• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.163-170
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• 2007

To evaluate on the applicability of Chemical Compaction Pile (CCP) method to weak soil improvement, two kinds of testing chambers were fabricated and the changes of water content and shear stress associated with soil types, ages and distances from the center of pile were measured with different mixing proportions of CCP such as bottom ash, lime powder and added admixture. As results of test, it was noted that water content and shear stress of ground are mainly affected by the amount of lime powder and increase of the amount corresponds to rapid improvement of soil. And the improvement depended greatly on the types of soil also. It was finally found that CCP developed can be applicable to bearing pile as well as soil improvement since CCP has a bearing capacity enough to carry loads.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.85-92
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• 2014

Structures that have constructed in soft clay might suffer from many issues related to consolidation settlement or lateral movement of soft-clay during long-term period. Therefore, it is important to establish proper design and construction processes related to site investigation, soil improvement, construction management, and so on. This case study focused on the construction of the rahmen structure supported by pile foundations. Especially, the structure in this case had been constructed without improving underlying soft clay and before constructing backfill embankment due to the limited construction time and the traffic connection of the old road crossing new highway. Therefore, in order to satisfy the structural stability, the construction processes and countermeasure methods were carefully planned based on the results of preliminary numerical analyses and monitoring of ground behaviors. Through the trial and error precess during the construction, the structures had been successfully constructed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.4
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• pp.319-321
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• 2002

Recently, the injection of cement stabilizer is used as one of ways to improve soft sea-bottom. However, this method makes an argument with $Cr^{6+}$subject to emerge to the seawater from the cement stabilizer. To investigate the amount of$Cr^{6+}$field measurements were carried out in Ochun harbor of Chunsoo Bay. The analysis shows the amount of $Cr^{6+}$in the seawater met the demand of environmental criterion.

• Journal of the Korean GEO-environmental Society
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• v.2 no.2
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• pp.59-64
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• 2001

Recently, the application of shallow mixing method using hardening agent has increased because of the advantage of securing trafficability, reducing the working period, solving environmental problems caused by dumped and replaced soil, etc. In this paper, three types of representative hardening agents in Korea are used to achieve the optimum of ground improvement. 1he unconfined compression tests are carried out with specimens under various mixing ratios and curing periods of hardening agent to assess the stabilizing ability. The unconfined strengths on site were estimated with various mixing ratios based on the results of the laboratory tests. It was estimated that the improved strength on site was higher than that of the required strength $5.0kgf/cm^2$.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.131-145
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• 2020

The construction on these flimsy ground, activation of unsymmetrical surcharges, can often cause of the embankment road lateral flow or the destruction of the activities. In this study, the stability of the abutment pile foundation installed on soft ground and its behavior has been evaluated. The behavior of the abutment pile foundation under lateral flow was studied by verifying the behavior and reinforcement effects of the abutment pile foundation of previous studies about horizontal loads acting on the pile due to the lateral flow of the ground by performing finite element analysis. As a result of the consolidation analyses, the undrained cohesion or the strength of the soft ground, was increased by about 1.1 to 1.8 times by the increase in the strength of the soft ground according to the degree of consolidation. It is deemed reasonable to use 3.8 cm of the allowable displacement both economically and constructively, but considering the importance of the structure and the uncertainty of the ground, measurement shall be carried out during construction and thorough safety management of the lateral flow should be done.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.5-13
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• 2010

Low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground, and has advantage which construction is possible in insufficient space. However it has been not yet studied sufficiently to estimate the effect of ground improvement in design step and to prove the estimating method. So the method must be developed in order to use the low slump mortar grouting method in various cases. In this study, the field tests were performed in the reclaimed soils to measure the effect of ground improvement. Then it was compared with what was calculated by the existing formula that was formerly suggested. The results show that the value from the formula was similar with the value from the field tests. Also it was proved that the formula was available to estimate the effect of ground improvement in the loose granular soils.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2425-2433
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• 2011

DSM (Deep Soil Mixing) is to establish soil-cement column by injecting of cement slurry and blending it in soft ground and have been introduced to Singapore in 1980s and now a days quite popular and considered as alternative method to the jet grouting for temporary earth retaining works and foundations. Herein this paper, the results of lab mixing test based on comparison of characteristics between OPC (Original Portland Cement) and PBFC (Portland Blast Furnace Slag Cement), DSM field trial test and main installation results including monitoring, was presented and it would be referred to similar site later.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.83-90
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• 2012

Generally, the effect of the cement deep mixing method on the improvement of clay ground is far greater than the effect of physical improvement. Although it leads to great improvement strength in the initial stage, there are not many constructional precedents in Korea and it is hard to manage quality according to the cement-clay mixing method. In order to figure out the strength characteristics according to the mixing ratio of cement, sand, and clay and the improvement characteristics of weak ground according to the forms of the specimens to be improved, marine clay was used in this study to conduct the uniaxial compression test and soil bin model test. The test piece specimens for the uniaxial compression test were mixed with sand in a fixed ratio with the criterion of the water cement ratio. The cement was mixed with clay in the ratios of 10%, 20%, 30%, and 40% to the clay weight. The moisture content of the soil ground was made in the ratios of 40%, 60%, and 80%. The test piece specimens went through curing by moistening for 7, 14, and 28 days and underwent the uniaxial compression test according to the curing period. For the bearing test, the soil bin models were made and the ground improved in the Mat type was formed. After that, the bearing strength was compared in this study according to the improvement ratio and analyzed the intervening effect between the walls of the improved specimens.

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.77-83
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• 2012

The most of horizontal drainages, which is composed of the aggregates made of sand and crushed stone, are used to improve the soft ground. However, where the aggregates are used as the horizontal drainage, it often brings about the delay of consolidation. For this reason, the horizontal drain pipe system is applied to properly improve the soft ground using a drainage pipe instead of horizontal drainage. This system is direct drain method for disappearing the excess porewater pressure which is caused by placing of fill on the soft ground. The large-scale field test was conducted in order to evaluate the applicability and constructability of the horizontal drain pipe system. The settlement characteristics of improved ground with horizontal drain pipe system was observed. It is also compared to the conventional soft ground improvement method to confirm its effectiveness.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.15-24
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• 2020

In this study, the stress concentration ratio for the improved material of the low slump mortar grouting was evaluated through the composite ground method, the ground arching theory, the plastic angle method, the 2D and 3D numerical analysis and the 3D model experiment. The stress concentration ratio calculated by the composite ground method was 89.3, 3.75~59.0 when the three-dimensional ground arching theory was applied, and 82.8 for the three-dimensional plastic angle method. As a result of the 2D numerical analysis, the stress concentration ratio was 63.0~77.0, which was found to increase as the improvement ratio increased. The results of 3D numerical analysis were predicted to be 50.0~56.0 smaller than the results of 2D analysis. In the case of a special model experiment using a large triaxial compression cell, the stress concentration ratio for each load step was 53.0~60.0, and the stress concentration ratio evaluated by the experiment was measured within 2D and 3D numerical analysis predictions. In this study, a predictive equation for the stress concentration ratio according to the improvement ratio is proposed based on the analysis and experimental values for the improved ratio of the low slump mortar grouting.