• 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.

• 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.

• 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.

• 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.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.119-130
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• 2003

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.

• 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.

• Geomechanics and Engineering
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• v.12 no.2
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• pp.239-255
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• 2017

Various centrifuge model tests on the pile foundations were performed to investigate fundamental characteristics of a pile-soil-foundation system recently, but it is hard to find numerical analysis results of a pile foundation system considering the nonlinear behavior of soil layers due to the dynamic excitations. Numerical analyses for a pile-soil system were carried out to verify the experimental results of centrifuge model tests. Centrifuge model tests were performed at the laboratory applying 1.5 Hz sinusoidal base input motions, and nonlinear numerical analyses were performed utilizing a finite element program of P3DASS in the frequency domain and applying the same input motions with the intensities of 0.05 g~0.38 g. Nonlinear soil properties of soil elements were defined by Ramberg-Osgood soil model for the nonlinear dynamic analyses. Nonlinear numerical analyses with the P3DASS program were helpful to predict the trend of experimental responses of a centrifuge model efficiently, even though there were some difficulties in processing analytical results and to find out unintended deficits in measured experimental data. Also nonlinear soil properties of elements in the system can be estimated adequately using an analytical program to compare them with experimental results.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.51-58
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• 2008

The George Massey immersed tunnel passes the Fraser River near Vancouver, Western Canada. In this paper, dynamic analysis of the tunnel on sandy soils was performed using an effective stress constitutive model called UBCSAND. This model is able to calculate pore pressure rise and resulting tunnel deformation due to cyclic loading. Centrifuge tests conducted at RPI are used to verify the model performance. Centrifuge tests consist of 3 models: Model 1 is designed for an original ground condition, Model 2 for a ground improvement by compaction method, Model 3 for a ground improvement by gravel drainage. The results of centrifuge Model 1 are presented and compared with predictions of UBCSAND model. This model well captured the results of centrifuge test and therefore can be used to predict dynamic behavior of similar tunnels or underground structures on sandy soils.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.227-238
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• 2004

This paper is results of experimental and nunerical 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. Numerical analysis with the commercially available program of FLAC were performed to compare with results of centrifuge model experiment In numerical modelling. Mohr-Coulomb elasto-plastic constitutive model was used to simulaye the behavoor of Jumunjin Standard Sand and the interface element between the lining and the covered material was implemented to simulate the interaction between them. Compared results between model tests and numerical estimation with respect to displacement of the lining showed in good agreements.