• Geotechnical Engineering
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• v.1 no.1
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• pp.5-12
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• 1985

Ocassionally it is used for simple extensions of Terzahgi's theory to account for time-depend- tint loading but there is little evidence of application in more complicated consolidation theories that take into account such effects as nonlinear stress.strain, layered systems or large strains. The purpose of this paper provides an efficient computer algorthm based on numerical analysis using finite difference method which account for multi-layered soils to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically. The explicitly scheme of solving the consolidation equations has been investigated from the point of view of the stability conditions and the convergence with variance of the operator as well as to obtain an optimal divided depth ratios of total depth. A comparison of the settlement predictions with both the classical analysis and the algorithm based on numerical analysis indicates that the new algorithm scheme is found to be superior to the classical theory in the layered soils.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.5-11
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• 2006

A primary factor affecting on the design of soft ground is to determine the soil properties (Compression index, Coefficient of consolidation) and the depth of soft ground. It could be the basic sources to estimate settlement behavior of soft ground. Even though the reliable soil examination equipment was used to examine soil to determine the depth of soft ground, it's very hard to find out the accurate properties of soft ground, because the condition of indoor experiment cannot reproduce the circumstances of ground perfectly. Therefore, this study was re-estimated to find out the most reliable soil properties by using back-analysis with field monitoring data of "Site preparation for Airplane Mooring of Incheon International Airport Phase II Development" for 317days.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.65-75
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• 2016

This research was started in order to recognize the necessity of systematic and scientific approach to sinkholes, and to imply from an empirical point of view that a detailed evaluation method and measure for technique should be devised. As the result drew the risk factors that cause sinkholes by reflecting the opinions of water resources and ground experts, this research is expected to contribute to the development of a more systematic and pre-preventive evaluation index by preparing a countermeasure against sinkholes. In the future, it is necessary to develop an evaluation index toward the risk factors of sinkholes, in order to establish a scientific basis and objectivity that can determine priority, by subdividing the decision-making process that is required for preparing a countermeasure against sinkholes. In addition, a detailed methodology and related technique to measure each evaluation index should be continued to be discussed, in order to review the applicability of evaluation indices on actual sites.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.123-131
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• 2005

Recently, construction activities in reclaimed onshore areas increase in our country In this case, the stability evaluation of the piles for negative skin friction is an important factor for the design of pile foundation in soft grounds. Nevertheless, the design of piles for negative skin friction (or downdrag forces) is probably poorly understood by many geotechnical engineers. It is mainly because only the bearing capacity aspect is taken into account for the downdrag evaluation of piles in most of design specifications. However, the problems fur negative skin friction of piles are mostly related with settlement rather than bearing capacity Meanwhile, LRFD (Load Resistance Factor Design) approach considers both ultimate limit state in terms of bearing capacity and serviceability limit state in terms of settlements. This paper proposes LRFD approach for the downdrag evaluation of piles and compares this approach to traditional design approach. And also a case history is analyzed. Through the analysis some suggestions to solve the problems for the design of piles for negative skin friction are suggested.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.67-74
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• 2008

Many industrialized countries of the world have many problems about the reuse of waste landfill area because of the increase of terminated waste disposal landfill. Especially, the effective use of the terminated waste disposal landfill nearby the urban area has been demanded, because of the lack of the usable land. However, in case of the construction of the building on such a landfill, ground settlement and reduced bearing capacity would be occurred without ground stabilization and proper reinforcement. This study is to evaluate the applicability of geosynthetics for the increment of bearing capacity of solid waste landfill ground. A numerical simulation has been undertaken to model a layer of weathered soil overlaying a layer of geosynthetic reinforcement and waste disposal ground. The proposed analytical model can be used to obtain surface settlement characteristic in the two-dimensional deformation related reinforcement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.304-310
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• 2018

The aim of the research is to provide possibility of quality controlling by rheological properties for lightweight foamed concrete. The lightweight foamed concrete achieves its low density by containing air bubbles (foam) produced during the mixing process. Therefore, containing foamed volume during setting period is critical for the securing the performance as an insulating material. In this research, regarding foam collapse during the setting period, rheolgocial properties of fresh state lightweight foamed concrete were assessed to get its relationship with volume stability, or foam stability. For the experiment regarding foaming factors including mixing time, mix design of contents for materials, rheological properties of fresh state lightweight foamed concrete were tested with its density and settling depth. Based on the settling depth with various factors, relationship with rheological properties was analyzed, and especially, close relationship of plastic viscosity and settling depth was found. Therefore, from the results of this research, it is considered to contribute on suggesting a new approach of quality controlling for lightweight foamed concrete using rheological test method.

• Journal of the Korea Institute of Construction Safety
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• v.3 no.1
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• pp.18-24
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• 2020

The purpose of this study is to propose a system improvement plan to prevent ground sinking accidents. To do this, follow the procedure below. First, it defines terms that are used interchangeably, such as ground subsidence and ground depression. Second, analysis of the current status and cause of ground sink, and the analysis of the correlation between rainfall and ground sink causes, derives priority management causes. Third, we propose a system improvement plan for the cause of priority management. As a result, damage to underground pipes and inadequate underground works were identified as the cause of priority management, and two system improvement plans to manage them were proposed. The results of this study can be used as basic data for improving the system for more effective prevention of underground sink in the future.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.121-129
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• 2006

Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.239-250
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• 2009

Tunnelling-induced settlements and lateral ground movements have been investigated by numerical parametric studies considering ground condition, excavation characteristics, and ground layers. Before the numerical study the existing methods of ground movement estimation have been collected and analysed to have some information of ground movements and to improve them providing a fundamental material for the numerical study. Numerical model simulation has been performed of a physical model test of tunnel excavation in which the ground movements were measured reliably and the results have been used to determine the numerical approach and the appropriate soil constitutive mode. With this procedure done, the results of numerical parametric studies have been put together to analyze and understand tunnelling-induced settlements and lateral ground movements.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.211-216
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• 2003

굴폐각은 굴양식 후 남는 것으로 남해안에서 주로 집중적으로 발생하는데 연간 28만톤의 발생량 중 상당양은 폐기물로 계속 누적되고 혹은 불법매립되어 환경오염 문제까지 발생시키고 있다. 본 연구에서는 산업폐기물로 분류되는 굴패각을 지반공학 분야에서 활용하기 위한 대안으로 해성점토와 혼합하여 매립재료로써의 적용성을 평가하기 위하여 대형 압밀기를 이용하여 실험을 실시하고 이를 토대로 기초자료를 획득하고자 하였다. 원형의 굴패각을 파쇄하여 입도별로 분류하고 이중 사질토 입경 크기의 재료에 대한 기본 물성치를 평가하고 지반 재료로써의 적용성를 분석하였다. 해성점토 내의 굴패각입자의 혼합비를 변화시켜 만들어진 혼합토에 대한 압밀 실험 결과 굴패각의 혼합율이 증가할수록 체적변화율이 작게 되고, 침하 속도는 빠르게 증가함을 알 수 있었다. 이는 압밀응력의 일부를 굴패각 입자의 골격구조가 부담함으로써 실제 점토부분에 작용하는 압밀응력은 굴패각 혼합율이 증가할수록 작아지는 것으로 판단된다.