• Journal of the Korean GEO-environmental Society
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• v.6 no.4
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• pp.59-64
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• 2005

Although high pressure discharge method is widely used for improving soft ground, it has various problems including lack of strength increase and the possibility of water pollution and soil contamination. MJM(Morta Jet Method) uses sand in addition to cement as the injection material. MJM uses triple rods with a built-in nozzle that allows easier discharge of the slime, resulting in higher replacement area ratio and more uniform formation of pillar hydrates, and thus results in significant increase in strength. MJM is expected to perform especially well as piles in marine clays. This study investigates the field applicability of the MJM through extensive laboratory and field tests.

• 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 GEO-environmental Society
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• v.10 no.6
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• pp.69-77
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• 2009

The shortage of bearing capacity and settlement, shear deformation may occur when constructing a structure such as harbor, airport and bridge on soft ground such as marine clay, silty clay, sandy soil because it is very soft. The various ground improvement methods were applied to obtain preceding settlement of soft ground and strength increase. The vertical drain method has been used to reduce the required time for consolidation of the soft ground. Especially, the PBD (Plastic Board Drain) has been widely used among in the vertical drain method. In this study, a behavior of characteristic was evaluated by operating a compound drainage capacity test about the PBD (Plastic Board Drain) method applied in soft clay in deep depth. As a result, the settlement gradually occurred with increase of surface load. The consolidation settlement was processed with dissipation of pore pressure after surface load of $500kN/m^2$. Accordingly, it was found that change of settlement through load steps was resulted from dissipation of pore pressure. It was also found that the drainage capacity of vertical drains was considerably reduced with pressure increase and time elapse.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.03a
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• pp.147-152
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• 1997

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.271-274
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• 2003

국내 해안지역의 표층에는 두께 약 5~60m의 연약한 해성 충적 점성토층이 형성되어 있어 상부에 구조물을 축조할 경우 목적에 부합되게 다양한 말뚝시공에 의한 연약지반 개량공법을 적용하고 있는 실정이다 따라서 매우 연약한 지반특성을 나타내는 경우에는 설계에서 정해진 단면이상으로 콘크리트 재료가 지반 중으로 투입되어 콘크리트 재료의 손실이 많이 발생하여 합리적인 시공을 수행하여도 비경제적인 공사가 될 우려가 크다. (중략)

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.39-46
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• 2019

Most of the soil used for reclamation is marine clay generated from dredging construction.The soft ground made of dredged clay has high water content and high compressibility, so the bearing capacity of the ground is very weak and it is difficult to enter the ground improvement equipment. Therefore, surface hardening treatment method is used to enter equipment prior to full-scale civil engineering work, and stabilizer is mainly used for cement series. Cement-based stabilizers have the advantage of improving the ground in a short period of time and have excellent economic efficiency, but they are disadvantageous in that they cause environmental problems due to leaching of heavy metals such as hexavalent chromium. In this study, environmental effects evaluation of dredged clay mixed with normal portland cement and environmentally friendly stabilizer was evaluated, and uniaxial compressive strength test and indoor model test were conducted to confirm the bearing capacity characteristics of the solidified layer.

• 지반과기술
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• v.8 no.2
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• pp.23-31
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• 2011

• Proceedings of the Korean Geotechical Society Conference
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• 1993.06d
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• pp.71-78
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• 1993

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3216-3223
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• 2012

Deep cement mixing method (DCM) is one of the most effective improving methods for deep soft ground. The strength of soft soil can be increased in a short period of time with less noise and vibration. However, it is necessary to determine the stress transferring and concentration ratio of the composite soft ground for estimating the settlement behaviors. In this study, a model test was undertaken to investigate the stress distribution of the improved soil. Results of the model test shows that stresses were concentrated mainly on the improved areas by DCM and the concentration ratios (35.4, 28.6, 27.02) were obtained using several different techniques. These were well in accordance with other previous research results (26.52, 32.5).

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.5-13
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• 2014

This paper presents the results of a numerical investigation on applicability of Light-weighted Foam Soils (LWFS) consisted of dredged soils for soft ground improvement. The engineering properties of LWFS were comprehensively investigated based on the previous experimental tests. And three dimensional numerical models which reflect soft ground conditions were adopted to evaluate the applicability of LWFS compared to SCP and DCM. A number of cases were analyzed using a stress-pore pressure coupled model. The results indicated that LWFS method enables to reduce more settlement, lateral flow and heaving than SCP method and enable to reduce more residual settlement than DCM method. Also it was revealed that such effect depends on the properties of LWFS such as unit weight, unconfined compressive strength, deformation modulus and Poisson's ratio.