• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.47-59
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• 2008

Application of mechanically stabilized earth wall (MSEW) abutment has been rapidly increasing in United States of America, Pennsylvania since 2002. MSEW is effective for reducing construction cost and period compared to general concrete reinforced wall. In the paper, theoretical background and conventional criterion of MSEW abutment that is widely used abroad are analyzed. Based on the results, application of suitable MSEW abutment to domestic bridge type is examined. For the application of MSEW abutment in Korea, load interacting with upper shoe in domestic bridge types and structural analyses of beam seat and pile are investigated. As a result, all applications are possible except for PSC BOX Bridge that has heavy self-weight of girder. Through two and three dimensional numerical analyses, horizontal behaviour mechanisms between pile and MSEW were analyzed and field tests are also carried out for seven piles behind earth walls. From results of field tests, it is confirmed that an angle of internal friction of backfill material needs to be greater than 34 degree to use H-Pile as foundation of MSEW.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.13-26
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• 2016

In this study, more economical than conventional reinforced soil retaining walls, we compared the behavior characteristic about the safety block type numerically for reinforced retaining wall. In this study, reinforced soil retaining wall, first, was integrated a wall putting shear key on the blocks. Second, construction reinforcement focused on the theoretical failure surface was satisfied with the stability of a retaining wall reinforced by a shear plane. when analyzing, element of using reinforcement was carried out a numerical analysis for the cable element and the strip element, and they were analyzed under the conditions according to the stiffener length, distance, with or without shear key. Analysis for the integration of the front wall was reinforced soil retaining walls by installing a larger displacement shear key confinement effect, if reinforced construction and reinforcement with 1 interval and 2 interval, the failure surface was bigger displacement constraints. Generating a deformation amount was smaller than the generation amount of deformation accrued during construction of AASHTO so that it was stable.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.95-105
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• 2005

Generally, a modified version of limit equilibrium method can be used to evaluate a slope stability of the geosynthetic reinforced soil slopes. In most cases, resisting effects of geosynthetic reinforcement are dealt with considering an increased shear strength on the potential slip surface. However, it is not clear that the methods satisfy all three equilibrium equations. As we know, the pattern of normal stress distribution along the slip surface is the key factor in calculating the safety factor of slopes. In this study, the new slope stability analysis method in which not only reinforcing effects of geosynthetics can be considered but also all three equilibrium equations can be satisfied was proposed with assuming the normal stress distribution along the slip surface as quadratic curve with horizontal $\chi-coordinate$. A number of illustrative examples, including published slope stability analysis examples for the reinforced and unreinforced soil slopes, loading test of large scale reinforced earth wall and centrifuge model tests on the geotextile reinforced soil slopes, were analyzed. As a result, it is shown that the newly suggested method yields a relatively accurate factor of safety for the reinforced and unreinforced soil slopes.

• Journal of the Korean Geosynthetics Society
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• v.9 no.4
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• pp.1-7
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• 2010

The soil nailing method have been developed on the basis of experimental works as well as theoretical backgrounds. As for the experimental research works, most of the data have been measured during the application of load in service. However, not only the soil-nailed structure behavior in service but also the failure behavior of the structure are the major concerns to evaluate and even establish a design method of soil-nailed walls. In this paper for the apprehension of behavior in the soil-nailed structure which the front of nail is connected, a relatively large-scale experiment was carried out to figure out the failure behavior of soil-nailed wall. A number of data have been acquired and analysis.

• Geomechanics and Engineering
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• v.4 no.4
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• pp.263-279
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• 2012

The present paper deals with the analysis of combined footings resting on geosynthetic reinforced granular fill overlying stone column improved poor soil. An attempt has been made to study the influence of inclusion of geosynthetic layer on the deflection of the footing. The footing has been idealized as a beam having finite flexural rigidity. Granular fill layer has been represented by Pasternak shear layer and stone columns and poor soil have been represented by nonlinear Winkler springs. Nonlinear behavior of granular fill layer, stone columns and the poor soil has been considered by means of hyperbolic stress strain relationships. Governing differential equations for the soil-foundation system have been derived and solution has been obtained employing finite difference scheme by means of iterative Gauss Elimination method. Results of a detailed parametric study have been presented, for a footing supporting typically five columns, in non-dimensional form in respect of deflection with and without geosynthetic inclusion. Geosynthetic layer has been found to significantly reduce the deflection of the footing which has been quantified by means of parametric study.

