• Geotechnical Engineering
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• v.14 no.3
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• pp.63-72
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• 1998

Laboratory model test results for ultimate uplift capacity of horizontal circular anchors embedded in soft clay overlain by dense sand are presented. The effect of the critical embedment ratio on the thickness of the clay layer was evalyated. An approximate preocedure for estimating the net ultimate capacity is presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.97-108
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• 2010

발포우레탄 패커를 이용한 압력식 쏘일네일링 공법은 기존 쏘일네일링 공법의 단점을 보완하기 위하여 개발되었으며, 그라우팅 두부에 패커를 설치하여 네일 정착부를 완전히 밀폐하고 압력 그라우팅을 실시하여 정착부의 유효직경 및 인발저항력을 증가시켜 안전율을 향상시키는 공법이다. 압력식 쏘일네일링 공법에 대한 효용성을 검증하기 위하여 발포우레탄 패커 특성시험 및 현장조건을 묘사한 실내 그라우팅 주입실험, 현장시험 및 FEM해석을 수행하였다. 본 공법의 필수요소인 발포우레탄 패커의 정착력 확인을 위한 패커 특성시험 결과, 공내에 작용하는 압력에 대하여 패커가 충분히 저항함을 알 수 있었으며, 인발저항력 증가 원인 분석을 위한 실내 및 현장 시험결과, 압력 그라우트에 의하여 그라우트의 품질확보, 보강력증가 및 주변지반의 압밀효과를 확인 하였다. 끝으로 압력식 쏘일네일링 공법을 적용한 사면 및 흙막이 벽체 설계/시공 사례를 분석하여 현장 적용시 본 공법의 효용성 및 대처능력의 우수함을 입증하였다.

• Journal of the Korean Geotechnical Society
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• v.30 no.9
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• pp.5-17
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• 2014

A series of model tests were conducted in order to observe the failure surface generated around a diaphragm wall embedded in ground with high groundwater table. Images of the soil deformation around the model wall were captured during the test. The configuration of the failure surface in soil around the model wall could be obtained from analyzing the image of the soil deformation. Based on the configuration of the failure surface observed in the model test, an analytical approach was proposed to predict the uplift capacity of a diaphragm wall installed in ground. The analytical approach considers not only the wall properties such as length, thickness and surface roughness of diaphragm walls but also the soil strength properties such as the internal friction angle and the cohesion of soil. The predicted uplift capacity of a diaphragm wall shows a good agreement with the experimental one measured in the model test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.99-106
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• 2006

Due to single symmetry of cross section, T-shaped members are likely to buckle in a flexural-torsional mode when they are subjected to axial compression. Therefore, the flexural-torsional buckling can be regarded as a governing mode of global buckling. An experimental program has been carried out to investigate the flexural-torsional buckling behavior of pultruded T-shaped members. Two types of pultruded members were tested in the experiment, and they were made of either E-glass/vinylester or E-glass/polyester. Lay-up and thickness of reinforcing layers, volume fractions of each constituents in layers, mechanical properties were experimentally determined. Two sets of knife edge fixure were used to simulate simple support condition for flexure and twisting, and the lateral displacements and the angle of twist were measured using three potentiometers. Every specimen buckled in a flexural-torsional mode, and most of the specimens showed post-buckling strength.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.105-117
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• 2002

In the design of foundations for the super-structures such as transmission towers and oil-platforms, the foundations must be considered as a medium to resist cyclic tensile forces. In this study, the uplift capacity of the drilled shaft used as the medium resisting to this pattern of forces is investigated by performing cyclic uplift test of a small model-drilled shaft constructed in compacted granite soil in a steel chamber. In this test, the behavioral difference between a pile loaded on the top of the pile and a pile loaded at the bottom of the pile was investigated intensively. The load transfer curves obtained from the test were investigated by changing the confining pressure in the chamber. The load tests also included creep test and cyclic test. It is found from the tests that uplift capacity of the shaft loaded at the bottom is greater than that of the shaft loaded on the top of the pile. It is found also from the creep test that the pile loaded at the bottom was more stable than the shaft loaded on the top. If a pile loaded at the bottom is pre-tensioned, the pile will be most effective to the creep displacement. It is found also from the cyclic tests that apparent secant modulus obtained in a cycle of the load increases with the number of cycles.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.83-89
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• 2012

