• Geotechnical Engineering
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• v.14 no.6
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• pp.153-166
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• 1998

This paper shows the results of a series of model tests on the behavior of steel pipe pile which is subjected to lateral and inclined loads in homogeneous and non-homogeneous Nak-dong River sands. Non-homogeneous soil consisted of two layers, upper and lower layer. The purpose of the present paper is to investigate the effect of ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer and inclined load on the behavior of single pile. These effects can be quantified only by the results of model tests. As a result. in non-homogeneous sand soil, it is shown that the lateral behavior depends upon the ratio of soil modules of upper layer to lower layer more than other factors. And it was found that the relationship between the deflection ratio of non-homogeneous sand to homogeneous sand and the ratio of lower layer height to embedded pile length can be fitted to exponential function of H/L by model tests results. For the inclined load applied, it is shown that the bending moment-depth relationship is not similar to the case of laterally loaded pile and the depth of maximum bending moment at relative density of 90% increases about 70% more than the pile only loaded laterally.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.427-435
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• 2008

In this paper, review was made for the excavation method and optimum bench length for unstable tunnel face in case of rock classification type V in order to make the best use of in-situ bearing capacity. 3D FEM analyses were performed to investigate the influences on the tunnel face and adjacent area with regard to the pattern and number of bolts when face bolts were used as a supplementary measure. As a result of this study, full section excavation method with sub-bench is effective in reducing the displacement greatly due to early section closure. Displacement-resistant effects in accordance with the bolting patterns are grid type, zig-zag type and then circular type in order of their effect. And horizontal extrusion displacement of tunnel face reduces as the number of bolts increase. A grid type face bolt covering $1.5m^2$ of tunnel face could secure the face stability in case of full section excavation method with sub-bench.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.323-330
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• 2008

The ship collision analysis of steel pile group as protection system of bridge in navigable waterways was performed to analyze the structural characteristics of protective structure during ship collision. The analysis encompassed finite element modeling of ship and pile, modeling of material non-linearity, hard impact analysis, displacement-based analysis and soft impact analysis for collision scenarios. Through the analysis of hard impact with a rigid wall, impact load for each collision type of ship bow was estimated. In the displacement-based analysis the estimate of energy which protection system can absorb within its maximum horizontal clearance so as to secure bridge pier from vessel contact during collision was performed. Soft impact analysis for various collision scenarios was conducted and the collision behaviors of vessel and pile-supported protection system were reviewed for the design of protection system. The understanding of the energy dissipation mechanism of pile supported structure and colliding vessel would give us the optimized design of protective structure.

• Korean Journal of Remote Sensing
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• v.40 no.1
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• pp.19-31
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• 2024

Ports are vital social infrastructures that significantly influence both people's lives and a country's economy. In South Korea, the aging of port infrastructure combined with the increased frequency of various natural disasters underscores the necessity of displacement monitoring for safety management of the port. In this study, the time-series displacements of Yeongilman Port and surrounding areas in Pohang, South Korea, were measured by applying Permanent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) to Sentinel-1 SAR images collected from the satellite's ascending (February 2017-July 2023) and descending (February 2017-December 2021) nodes, and the displacement associated with the 2017 Pohang earthquake in the port was analyzed. The southern (except the southernmost) and central parts of Yeongilman Port showed large displacements attributed to construction activities for about 10 months at the beginning of the observation period, and the coseismic displacement caused by the Pohang earthquake was up to 1.6 cm of the westward horizontal motion and 0.5 cm of subsidence. However, little coseismic displacement was observed in the southernmost part of the port, where reclamation was completed last, and in the northern part of the oldest port. This represents that the weaker the consolidation of the reclaimed soil in the port, the more vulnerable it is to earthquakes, and that if the soil is very weakly consolidated due to ongoing reclamation, it would not be significantly affected by earthquakes. Summer subsidence and winter uplift of about 1 cm have been repeatedly observed every year in the entire area of Yeongilman Port, which is attributed to volume changes in the reclaimed soil due to temperature changes. The ground of the 1st and 2nd General Industrial Complexes adjacent to Yeongilman Port subsided during the observation period, and the rate of subsidence was faster in the 1st Industrial Complex. The 1st Industrial Complex was observed to have a westward horizontal displacement of 3 mm and a subsidence of 6 mm as the coseismic displacement of the Pohang earthquake, while the 2nd Industrial Complex was analyzed to have been little affected by the earthquake. The results of this study allowed us to identify the time-series displacement characteristics of Yeongilman Port and understand the impact of earthquakes on the stability of a port built by coastal reclamation.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.55-66
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• 2013

