• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.43-50
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• 2016

A reinforcement is required to ensure the structural safety in case of railway embankment excavation under railway load. A large diameter soil nailing with concrete wall is applied as the reinforcement method instead of the conventional soil nailing system. In this study, a series of 3 dimensional numerical analyses are performed to investigate the optimum reinforcement considering 15 different conditions based on the length, lateral spacing, diameter, and inclination of the reinforcement. The interface between soil nail and perimetric grout is considered by means of cohesion, stiffness and perimeter of the grout. 0.3 m of reinforcement diameter is assessed as the most appropriate based on the economical viewpoint though ground displacement decreases with the increase of diameter, however the difference of displacement is negligible between 0.4 m and 0.3 m of diameter. Surface settlement, lateral displacement of wall, and stress of reinforcement are calculated and economic viewpoint to reinforce embankment considered. Consequently, the optimum reinforcement conditions considering those factors are evaluated as 3 m in length, 0.3 m in diameter, 1.5 m in lateral spacing, and 10 degree of inclination angle in the case of 3 m of excavation depth. Additionally, inclined potential failure surface occurs with approximately 60 degrees from the end of nails and the surface settlement and wall lateral displacement are restrained successfully by the large diameter soil nailing, based on the result of shear strain rate.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.257-264
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• 2001

This study presents the slope stability analysis results for the model slope test. The model slope was made of the soil reinforced by FPF(Fibrillated Polyprophylene Fiber). The shear strength properties of the soil reinforced by FPF fibers were evaluated through the direct shear tests. The model slope 1:1 and 1:1.5 were made and the load tests were performed. Back analysis using limit equilibrium method was carried out to evaluate the shear strength increase on the FPF reinforced slope. The factor of safety of the FPF reinforce slope increased about 23% over unreinforced slope.

• Geomechanics and Engineering
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• v.13 no.4
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• pp.641-651
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• 2017

Ground improvement with use of geosynthetic products is globally accepted now. The present paper discusses the improvement in bearing capacity of square footing placed at surface of cohesionless soil reinforced with geocell. Mohr-Coulomb failure criterion has been used in the observations. To study effects of geocell with respect to planar geogrid, model tests were conducted on planar reinforcement also. A comparative study of unreinforced soil and soil reinforced with plane geogrid and geocell has also been made. Numerical analysis results obtained by PLaxis have been compared with those obtained from model tests and were found to be in good agreement. A parametric study revealed the role of length of reinforcement, spacing between layers, placement of reinforcement from top surface etc. on bearing capacity. A design example given in paper illustrates the savings in cost of construction of footing on reinforced sand. The study shows that there is improvement in bearing capacity with respect to unreinforced soil which is of the order of 86%. Similarly settlement reduction is 13.07% for single layer of geocell which for double layers of geocell is 693% and 86.48% respectively. The cost reduction in case of reinforced soil is 35% as compared to unreinforced soil.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.27-36
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• 2013

LEM (Limit Equilibrium Method) based programs are commonly used for the designs of soil nailing as a slope reinforcement. However, there is a drawback that the interaction between ground and soil nailing is not properly reflected in those programs, which needs to be solved. For economical constructions and designs, research is also required on the support pattern of soil nailing. In this study, therefore, reinforcement effects of soil nailing were compared and analyzed by performing finite difference analyses which could properly consider the interaction between ground and soil nailing. As a result, when the angle from slope to nail is $90^{\circ}$, failure slip surface becomes the largest and thus the factor of safety becomes maximum.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.2
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• pp.79-91
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• 2017

