• 한국지반공학회논문집
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• 제24권6호
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• pp.101-116
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• 2008

보강토 옹벽의 영구구조물로서의 적용성이 증가함에 따라 지속 혹은 반복하중 등 다양한 하중조건하에서 장기적인 잔류변형이 설계/시공시 주요 관점이 되고 있다. 본 연구에서는 교량구조물의 피어 및 Back-to-Back(BTB) 형태의 보강토 옹벽을 대상으로 사용하중 작용 이전에 작용시키는 선행하중이 보강토 구조물의 잔류변위를 제어에 미치는 영향을 고찰하였다. 이를 위해 모형 피어와 BTB 옹벽을 축조하여 단순재하, 지속하중, 반복하중 등 다양한 하중조건 및 시공조건에 대한 모형실험을 수행하였다. 그 결과 선행재하 공법은 다양한 하중 및 시공조건에서 잔류변위 제어에 탁월한 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제18권11호
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• pp.27-33
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• 2017

Nonlinear dynamic analysis is performed to calculate the response of U-shaped cantilever retaining structure under seismic loading using the finite element (FE) analysis program OpenSees. A particular interest of the study is to evaluate whether the moment demand in the cantilever can be accurately predicted, because it is an important component in the seismic design. The numerical model is validated against a centrifuge test that was performed on cantilever walls with dry medium dense sand in backfill. Seismic analysis is performed using the pressure-dependent, multi-yield-surface, plasticity based soil constitutive model implemented in OpenSees. Normal springs are used to simulate the soil-structure interface. Comparison with centrifuge show that FE analysis provides good estimates of both the acceleration response and bending moment. The lateral earth pressure near the bottom of the wall is overestimated in the numerical model, but this does not contribute to a higher prediction of the moment.

• Geomechanics and Engineering
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• 제31권6호
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• pp.599-614
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• 2022

One of the methods of stabilizing retaining walls, embankments, and deep excavations is the implementation of plate anchors (like the Geolock wall anchor systems). Back-to-back Mechanically Stabilized Earth (BBMSE) walls are common stabilized earth structures that can be used for bridge ramps. But so far, the analysis of the interactive behavior of two back-to-back anchored walls (BBAW) by double-plates anchors (constructed closely from each other and subjected to the limited-breadth vertical loading) including interference of their failure and sliding surfaces has not been the subject of comprehensive studies. Indeed, in this compound system, the interaction of sliding wedges of these two back-to-back walls considering the shear failure wedge of the foundation, significantly impresses on the foundation bearing capacity, adjacent walls displacements and deformations, and their stability. In this study, the effect of horizontal distance between two walls (W), breadth of loading plate (B), and position of vertical loading was investigated experimentally. In addition, the comparison of using single and equivalent double-plate anchors was evaluated. The loading plate bearing capacity and displacements, and deformations of BBAW were measured and the results are presented. To evaluate the shape, form, and how the critical failure surfaces of the soil behind the walls and beneath the foundation intersect with one another, the Particle Image Velocimetry (PIV) technique was applied. The experimental tests results showed that in this composite system (two adjacent-loaded BBAW) the effective distance of walls is about W = 2.5*H (H: height of walls) and the foundation effective breadth is about B = H, concerning foundation bearing capacity, walls horizontal displacements and their deformations. For more amounts of W and B, the foundation and walls can be designed and analyzed individually. Besides, in this compound system, the foundation bearing capacity is an exponential function of the System Geometry Variable (SGV) whereas walls displacements are a quadratic function of it. Finally, as an important achievement, doubling the plates of anchors can facilitate using concrete walls, which have limitations in tolerating curvature.

• 한국해양공학회지
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• 제27권3호
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• pp.15-21
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• 2013

Anchors are primarily designed and constructed to resist outwardly directed loads imposed on the foundation of a structure. These outwardly directed loads are transmitted to the soil at a greater depth by the anchors. Buried anchors have been used for thousands of years to stabilize structures. Various types of earth anchors are now used for the uplift resistance of transmission towers, utility poles, submerged pipelines, and tunnels. Anchors are also used for the tieback resistance of earth-retaining structures, waterfront structures, at bends in pressure pipelines, and when it is necessary to control thermal stress. In this research, we analyzed the uplift behavior of plate anchors in clay using a laboratory experiment to estimate the uplift behavior of plate anchors under various conditions. To achieve the research purpose, the uplift resistance and displacement characteristics of plate anchors caused by the embedment ratio, plate diameter, and loading rate were studied, compared, and analyzed for various cases.

