• 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.

• Geomechanics and Engineering
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• v.10 no.6
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• pp.757-774
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• 2016

Soils are usually weak in tension therefore different materials such as geosynthetics are used to address this inadequacy. Worldwide annual consumption of geosynthetics is close to $1000million\;m^2$, and the value of these materials is probably close to US$1500 million. Since the total cost of the construction is at least four or five times the cost of the geosynthetic itself, the impact of these materials on civil engineering construction is very large indeed. Nevertheless, there are several significant problems associated with geosynthetics, such as creep, low modulus of elasticity, and susceptibility to aggressive environment. Carbon fiber reinforced polymer (CFRP) was introduced over two decades ago in the field of structural engineering that can also be used in geotechnical engineering. CFRP has all the benefits associated with geosynthetics and it boasts higher strength, higher modulus, no significant creep and reliability in aggressive environments. In this paper, the performance of a CFRP reinforced retaining wall is investigated using the finite element method. Since the characterization of behavior of soils and interfaces are vital for reliable prediction from the numerical model, soil and interface properties are obtained from comprehensive laboratory tests. Based on the laboratory results for CFRP, backfill soil, and interface data, the finite element model is used to study the behavior of a CFRP reinforced wall. The finite element model was verified based on the results of filed measurements for a reference wall. Then the reference wall simulated by CFRP reinforcements and the results. The results of this investigations showed that the safety factor of CFRP reinforced wall is more and its deformations is less than those for a retaining wall reinforced with ordinary geosynthetics while their construction costs are in similar range.

• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.27-36
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• 2004

This paper presents the results of stability analyses on soil-reinforced segmental retaining walls in a tiered arrangement. Four different walls were examined to investigate the appropriateness of their designs within the context of the current design guidelines based on limit equilibrium. Slope stability analysis against the compound failure mode, which is frequently ignored during design, was also performed based on the method recommended by FHWA design guidelines. Also presented are the results of instrumentation on a full-scale field trial wall constructed as part of this study. The implications of the findings from this study are discussed.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.107-118
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• 2013

Geosynthetic reinforced soil (GRS) walls have been increasingly applied recently due to its numerous geotechnical engineering applications. However failure occurs in some cases of constructed GRS walls. These GRS wall failures are mostly due to the unpredictable characteristics of intensive rainfall. Hence, the need for new and innovative ideas for rehabilitation methods has been getting attention. This paper introduces a case study for the design and restoration method of collapsed GRS wall using Limit equilibrium and Numerical Analyses. Restoration method includes: (1) soil nailing without backfill excavation and (2) reconstruction with GRS wall after collapsed backfill excavation. Analyses results show minimal horizontal displacements and shear strain on the reinforced concrete facing for the restoration case with soil nailing. On the other hand, horizontal displacements are developed in the middle of the mortar block facing and shear strains are developed at the bottom facing with spiral curves for the reconstructed GRS wall after collapsed backfill excavation. Therefore, the collapsed GRS wall was restored with the soil nailing without backfill excavation and its construction procedures are discussed in this paper.

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.29-38
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• 2005

It is essential to take consideration of long-term deformation characteristics of mechanically stabilized earth wall user sustained and repeated loads for design and construction, especially for use as part of permanent structures. This paper presents the long-term performance of a full-scale geogrid reinforced segmental retaining wall results based on the measured strains in geogrids for three years. The results indicate that the reinforcement tensile strains tend to continuously increase after wall completion with the increase being more pronounced in the reinforcement layers in the lower tier. It can be concluded that the long-term deformation should be taken in account for walls constructed as part of permanent structures for which wall deformation should be controlled.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.467-475
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• 2012

