• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.53-68
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• 2011

This paper presents the fundamental parameters for designing the NATM Composite Lining to be used in NATM tunnel construction. Firstly, the concept of NATM Composite Lining behaviour is introduced and reviewed in construction-performance. For the fundamental study, the optimal mix ratio tests and backfill material property tests to develop high-quality composite lining (PC panel lining) are fundamentally carried out. And the light-weight foamed mortar which is used for backfill material is developed. Full-scale loading tests to verify a performance of the NATM Composite Lining is also performed. From this research, it is clearly found that the NATM Composite Lining is very applicable method to considerably increase the stability and constructability of tunnel structure.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.23-34
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• 2006

In this study, the centrifugal tests were performed to evaluate the behavior of reinforced retaining wall that allows the settlement of reinforcement strip. To analyze the stability of reinforced retaining wall, which drives the settlement of reinforcement strip, the results were compared with the conventional reinforced retaining wall. In the centrifugal tests, the aluminum plate for the face was used and the aluminum foil was used as a reinforcement. The decomposed granite soil was adopted as a backfill. As a result, the settlement free reinforced retaining wall reached to the failure at 80g-level. In contrast, the conventional reinforced retaining wall was collapsed at 69g-level. It means that the settlement free reinforced retaining wall has the stronger stability than the conventional reinforced retaining wall. Also, vertical earth pressure of the settlement free reinforced retaining wall near the base of wall was higher 16% than that of the conventional reinforced retaining wall.

• Journal of the Korean Geosynthetics Society
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• v.2 no.2
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• pp.3-11
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• 2003

Researches on the induced trench method using compressible materials such as clay, mud, straw, or EPS block have been performed to reduce the load acting on buried conduits under a high fill. The induced trench method has the problems that the arching area due to the compressible arching material is one dimensional or localized in a narrow zone. The main purpose of this study is to solve the problems of the induced trench method mentioned above. The various types of laboratory model tests are conducted to find the effects of the variations of EPS block width, multilayer application, soil density, and diameter of the flexible steel pipe. A series of model tests was conducted to evaluate the reduction of earth pressure on conduits using EPS block. Based on modeling test it is found that the magnitude of vertical earth pressure on conduits was reduced about 60% compared with conventional flexible conduit systems.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.21-30
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• 2010

To understand the deformation behavior of nonwoven geotextiles(NWGT) reinforced soil wall, analyses of load-elongation properties, soil-reinforcement interface friction, laboratory model tests, and field cases throughout literature reviews are being studied in this paper. According to the analyses results, the stiffness and tensile strength of NWGT is increased in proportion to confinement pressures, and the interface shear strength at soil-NWGT appeared to be stronger than soil-geogrid interface. The deformation at the beginning of loading on NWGT reinforced soil wall is larger than geogrid reinforced soil wall, but the wall deformation with NWGT is smaller than the wall of geogrid after passing some loading point in laboratory model tests. Case analysis results have shown that the facing of NWGT reinforced soil wall should be rigid enough to be used as a permanent wall, and NWGT and in-situ poor soil can be used for reinforcement and backfill respectively if the wall is constructed as pre-reinforced soil body and with post-facing that has a full-height rigid concrete.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.11-19
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• 2013

Coarse-grained soils are typical engineering materials commonly used in many civil engineering applications such as structural fills, subgrade and drainage fills for dam, railway and bridge. Various researches have been performed with related to constitutive laws for numerical analysis of such structures. This paper presents a parametric study for a constitutive model for coarse grained materials. The model is a kind of the bounding surface models based on critical state theory. A distinct feature of the model is to capture the response of coarse-grained materials with different void ratios and confining pressures using a single set of model parameters. The model behavior is defined with a set of elastic parameters, critical state parameters, and model-specific parameters. The parametric study was performed for the model-specific parameters. The result of parametric study shows that the model is capable to capture stress-dilatancy behavior and kinematic-hardening under non-associative plastic flow.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.97-105
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• 2004

