• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.168-175
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• 2008

The method of reinforced earth walls has grown remarkably and the frequency of utilization has been increased on a national scale thereafter introduced in the middle 1980s in Korea. Furthermore the construction case of the extensive Geosynthetic-Reinforced Segmental Retaining Walls had been increased. Currently, the design criterion of FHWA and NCMA mainly used in Korea suggest determining the horizontal distance of the upper/lower retaining wall based on the study results of the internal stability and the external stability of Segmental Retaining Walls but in many cases are not suitable for the actual situation in Korea. Therefore, in this study reviewed the design criterion of Geosynthetic-Reinforced Segmental Retaining Walls, performed the internal and external stability in Paju, Gyeonggi-do based on the design criterion of FHWA and NCMA, suggested the modified design criterion of FHWA with analyzing the results, and performed the stability analysis for the internal and external stability and the compound failure. Moreover for the confirmation of the modified FHWA design standard, the suggestion and the analysis of the numerical analysis approaching method using shear strength reduction technique were performed and the design cases utilized the modified FHWA design standard based on the study analysis were introduced.

• 한국지반환경공학회 논문집
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• 제19권12호
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• pp.5-14
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• 2018

최근 국내에 사용되고 있는 보강토옹벽 공법은 전면체의 재질, 보강재, 축조방법, 축조경사에 따라 수많은 종류가 제안되었으나 각 공법에 따른 설계방법이나 상세검토항목 등의 규정이 명확하지 않으며 집중호우에 따른 붕괴도 빈번하게 발생하고 있는 실정이다. 본 연구에서는 이러한 보강토옹벽의 설계에 있어서 좀 더 안정된 기술적 접근을 위해 설치높이별 단면을 가정하고 단일 강도의 보강재를 사용한 보강토옹벽의 인발파괴와 높이별 최적의 보강재 조합을 산정하고 산정된 각 단면에 대해서 보강길이비(L/H)에 따른 안전율 변화를 통하여 보강재의 최적 설계와 다단식 보강토옹벽의 최적 설계 그리고 보강재인 토목섬유의 재질에 따른 최적 길이비를 산정하여 제시하였다.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.235-261
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• 2009

This study illustrates the differences between the elasto-plastic cap model and Lade's model with Cosserat rotation through the analyses of two large-scale geosynthetic-reinforced soil (GRS) retaining wall tests that were brought to failure using a monotonically increasing surcharge pressure. The finite element analyses with Lade's model were able to reasonably simulate the large-scale plane strain laboratory tests. On average, the finite element analyses gave reasonably good agreement with the experimental results in terms of global performances and shear band occurrences. In contrast, the cap model was not able to simulate the development of shear banding in the tests. In both test simulations the cap model predicted failure loads that were substantially less than the measured ones.

• 한국지반공학회논문집
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• 제19권2호
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• pp.97-106
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• 2003

본 연구에서는, 4가지 종류의 토목섬유를 대상으로 토목섬유에 가해지는 구속응력의 크기 및 토목섬유 온도 변화에 따른 응력-변형률 관계를 규명하기 위한 온도제어 구속인장시험(Temperature Dependent Confined Tension Test)을 수행하였다. 또한, 보강토옹벽 내부 보강재의 온도변화를 측정하기 위한 온도계측을 수행하였다. 온도제어 구속인장시험 결과를 토대로하여, 토목섬유에 가해지는 구속응력 및 온도 변화에 따른 토목섬유 할선계수의 변화량을 정량적으로 평가할 수 있는 관계식을 제시하였다. 본 관계식을 이용한 토목섬유 보강토옹벽의 유한차분해석 예를 통해 다양한 보강토구조물의 변위해석시 온도변화에 따른 보강재의 특성변화를 고려할 수 있는 기법을 제시하였다. 유한차분해석 결과, 보강재의 온도가 5$^\circ$인 경우에 비하여 30$^\circ$인 경우에 전면부벽체의 최대변위량은 약 46.4% 증가하는 것으로 나타났다.

• 한국지반신소재학회논문집
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• 제5권1호
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• pp.1-7
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• 2006

보강토 옹벽이 콘크리트 옹벽에 비해 다양한 이점을 가짐에도 불구하고 영구구조물로서 지속하중이 작용하는 경우에 대해 장기변형이 발생할 소지가 있다는 우려가 있다. 본 논문에서는 이러한 관점에서 축소모형실험을 실시하여 수집된 보강토 옹벽의 장기변형 메카니즘에 대한 내용을 다루었다. 실험결과 지속하중이 작용하는 경우에 있어 장기적으로 잔류변형이 발생할 우려가 있는 것으로 나타났으며 이는 지속하중의 특성과 보강재 강성에 따라 좌우되는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.85-94
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• 1999

Reinforced Soil Wall has several merits comparing with conventional retaining wall. The conventional method has the limit of wall height, ununiform settlement of the foundation ground, quality assurance of the embankment body, shortening of construction period, economical construction and so on. Basis of previous mentioned things reinforced soil wall is the substitutional method of conventional retaining wall and its necessity is continuously increasing. The embanking material used in reinforced soil wall is generally limited such as a good quality sandy soil, and in many case constructors have to transfer such a good embanking material from far away to construction site. As a result, they would pressed by time and economy. If poor soils could be used embanking material, for example, clayey soil produced in-situ by cutting and excavation, the economical merit of reinforced soil wall would be increased more and more. Likewise, a lot of study about laboratory experimental behavior of reinforced soil wall using a good quality soil is being performed, but is rare study about clayey soil containing much volume of fine particle relatively in korea. In this study, the authors investigated behavior of the geosynthetic reinforced and unreinforced soil walls using clayey soil as embanking material in view of horizontal movement of walls, bearing capacity and reinforcement stress.