Static and dynamic train load tests were conducted to evaluate the train load transfer mechanism in the roadbed which was retained by two types (fully and partially) of segmental retaining walls reinforced by geogrid. The test roadbed was 2.6m high, 5m wide, and 6m long. A combination of earth pressure gages, displacement transducers, and strain gages were placed in specific locations to measure the responses. Test results showed that the wall displacement pattern as well as the earth pressure for the fully reinforced retaining wall was different from those for the partially reinforced retaining wall. In the dynamic train load test, the strain in the upper part of the wall tended to decrease, and both the residual deformation and the rate of the deformation were significantly lower than those in the current design standard.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.135-143
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• 2005

This paper presents a case history of a geosynthetics-reinforced segmental retaining wall, which collapsed during a severe rainfall immediately after the completion of the wall construction. In an attempt to identify possible causes for the collapse, a comprehensive investigation was carried out including physical and strength tests on the backfill, stability analyses on the as-built design based on the current design approaches, and slope stability analyses with pore pressure consideration. The investigation revealed that the inappropriate as-built design and the bad-quality backfill were mainly responsible for the collapse. This paper describes the site condition including wall design, details of the results of investigation and finally, lessons learned. Practical significance of the findings from this study is also discussed.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.165-174
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• 2017

There are natural disasters caused by abnormal climate in the world. In particular, there are frequent disasters such as floods and landslides caused by rainfall in summer. Rainfall will have a major impact on the stability of a retaining wall. If drainage during rainfall activities within the retaining wall is not made properly, permeated water brings a significant increase in pore pressure inside of the backfill soil and reduces the shear strength of the soil. Therefore, research how to install the drainage layers to reduce the infiltrated water inside of the backfill soil is very necessary. In this study, we performed a numerical modeling to find the optimum installation conditions of the location and number of drainage layer related to stability of the reinforced retaining wall during rainfall installed geosynthetics.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.33-42
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• 2006

Geosynthetics reinforced soil (GRS) walls with a flexible wall face allow deformation. GRS walls constructed on the weak ground change in both horizontal earth pressures on wall faces and the tensile stress of geosynthetics, affecting the backfill in time until the deformation of the backfill and the foundation is completed. However, there are few studies that were done to measure and analyze the horizontal earth pressures and geosynthetics deformation on GRS walls constructed on the soft ground for a long period of time. Two field GRS walls in this study are constructed on a shallow layer of a weak foundation to measure and analyze geostynthetics deformation, horizontal earth pressures, and pore water pressures for the duration of approximately 16 months. Strain gauges are used to measure geosynthetics deformation; this study specifically suggests a new method of measuring nonwoven geotextile using strain gauges. Most geosynthetics deformation occurred within a month after the construction of GRS walls. The maximum deformation measured for approximately 16 months appeared as follows: nowoven geotextile: 6.05%, woven geotextile: 2.92%, and geogrid: 2.33%. Pore water pressures on the GRS wall can be ignored; however, horizontal earth pressures on the bottom and the upper part of the wall face appear larger than earth pressures at rest.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.21-31
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• 2017

Geobag method is an eco-friendly method to minimize the impact on the environment in the construction of retaining wall structure as a kind of geosynthetic reinforced retaining walls. In this study, evaluated behavior of full scaled geobag retaining wall about four different types of geobag retaining walls, that is, non-compacted geobags wall, compacted geobag wall, combination of longitudinal and transversal laied geobags wall, gabion and geobag wall were constructed in the field with instrumentation. Based on the results of field measurement, transversal layered geobag wall for non-compacted case was displaced 30% more than that of mixed gabion wall. Also, the more than 2m geobag walls without reinforcement at the backfill area are turned out to be unstable in terms of wall displacement. On the one hand, the distribution of the earth pressure for all geobag retaining walls sites show within the range of Rankine's and Coulomb's earth pressure after construction. But after intensity rainfall, the transversal laied geobag walls significantly increment of soil pressure. The geobag walls which constructed in the way of mixed wall systems such as gabion and geobag, longitudinal and transversal laied geobags are much stable with comparison of transversal laied geobag wall.