• Geomechanics and Engineering
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• 제36권1호
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• pp.71-81
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• 2024

This study analyzes the pull-out behavior of tunnel-type anchorage under various joint conditions, including joint direction, spacing, and position, using a finite element analysis. The validity of the numerical model was evaluated by comparing the results with a small-scaled model test, and the results of the numerical analysis and the small-scaled model test agree very well. The parametric study evaluated the quantitative effects of each influencing factor, such as joint direction, spacing, and position, on the behavior of tunnel-type anchorage using pull-out resistance-displacement curves. The study found that joint direction had a significant effect on the behavior of tunnel-type anchorage, and the pull-out resistance decreased as the displacement level increased from 0.002L to 0.006L (L: anchorage length). It was confirmed that the reduction in pull-out resistance increased as the number of joints in contact with the anchorage body increased and the spacing between the joints decreased. The pull-out behavior of tunnel-type anchorage was thus shown to be significantly influenced by the position and spacing of the rock joints. In addition, it is found that the number of joints through which the anchorage passes, the wider the area where the plastic point occurs, which leads to a decrease in the resistance of the anchorage.

• 한국지반공학회지:지반
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• 제12권4호
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• pp.87-100
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• 1996

그리드(grid) 형태의 토목섬유와 흙 사이의 마찰특성은 표면마찰 뿐만아니라 그리드에 의한 수동저항을 동시에 측정할 수 있는 인발시험(pull-out test)에 의해 평가되고 있다. 본 연구에서는 보강토 구조물에서 가장 많이 사용되고 있는 지오그리드(geogrid)와 국내에 널리 분포되어 있는 화강 풍화토를 대상으로 실내 인발시험을 수행하였으며, 인발시험의 주요 영향 인자들인 인발속도, 토조 전면벽의 위치, 지오그리드 시료의 폭 및 지오그리드 수동 저항부재의 유.무 등이 흙/지오그리드 마찰특성에 미치는 영향을 평가하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1114-1119
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• 2010

Pile foundations have been used for upholding superstructure's loads. The researches on pile foundations subjected to compressive forces or horizontal loads have been actively carried out. However, recently, pile foundations, which are subjected to pull-out forces, are getting increased. The study on the pull-out resistance of piles becomes to be important. In addition, it is expected that belled piles will be used more and more, since the belled piles are effective to resist the pull-out forces. But there is still a lack of research on pull-out resistance of belled piles. Therefore, in order to investigate the resisting effect against pull-out of belled piles which is embedded in cohesionless soil. a series of pull-out test is performed on belled piles in field. Especially, the relation between load and displacement is analyzed through the pull-out test.

• 한국지반공학회논문집
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• 제33권11호
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• pp.35-43
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• 2017

본 연구에서는 정착부 표면에 저항체를 설치한 앵커의 인발거동특성을 모형시험을 통해 규명하였다. 모형시험은 원형의 토조 중앙에 앵커체를 설치한 후 앵커를 등속으로 인발하면서 인발저항력을 측정하였다. 본 연구에서는 앵커형식(저항체 설치 유무), 앵커체 표면의 마찰조건($1/3{\phi}$, $2/3{\phi}$, ${\phi}$)과 돌기형 저항체 개수(1set, 2set, 4set), 돌기형 저항체 높이(0.05d, 0.10d, 0.20d) 등 총 10가지의 조건에 대하여 인발시험을 실시하였다. 인발시에는 일정한 속도(1mm/min)를 유지하였으며, 최대 80mm까지 인발하여 각 조건별 인발하중 및 변위를 측정하였다. 인발시험 결과 확장형 앵커는 마찰형 앵커와 비교하여 최대 인발저항력 뿐만 아니라 잔류 인발저항력도 크게 발생하는 것으로 분석되었다. 돌기형 저항체의 설치개수 증가에 따라 최대 인발저항력이 증가하였으며, 잔류 저항력 비율은 171~591%로 마찰형 앵커에 비해 현저하게 증가하였다.

• Geomechanics and Engineering
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• 제31권6호
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• pp.573-582
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• 2022

The geometry of the gravity-type anchorage changes depends on various factors such as the installation location, ground type, and relationship with the upper structure. In particular, the anchorage geometry embedded in the ground is an important design factor because it affects the pull-out resistance of the anchorage. This study examined the effect of four parameters, related to anchorage geometry and embedded ground conditions, on the pull-out resistance in the gravity-type anchorage through two-dimensional finite element analysis, and presented a guide for major design variables. The four parameters include the 1) flight length of the stepped anchorage (m), 2) flight height of the stepped anchorage (n), 3) the anchorage heel height (b), and 4) the thickness of the soil (e). It was found that as the values of m increased and the values of n decreased, the pull-out resistance of the gravity-type anchorage increased. This trend is related to the size of the contact surface between the anchorage and the rock, and it was confirmed that the value of n, which has the largest change rate of the contact surface between the anchorage and the rock, has the greatest effect on the pull-out resistance of the anchorage. Additionally, the most effective design was achieved when the ratio of the step to the bottom of the anchorage (m) was greater than 0.7, and m was found to be an important factor in the pull-out resistance behavior of the anchorage.