The purpose of this study is to provide the ways of recycling of by-product limes as lightweight fill, backfill materials, and lightweight blocks by performing experimental study. New lightweight fill materials and blocks were devised by mixing by-product lime, weathered granite soil, small pieces of waste EPS, and Portland cement. Physical, geotechnical, and environmental properties of the lightweight mixed soils and blocks were analysed by laboratory experiments for mixed samples manufactured with various mixing ratios. KMS tests were also performed to evaluate the concentration variation of the chemical components of the light weight blocks leachates. It is expected that this study will contribute to resolving the problem of by-product lime disposal as well as to recycling the by-product limes as fill materials and blocks.

• Geotechnical Engineering
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• v.4 no.1
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• pp.7-16
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• 1988

The safety factor has been used widely and uniquely at present to check the safety of the structure . However, probability of failure would be logically attempted to check the reliability of the structure in future Coulomb's theory or Rankine's theory has been applied in practice to retaining earth structure in spite of the fact that the lateral earth pressure, which is the primary factor in the determination of wall structure, depends on the modes of wall movement . This study is concentrated on the two modes of , wall movement (active case rotation about bottom(AB) , active case rotation about top(AT)) of the overturning'failure of vertical wall with horizontal sand backfill . The static active earth pressure is determined by applying each of Coulomb's theory, Dubrova's redistribution theory and Chang's method The earthquake active earth pressure is determined by adding Seed and Whitman's earthquake pressure to the static earth pressure , On the condition that design variables are fixed with each of the above earth pressure, reliability is analyzed using the recently developed method of AFOSM (Advanced First Order Second Moment)

• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.3-15
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• 2004

Geogrid reinforced soil structures with segmental block facing have been increased since 1990's, because of the convenience of installation and the flexible appearance. In this paper, the behavior of the segmental reinforced retaining wall was analysed with the results of field monitoring. The height and length of reinforced wall are 12m and 25m, respectively. The field measurement equipments are horizontal and vertical earth pressure cells, settlement plate, strain gauge, inclinometer, and displacement pin. Based on the field monitoring, the horizontal earth pressure was approximately 0.3times higher than that of the theoretical method and the maximum tensile strength of reinforcement was 26.2kN/m. The displacement of facing wall was 23mm at the point of 7.1m height of the wall and toward the wall facing. The results of the study indicate that the segmental reinforced retaining wall is in a stable condition because of good compaction & reinforcement effects, and long period of construction time. Finally, the computer program of SRWall is very useful tool to design the segmental reinforced retaining wall.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.107-117
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• 2008

In this study, the failure and deformation characteristics of steel fiber reinforced shotcrete (SFRS) which is a primary tunnel support was investigated to find out ground-support mutual behavior. To this end, a mock-up of a tunnel was made and experimented with the conditions of lateral earth pressure coefficient 0.5 and 1.0. During the tests, 11 hydraulic cylinders were used for loading. for better simulation of the lateral earth pressure effect, these cylinders were controlled separately by two groups; crown and side wall. Meanwhile, the deformation of shotcrete was measured by 11 LVDTs. Backfill material was also used fur better load transfer from hydraulic cylinders to shotcrete. For the validation of the mock-up test results, 3D numerical analysis is carried out. To do numerical analysis under the same condition as a mock-up test, the load history curve which was obtained during the test was tried to be simulated using an individual FISH routine in the numerical analysis.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.321-332
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• 2021

Though development of reinforced earth wall is on the rise recently, safety verification for various methods remains behind which has caused the problems including collapse after installation. This study aims to evaluate the field applicability of the shape of flexible strip reinforcement according to pullout resistance test and field damage test. The test specimens were 3 shape of reinforcement, the typical flexible band reinforcement, developed luged band reinforcement, and band type reinforcement made by cutting geogrid. It was found that reinforcement of type have strengths and weaknesses, respectively. The best type of flexible strip reinforcements can be selected, if the conditions are considered with the installation conditions of the reinforcing earth retaining wall and the particle size of the backfill materials.