• Geomechanics and Engineering
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• v.7 no.2
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• pp.165-181
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• 2014

In the past decade, different types of underreamed ground anchors have been developed for substructures requiring uplift resistance. This article introduces a new type of umbrella-shaped anchor. The uplift behavior of this ground anchor in clay is studied through a series of laboratory and field uplift tests. The test results show that the umbrella-shaped anchor has higher uplift capacity than conventional anchors. The failure mode of the umbrella-shaped anchor in a large embedment depth can be characterized by an arc failure surface and the dimension of the plastic zone depends on the anchor diameter. The anchor diameter and embedment depth have significant influence on the uplift behavior. A finite element model is established to simulate the pullout of the ground anchor. A parametric study using this model is conducted to study the effects of the elastic modulus, cohesion, and friction angle of soils on the load-displacement relationship of the ground anchor. It is found that the larger the elastic modulus and the shear strength parameters, the higher the uplift capacity of the ground anchor. It is suggested that in engineering design, the soil with stiffer modulus and higher shear strength should be selected as the bearing stratum of this type of anchor.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1434-1441
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• 2005

For anchored system applications, each ground anchor is tested after installation and prior to being put into service to loads that exceed the design. This load testing methodology, combined with specific acceptance criteria, is used to verify that the ground anchor can carry the design load without excessive deformations and that the assumed load transfer mechanisms have been properly developed behind the assumed critical failure surface. After acceptance, the ground anchor is stressed to a specified load and the load is locked-off. The two types of load tests conducted during the research program included performance test and creep test which were carried out in accordance with testing procedures by AASHTO(AASHTO 1990) and FHWA(Weatherby 1998) at Samsung-Dong 00 Site. Form the measurements, ultimate load and creep rate of anchors are proposed for straight shaft pressured grouted anchors in waste landfill. The load distribution on the grout was obtained from the measured strain data at each fraction of the ultimate load during the load tests.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.97-104
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• 1999

This case study has been prepared to provide the practical data about construction of temporary shoring facilities (i.e. braced sheet pile excavation) and to utilize the case study information effectively for design and construction of future facilities. This case study includes information such as 1) installing measurement devices to monitor the deformation of the sheet pile walls and the subsoil in the vicinity after establishing the criteria for the sheet pile deflection; 2) monitoring the actual movement of the temporary facility after setting up the survey control standard (due to the movement of the temporary facility) : 3) inspecting the suitability of the temporary facility construction: and 4) analyzing and studying the result of the tension test after installing ground anchors.

• Geotechnical Engineering
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• v.9 no.1
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• pp.59-68
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• 1993

In deep excavations for creation of underground spaces, it would be difficult to predict earth pressure, especially multilayered ground including rock strata. The earth pressures and displacements on the retention walls are measured by load cell, strain gauge and inclinometer which were installed at struts or anchors at 4 deep excavation sites in Seoul area. In this paper, the measured earth pressure from the struts or anchors are compared with Peck's empirical values, and the coefficient of the earth pressures for each strata and horizontal wall displacement are investigated. The coefficient of earth pressure distribution, a(0.65zka), in the flexible and the rigid walls was about 74% and 88% of Peck's value respecitively. The measured earth pressure distributions for the 4 sites showed about 70%∼80% of Peck's empirical values and the average earth pressure coefficients based on the measured data were 0.3 for the felted layer, 0.23 for the weathered rock and 0.19 for the weak rock. The maximum w리1 displacements were found to be less 0.2% of excavation depth.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.109-117
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• 2006

This study is an numerical study of predicting the behavior of anchor embedded in weathered rocks, subjected to uplift loads, about ultimate pullout capacity and the failure mechanism. Factors influencing the behavior of anchors were investigated by reviewing the data about in-situ anchor tests performing numerical modelling with changing the bondage length of anchor, diameter of anchor body and diameter of tenden, and by Correlations between those factors were evaluated to apply them to predict the behavior of anchors. As results of numerical analysis, a linear relationship between bondage length, diameter of anchor body and diameter of tenden with ultimate pullout capacity was obtained on the one hand, from the result of numerical analysis changing the Young's modulus of weathered rock, this parameter was found to inflence to load-displacement and ultimate pullout capacity within the range of 10%, which was mot so significant to affect.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1014-1021
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• 2008

Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The pulse powered anchor is an underreamed anchor by using high voltage electrokinetic pulse energy. In this paper, conceptual introduction of the pulse powered anchor was presented. Anchor pull-out tests were performed at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. Data were analyzed in order to verify the performance of pulse powered anchors.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1354-1359
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• 2009

Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The anchor is an underreamed anchor by using high voltage electric discharge energy. In this study, a series of field test were carried out in order to find ultimate load of underreamed anchors in weathered soil at the new apartment construction site located in Inchon, Korea. Data were analyzed in order to define a relation between ultimate load and the number of electric discharge.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.493-511
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• 2018

This paper deals with visual confirmation device for tensile force verification in order to cope with tensile force loss of ground anchor. Ground anchors are constructed to ensure the stability of social infrastructure facilities, but continuous loss of tensile force is seriously concerned about safety of the facilities. This requires the maintenance of the anchors, but the current measuring of residual tensile force is done by sampling, taking into account economic aspects, which limits precision. In this paper, conducted a conceptual design, tensile experiment, and field test for the purpose of developing an anchor tensile force visual device to check the tensile force of the anchors.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.673-682
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• 2020

The ground shear force at the expected failure surface and resistance force due to reinforced anchor can act as important factors according to a failure type from the stability viewpoint at a slope. Furthermore, the anchor's axial force may vary at an anchor-reinforced slope due to ground weathering, settlement, and corrosion in the incompletely anti-corrosion treated steel wire strand at a ground where the bearing plate is installed. However, in case that the resistance force of the anchor is locally lost due to the variation of the anchor's axial force, the resistance force may not play the role so that the external force tends to be transferred to the surrounding anchors, causing an increase in the tensile force in the surrounding anchors. Accordingly, a stability problem at the entire slope may occur, which requires much attention. Thus, this study proposed a method to monitor a variation trend of the tensile force of anchors installed at a slope and infer the external stability at the entire slope considering the monitoring result.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.5-10
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• 2009

The ground anchor is not usually used in soft clay and loose sand, because the pullout resistance of anchors can not be guaranteed. However, there is a method to increase the capacity of anchors using electric discharge geotechnical technologies, which are also known as pulse discharge and electric-spark technologies. The pulse-discharge anchor has a bulbed (or underreamed) bond length that is expanded by high voltage electrokinetic pulse energy. 24 anchors were installed in the weathered soil and sandy clay at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. In this study, in order to define a relation between expansion rate of the anchor diameter and ultimate load, anchor load tests were carried out in accordance with testing procedures by AASHTO (AASHTO 1990) and FHWA (Weatheb 1998). And then several anchors were exhumed to measure the diameter of the pulse discharge anchors.