• 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.

• 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.

• 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 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.

• 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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.944-955
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• 2009

In this thesis the model tests were performed to the pull-out characteristics of a suction pile subjected to a pull-out in sands. For this model tests, three different soil conditions ($D_r$=45, 65, 82%), three pile diameters (D=100, 150, 200mm) and three pile lengths (L=100, 150, 200mm), 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 pull-out resistances increased as the relative density of sands, pile diameter, length and the ratio of pile length to diameter increased. The ultimate pull-out resistance by Meyerhof method(1973) overestimated that by the model test, but the results using the soil-pile friction angle suggested by Aas(1966) in the Meyerhof(1973) method were in good agreement with the experimental results.

• 한국지반신소재학회논문집
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• 제8권4호
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• pp.19-25
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• 2009

본 연구에서는 접이식 웨지가 장착된 경량 강관네일의 인발저항 증진효과를 평가하기 위하여 동일 지반조건에서 시험시공을 통한 접이식 웨지가 장착된 네일과 웨지가 장착되지 않은 네일의 현장 인발거동 특성을 평가하였다. 강관네일의 현장 인발거동 특성 평가는 극한인발저항력 ($T_L$), 단위주면 마찰저항($q_s$, $u_{max}$), 인발강성계수($K_{\beta}$) 및 네일의 인장력 분석을 통하여 수행되었으며, 그 결과 접이식 웨지를 장착할 경우 풍화토 지반에서 약 30% 정도의 인발저항 증진효과가 있는 것으로 나타났다.

• 대한토목학회논문집
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• 제29권6C호
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• pp.313-319
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• 2009

본 연구에서는 접이식 웨지를 장착한 강관네일의 거동 특성 평가를 위해 현장인발시험 및 3차원 수치해석을 수행하였다. 접이식 웨지를 장착한 강관네일의 현장인발시험 결과 접이식 웨지가 없는 경우에 비해 약 30% 정도의 인발 저항 증진효과가 있는 것으로 평가되었다. 한편, 강관네일의 합리적인 인발거동 분석을 위해 3차원 수치해석에서는 접이식 웨지가 장착 되지 않은 강관네일의 역해석을 통하여 현장 인발거동과 일치하는 네일과 지반사이의 마찰 특성을 평가하고, 이를 접이식 웨지가 장착된 강관네일의 해석에 도입하여 그 거동을 분석하였다. 시행착오를 통한 역해석 결과 그라우트와 지반 사이의 마찰계수(${\mu}$)는 약 1.2 정도가 발휘되는 것으로 평가되었으며, 강관네일의 극한인발저항력은 $$T_L{\sim_=}32$$ tonf으로 접이식 웨지가 장착되지 않은 네일의 $$T_L{\sim_=}24$$ tonf 보다 약 33% 증가하는 것으로 평가되어 현장인발시험결과와 거의 일치하는 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.65-72
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• 1993

Steel fiber reinforced concrete(SFRC) which is made by short, randomly distributed steel fibers in concrete is superior in its tensile mechanical properties to plain concrete in enhancement of tensile strength and tensile ductility. These improvements are attributed to crack arresting mechanism and formation of longer crack paths due to fibers , which as a consequence lead to increase in energy absorption capacity of SFRC. In the post-peak region under tensile stresses, major macrocrack forms at critical section. The opening of this macrocrack is mainly resisted by both of the fiber pull-out bridging the cracked surfaces and the resistance by matrix softening. In this study, micromechaincal approach has been made in order to simulate tensile behavior of SFRC and based on which the theoretical model is presented. This model reflects the features of both the composite material concept and the spacing concept in predicting tensile strength of SFRC. The model also takes into account for the effects of matrix tensile softening and fiber bridging by pull-out on the resistance for the post-peak behavior of SFRC. It has been shown that the developed model satisfactory predicts the experimental results.

• Structural Engineering and Mechanics
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• 제5권4호
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• pp.339-353
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• 1997

Fiber reinforced plastic (FRP) rods provide certain benefits over steel as concrete reinforcement, such as corrosion resistance, magnetic and electrical insulation, light weight, and high strength. FRP composites can be combined with a steel core to form hybrid reinforcing rods that take advantage of properties of both materials. The objective of this study was to characterize the bond behavior of hybrid FRP rods made with braided epoxy-impregnated aramid or poly-vinyl alcohol FRP skins. Eleven rod types were tested using two concrete strengths. Specific topics examined were bond strength, slip, and type of failure in concentric pull-out tests from concrete cubes. From analysis of identical pull-out tests on both hybrid and steel rods, information on relative bond strength and behavior were obtained. It is concluded that strength is similar but slip in hybrid rods is much higher. Hybrid rods failed either by pull-out or splitting the concrete block (with or without yielding of the steel core). Experimental data showed consistency with similar test results presented in the literature.