• Journal of Forest and Environmental Science
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• 제24권2호
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• pp.111-118
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• 2008

산림 훼손지 비탈면 녹화에 주로 사용되는 관목류 7종에 대한 인발저항실험을 실시하였다. 조사수종의 평균인발력은 두릅나무 37.26 kgf, 버드나무 34.56 kgf, 국수나무 26.00kgf의 순으로 측정되었으며, 뿌리의 근원경 및 뿌리체적이 크면 클수록 인발력은 높게 산출되었다. 뿌리 근원경과 뿌리 체적에 대한 인발력은 산딸기나무가 가장 상관관계가 높았으며, 산초나무가 가장 낮았다. 그리고 뿌리의 근원경에 따른 인발력은 대부분 유의적인 차이가 있는 것으로 나타났으며, 뿌리체적에 따른 인발력은 뿌리체적이 20 ml미만에서만 수종간의 인발력 차이가 있는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.342-347
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• 2004

Excavation nearby the existing structures is being performed vigorously to get the greatest use of land along with fast economic growth in the downtown area. The application of soil nailing system gradually increases because of an advantage of soil nailing system adjacently constructed in the existing structures. In this study, friction resistance by pull-out is considered as main resistance except resistance formed by flexural rigidity of nail observing that resistance of flexural rigidity is about $0{\sim}15\;%$ of whole safety factor according to degree of flexural rigidity in general soil nail wall and application of geosynthetic fiber soil nailing system is evaluated through laboratory tensile strength test and field pull-out test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1120-1131
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• 2010

In this thesis the model tests were performed to the horizontal pull-out characteristics of a suction pile subjected to a pull in sands. For this model tests, soil conditions ($D_r$=65), three pile diameters (D=100, 150, 200mm) and five loading points (h/L=0, 0.25, 0.5, 0.75, 1) were changed. And the experimental results were also compared with those by the theoretical methods. The results by the experimental and theoretical analysis are as follows. The ultimate horizontal pull-out resistance by the model test increased as the loading point (h/L) moved downwards from the pile top, and the maximum value reached at the h/L=0.75. The theoretical ultimate horizontal pull-out resistance by Broms(1964) and Hong(1984) agreed well with that by the model test at h/L=0 and 0.25, but their results overestimated the experimental result at lower part of pile and the differences between the theoretical and experimental results were of great. While the horizontal loading applied at the upper part of pile, the pile moved to the horizontal direction with rotating clockwise. As the loading point moved downwards from the pile top, the rotating angle of pile was smaller.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 사면안정학술발표회
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• pp.145-154
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• 2003

When a nail pulled out in dense, granular soil, the soil in the vicinity of the nail tends to dilate, but its dilatancy results in a normal stress concentration at the soil/nail interface, thereby increasing the pull-out resistance of the inclusion. It is thought to be occurring within the resistance zone where the soil mass is at stationary state and the reinforcement are held in position by the soil, due to the friction or bond. In this paper, A series of direct shear and interface tests were conducted by using so called‘Constant Normal Stiffness Test Apparatus’which was modified and improved from the conventional direct shear box test rig. Unlikely the normal shear box test, this enables to simulate the different constraint effects of surrounding soil during shear under the conditions of constant stress and volume, constant normal stiffness. The aim of the research programme is to get better understanding of pull-out bond mechanism, thus to explore the possibility of evaluating the pull-out bond capacity of soil/reinforcement at the preliminary design stage from the laboratory test.

• 풍력에너지저널
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• 제13권3호
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• pp.22-32
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• 2022

Conventionally, a monopile that has reached the end of its design life is required to be removed. While monopiles have been left on site due to economic and technical reasons, cases of decommissioning monopoles have recently been reported, and a decommissioning market is emerging. This paper introduces a new type of monopile with decreased pull-out resistance by prior lifting up of a wedge segment installed on the outer wall of the monopile; consequently, the monopile can be dismantled easily from the operation site. The study conducted several numerical investigations, using finite element analysis, of the effect of segment pull-out for the monopile. After pulling out several segment sizes in the numerical model represented by soil element deletion corresponding to the segment volumes, the pull-out forces were compared to those of the conventional monopile. The results showed that for a segment with a thickness of 5 cm and circumferential angle of 30°, the pull-out resistance of the proposed monopile was reduced by 32.5% relative to that of a conventional monopile. Also, the results indicated that an increase in the segment angle was a more effective way to reduce resistance than that of the thickness.