settlements developing at the wall, and shear strains developing in a soil deposit. The stability of wall is, then, evaluated by comparing these values with the safety criteria determined on the basis of the literature. Based on the investigation, it is shown that the behavior of wall is influenced naturally from soft soil thickness(t), replacement depth(d) and wall height(h), but more significantly from d and h. In addition, it is also shown that the normalized replacement depth, d/h, required for the safety of wall is not influenced significantly by the variations of t and h. Consequently, it can be concluded that the proper replacement depth can be suggested in an equivalent value in terms of d/h, even for the cases where the wall height is varying with stations, but the variation is not significant.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.71-81
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• 2005

Surface wave techniques were initially based on 2-D plane waves and were later improved to the techniques based the 3-D based cylindrical waves. However, body-wave interference, near-field effect and limited technology in surface wave measurements restricted the use of 3-D cylindrical waves to the 1-D evaluation of subgrade stiffness. In this study, by the numerical simulation of SASW measurements, the dispersion properties of surface waves including vertical, horizontal Rayleigh waves and Love waves were thoroughly investigated in the 3-D domain, and a new filter criteria to minimize the near-field effect was established, which led to CAP (common-array-profiling)-SASW technique. The CAP-SASW technique enabled the evaluation of subgrade stiffness fur a specific subgrade segment, not for a whole section of measurement array. Therefore, a contour plot of subgrade stiffness with a ground-truth quality can be obtained by the CAP-SASW technique. The procedure proposed in this study was verified by comparing the shear-wave velocity profiles with the shear-wave velocity profiles of downhole testing at two geotechnical sites.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.1
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• pp.27-41
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• 2023

Submerged floating tunnels must be connected to the ground to connect continents. The displacement imbalance at the shore connection between the underground bored tunnel and submerged floating tunnel can cause stress concentration, accompanying a fracture at the shore connection. The elastic joint has been proposed as a method to relive the stress concentration, however, the effect of the elastic joints on the dynamic behavior should be evaluated. In this study, the submerged floating tunnel and shore connection under dynamic load conditions were simulated through numerical analysis using a numerical model verified through a small-scaled physical model test. The resonant frequency was considered as a dynamic behavioral characteristic of the tunnel under the impact load, and it was confirmed that the stiffness of the elastic joint and the resonant frequency exhibit a power function relationship. When the shore connection is designed with a soft joint, the resonant frequency of the tunnel is reduced, which not only increases the risk of resonance in the marine environment where a dynamic load of low frequency is applied, but also greatly increases the maximum velocity of tunnel when resonance occurs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.1
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• pp.37-47
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• 2007

The shield tunneling method has been increasingly employed to minimize environmental damages and civil complaints in the populated and developed area. A lining segment, which is a main structure of the shield tunnel, consists of joints. Conventional foreign and domestic design data have been commonly used for design practices without a specific verification of structural analysis models, design load, and the effect of soil characteristics on the performance of lining segment. In this study, the suitability of existing analytic models used for the design of shield tunnel lining segment has been evaluated through a comparison between analytical and numerical solutions. Based on the evaluation of their suitability performed in the study, a full-circumferential beam jointed spring model (1R-S0) is proposed for design practices by considering user's convenience, the applicability of field conditions and the accuracy of analysis result. By using the proposed model, the parameter analysis was performed to investigate the effects of joint stiffness, ground rigidity, joint distribution and the number of joints on the behavior of lining segment. Parameters considered in the investigation have been appeared to affect the behavior of lining segment. Among those parameters, joint stiffness has been appeared to have the most significant effect on the bending moment and displacement of lining segment.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.11a
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• pp.21-30
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• 1997