• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.203-212
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• 2000

샌드파일 주변지반은 교란으로 스미어 영향과 베수저항에 의해 압밀지연 현상이 발생하는 것으로 알려져 있다. 이와 같이 샌드파일 주변지반의 압밀특성에 미치는 영향을 파악하기 위하여 지반물성치에 따른 예측치와 계측을 통한 실측치에 대한 비교검토를 실시하였다. 압밀계수 특성인 압밀소요기간은 수평과 연직압밀계수를 동일하게 평가할 경우 예측과 실측치가 매우 유사한 결과를 보여주는 것으로 나타났다. 압축지수 특성인 침하량 분석결과 예측치에 비해 60~90%정도로 작게 평가되는데 이것은 공동확장이론에 의한 초기 방사(측)방향 압축을 고려할 경우 유사한 값을 얻을 수 있다. 따라서 샌드파일 주변지반에서의 거동특성을 파악하기 위하여 스미어 배수저항뿐 아니라, 초기 방사(측)방향 압축을 고려한 개량특성으로서의 평가도 필요한 것으로 판단된다.

• Geotechnical Engineering
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• v.12 no.5
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• pp.41-54
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• 1996

In this paper, the consolidation settlement of the landfill foundation during and after the period of disposal is analyzed using the program CONSOL which can include the influence of waste load and the leachate level into the analysis. the stability analysis of the embankment is also performed under the varied strength of foundation soil which results from the increase of effective stress due to consolidation of the clay under the landfill. The predicted settlement from CONSOL is compared with the field measured settlement. The results show that, when the leachate level increases with the increase of waste height, the increase of the effective stress of foundation clay is negligible and the stability of the slope of the landfill may not be secured as the disposal of the waste proceeds. Several complementary repairworks, e. g. the reduction of current slope of the fill, application of drain methods to stop or reduce !he leachate level are recommended. The predicted settlement consists moderately with the field measured settlement.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.89-98
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• 2003

A 5∼12m thick tideland has been created in front of a new sea-dyke due to the rapid sedimentation occurring for 22 years. It is confirmed from theoretical analysis and soil tests that the deposit is in under-consolidation state. An analysis shows that when the average sedimentation rate is over 1-5cm/year for a soil with $c_v$=0.0005-0.001$cm^2$/s, excess pore water pressure exists in the deposit. It is known that the lower sedimentation rate than average in the initial deposition stage results in lower dissipation of excess pore pressure and vice versa. It is emphasized that under-consolidation behavior should be taken account in settlement analysis because structures founded on such deposits give higher settlements.

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.35-43
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• 2010

The behavior of the Top-Base foundation was investigated by carrying out 3D finite element method. Special attention is given to the settlement behavior of concrete Top-Base foundation due to the consolidation settlement of the embedding depth and the effect of footing dimensions which are not included in the practical design. To obtain the detailed informations, a series of numerical analyses were performed for different pile configurations. It is shown that as the number of piles in a group increases, the calculated settlement also increases. However, for the $7\times7$ group, there is no further increase in settlement. Based on this study, it is found that the total settlement of Top-Base foundation is highly influenced by the consolidation settlement and footing configurations. It is also found that the current design method overestimates the settlement, and thus, needs to be modified and supplemented.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.29-36
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• 2009

A series of two-dimensional (2D) finite element analyses have been performed to study the behaviour of single piles in consolidating ground. The analysis was conducted based on coupled analyses by considering changes of pore water pressure in the clay. In the analyses the soil slippage at the pile and the soil interface has been included. The method widely used in practice somewhat overestimates dragload by about 25% compared to the rigorous numerical analysis since partial mobilization of skin friction near neutral plane and reductions in the vertical soil stress is not incorporated. When soil slip develops at most of the pile length at the pile-soil interface during consolidation, further increases in dragload is not significant. Application of coating on the pile surface can reduce dragload and pile settlement substantially, but under an axial load on the pile head very large pile settlement can be developed unless pile tip is located to a stiff bearing layer.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.47-57
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• 2016

Many researchers reported that artesian pressure exists in thick soft ground of Busan Nakdong river estuary. Artesian pressure in soft ground could affect rate of consolidation, settlement and drainage capasity of prefabricated vertical drain(PVD). This paper investigated consolidation behaviors of soft ground with partially penetrated PVD subjected to artesian pressure. Laboratory tests with 1-dimensional large column equipment and their numerical analyses were carried out. Test results showed that the consolidation settlement of clay ground with artesian pressure was higher than that without artesian pressure. Due to artesian pressure, the dissipation rate of excess pore water pressure was reduced in soft ground with artesian pressure, especially at bottom part of clay ground. Numerical results were in good agreement with experimental test results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.1
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• pp.18-26
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• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.95-107
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• 2007

This study describes compressive characteristics of marine clay at southwestern coast in Korea by large block and piston samples. Through the analysis of disturbance effect and various consolidation test, consolidation result shows that volumetric strain from large block samples is lower than piston samples and compression index of large block samples is larger than piston samples value. We suggest new empirical equation of compression index by the effect of compression index following sampling method. If consolidation settlement is presumed using empirical equation of compression index, the resort will be more reasonable in predicting settlement than that obtained by the decision of compressibility characteristics from piston samples.

• Journal of the Korean Geotechnical Society
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• v.17 no.1
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• pp.99-107
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• 2001

일반적으로 샌드파일 설치로 인해 파일주변지반은 교란되어 스미어 영향과 배수저항에 의해 압밀지연 현상이 발생하는 것으로 알려져 있다. 특히 예민한 점성토 지반일 경우 교란정도가 크며, 틱소트로피현상이 지연될 경우 지지력 및 압축특성은 불리하게 된다. 본 연구에서는 원지반 특성이 파악된 채취시료를 이용하여 완전 교란조건에서의 실내모형시험과, 염분농도변화에 의한 실내역학시험을 실시하였다. 실내모형시험 결과 낮은 하중단계에서의 압밀계수는 비교란 시료의 특성과 유사하게 나타났으며, 염분농도 증가에 따라 일축압출강도가 증가하고 강도회복은 빠르며 압축지수는 작게 나타났다. 결과적으로 점성토지반 간극수중 염분농도는 강도증대와 압축특성 변화에 영향을 주며, 틱소트로피 증대의 영향요소가 적은 담수지반에서 샌드파일을 시공할 경우 발생하는 과다침하의 한 원인으로 여겨지는바, 이와 같은 요인은 측방유동에 의한 침하거동과 함께 고려하여야 할 영향요소로 파악되어야 할 것으로 판단된다.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.39-47
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• 2024

In this study, physical property tests and standard consolidation tests were conducted on the marine clay of Busan New Port and North Port, the middle and lower reaches of the Nakdong River including Gimhae and Yangsan, and Ulsan regions. The moisture content, a property unrelated to sample disturbance with small individual test errors, was used for regression analysis with the compression index, virgin compression index, consolidation coefficient, expansion index, and secondary compression index, among others. Subsequently, the correlation and accuracy were evaluated. Upon analyzing the correlation between the moisture content, void ratio, and liquid limit commonly used physical properties for calculating compression indexes, it was confirmed that the liquid limit had the lowest correlation. Through a linear regression analysis of the consolidation constants using the current moisture content in the natural state, a high correlation was demonstrated. Relationship equations were then presented to determine settlement and settlement time. This study suggests that moisture content can be utilized as an alternative for evaluating and calculating consolidation constants when examining ground settlement in sedimentary clays distributed in the Busan and Gyeongnam regions.