• Journal of Industrial Technology
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• v.23 no.A
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• pp.131-137
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• 2003

This thesis is results of centrifuge model experiments to investigate the behavior of replacement method in dredged and reclaimed ground. For experimental works, centrifuge model tests were carried out to investigate the behavior of replacement method in soft clay ground. Basic soil property tests were performed to find mechanical properties of clay soil sampled from the southern coast of Korea which was used for ground material in the centrifuge model tests. Reconstituted clay ground of model was prepared by applying preconsolidation pressure in 1g condition with specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50g. Replacing material of leads having a certain degree of angularity was used and placed until the settlement of embankment of replacing material was reached to the equilibrium state. Vertical displacement of replacing material was monitored during tests. Depth and shape of replacement, especially the slope of penetrated replacing material and water contents of clay ground were measured after finishing tests. Model tests of investigating the stability of embankment after backfilling were also performed to simulate the behavior of the dike treated with replacement and backfilled with sandy material. As a result of centrifuge model test, the behavior of replacement, the mechanism of the replacing material being penetrated into clay ground and depth of replacement were evaluated.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1372-1377
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• 2008

Recently, centrifuge tests have been widely used as tools in geotechnical engineering researches in domestic and foreign. However, the size of these centrifuge facilities is very large and thus the tests require for long time, high expense, and many labors. In this study, therefore, a small size of instructional centrifuge, which can conduct tests in a short period of time effectively, was introduced. This centrifuge facility introduced in here was developed for geotechnical engineering education for graduate and undergraduate students. The slope stability model having $65^{\circ}$ slope formed with clay was used to investigate the application of the instructional centrifuge by considering experimental procedures and results.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.79-86
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• 2012

In this paper, centrifuge model tests and numerical analysis on the breakwater structure were performed to investigate the stability and behavior of breakwater in field. In centrifuge model tests, construction sequence of breakwater structure such as preparation of weathered rock and sand deposit, construction of D.C.M, rubble mound with crushed stones and installment of breakwater structure was reconstructed like field condition and the behavior of ground settlement and breakwater displacement during stage of construction was observed during tests. For the final stage of simulating the horizontal movement of breakwater due to wave force, horizontal load was applied by horizontal loading apparatus being specially designed so that horizontal displacement of structure could be observed. Numerical analysis were also carried out and its results were compared with test results to assess the property of centrifuge model tests with respect to the behavior of structure as well as ground.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1254-1259
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• 2008

Recently, centrifuge tests have been widely used as tools in geotechnical engineering researches in domestic and foreign. However, the size of these centrifuge facilities is very large and thus the tests require for long time, high expense, and many labors. In this study, therefore, a small capacity(2g ton) of instructional centrifuge, which can conduct tests in a short period of time effectively, was introduced. The results of centrifuge tests conducted on the retaining wall both passive and active cases was used. Medium size of sand was used with sieve off fines in sand using #40 sieve. Based on the test results, this centrifuge facility introduced in here can be enough used for geotechnical engineering education for graduate and undergraduate students.

• Journal of Ocean Engineering and Technology
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• v.20 no.5 s.72
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• pp.42-48
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• 2006

This paper shows theresults of centrifuge model experiments to investigate the behavior of a replacement method in dredged and reclaimed ground. For this experimental work, centrifuge model tests were carried out to investigate the behavior of a replacement method in soft clay ground. Basic soil property tests were performed to find the mechanical properties of clay soil sampled from the southern coast of Korea, which was used for the ground material in the centrifuge model tests. The reconstituted clay ground of the model was prepared by applying reconsolidntion pressure in a 1 g condition with a specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50 g. Replacement material of lead with a certain degree of angularity was used and placed until the settlement of the replacement material embankment reached a state of equilibrium. Vertical displacement of the replacement material was monitored during tests. The depth and shape of the replacement, especially the slope of the penetrated material and the water content of the clay ground were measured after finishing tests. Model tests for investigating the stability of an embankment after backfilling were also performed to simulate the behavior of a dike treated with replacement and backfilled with sandy material. As a result of the centrifuge model test, the behavior of the replacement, the mechanism of the replacement material being penetrated into clay ground, and the depth of the replacement were evaluated.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.191-197
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• 2002

This paper is experimental and numerical research results of performing centrifuge model tests to investigate the geotechnical engineering behavior of slag compaction pile as a substitute of sand compaction pile. In order to find the geotechnical engineering characteristics of the soft clay and the slag used in centrifuge model experiments, basic soil property tests, consolidation test, permeability tests and triaxial compression tests were performed. For centrifuge model tests, slags with changing relative density were used and their bearing capacity, stress concentrations in between pile and soft clay, settlement characteristics, and failure modes were investigated. As a results of centrifuge model tests, it was found that the bearing, capacity of model was increased with increasing density of slag pile and general shear failures were occured. Miniature soil pressure gauges were installed on model pile and soft ground respectively and thus vertical stress acting on them were measured. Stress concentration ratio was found to be in the range of 2.0~3.0. Bearing capacity obtained from the model test with slag was greater than that from the model test with a sand having the identical layout to each other. Thus it was confirmed the slag was an appropriate substitution of pile for sand.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.97-104
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• 2006

