• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.867-874
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• 2003

섬유보강재를 이용한 성토제체의 설계에서 기존의 방법은 보강재의 변형을 무시하고 흙의 변형만을 중요시하고 있다. 보강재에 의해 보강된 성토제체의 파괴면에서 보강재와 흙의 거동은 초기응력단계에서는 일체거동현상을 나타내지만 응력의 증가에 따라 변형량에서 차이를 보인다. 이러한 문제는 토공구조물의 보강재를 설계하는데 있어서 중요한 요소로서 보강효과에 큰 영향을 미칠 수 있다. 본 연구에서는 연약지반 위에 PET Mat로 보강하여 축조한 성토제체에서 보강재와 흙의 응력 - 변형거동을 수치해석을 통하여 분석하였다. 연구결과, 파괴면에서 보강재의 변형은 보강재의 인장강도 크기에 따라 큰 차이를 보이고 있다. 외부하중에 의해 보강재에 발생하는 최대응력은 보강재의 항복인장강도를 초과하지 않으며, 보강재에 발생하는 응력이 성토체에서 발생하는 응력이상일 때 이상적인 것으로 나타났다. 또한 제체의 전단파괴에 대한 안전율은 보강재의 항복인장강도가 증가할수록 증가하는데 보강재와 흙의 변형이 일치되는 이후부터는 안전율의 증가율은 거의 미미한 것으로 나타났다.

• Journal of the Korean Geosynthetics Society
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• v.9 no.3
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• pp.9-18
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• 2010

A series of model tests were performed to investigate the load transfer by soil arching in geosynthetic-reinforced and pile-supported(GRPS) embankment systems. In the model tests, model piles with isolated cap were inserted in the model container and geosynthetics was laid on the pile caps below sand fills. The settlement of soft ground was simulated by rubber form. The loads acting on pile caps and the tensile strain of geosynthetics were monitored by data logging system. At the given interval ratio of pile caps, the efficiency in GRPS embankment systems increased with increasing the height of embankment fills, then gradually converged at constant value. Also, at the given height of embankment fills, the efficiency decreased with increasing the pile spacing. The embankment loads transferred on pile cap by soil arching increased when the geosynthetics installed with piles. This illustrated that reinforcing with the geosynthetics have a good effect to restraint the movement of surrounding soft grounds. The load transfer in GRPS embankment systems was affected by the interval ratio, height of fills, properties of grounds and tensile stiffness and so on.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.379-385
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• 2003

In the existing method to design geosynthetic reinforced embankment, the required strength of reinforcements is determined by vertical stress only rather than strain. This strength is not in accord with tensile strength that behaves as reinforcement in earth structures. The reinforcement and adjacent soil on the failure plan behave in one unit at the initial stress phase but they make a gap in strain as stress increases. This issue may cause a big impact as a critical factor on geosynthetic reinforcement design in earth structures. The quantitative analysis on strain behavior was performed with a PET Mat reinforced embankment on soft ground. From this study, several outstanding discussions are found that tensile strength of reinforcement governs the failure of embankment when the soil stress is greater than failure stress. Also the optimum required tensile strength of geosynthetic reinforcement(Tos) should be determined by stress, displacement, displacement gap and safety factor of soil-PET Mat at the location of PET Mat.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.276-284
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• 2009

Recently pile-supported embankments have emerged as an optimum method when the rapid construction and strict deformation of structures are required on soft soils. Especially geosynthetic-reinforced and pile-supported (GRPS) embankments are used worldwide as they can provide economic and effective solutions. However the load transfer mechanism in GRPS embankments is very complex, and not yet fully understood. Particularly the purpose and effect of geosynthetic inclusion are ambiguous and considered as an auxiliary measure assisting the arching effect of piles. Numerical parametric study using 3D finite element method has been conducted to investigate the effect of geosynthetic reinforcement on the load transfer mechanism of GRPS embankments. Numerical results suggested that as more stiffer geosynthetic is included, arching effect decreases considerably and the load concentration to the piles mostly caused by tension effect of geosynthetic. This finding is contradictory to the common understanding that geosynthetic inclusion only enhance the efficiency of load transfer. Consequently the design parameters determined from the numerical analyses are compared with those of three existing design methods. The problems of the existing methods are discussed.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.1-10
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• 2011

When an embankment is performed on the soft ground of the coastal with possibilities of lateral flow, lateral displacement occurs to the bottom of the surface of the ground. This lateral displacement can affect existing infra structures that are buried in the adjacent underground by causing a displacement in the nearby base foundation. Soft ground supporting piles and reinforced piles were applied as reinforcement remedies against the lateral displacement. And for the effect analysis, numerical analysis was performed under the classifications of non-reinforcement base and reinforced base. The result of the numerical analysis showed that the reinforced piles had more effects by 1.9 times than non-reinforced piles. Soft ground supporting piles showed better effects by 2.6 times than non-reinforced piles. Additionally, between the two reinforced remedies, soft ground supporting piles showed greater effects by 1.3-1.6 times than the reinforced piles.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.13-22
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• 2021

