• The Journal of Engineering Geology
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• v.17 no.4
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• pp.601-613
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• 2007

It is reported that factors affecting the behavior of reinforced earth retaining walls built on soft ground are not only basic physical properties but also the increase of load by the reinforced earth retaining walls, consolidation period, pore water pressure, etc. This study analyzed the behavior of reinforced earth retaining walls and soft ground using SAGE CRISP, a ground analysis program. First, we examined the effect of the replacement method, which was to prevent the excessive displacement of reinforced earth retaining walls, in improving the behavior of the walls. Second, we compared and analyzed how the behavior of ground is affected by the vertical interval of stiffeners on the back of reinforced earth retaining walls after the application of the replacement method. Lastly, we proposed the optimal replacement width and depth in the application of the replacement method. The results of this study proved that the replacement method is considerably effective in improving the behavior of reinforced earth retaining walls. In addition, the vertical interval of stiffeners on the back of reinforced earth retaining walls appeared effective in improving the horizontal displacement of the top of retaining walls but not much effective in improving the vertical displacement of the back of retaining walls. In addition, improvement in horizontal-vertical displacement resulting from the increase in replacement width was not significant and this suggests that the increase of replacement width is not necessary. With regard to an adequate replacement depth, we proposed the ratio of replacement depth to the height of retaining walls(D/H) according to the ratio of the thickness of the soft layer to the height of retaining walls(H/T).

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.77-83
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• 2012

The most of horizontal drainages, which is composed of the aggregates made of sand and crushed stone, are used to improve the soft ground. However, where the aggregates are used as the horizontal drainage, it often brings about the delay of consolidation. For this reason, the horizontal drain pipe system is applied to properly improve the soft ground using a drainage pipe instead of horizontal drainage. This system is direct drain method for disappearing the excess porewater pressure which is caused by placing of fill on the soft ground. The large-scale field test was conducted in order to evaluate the applicability and constructability of the horizontal drain pipe system. The settlement characteristics of improved ground with horizontal drain pipe system was observed. It is also compared to the conventional soft ground improvement method to confirm its effectiveness.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.271-282
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• 2006

The behavior of the concrete slabs on grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the thermal load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom employing the thin plate on an elastic foundation that is widely used for the analysis of concrete slabs-on-grade and rigid pavement systems. Finite element formulations have then been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vortical stiffness of the foundation when subjected to the temperature gradient between the top and bottom of the slab and the uniform temperature drop throughout the slab depth. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab when the thermal loads are applied.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.1-13
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• 2013

Most rahmen-type temporary bridges are constructed with limited bridge length to prevent excessive horizontal forces due to the thermal expansion of main girder. To achieve a long length temporary bridge several independent bridges are required and they can not share the bents, at the rahmen-type ends, with the adjacent ones. The additional bents require more cost and reduce the section space under bridges. In order to remove extra bents with keeping the rahmen effect at the bridge ends, this study proposes a new rahmen-type movable joint system for temporary bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.863-866
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• 2008

One of the most important requirements for reinforced concrete constructions is the bond behavior between concrete and reinforcement. In this study, the positions (i.e., vertical, horizontal) and the locations (i.e., 225mm and 75mm) of reinforcement were considered as a main test parameter. The ready mixed recycled aggregate concrete concrete with specified strength of 21MPa was prepared with different replacement ratio(i.e 0%, 100%) of recycled coarse aggregate. From the test results, it was bond that under the same mix proportion (i.e., the mix proportions are the same, except for deformed bars position), the bond strength between the recycled coarse aggregate concrete and the reinforcement has obvious relation with reinforcement position. Also, the specimens of top position showed a lower bond stress than that provided in CEB-FIP Code.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.428-434
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• 2007

Displacement of tunnel face is important issues for the evaluation of tunnel safety. In this study, conventional convergence and displacement data measured from horizontal inclinometer were analyzed to investigate the trend and characteristics of tunnel deformation during construction. Trend of measured displacement agreed with general understanding of tunnel deformation prior to excavation. It shows that displacement measured from horizontal inclinometer can be used to preestimate the total deformation of tunnel.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.21-31
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• 2018