Anchor, soil nail and micropile have been widely used for slope reinforcement and foundation. These all methods need grouting work after placing reinforcing member. The pressure injection-grouting techniques helps to increase the bearing capacity of reinforcing member by enhancing larger effective pile diameter and increasing the radial stresses acting on the grout body and causing irregular surface. However, the pressure reinjection-grouting techniques is not commonly used because grouting equipment and practical application example are short and the verification of reinforcing effect is difficult. In this study, the laboratory test was performed to evaluate the reinforcing effect with variation of grouting methods in clay. As a result of the test, the pressure reinjection-grouting techniques showed that the pullout capacity of reinforcing member increased up to 1.22~2.61 times comparing to the gravity fill techniques.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.23-29
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• 2011

In this experimental study, bond splitting strength and behavior were evaluated through pull-out tests. The tests were conducted on a GFRP rebar with roughened surface which was produced by Canadian manufacturer. The used variables in this study were rebar diameter, cover depth and compressive strength of concrete. For each variable, five specimens were made and tested to obtain good results. The bond splitting behavior was investigated from the relationship of pull-out force and slip. The experimental bond splitting strength was compared with the predicted strength obtained from the equations presented by some researchers. The results of the comparison demonstrated that the strength could be predicted well by using the Harajli et al's equation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.555-563
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• 2006

Recently, many bridges become not only functionally obsolete of bridge deck due to inadequate width but also structurally deficient of substructure due to erosion. In these cases, widening is almost always more economical than complete replacement, and therefore there is a need to make available the results of research and field experience pertaining to the widening of bridge substructure. But, an experimental study for the guarantee of unification between existing and new substructure with adhesive anchor is so insufficient that the development of adhesive anchor system for the unification should be settled promptly. The purpose of the present study is to explore pull out and shear characteristics of adhesive anchor system. For this purpose, several series of concrete specimens have been tested. Major test variables were the bonded length, anchor diameter and anchor slope. The pull out strength, bond stress and shear strength of adhesive faces were measured for the specimens. The present study indicates that the pull out strength increased with more bonded length and more anchor diameter, and that the bond stress decreased with more bonded length and more anchor diameter. The pull out strength and the bond stress increases with more anchor slope and it is considered that the slope of $5^{\circ}$ was more efficient. From the shear tests, it is supposed that anchor diameters more than D19 was proper to the adhesive anchor. Finally, it is expected that both experimental data in these tests and further study including mock-up tests will contribute to the establishment of the unification between existing and new substructure with adhesive anchor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.221-229
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• 2004

In Recent experimental research results of connection method between steel pipe pile and concrete footing are provided based on various experimental observations. It gives a shedding light toward developing better connection method for steel pipe pile at the field application. In this study, the newly developed method is tested for compressive, pull put and combination load including moment with carefully designed monitoring system. The measured data show that new method have at least equivalent or better load resistant capacities compared with those of specified method in Korea Road Design Specification. It is also tried to define and investigate the load transfer mechanism for new method.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.87-98
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• 2004

In this study reinforcing effect of soil nailed-drilled shafts subjected to axial and lateral loads was evaluated. Special attention was given to the reinforcing effects of soil nails placed from the drilled shafts to surrounding weathered- and soft-rocks based on model tests, numerical analyses and field tests. The model tests and numerical analyses are conducted to analyze the reinforcing effect of various conditions of number, inclination, position and length. The results of 1/40 scale model tests and numerical analyses show that as the number of reinforcing level increases, the incremental effect of reinforcement tends to increase, whereas the reinforcing effect on relative position is negligible. In addition there is a reinforcing effect as the inclination angle increase up to 30 degrees. Based on the results of tensile load tests, soil nailed-drilled shaft has a considerably smaller settlement to reach the ultimate level compared with the result of un-reinforced drilled shafts. For compression tests, there is a reinforcing effect of about 200% measured.