• 한국지반신소재학회논문집
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• 제10권3호
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• pp.43-51
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• 2011

본 연구에서는 수동저항부를 형성시킨 띠형 섬유보강재의 인발저항 특성을 평가하기 위해 일련의 실내인발시험을 수행하였다. 이 띠형 섬유보강재는 중간에 길이방향으로 접힘홈이 형성되어 있어 보강재를 반폭으로 접어 콘크리트 블록에 직접 체결할 수 있고 후단부에는 보강재를 '${\cap}$' 형태로 세워서 수동저항부를 형성시킬 수 있다. 이 띠형 섬유보강재는 후단부에 수동저항부가 형성되어 있기 때문에, 흙과 보강재 사이의 표면마찰저항과 수동저항부에서의 지지저항력이 함께 발현되는 인발저항 특성을 가진다. 따라서, 인발저항 평가시 마찰저항과 지지저항을 각각 산정하여 설계에 반영해야 한다. 일련의 인발시험 결과 수동저항부를 형성시키면 인발저항강도가 10~65% 정도 증가하고 수직응력이 클수록 증가량이 점차 커지는 경향을 보이는 것으로 나타났으며, 이를 근거로 수동저항부 형성에 의해 발현되는 지지저항력 산정 방법을 제안하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1580-1587
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• 2005

To calculate the long-term allowable strength of geosynthetic reinforcement, replacement method was recommended. The isochronous creep curve by S. Turner was used to define the relation between creep strain and allowable strength. In isochronous curve at given time, one can read the allowable strength at allowable creep strain. The allowable strain gets from specification by directors or manufacturers according to the allowable displacement of reinforced structures. The allowable strength can be determined in relation to the allowable horizontal displacement each structures case by case. The effect of install damage on isochronous behaviors of geosynthetic reinforcement was little. In previous study, install damage increase the creep strain slightly. And the degradation was not identified. But it is supposed that degradation increase the creep strain. In conclusion, The recommended model to determine long-term allowable strength of geosynthetic reinforcements considering tensile deformation of reinforcement and soil is fit for proper, correct and economic design for reinforced earth walls.

• Geomechanics and Engineering
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• 제10권5호
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• pp.635-655
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• 2016

The effects of reinforcement on the horizontal and vertical deformations of geosynthetic reinforced retaining walls are investigated under a well-known seismic load (San Jose earthquake, 1955). Retaining walls are designed with internal and external stability (with appropriate factor of safety) and deformation is chosen as the main parameter for describing the wall behavior under seismic load. Retaining walls with various heights (6, 8, 10, 12 and 14 meter) are optimized for geosynthetics arrangement, and modeled with a finite element method. The stress-strain behavior of the walls under a well-known loading type, which has been used by many previous researchers, is investigated. A comparison is made between the reinforced and non-reinforced systems to evaluate the effect of reinforcement on decreasing the deformation of the retaining walls. The results show that the reinforcement system significantly controls the deformation of the top and middle of the retaining walls, which are the critical points under dynamic loading. It is shown that the optimized reinforcement system in retaining walls under the studied seismic loading could decrease horizontal and vertical deformation up to 90% and 40% respectively.

• Geomechanics and Engineering
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• 제25권3호
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• pp.195-205
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• 2021

Time effect on the deformation and strength characteristics of geogrid reinforced sand retaining wall has become an important issue in geotechnical and transportation engineering. Three physical model tests on geogrid reinforced sand retaining walls performed under various loading conditions were simulated to study their rate-dependent behaviors, using the presented nonlinear finite element method (FEM) analysis procedure. This FEM was based on the dynamic relaxation method and return mapping scheme, in which the combined effects of the rate-dependent behaviors of both the backfill soil and the geosynthetic reinforcement have been included. The rate-dependent behaviors of sands and geogrids should be attributed to the viscous property of materials, which can be described by the unified three-component elasto-viscoplastic constitutive model. By comparing the FEM simulations and the test results, it can be found that the present FEM was able to be successfully extended to the boundary value problems of geosynthetic reinforced soil retaining walls. The deformation and strength characteristics of the geogrid reinforced sand retaining walls can be well reproduced. Loading rate effect, the trends of jump in footing pressure upon the step-changes in the loading rate, occurred not only on sands and geogrids but also on geogrid reinforced sands retaining walls. The lateral earth pressure distributions against the back of retaining wall, the local tensile force in the geogrid arranged in the retaining wall and the local stresses beneath the footing under various loading conditions can also be predicted well in the FEM simulations.