This paper analyzes the displacements of CFRD which was completed by field measurement. It is to understand the deformation behavior of the dam body according to the water level change from the impounding time. And it was compared with numerical analysis results. As a result of measuring the behavior of the dam crest and downstream slope according to impounding, horizontal displacements in axis direction of the dam, upstream and downstream displacements and settlements occurred mostly when the water level reaches about half of the dam height. The displacements continued until the water level reached its maximum. After that, it showed a constant convergence regardless of the water level. Horizontal displacements of the face slab which is the most important in CFRD were similar at all locations. The Horizontal displacements of the face slab showed the trends of increasing in winter and decreasing in summer due to the effect of the outside temperature before impounding. Also, the displacements increased until the water level reached about half of the dam height. After that, they decreased with rising in water level. As a result, the face slab behaviors according to seasonal change after impounding as well as water level condition. It is judged because of the material characteristics of the concrete slab. Numerical analysis showed slightly different maximum settlement and depth of occurrence from the measuring data after construction of the dam. It is considered that this is due to various design and construction differences such as the estimation of input parameters in analysis, construction period, and the layer thickness of construction. For the overall period of the dam, the settlements were mostly completed during the construction period and some settlements occurred in the early days of impounding and then converged.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.475-475
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• 2023

직경 5 mm 이하의 미세플라스틱은 인류 활동에 의해 생산되어 하수처리장 처리수, 우수토구, 도로 분진 등 다양한 경로를 통해 하천에 유입되고 있다. 하천에 유입된 미세플라스틱은 하천흐름을 따라 하류로 이동하여 해양환경에까지 이른다. 미세플라스틱은 수체를 따라 이동할 뿐 아니라 수생생물에 의해 섭식되기도 하여 인체 위해성이 우려되는 상황이다. 특히 서울과 경기도의 주요 상수원인 팔당호는 북한강, 남한강, 경안천이 유입되어 형성되기 때문에 미세플라스틱의 유입에 따른 이송-분산 거동 평가가 중요한 영역이다. 본 연구에서는 준3차원 입자추적기법을 이용한 미세플라스틱 거동해석 모형, MPT-Q3D를 개발하였으며 팔당호 내 미세플라스틱의 거동 특성을 분석하였다. MPT-Q3D 모형은 2차원 흐름해석모형과 연계한 입자의 준3차원 거동해석을 위해 step-by-step computation method를 적용하였으며, 전단류에 의한 입자의 수평거동과 난류확산에 및 침강속도에 의한 연직거동 두 단계 계산과정에 따라 입자의 거동을 해석했다. 전단류는 2차원 흐름해석결과로부터 유속의 연직분포식을 적용하여 생성하였으며, 생성된 전단류에 의해 각 연직층 별 유속이 계산되고 𝚫t 이후 입자의 종, 횡 방향 이동거리를 계산한다. 또한 난류확산에 의한 무작위적 거동 계산을 위해 Gaussian 분포를 따른 난수 생성을 통해 무작위적 거동을 계산했다. 각 연직층에 위치한 미세플라스틱 입자의 종, 횡 방향 거동을 계산한 후 입자의 연직거동을 계산한다. 입자의 연직 위치는 난류확산과 침강속도에 따라 계산되며 침강속도는 미세플라스틱의 밀도 및 직경에 따라 결정된다. 현장 샘플링 결과에 따라 팔당호로 유입되는 미세플라스틱은 폴리스틸렌(PS), 폴리에틸렌(PE), 폴리에스테르(Polyester)가 있으므로, 세 종류의 미세플라스틱을 동시에 주입하여 팔당호 내 거동을 분석했다. 남한강, 북한강, 경안천의 유량 차이로 인해 팔당호로 유입되는 미세플라스틱은 대체로 남한강과 북한강의 흐름특성에 영향을 받았다. 경안천의 경우 유량이 낮아 팔당호로 유입되지 못하고 좌안을 따라 하류로 이동됐다. 남한강과 북한강에서 유입된 미세플라스틱은 주로 팔당호 내 소내섬을 거쳐 팔당댐 쪽으로 이동했다. 또한 팔당댐 인근에서는 PP, PE, Polyester 순으로 많은 양이 유입되는 결과가 나타났다.

• Journal of the Korean GEO-environmental Society
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• v.18 no.6
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• pp.39-44
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• 2017

The behavior of the lateral resistance beyond the yield condition on single pile has been evaluated by comparative analysis. Pushover analysis of single pile has been performed to compare to the results on lateral load test of the pile foundation. The study for the behavior beyond the yield condition on single pile had been performed on the results on the lateral load test and pushover analysis considering mechanical conditions of the ground soil and the pile foundation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.239-250
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• 2009

Tunnelling-induced settlements and lateral ground movements have been investigated by numerical parametric studies considering ground condition, excavation characteristics, and ground layers. Before the numerical study the existing methods of ground movement estimation have been collected and analysed to have some information of ground movements and to improve them providing a fundamental material for the numerical study. Numerical model simulation has been performed of a physical model test of tunnel excavation in which the ground movements were measured reliably and the results have been used to determine the numerical approach and the appropriate soil constitutive mode. With this procedure done, the results of numerical parametric studies have been put together to analyze and understand tunnelling-induced settlements and lateral ground movements.