The experiment of model soil structures has been executed for the soil retaining wall in various conditions of excavation, in this study, to analyze the behavior of the corner of opening. The ground for experiment has been constituted with the sandy soil of relatively loose density, the construction condition has been divided into the opening length of corner, embedded depth, existence of strut, etc., and the excavation has been carried out for 4 stages in total. The behavior characteristics at the corner of opening area has been verified by concentrate analysis of the displacement of wall and the subsidence of ground surface, for each construction and excavation condition, using the measuring instrument mounted inside the model soil structure. In the result of experiment, it has been analyzed that the opening area of corner is unstable structurally compared to the linear area, as it shows that the wall displacement and subsidence of ground surface have been increased when the opening length of corner gets longer. The longer the embedded depth, ground surface settlement of coner was decreased 40%. To apply deeper embedded depth than designed estimate was an advantage in the safety. As a result of the analysis of coner behavior with added struts, maximum surface settlement and maximum horizontal displacement was evaluated 40% and 30%, respectively. Hence increased embedded depth with the added struts in coner edge was effective in the safety.

• Tunnel and Underground Space
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• v.27 no.3
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• pp.146-160
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• 2017

$CO_2$ sequestration for alleviating global warming is a hot issue in the world. In this study, TOUGH2 and FLAC3D were combined for analyzing the hyro-mechanical coupling behaviors expected in $CO_2$ sequestration and applied it to Sleipner project carried out in Norway. In the analysis, the influence of pore pressure on in situ stress was considered and the influence of caprock permeability on hydro-mechanical behaviors was analyzed. In the condition of constant injection rate, pressure and saturation at the injection well, liquid and gas saturation in rock, major and minor stress variations with time and distance from the injection well, and horizontal and vertical displacements after injection could be investigated. The major principal stress was quickly increased in the early stage and then slowly decreased to a stable value, which was higher than the initial value. In contrast, the minor principal stress returned to initial value after some increase in the early stage. Surface upheaval was steadily increased and it was up to 15mm in 2 years after injection. When the caprock's permeability was changed from $3e-15m^2{\sim}3e-18m^2$, it was found that the injection well pressure and surface upheaval were inversely propotional to the permeability.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.197-197
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• 2011

최근 들어 전력 사용량의 증가로 인한 화력발전소의 부산물인 석탄회 중 바텀애시와 각종 공공사업과 관련하여 해마다 현장발생토의 발생량이 지속적으로 증가하고 있는 추세이다. 바텀애시와 현장발생토사를 효과적으로 재활용하는 방법 중 유동성 뒤채움재를 개발하여 활용하는 방안을 모색하기 위한 연구이다. SP로 분류된 흙 현장발생토와 서천 화력발전소에서 발생하는 석탄회 중 입경이 0.9~1.5mm의 바텀애시만을 선별하여 현장발생토와 바텀애시의 비율을 7 : 3으로 변환한 최적배합을 선정하여 강재로 제작된 가로 80cm, 세로 60cm, 높이 90cm의 모형토조를 이용하여 실험을 진행하였으며, 사용상 지하 매설이 되는 관의 거동 특성은 확인하기 위하여 내경 30cm, 두께 8mm의 연선관 중 하나인 PVC관을 원형지하매설관으로 선정하여 배합을 타설하는 과정과 타설 후 7일간의 양생기간을 거친 후 차량하중으로 가정할 수 있는 하중을 가하여 원형지하매설관의 관외부에서 수직방향과 수평방향의 토압과 관내부의 수직 수평방향 변위 그리고 관 자체의 횡 종단 변형을 측정하여 원형지하매설관의 거동특성을 파악하였다. 타설시 지하매설관은 유동성 뒤채움재의 특성으로 인하여 시간이 지남에 따라 안정화되는 것을 확인할 수 있었으며, 최대하중을 3300kgf로 하여 하중 재하 후 지하매설관의 거동특성은 대체적으로 일반 모래를 사용하여 실험한 값보다 적은 변형 특성을 보이고 있으나 수평토압의 경우 일반적인 흙의 변형과 전혀 상이한 결과값을 보이는 경우도 있어 추가적인 실험 및 고찰의 필요하다. 본 실험에서 사용한 최적배합비 이외의 배합으로 같은 실험을 수행하여 바텀애시 량의 가감 및 재활용 재료인 폐타이어 고무칩등을 첨가한 실험을 계획하고 있으며 추후 실내시험과 모형실험을 토대로 유한요소해석을 추가로 시행하여 실험값과 해석값의 비교를 할 예정이다.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.177-177
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• 2011

