• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.02a
• /
• pp.23-35
• /
• 1999

Although the purpose of dredging in the past was merely as a means of lowering the water level, presently land reclamation from dredged fill is of greater interest. From an economical standpoint, due to the difficulties in acquiring landfill for coastal projects, there is a growing trend toward simply using easily obtainable marine clay for use as fill. But because the ground formed by dredged fill has but low strength and is accompanied by large settlements, it is important that the engineering characteristics be fully investigated. In order to use dredged Masan marine clays as fill material, the engineering characteristics have been studied in this paper.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.149-156
• /
• 2000

Sedimentation and self-weight consolidation tests in cylinder and large model tank and field measurement such as settlement and pore water pressure at each layer by wireless automatic instrumentation system were carried out to investigate the behaviour of dredged marine clay fill. The consolidation behaviour for each reclaimed layer was analyzed from these measured data and numerical analysis result using finite strain consolidation theory. It was fond from this study that the consolidation behaviour of dredged clay fill is heavily dependent on the filling process.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.499-506
• /
• 2004

The use of dredged soft marine clay is increasing due to a shortage of coarse material available. This paper presents a stabilization method that can increase shear strength of the surface layer of a dredged clay deposit at dates much earlier than usual. The desiccation of the upper soft 1-2m layer can be accelerated by interrupting water seeping from its bottom with impervious geotextile. Just below the geotextile, enough pervious material is provided so that the underlying deposit can be drained through it. This scheme is proved to be effective through theoretical analysis.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.151-154
• /
• 2003

This paper reviews depositional environments and consolidation characteristic of Soft Dredged Clay fill and then analytical solution of self-weight consolidation is made to find consolidated state. It's known that Soft Dredged Clay Ground is in the under-consolidated state under $U{\fallingdotseq}30%$ from analytical solution. It is effective for higher consolidation rate that the time of Dredge is shorter ani the time of leave is longer. It is conclude that the under-consolidated state should be considered in prediction of consolidation settlement.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1992.10a
• /
• pp.75-86
• /
• 1992

The elevation of reclamation work in the coastal area for the industrial complex is determined through the investigation and review of marine conditions, drainage plan and fill materials. The embankment to be constructed with crushed stone on the soft soil should be safe against the wave force, immediate and long term consolidation settlement, overturning and sliding due to self-weight and other forces. Because of lack of fill material from the borrow pit, the soft marine clay to be dredged shall be used as the reclamation material. And Paper Drain Board is used as the improvement method for the deep soft clay strata.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.1
• /
• pp.5-13
• /
• 2001

The purpose of this paper is to present the pressuremeter test result and analysis for Yulchon Combined Cycle Power Plant(CCPP) site. The CCPP site is old backfill area with the hillcut materials obtained from the borrow sources near the mountains. The geology of this area consists of 6-layers from the ground level such as hillcut material, dredged clay fill, silty sand, original marine clay, weathered rock, soft rock, etc.. The pressuremeter test has been carried out with three different probe, in size and membrane type for all layers except the clay layers. The cone penetration test has been also carried out to collaborate with the pressuremeter test in the hillcut material layer.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.569-576
• /
• 2002

Recently, the hydraulic fill method is commonly used in many reclamation projects due to lack of fill materials. The method of hydraulic fill in reclamation is executed by transporting the mixture of water-soil particles into a reclaimed land through dredging pipes, then the dredged soil particles settle down in the water or flow over an out flow weir with the water. In the present study, to compare the soil and sand-mat mixed method with sand-air jet method for shallow improvement of hydraulic fills at southern seashore, the model tests were performed. Through the model test results, the behavior of surface as disturbance of desiccation crust is analyzed.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.9
• /
• pp.33-40
• /
• 2008

This paper describes the performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area composed of soft marine clay with high water content and high compressibility. From field monitoring results, excessive ground settlement compared with predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared with field monitoring results after additional surcharge was applied. It might be used for verification of recalculated results.

• Geomechanics and Engineering
• /
• v.17 no.6
• /
• pp.507-513
• /
• 2019

Reinforced soil and Expanded Polystyrenes (EPS) mixture (RSEM) is a geomaterial which has many merits, such as light weight, wide strength range, easy for construction, and economic feasibility. It has been widely applied to improve soft ground, solve bridge head jump, fill cavity in pipeline and widen highway. Reutilizing dredged sediment to produce RSEM as earthfill can not only consume a large amount of waste sediment but also significantly reduce the construction cost. Therefore, there is an urgent need understand the basic stress-strain characteristics of reinforced dredged sediment-EPS mixture (RDSEM). A series of cyclic triaxial tests were then carried out on the RDSEM and control clay. The effects of cement content, EPS beads content and confining pressure on the cyclic stress-strain behaviour of RDSEM were analyzed. It is found that the three stages of dynamic stress-strain relationship of ordinary soil, vibration compaction stage, vibration shear stage and vibration failure stage are also applicative for RDSEM. The cyclic stress-strain curves of RDSEM are lower than that of control clay in the vibration compaction stage because of its high moisture content. The slopes of backbone curves of RDSEMs in the vibration shear stage are larger than that of control clay, indicating that the existence of EPS beads provides plastic resistance. With the increase of cement content, the cyclic stress-strain relationship tends to be steeper. Increasing cement content and confining pressure could improve the cyclic strength and cyclic stiffness of RDSEM.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.4
• /
• pp.136-145
• /
• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.