Pile or column supported embankments have been increasingly employed to construct highway or railway embankments over soft soils. Piles or columns of stiffer material installed in the soft ground can provide the necessary support by transferring the embankment load to a firm stratum using a soil arching. However, there has been reported to occur a relatively large differential settlement between the piles and the untreated soils. Geosynthetic reinforced pile or column supported embankment (GRPS) is often used to minimize the differential settlement. Two dimensional finite element anlyses have been performed on both the column supported embankments and the geogrid reinforced column supported embankments by using a PLAXIS 2D to evaluate the soil arching effect. Based on the results obtained from finite element analyses, the stress reduction ratio decreases as the area replacement ratio increases in the column supported embankments. For the geogrid reinforced column supported embankments, the geogrid reinforcemnt can reduce differential settlements effectively. In additon, the use of stiffer geogrid is appeared to be more effective in reducing the differential settlements.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.5-16
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• 2005

Geosynthetic-reinforced and pile-supported embankments have been increasingly used and researched around the world. The inclusion of one or multiple geosynthetic reinforcements over the pile is intended to enhance the efficiency of load transfer from soft ground to piles, to reduce total and differential settlement and increase global or local stability. In this paper, the reinforcement effectiveness and arching effect of the geogrid-reinforced and pile-supported embankments have been studied in terms of field model tests and numerical analysis with varying the space between piles and reinforcement. 2-dimensional numerical analysis has been conducted using the FLAC (Fast Lagrangian Analysis of Continua) program. And load transfer mechanisms between soil-piles-geogrid were investigated. The mechanisms of load transfer can be considered as a combination of embankment soil arching, tension geogrid, and stress concentration due to the stiffness difference between pile and soft ground. Based on the field model test and numerical analysis results, it was found that the geosynthetic reinforcement slightly interferes with soil arching, and helps reduce differential settlement of the soft ground. Also. at the D/b=3 (D: spacing of pile cap, b: diameter of pile), the total settlement is reduced by about $40\%$ compared to that without reinforcement. For $D/b{\ge}6$, the effectiveness of geogrid reinforcement in reducing settlement is negligible.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2C
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• pp.133-141
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• 2008

Theoretical analysis are developed to estimate the load transfer by soil arching in geosynthetic-reinforced and pile-supported(GRPS) embankment systems. According to the results of analyses, the efficiency of embankment pile systems increases when the geosynthetics are installed with piles. Especially the increment of efficiency is more remarkable in the low embankment height, where soil arching can not be fully developed. The factors affecting the load transfer in GRPS embankment systems are the pile spacing, the height and properties of embankments, and the strength of geosynthetics. The efficiency decreases with increasing the pile spacing, while it increases with the height and internal friction angle of embankment fills, and the strength of geosynthetics. These results of analyses show the proposed analysis method is resonable to estimate the soil arching in GRPS embankment systems.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.11-20
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• 2018

Surplus soil is commonly used at construction sites, because suitable fill material is not always immediately available and leads to additional costs. However, most surplus soils do not meet the requirement of suitable fill material to achieve the stability and strength of embankments. In this study, Proctor compaction tests and field compaction tests were performed by installing geosynthetics to resolve the problems caused by compacting unsuitable soils. Compaction energy and the number of geosynthetics were changed under the type A- and D- and type A Proctor compaction tests (KS F 2312), respectively. The field compaction testing using geosynthetics was performed on surplus soils of high water content. Optimum water content and maximum dry density of compacted soil decreased and increased by reinforcing geosynthetics, respectively. Compaction curves behaved with geosynthetics as the compaction curves behaved with higher compaction energy. Efficient compaction was possible because the compaction energy increased to 2.10 and 2.71 times the compaction energy required to achieve the same maximum dry density with one and two geosynthetic layer(s), respectively. Furthermore, field compaction tests verified that efficient compaction was possible because the dry density of unsuitable surplus soils of high water content was increased by reinforcing geosynthetics.

• Journal of the Korean Geotechnical Society
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• v.34 no.12
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• pp.71-82
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• 2018

This study presents a reasonable and economical DCM reinforcement length for the various factors (the embankment height, the distance from the embankment to the underground structure, the depth of the soft ground, and the compression index and the swelling index of the soft ground) that affect the stability of the structure due to lateral movement. Based on these results, we analyzed each factor's degree of influence and figured out which factor influenced the lateral movement most. The cross section of the embankment on the soft ground was modeled by using the Finite Element Program and reinforced with DCM. The results show that the increase rate of the reinforcement length with the increase of the embankment height is about 9~50%, the increase rate of the reinforcement length with the depth of soft ground is about 13~30%, and the increase rate of the reinforcement length with increasing compression index is about 3~25%. In addition, the influence of each factor on each other was analyzed. As a result, among the separation distance, the compressive index and the maximum to minimum slope ratio of the reinforcement length of the embankment height, the separation distance was the largest for the depth of soft ground. As the depth of the soft ground increases, the ratio of the maximum to minimum slope of the reinforcement length according to the embankment height is 3.75, the ratio of the maximum to minimum slope of the reinforcement length according to the spacing distance is 4.3, and the ratio of maximum to minimum slope according to compression index is 2.5. From these results, it is confirmed that the three factors are greatly affected by the depth of soft ground.