• Journal of the Korean Geotechnical Society
• /
• v.22 no.3
• /
• pp.13-21
• /
• 2006

Geosynthetic damage has attracted a major attention since the introduction of geotextiles for civil engineering applications. In this study 3 pilot trial embankments were carried out to investigate the behaviours of reinforced embankments over soft cohesive soils and to find the optimum methodology of embankments over soft soils. As the seamed part of polyester mat (PET, tensile strength 15 ton) used in the first full-scale field test was ruptured under progressing rotational slope failure because of unexpectedly rapid construction of embankments, the excessive pore water pressures were measured. On the soil behavior where tension explosion of mat was continued, pore pressure larger than the one caused by embankment height was measured. Especially, at the depth of 5.0 m under the ground pore pressure increased over long term. It was discussed with respect to the height of embankment and heaving behavior of soft soils.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.11
• /
• pp.17-28
• /
• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials, because they additionally provide a radial drainage path in a deep soil deposit. In practice, vertical drains are commonly installed in the process of self-weight consolidation of a dredged soil deposit. The absence of an appropriate analysis tool for this situation makes it substantially difficult to estimate self-weight consolidation behavior considering both vertical and radial drainage. In this paper, a new method has been proposed to take into account both vertical and radial drainage conditions during nonlinear finite strain self-weight consolidation of dredged soil deposits. For 1-D nonlinear finite strain consolidation in the vertical direction, the Morris (2002) theory and the PSDDF analysis are adopted, respectively. On the other hand, to consider the radial drainage, Barron's vertical drain theory (1948) is used. The overall average degree of self-weight consolidation of the dredged soil is estimated using the Carillo formula (1942), in which both vertical and radial drainage are assembled together. A series of large-scale self-weight consolidation experiments being equipped with a vertical drain have been carried out to verify the analysis method proposed in this paper. The results of the new analysis method were generally in agreement with those of the experiments.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.11
• /
• pp.77-85
• /
• 2007

This paper investigates the mechanical characteristics of composite geo-material which was developed to reuse both dredged soils and bottom ash. The composite geo-material used in this experiment consists of dredged soil taken from the construction site of Busan New Port, cement, air foam and bottom ash. Bottom ash is a by-product generated at the Samcheonpo thermal power plant. Several series of laboratory tests were performed to investigate behavior characteristics of composite gee-material, in particular the reinforcing effect by mixing bottom ash. The experimental results of composite geo-material indicated that the stress-strain relationship and the unconfined compressive strength are strongly influenced by mixing conditions. Especially it was observed that the compressive strength of composite geo-material increased with an increase in bottom ash content due to reinforcing effect by the bottom ash. Compressive strength of composite geo-material increased with the increase in curing time. The 28-day strength of composite geo-material is $1.7{\sim}1.8$ times higher than the 7-day strength. The moist unit weight strongly depended on air-foam content as well as bottom ash content added to the composite goo-material. In composite geo-material, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of bottom ash.

• Journal of the Korean GEO-environmental Society
• /
• v.16 no.7
• /
• pp.15-22
• /
• 2015

This study gives the characteristics of sedimentation-consolidation and surface strength for dredging and landfill areas in each coast. For the analysis of the sedimentation-consolidation characteristics, the column tests were performed and the results were compared with existing various literatures and design reports for dredged soil disposal. The surface strength of landfill soils of west and south coast were investigated by using the portable cone tester. As a results of analysis, the coefficient of sedimentation-consolidation on south coastal dredging soils is more sensitive with variation of initial water contents than on the west coastal dredging soils. And the surface strength of the dredging landfills is a higher in the west coast than in the south coast. Finally, the results of this study will be utilized as a basis data for analysis and design in the field of dredging and landfill.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.767-772
• /
• 2003

The clay which transported into a pond under the high water content condition have no effective stress which develop from the starting point of sedimentation and self-weight consolidation. Since sedimentation and self-weight consolidation dependent on self-weight of solids is made progress over a long time, to accelerating it have many advantages in the economic view In this paper, sand spreading method which is one of sedimentation and self-weight consolidation acceleration method is studied through a series of experiments considering the mixing ratio of sand and clay. The test results show that the mixing ratio of clay and sand of 1:0.2 is the biggest rate of consolidation and the pouring at the end point of sedimentation considerably effects on consolidation rate.