The centrifuge and 1-g shaking table tests were performed simultaneously to compare the dynamic behaviors of loose sands of same geotechnical properties. The prototype soils were 10 m thick liquefiable loose sands. The geometric scaling factors were 20 for 1-g and 40 for centrifuge tests. The excess pore pressure, surface settlement, and acceleration in the soil were measured at the same locations in the 1-g and centrifuge tests. The total excess pore pressure from development to dissipation was measured. In the centrifuge test, viscous fluid was used as the pore water to eliminate the time scaling difference between dynamic time and dissipation time. In the 1-g tests, the steady state concept was applied to determine the unit weight of the model soil, and two different time scaling factors were applied for the dynamic time and the dissipationtime. It is concluded that the 1-g tests can simulate the excess pore pressure of the prototype soil if the permeability of the model soil is small enough to prevent dissipation of excess pore pressure during shaking and the dissipation time scaling factor is properly determined.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5C
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• pp.351-358
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• 2006

The purpose of this study is to recommend the simulation method and procedure of behaviors of CFRD(Concrete Faced Rockfill Dam) concrete face slab with impoundment by centrifuge tests, to examine the effects of the flexural rigidity of the concrete face slab on the face slab deformation from the centrifuge tests, and to evaluate the effects of the stiffness of face supporting zone on the displacement and moment of face slab by numerical analysis which is verified by the centrifuge tests. In this study, the centrifuge tests on the two model dams with the concrete face slab of different flexural rigidity were carried out. Also, the centrifuge tests were simulated by numerical analysis of which input material properties were obtained by the triaxial tests on the model materials. The validity of numerical analysis was evaluated by comparison between the results of centrifuge tests and numerical simulation. The deformation pattern of the concrete face slab was examined with the various stiffness of the face supporting zone by numerical analysis. From the results of centrifuge tests, the effects of face slab thickness on the deformation of face slab were negligible. From the results of centrifuge tests and numerical analysis, it was found that the amplitude of the maximum displacement of face slab and the position where the maximum displacement was mobilized with impoundment were affected by the stiffness of face supporting zone rather than the flexural rigidity of concrete face slab.

• Journal of Ocean Engineering and Technology
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• v.38 no.1
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• pp.30-42
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• 2024

This study examined the jack-up spudcan penetration for a new type of offshore wind substructure newly proposed using the jack-up concept to reduce construction costs. The jack-up spudcan for offshore wind turbines should be designed to penetrate a stable soil layer capable of supporting operational loads. This study evaluated multi-layered soil conditions using centrifuge tests: loose sand over clay and loose sand-clay-dense sand. The penetration resistance profiles of spudcan recorded at the centrifuge tests were compared with the ISO and InSafeJIP methods. In the tests, a spudcan punch-through effect slightly emerged under the sand-over-clay condition, and a spudcan squeezing effect occurred in the clay-over-sand layer. On the other hand, these two effects were not critically predicted using the ISO method, and the InSafeJIP result predicted only punch-through failure. Nevertheless, ISO and InSafeJIP methods were well-matched under the conditions of the clay layer beneath the sand and the penetration resistance profiles at the clay layer of centrifuge tests. Therefore, the ISO and InSafeJIP methods well predict the punch-through effect at the clay layer but have limitations for penetration resistance predictions at shallow depths and strong stratum soil below a weak layer.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.107-116
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• 2004

This thesis is results of experimental works on the behavior of the cut-and-cover tunnel. Centrifuge model tests were performed to simulate the behavior of the cut-and-cover tunnels having cross sections of national road and subway tunnels. Model experiments were carried out with changing the cut slope and the slope of filling ground surface. Displacements of tunnel lining resulted from artificially accelerated gravitational force up to 40g of covered material used in model tests, were measured during centrifuge model tests. In model tests, Jumunjin Standard Sand with the relative density of 80 % and the zinc plates were used for the covered material and the flexible tunnel lining, respectively. Basic soil property tests were performed to obtain it's the property of Jumumjin Standard Sand. Shear strength parameters of Jumunjin Standard Sand were obtained by performing the triaxial compression tests. Direct shear tests were also carried out to find the mechanical properties of the interface between the lining and the covered material. Compared results model tests estimation with respect to displacements of the lining.