• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1094-1101
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• 2005

The stability of embankment on the soft ground has included problems on stabilities of embanked body and soft soil, which related with vertical displacement and lateral movement of the soft ground especially. The judge methods for the potentialities of lateral movement have been used in order to stabilization assessment during and after construction of the embankment. In this study, the judge methods on the improved soft ground suggested, which compared with exist judge methods on lateral movement. It is due to recent trend using embanked structures on the soft ground most of improved.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.490-496
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• 2006

In order to design accurately plastic board drain (PBB) method, it is important to determine the equivalent circle of PBD. In this paper, a series of numerical analyses on soft ground improved by PBD were carried out, in order to investigate the resonable equivalent circle of PBD considering consolidation behavior of improved soft ground by PBD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of soft ground improved by PBD. And, through the results of the numerical analyses, consolidation behaviors of soft ground during consolidation was elucidated, together with the equivalent circle of PBD considering consolidation behaviors.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.529-536
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• 2002

The purpose of this paper os to present and discuss some of flow and drain observed in modelling results. Because dredged fill ground of Yul-Chon located in the south coast of Korea is very soft, this ground should be improved after operation of surface stabilization. There are surface stabilization method such as chemical stabilization, desiccation, horizontally vacuum drain, replacement, and geosynthetics. In Yul-Chon, PTM(Progressive Trenching Method) is adopted to provide the necessity condition of surface desiccation. In the case trench in the dredged soft ground is formed by PTM equipment, pore water in the ground is drained through trench. There, drain and desiccation of surface ground increase, and bearing capacity is improved. In this research, when trench in the dredged soft ground is formed by PTM equipment, permeable characteristics and drain efficiency of pore-water are analyzed using SEEP/W software package. Results show variation of total head, pressure head, flux, hydraulic gradient, and flow quantity.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.809-814
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• 2009

Deep mixing method has been used for ground improvement and foundation system for embankment, port and harbor foundations, retaining wall, and liquefaction mitigations. It has attractive benefits because it is not only improved strength of soft ground but superior for prevention of settlement. However, the quality controls of improved mass affect to the efficiency of the deep mixing method is not properly established. These effects vary depending upon the construction environments and conditions of agitation in consideration of an agitator. The strength and shape of the improved column are not unique and these are affected by mechanical properties of agitators. In this study, in order to investigate the efficiency of deep mixing method for ground improvement on a soft clay ground, experimental studies are performed considering mechanical properties of agitator; the location of exit-hole of admixtures, an angle of mixing wing and a speed of revolution. The experiments are conducted with the simulated apparatus for deep mixing plant that reduced the scale in 1:8 of the real plant. According to the results, the diameter and shape of improved column mass vary depending on the mechanical properties and operating conditions of agitator. Its quality is better when the exit-hole of admixtures is located in the mixing wing, when an angle of mixing wing is large, and when the speed of revolution is rapid.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.67-73
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• 2005

In this research, centrifuge model experiments and numerical approach of finite element method to analyze experimental results were performed to investigate the behavior of improved ground with sand compaction piles. One of typical clay minerals, kaolinite powder, were prepared for soft ground in model tests. Jumunjin standard sand was used to sand compaction pile installed in the soft soil. In order to investigate the characteristics of mechanical behavior of sand compaction piles with low replacement ratios, centrifuge model experiments with the replacement ratio of 40%, changing the width of improved area with respect to testing results the width of surcharge loads, were carried out to obtain of bearing capacity, characteristics of load-settlement, vertical stresses acting on the sand pile and the soft soil failure mechanism in improved ground.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.17-23
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• 2003

Accurate prediction of consolidation behaviors of the soft ground improved by plastic board drains is not easy because the consolidation characteristics of the improved ground has not been fully elucidated yet. The shape of drains is one of the most important factors which affect the consolidation characteristics of the improved ground. In this paper, a series of model consolidation tests of soft clay ground improved by plastic board drain were carried out, in order to investigate the effect of both plastic board width and stress level on consolidation characteristics of the improved ground. As the results, behaviors of both settlement and excess pore pressure dissipation were elucidated. Also, the non-uniform distribution of water content in the model ground was obtained. Then, in order to investigate the effect of vertical drainage on the consolidation behavior in the model tests, the comparison between experimental consolidation behaviors and Barron's theoretical ones were carried out. As the results, it was elucidated that the consolidation behavior in the model tests was affected not only by radial drainage but also by vertical drainage.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.61-70
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• 2010

A series of shaking table tests were conducted to estimate the seismic performance of soft ground deposits improved by stone column. The amplification of acceleration, shear strain, and shear wave velocity were evaluated to compare the seismic response of unimproved ground deposits with that of improved ground deposits. From the test results, it was shown that the stone column can prevent large shear deformation in ground deposits. However, it was also found that the acceleration of improved ground deposits may be amplified more than that of unimproved ground deposits when it was subjected to short periodic seismic wave. The results suggest that it is necessary to perform the ground response analysis with model experiments for both unimproved and improved ground deposits to evaluate the effect of stone column on the seismic performance of improved ground deposits.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.59-66
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• 2004

Sand compaction pile (SCP)-improved ground is composite soil which consists of the SCP and the surrounding soft soil. When a surcharge load is applied to composite ground, time-dependent behaviors occur in the composite soil due to consolidation according to radial flow toward the SCP. In addition, stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground that was conducted to investigate smear effect on consolidation behaviors of SCP-improved ground. The results showed that the smeared zone of soft clay had a significant effect on effective stress-pore water pressure response, stress transfer mechanism and stress concentration ratio of composite ground. Amount of stress transfer between the clay and the SCP was maximum in depth of z/H=0.25, and decreased with depth. Stress concentration ratio of composite ground was not constant, but depended on consolidation process. It was also found that the value of stress concentration ratio in soft clay with smeared zone was larger than that in soft clay without smeared zone.

• Journal of the Korean Geosynthetics Society
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• v.4 no.4
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• pp.39-46
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• 2005

A series of numerical analyses on soft clay ground improved by plastic board drain(PBD) were carried out, in order to investigate the consolidation behavior considering viscosity of the improved ground. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method is applied in this study, was confirmed through comparison between experimental and analytical results. As the analytical results, consolidation behavior of both settlement and excess pore pressure and effective stress in clay were elucidated. Then secondary consolidation characteristics of improved ground were estimated through compare with results of typical one-dimensional consolidation analysis.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.45-50
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• 2005

Sand pile method, such as sand drain method and sand compaction pile method, has been popularly used as an improved method for soft clay grounds. The effect of accelerating consolidation of soft clay grounds has been evaluated with Barren's solution. The consolidation behavior of soft clay ground with sand piles strongly depends on both the nonlinear mechanical interaction between sand piles and surrounding clays and the degradation permeability of clays. In this paper a method of determining consolidation parameters of soft clay ground with sand drains by using Barren's solution was proposed through a series of numerical simulations. Through the method, the change in both volume compressibility and permeability during consolidation was reasonably evaluated.