• Proceedings of the Korea Contents Association Conference
• /
• 2014.11a
• /
• pp.395-396
• /
• 2014

지속가능한 물관리 방법으로 중 소규모의 저수지 개발 필요성이 증대하고 있는 가운데 하천 유지용수의 확보 및 물순환 건전화를 위해서는 저수량 확보를 위한 과학적인 분석과 체계적인 관리 기반으로 단위 저수지에 대한 정량적 퇴적 및 준설토량의 산정 시스템이 필요하다. 저수지 준설을 위한 퇴적 토사량의 산정을 위해서는 최근 측량 현장에 도입되어 활발하게 사용되고 있는 위성측량시스템 및 음향측심기를 사용한 측량성과와 대상지역 항공사진 및 연속지적도의 다차원지형공간정보 데이터를 활용하여 관련시스템을 구축할 필요성이 있다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.504-510
• /
• 2009

Dredging and Reclamation which have been conducted steadily for creation of new coastal area have demerit that takes a long time. Hence, a lot of researches on acceleration of self-weight consolidation is proceeding continuously. In this paper, 30 cases of laboratory self-weight consolidation tests were conducted to understand application of PDF method, one of the self-weight consolidation acceleration methods, to domestic dredged soils. Acceleration effect of self-weight consolidation was confirmed through comparison and analysis on completion time and settlement of self-weight consolidation for none installed case and 4 kinds of common used PBD installed cases.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.2
• /
• pp.133-140
• /
• 2018

The objective of this study is to propose a reliable mixing design procedure of concrete using artificial lightweight aggregate produced from expanded bottom ash and dredged soil. Based on test results obtained from 25 mixes, empirical equations to determine water-to-cement ratio, unit cement content, and replacement level of lightweight fine aggregates were formulated with regard to the targeted performance (compressive strength, dry density, initial slump, and air content) of lightweight aggregate concrete. From the proposed equations and absolute volume mixing concept, unit weight of each ingredient was calculated. The proposed mix design procedure limits the fine aggregate-to-total aggregate ratio by considering the replacement level of lightweight fine aggregates, different to previous approach for expanded fly ash and clay-based lightweight aggregate concrete. Thus, it is expected that the proposed procedure is effectively applied for determining the first trial mixing proportions for the designed requirements of concrete.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.4
• /
• pp.13-20
• /
• 2005

In this study, consolidation test and numerical analysis were performed with the aim of investigating the characteristics of consolidation behavior of mixed soil with the amount and particle shape of inserted materials. Mixed soil was made up of matrix (dredged clay) and inserted material (crashed oyster shell and/or sand). The concept of stress share ratio was introduced to evaluate the consolidation characteristics of mixed soils. And the finite differential numerical analysis was carried out by applying the Mikasa's consolidation theory. From the results of experiments and numerical analysis, it was verified that mixed soil consolidation behavior is affected by changes in inserted material. When a similar amount of granular material was inserted, the compressibility of the clay matrix of oyster shell mixed soil was smaller than that of sand mixed soil.

• Geomechanics and Engineering
• /
• v.25 no.2
• /
• pp.143-157
• /
• 2021

Expansive soil is the most predominant geologic hazard which shows a large amount of shrinkage and swelling with changes in their moisture content. This study investigates the macro-mechanical and micro-structural behaviours of dredged natural expansive clay from coal mining treated with ordinary Portland cement or hydrated lime addition. The stabilised expansive soil aims for possible reuse as pavement materials. Mechanical testing determined geotechnical engineering properties, including free swelling potential, California bearing ratio, unconfined compressive strength, resilient modulus, and shear wave velocity. The microstructures of treated soils are observed by scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy to understand the behaviour of the expansive clay blended with cement and lime. Test results confirmed that cement and lime are effective agents for improving the swelling behaviour and other engineering properties of natural expansive clay. In general, chemical treatments reduce the swelling and increase the strength and modulus of expansive clay, subjected to chemical content and curing time. Scanning electron microscopy analysis can observe the increase in formation of particle clusters with curing period, and x-ray diffraction patterns display hydration and pozzolanic products from chemical particles. The correlations of mechanical properties and microstructures for chemical stabilised expansive clay are recommended.