This study was conducted to find out the physical properties and soil shearing strength reinforcement effect of herbaceous plants for the slope revegetation works. Two native plants(Pennisetum alopecuroides and Miscanthus sinensis) were used for this experiment, because they have excellent seed germination rates without preconditioning, and grow naturally around rivers. To identify the physical properties, the partial dry weight of plants were investigated. To identify the soil shearing strength reinforcement effect, the respective soil shearing strengths of the control soils, Pennisetum alopecuroides, Miscanthus sinensis samples were measured. Also, we did a correlation analysis to examine the relation of shearing strength to plant features. The results are summarized as follows: 1. The average dry weight of Pennisetum alopecuroides samples consists of 52.36% above ground and 47.64% at root. And in dry weight, 78.24% of it's root distributes within 10 cm in soil depth. Meanwhile the average dry weight of Miscanthus sinensis samples consists of 52.91% above ground and 47.09% at root. And in dry weight, 82.95% of it's root distributes within 10 cm in soil depth. 2. The results of correlation analysis showed that for both Pennisetum alopecuroides and Miscanthus sinensis, it could not be said that there was any correlation between shearing strength and plant characteristics, and statistically they were not meaningful. 3. In the shearing strength test with control soils, Pennisetum alopecuroides, Miscanthus sinensis as subjects, the differences in shearing strength measurement results were modest, and the order was shown as control soils < Pennisetum alopecuroides < Miscanthus sinensis, so the soil shearing strength reinforcement effect by the Pennisetum alopecuroides and the Miscanthus sinensis on loamy sand at river banks surface was confirmed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.6
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• pp.115-123
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• 2002

This study was performed to provide basic data for development and construction of reinforced soil wall that mixed with reinforcements such as calcium carbonate, monofilament fiber. In order to determine proper moisture content and mixing ratio by weight of reinforcement, Poisson's ratio and compressive strength tests for sandy soil had been conducted. Model tests for long-term behavior of reinforced soil wall were carried out to investigate the effect of reinforcement during loads and under static loads. The results of creep and model tests for sandy soil compared with clayey soil. Reinforced sandy soil mixed with calcium carbonate and cement showed brittle rupture by shear but that of mixed with monofilament fiber showed ductile rupture due to the tension force of fiber. It was shown that when age increased, creep strain of reinforced soil under sustained load approached constant values.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.724-731
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• 2006

The purpose of this study is to estimate a landslide using the SLOPILE program from the slope reinforced by slope stability systems such as soil nailing and pile. To do this, cutting slope located at Donghae-Highway in Kwangwon-Do was considered. The behavior of slope was monitored for a long term by using instrumentation according to the reinforcement stages. The sequence of reinforcement stages was followed as pile installation, boring, soil nailing installation, anchoring and embankment. The result from this case study shows that the safety factor of slope depends on the reinforcement stage more or less.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.04a
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• pp.29-33
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• 1991

This paper reports the application study of the ground reinforement under a buried pipeline subjected to differential settlement via a finite element modelling. The Soil-reinforrement interaction helps to mimimize the differential settlement between the adjoining pipe segments. The settlement pattern and deformation slope of a pipeline have been evaluated for a boundary condition at the joint between a rigid structure and apipeline. The analysis results are compared for both non-reinforied and reinforced cases to measure the effectiveness of the soil reinforcement for restraining the settlement of the pipeline.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.241-249
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• 2017

In a reinforced soil structure, the interaction between soil and an reinforcement occurs due to the frictional resistance on the contact surface between them or the pullout resistance of the reinforcement. Generally, a pullout test is conducted to measure pullout parameters of extensible geogrids. The factors affecting the pullout parameters in a pullout test include a density of backfill, shape of reinforcements, overburden pressure, length of spread reinforcements, and so on. The purpose of this study is to suggest a length of the spreading of an extensible reinforcement that can be used in estimating suitable pullout parameters of a pullout test. To this end, a pullout test was carried out. For the test, the length of spreading of an extensible reinforcement was set as 32 cm, 52 cm, 72 cm, and 100 cm, and effects of the lengths on pullout parameters were analyzed. As a result of the pullout test, it was confirmed that the frictional resistance between the soil and the reinforcement increases with the increase of the length of the reinforcement.

• Interaction and multiscale mechanics
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• v.5 no.4
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• pp.369-383
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• 2012

In this paper, soil-structure interaction analysis has been presented for beams resting on multilayered geosynthetic-reinforced granular fill-soft soil system. The soft soil and geosynthetic reinforcements are idealized as nonlinear springs and elastic membranes, respectively. The governing differential equations are solved by finite difference technique and the results are presented in non-dimensional form. It is observed from the study that use of geosynthetic reinforcement is not very effective for maximum settlement reduction in case of very rigid beam. Similarly the reinforcements are not effective for shear force reduction if the granular fill has very high shear modulus value. However, multilayered reinforced system is very effective for bending moment and differential settlement reduction.