현재 대부분 사용되는 지하매설물용 뒤채움재는 다짐공법을 많이 사용하고 있으며, 실제로 이러한 방법은 부적절한 다짐으로 인해 침하 및 내구성 저하로 인해 파손을 초래하는 경우가 많다. 이러한 문제를 해결 할 수 있는 하나의 대안으로 유동성 뒤채움재를 이용할 수 있다. 유동성 뒤채움재는 초기 유동성, 시간에 따른 자기 강도 발현 무다짐공법 적용 등 많은 장점을 가지고 있다. 본 연구에서는 현장발생토사, 정수장슬러지 및 폐타이어분말 등 재활용 재료를 이용한 유동성 뒤채움재의 기본물성을 평가하였다. 각각의 재활용재료에 대한 입도 및 비중을 평가하였고, 최적배합설계를 결정하였으며, 모형 시험과 유한요소 해석을 위한 기본 물성값을 위해 일축압축시험, 삼축압축시험, 공진주시험 등을 수행하였다. 최적배합설계를 산정하는 과정에서 수행한 실험중 대표적인 시험으로 자가수평능력 및 자기다짐등에 필요한 유동성을 판단하는 Flow시험(ASTM D 6133) 결과 기준으로 정한 20cm이상의 값을 얻을 수 있었으며 일축압축강도의 경우 시공 후 유지 보수가 용이한 강도인 $3.0kg/cm^2{\sim}5.6kg/cm^2$이하로 설계하였으며 28일재령 일축압축강도 결과 $3.15{\sim}3.74kg/cm^2$라는 유지보수에 적당한 결과값을 나타내었다. 이 배합이 현장에서 사용이 가능하다는 것으로 판단하고 현장모형시험과 유한요소해석를 통하여 현장에서 사용하였을 때 관의 변형과 관에 작용하는 하중변화를 확인하고 현장모형시험과 유한요소해석 간의 상관관계를 규명하였다. 현장 모형 시험은 현장과 비슷하게 제작된 모형을 이용하였으며 최대한 현장과 비슷한 조건에서 뒤채움재를 타설과정 중과 타설이 완료된 상태에서 7일 양생 후 하중재하와 같이 두가지 경우에서 수직 수평토압, 관의 수직 수평변위, 관의 종단변형을 측정하였다. 유한요소해석 프로그램은 Midas GTS를 이용하여 실시하였으며 관의 변형률, 유효응력을 측정하여 규명하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.245-256
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• 2008

The steel rib, one of the main support of tunnel, plays a very important role to stabilize tunnel excavation surface until shotcrete or rockbolt starts to perform a supporting function. In general, a steel rib at the horizontal funnel is being installed in the direction of gravity which is known favorable in terms of constructability and stability. However, as the direction of principal stress at the inclined tunnel wall is different from that of gravity, the optimum direction of steel rib could be different from that at the horizontal tunnel. In this study, a numerical method was used to analyze the direction of force that would develope displacement at the inclined tunnel surface, and that direction could be the optimum direction of steel rib. The support efficiency of steel rib could be maximized when the steel rib was installed to resist the displacement of the tunnel. Three directions which were recommended for the inclined tunnels in the Korea Tunnel Design Standard were used for the numerical models of steel rib direction. In conclusion, the results show that all displacement angle of the models are almost perpendicular to the tunnel surface regardless of face angle. So if the steel rib would be installed perpendicular to the inclined tunnel surface, the support efficiency of steel rib could be maximized.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.597-605
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• 2019

IPM bridge is an integral bridge that can be applied from span 30.0m up to 120.0m, the shape conditions of IPM bridge is also applicable to the rahmen bridge. In this study, to perform the structural analysis of Rahmen bridge and IPM Bridge, the researchers compared the distribution types such as load, moment, and displacement of those bridges. Structural analysis was carried out on four span models ranging from single span bridges to four spans of 120.0 m, based on span length of 30.0 m. Structural analysis was carried out on those bridge with span 30.0m up to 120.0m. The conclusions drawn from this study are as follows. 1) The bending moments were calculated to be large for the Rahmen bridge, and the horizontal displacements were estimated to be large for the IPM bridge. 2) Since the bending moments are derived by the span length rather than the extension of the bridge, the permissible bending moment for the span length should be considered in the design. 3) The pile bent of the IPM bridge did not exceed the plastic moment of the steel pipe pile at 120.0m span, but because the horizontal displacement in the shrinkage direction is close to 25mm, the design considerations are needed. 4) In the actual design, it is important to ensure stability against member forces, so review of the negative moment is most important.