• Geotechnical Engineering
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• v.20 no.11
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• pp.58-66
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• 2004

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.75-81
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• 2000

본 연구에서는 진동대 시험을 실시하여 지진동에 대한 일반 안벽 구조물과 내진 보강된 안벽 구조물의 동적거동을 분석하고 내진보강기법의 성능을 평가하였다. 진동대 시험은 기초지반이 조밀한 경우와 느슨한 경우, 자갈 뒤채움재를 설치한 경우 그리고 내진대책공법으로 경량재 치환공법과 모래다짐말뚝 공법을 적용한 경우 등 총 5가지 시험단면에 대하여 실시하였다. 과잉간극수압, 가속도 반응 그리고 지반의 변형양상을 분석한 결과, 기초지반과 뒤채움 지반의 연약화가 안벽 구조물의 동적거동에 큰 영향을 미치며, 경량재 치환공법과 모래다짐말뚝공법이 안벽 구조물의 내진성능을 향상시키는에 효과적인 것으로 나타났다.

• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.43-51
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• 2013

Recently, engineering problems such as long-term settlement, differential settlement, and the resultant structural damage, have been frequently reported at construction sites. Use of Sand Compaction Piles(SCP) and Granular Compaction Piles(GCP) are good at remedying existing problems, improving bearing capacity and promoting consolidation. However, such compaction piles have the potential for clogging, which would limit their usability. Investigations into the potential for clogging in SCP, GCP, and GCP mixed with sand has not been thoroughly conducted and is the objective of this current study. Large scale direct shear tests were performed on sections of SCP, GCP, and sand mixed GCP to evaluate bearing capacity. Discrete Element Method analyses were conducted with PFC3D and Finite Element Analyses were conducted with MIDAS GTS to propose an algorithm to help reduce clogging in the granular compaction piles. Results from the large scale direct shear test and multiple simulations suggest a 70% gravel and 30% sand mixing ratio to be optimal for bearing capacity and reducing clogging.

• Journal of the Korean Geotechnical Society
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• v.33 no.6
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• pp.27-36
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• 2017

Gravel compaction pile method has been widely used to improve the soft ground on the land or sea as one of the soft ground improvement technique. The ultimate bearing capacity of the ground reinforced by gravel compaction piles is affected by the soil strength, the replacement ratio of pile, construction conditions, and so on, and various prediction equations have been proposed to predict this. However, the prediction of the ultimate bearing capacity using the existing models has a very large error and variation, and it is not suitable for practical design. In this study, multiple regression analysis was performed using field loading test results to predict the ultimate bearing capacity of ground reinforced by gravel compaction pile, and the most efficient input variables are selected through evaluation of error by leave one out cross validation, and a multiple regression equation for the prediction of ultimate bearing capacity was proposed. In addition, the prediction error was evaluated by applying artificial neural network using the selected input variables, and the results were compared with those of the existing model.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.41-46
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• 2009

In this paper, a series of model tests were performed in laboratory to evaluate promoting consolidation of compaction pile methods for soft ground improvement. For the model tests, composite soil samples that have 10% replacement area ratio were prepared by using sand, gravel, and sandy gravel for the materials of compaction piles. After loading to each composite soil sample, the excess pore pressure dissipation and settlement were investigated. In addition, the behavior of clay mixed with each compaction pile was also monitored at the end of consolidation to evaluate clogging phenomenon. As a test result, the effects for decreasing settlement and promoting consolidation by GCP were prominent, and the mixed clay was not monitored in all of the three compaction piles.

• 지반과기술
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• v.3 no.4
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• pp.62-67
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• 2006

• Journal of the Korean Geotechnical Society
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• v.20 no.4
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• pp.39-47
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• 2004

The SCP(sand compaction pile) method which is a vertical reinforcing technique for soft ground using a sand compaction pile has received increasing popularity in Korea. Currently, there are different methods to evaluate the bearing capacity of the reinforced ground by the SCP method. However, a method that can consider the effect of the replacement ratio on the bearing capacity is not yet available. This study investigated the effect of the replacement ratio on the bearing capacity of the reinforced ground by the SCP method. The study involved laboratory experiments which were conducted on a centrifuge facility. Test conditions included various ranges of replacement ratios (20, 30, and 40%), centrifuged consolidation, and loading. From the results of the study, a method which can evaluate the bearing capacity of the reinforced ground was proposed and verified using the weighted average of the replacement ratio.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.253-261
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• 2003

Mechanical behavior of composition pound improved by sand compaction pile (SCP) with low replacement area ratio could be more significantly affected by mechanical interaction between sand piles and clays than that of clay ground improved by SD or SCP with high replacement area ratio. It is essential to elucidate the mechanical interaction in the improved clay ground, in order to accurately estimate behavior in reducing settlement of the improved ground and increasing strength of clays. In this paper, through a series of model tests of composition ground improved by SCP with low replacement area ratio, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing behavior between sand piles and clays.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.73-83
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• 2006

The behaviour characteristics of Granular Compaction Pile (GCP) are mainly governed by the lateral confining pressure mobilized in the soft soil matrix to restrain the bulging failure of the granular compaction pile. The GCP method is most effective in soft soil with undrained shear strength ranging $15{\sim}50kPa$. However, the efficiency of this method reduces the more compressible soil conditions, which does not provide sufficient lateral confinement. In the present study, the GCP method reinforced with uniformly graded permeable concrete is suggested for the extension of application to the soft ground. Also, large triaxial compression tests are conducted on composite-reinforced soil samples for verification of availability of the suggested method and the settlement estimation method of the reinforced GCP is proposed. Furthermore, for the verification of the proposed method, predicted settlements by the proposed method are compared with results of 3-dimensional numerical analyses. In addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.117-128
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• 2000

Sand compaction pile(SCP) is one of the ground improvement techniques which is being used for not only accelerating consolidation but also increasing bearing capacity of loose sands or soft clay grounds. In this study, laboratory model test and large-scale direct shear test were performed to investigate the effects of area replacement ratio of composite ground in order to find out the optimum value of area replacement ratio for the ground improvement purpose. Area replacement ratios of 20%, 30%, 40%, 50%, 60% were chosen respectively in the model tests to study the effects of area replacement ratio on variations of stress concentration ratio, settlement and shear strength characteristics of composite ground. In large-scale direct she4ar tests, area replacement ratios of 20%, 30%, 46% were applied to study their effects on shear strength characteristics of composite ground.