• Journal of the Korean GEO-environmental Society
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• v.19 no.4
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• pp.17-26
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• 2018

This study systematically examines the changes in the compressive and tensile strength of soil cement reinforced by natural hair fiber, which is regularly produced from human. Extensive experimental tests of various test specimens have been carried out in a laboratory. Several factors are considered, including the soil type, amount of cement, amount of fiber, fiber length, loading type, and curing age. The test results indicate that both the compressive and tensile strengths are significantly affected by the fiber, either increasing or decreasing depending on the conditions. The increase in tensile strength is significant in the sand-based soil cement due to the tensile resistance of the fiber which is interlocked with the surrounding soil or cement particles. The natural fiber provides a larger strain to failure due to its extensibility, which allows greater deformation. Based on the test results, natural hair fibers can be an effective and environmentally friendly way to improve soil ground subjected to tensile loading, such as an embankment slope, road subgrade, or landfill, thus reducing the cost for cement and waste treatment. The study results provide a useful information of better understanding the mechanical behavior of natural hair fiber in soil cement and the practical use of waste materials in civil engineering. The findings can be practically applied for improving earth structures under tensile loading.

• Geotechnical Engineering
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• v.7 no.1
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• pp.33-40
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• 1991

This paper reports the application study of the ground reinforcement under a pipe joint. The soil-reinforcement interaction helps to minimize the stress concentration at joint. The settlement pattern and the earth pressure variation have been evaluated under the pipeline subjected to differential settlement. The pipeline is fixed at one side with the other side set free being loaded with a uniform surface loading. The problem has been studied by means of laboratory model test and flite element technique, and the analysis results are compared for both non-reinforced and reinforced cases to evaluate the effectiveness of the soil reinforcement for restraining the settlement of the pipeline.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.301-310
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• 2006

In this short paper, an elasto-plastic repair and retrofit element is developed for the investigation of the seismic performance of damaged reinforced concrete members. The developed element is capable of reflecting the increased characteristics due to both repair and retrofitting for degraded strength and stiffness of the members. The element having both birth and death time can freely be activated within the user-defined time intervals during static and dynamic time-history analysis. Comparative studies are conducted for reinforced concrete members being repaired and retrofitted. Analytical predictions including the developed element display reasonable correlation with experimental results. In short, it is concluded that the developed element is capable of providing salient features for the healthy assessment of seismic performance of RC members being repaired and retrofitted.

• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.233-244
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• 2018

This study aims at evaluating the performance of repairing technique with CFRPs in recovering cyclic performance of damaged columns in flexure in terms of structural response parameters such as strength, dissipated energy, stiffness degradation. A 2/3 scaled substandard reinforced concrete frame was constructed to represent the substandard RC buildings especially in developing countries. These substandard buildings have several structural deficiencies such as strong beam-weak column phenomenon, improper reinforcement detailing and poor material properties. Flexural plastic hinges occurred at the columns ends after testing the substandard specimen under both constant axial load and reversed cyclic lateral loading. Afterwards, the damaged columns were externally wrapped with CFRP sheets both in transverse and longitudinal directions and then retested under the same loading protocol. In addition, ambient vibration measurements were taken from the undamaged, damaged and the repaired specimens at each structural repair steps to identify the effectiveness of each repairing step by monitoring the change in the natural frequencies of the tested specimen. The ambient vibration test results showed that the applied repairing technique with external CFRP wrapping was proved to recover stiffness of the pre-damaged specimen. Moreover, the lateral load capacity of the pre-damaged substandard RC frame was restored with externally bonded CFRP sheets.

• Journal of the Korean Geosynthetics Society
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• v.2 no.3
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• pp.3-9
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• 2003

Geosynthetics as a reinforcing material for earth structures have ever increased due to their excellent economy, fine external appearance, and easy construction. Geogrids are high-strength, orientated-polymer grid structures used to reinforce soil. This paper deals with the construction and sire monitoring for a 5.1m high-reinforcd slope with $75^{\circ}$ steep. The purpose of site monitoring is to evaluate the applicability of reforced slope with geogrid. Full scale field performance during and after construction was monitored by incorporating instrumentation including strain gauges on the geogrid, and horizontal and vertical movements.