• 한국해양공학회지
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• 제26권5호
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• pp.31-39
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• 2012

Anchors are primarily designed and constructed to resist outwardly directed loads imposed on the foundation of a structure. These outwardly directed loads are transmitted to the soil at a greater depth by the anchors. Buried anchors have been used for thousands of years to stabilize structures. Nowadays, various types of earth anchors are used for the uplift resistance of transmission towers, utility poles, submerged pipelines, and tunnels. Anchors are also used for the tieback resistance of earth-retaining structures, waterfront structures, at bends in pressure pipelines, and when it is necessary to control thermal stress. In this research we analyzed the uplift behavior of plate anchors in sand using a laboratory experiment to estimate the uplift behavior of plate anchors under various conditions. To achieve the research purpose, the uplift resistance and displacement characteristics of plate anchors caused by the embedment ratio, plate diameter, and loading rate were studied, compared, and analyzed in various cases.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.330-335
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• 2005

Reliable predictions of the movement of earth retaining structures and the ground adjacent to braced walls in urban excavation are often difficult due to many variable factors. The ground settlement and the damage of adjacent structures in urban excavation has been an important issue. Therefore, the stability of the adjacent structures must be secured with the excavation support and research on the protection of adjacent structure is necessary. This study showed a countermeasure method for case of damage behavior in urban excavation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.514-527
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• 2007

Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

• 한국지반신소재학회논문집
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• 제20권2호
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• pp.45-56
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• 2021

지하공간의 활용이 활성화됨에 따라 지중구조물의 설치를 위해 깊은 굴착이 이루어지고 있으며, 굴착지반의 변형을 최소화하기 위해 흙막이벽체가 많이 활용되고 있다. 특히 도심지에서의 깊은 굴착이 진행함에 따라 벽체에 인접한 구조물의 피해가 발생하지 않도록 벽체 변형을 최소화하기 위한 방법들이 강구되어 왔으며, 이들 방법 중 하나가 버팀 선행하중 공법이다. 이 공법은 벽체의 버팀에 주동적으로 하중을 가해 벽체 변형을 억제하는 방법으로, 최근까지 이 공법에 관한 연구가 진행되어 왔다. 그러나 관련된 연구가 활발히 진행되었음에도 불구하고, 현재까지 선행하중에 대한 명확한 관리기준이 마련되어 있지 않다. 또한 굴착 깊이가 깊거나 배면지반의 상태에 따라 버팀의 작용력이 증가할 수 있으므로, 버팀에 가할 수 있는 선행하중의 크기가 감소할 수 있다. 그럼에도 불구하고 기존 연구결과에서 제안하고 있는 선행하중의 크기(작용하중의 50%이상)를 버팀에 일률적으로 적용하고 있다. 본 연구에서는 벽체의 배면지반조건에 따른 H-빔 버팀보의 선행하중 적용범위를 평가하고자 3차원 유한요소해석을 수행하였다. 해석결과, 연약한 지반조건이고 깊은 심도 굴착이 진행하는 경우 토압과 선행하중에 의한 버팀구조의 안정성에 문제가 발생할 가능성이 매우 큰 것으로 나타났다. 그리고 선행하중의 적용범위는 버팀 작용하중의 5%~70%인 것으로 나타났다.

• 대한토목학회논문집
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• 제33권3호
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• pp.889-900
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• 2013

대형 구조물의 기초나 지중 구조물 시공을 위한 대규모 굴착 시 매우 큰 토압이 발생할 수 있다. 이러한 큰 토압을 지지하기 위해 기존에 사용되어 온 강재 버팀보를 적용할 경우 경제성 및 효율성이 저하될 우려가 있다. 이러한 점을 개선하기 위해 PCT(Precast Concrete Truss) 시스템을 고안하였으며 이에 대한 실험 및 해석적 연구를 수행하였다. 콘크리트 트러스 부재의 조립 및 해체를 용이하게 하기 위해 적절한 연결방법이 제안되었다. 이러한 연결부를 포함한 PCT 시스템의 내하력을 검증하기 위해 실대형 실험이 실시되었으며, 실험결과는 구조해석결과와도 비교되었다. PCT 버팀보를 모사한 시험체는 극한하중 도달 시까지 좌굴이 발생하지 않았으나, 연결 부재 상세에 대한 일부 개선점이 도출되었다. PCT 시스템은 대규모 굴착 시 기존의 강재 버팀보를 대체하는 가설구조물로서 효율적으로 활용될 수 있을 것으로 기대된다.

• 한국지반공학회논문집
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• 제39권9호
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• pp.35-50
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• 2023

본 논문은 흙막이 가시설의 내진설계 가이드라인을 작성하기 위한 기초 연구로서, 국내외에서 적용되고 있는 내진설계 기준과 등가정적해석을 위한 동적토압 산정 방법에 대해 문헌연구를 수행하였다. 그리고 2차원 유한차분해석 프로그램인 FLAC 2D를 이용하여 Semirigid pressure 방법, Wood 방법, Mononobe-Okabe 방법에 따라 등가정적해석을 수행하고, 벽체의 모멘트와 지보재 축력에 대한 해석 결과를 동해석 결과와 비교하여 등가정적해석의 적용성을 평가하였다. Semirigid 방법은 0.4%H 이하의 수평 변위가 발생하는 Stiff wall의 모멘트를 가장 합리적으로 예측하였다. 지보재의 축력은 구조물과 흙 사이의 동적인 상호작용을 고려할 수 없어 정확하게 예측하는 것이 어려웠으나, 안전측으로 보수적인 설계를 위한 예비검토에 활용할 수 있을 것으로 판단된다.