• Geotechnical Engineering
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• v.12 no.5
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• pp.5-16
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• 1996

When braced excavation with temporary retaining wall installation, is performed in loose sand with high ground water level boiling may be induced and considerable damage on the excavation works and structures in the vicinity can take place. Recently, for the purpose of reinforcement of ground and cut-off of ground water behind the temporary retaining wall, high pressure jet grouting is widely used. The purpose of this paper is to investigate the effects of jet grouting on ground reinforcement and cut -off of the ground water behind temporary retaining walls for braced excavation. A series of both laboratory and field tests has been performed. The test results show that high pressure jet grouting has sufficient effects on reinforcement of stiffness of ground and retaining wall. The permeability of the improved ground was 10-f_ 10-3cm l s smaller than those of the original ground. Therefore, the effect on cut off of ground water behind temporary retaining walls could be improved by high pressure jet grouting method.

• Journal of the Korean Wood Science and Technology
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• v.34 no.1
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• pp.61-67
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• 2006

The purpose of this study was to develop soil conditioner using wood decay fungus. The effect of soil conditioner treated with SJ-28 fungus was tested by lettuce cultivation. Cultivating efficiency was investigated by the yield of lettuce. In the plot of soil conditioner treated with SJ-28 fungus (FPG) showed weight of lettuce leaves 4425 g of total yield which was greater than 2434 g shown in the control. Also the numbers of actinomyces and fungi were increased in the plot of soil conditioner treated with SJ-28 fungus (FPG), beneficial for soil. The number of bacteria showed decrease in FPG plot. FPG showed possibility as a soil conditioner.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.115-124
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• 2012

The responses of stone column-improved ground under seismic loading are investigated using a series of 1g shaking table tests. These tests show similar results to those of one dimensional numerical models for stone column-improved ground based on Baez's assumption on the soil and stone-column interaction. The experimental and numerical results show that the stone column can prevent large shear deformations incurred due to cyclic softening in clayey deposits, but they also show that the surface acceleration in the improved clayey deposits may amplify more than that in unimproved clayey deposits when subjected to short periodic seismic motions.

• Journal of the Korean Geotechnical Society
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• v.28 no.11
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• pp.53-67
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• 2012

In this research, stainless steel and heat-shrinkage tube were used for new TDR sensing line to solve the problems of ordinary TDR system. The new TDR line improved the sensitivity of water content and endurance, and reduced the data noise. The saturation degree test and acryl model test were done by revised TDR sensor. From the results, without additional data filtering and quantitative analysis, the raw data were separated into 3 zones; saturated, unsaturated and dried zones easily. In addition, the revised TDR sensor was installed in large-scale embankment model to perform the seepage test. The raw data of the model tests showed the distributed seepage behaviors and separated zones clearly, which were almost the same tendencies as the lab test results.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.433-440
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• 2020

In this study, a new type of Durometer was invented by modifying the currently used Durometer with the hemisphere shaped needle to columnar shaped needle. The aim of the study is, hence, to provide the feasibility of the advanced Durometer for assessing setting time of the concrete. Generally, the finishing of concrete surface should be conducted to secure the smooth surface, improve the permeability, and prevent the plastic shrinkage cracking. Although this surface finishing work should be conducted during the plastic phase between initial and final setting, currently in practical situations, the timing of starting the finishing work was determined by the sense of the worker. To improve this situation, Kato Junji suggested to use the hemisphere and needle shaped Durometers to determine the initial and final setting time, respectively. However, in this case, there are difficulties of using two different Durometers and of occurring failure of the Durometer due to the intruded cement paste. To prove the feasibility of new typed Durometer, setting time and surface hardness were evaluated by applying for the concrete with various replacing ratios of fly-ash and coal gasification slag as an aggregate.

• Korean journal of applied entomology
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• v.21 no.4 s.53
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• pp.191-194
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• 1982

Using the two different trunk-implantation methods, the systemic insecticides omethoate $(Folimat^{(R)}\;50\;EC)$, vamidothion $(Kilval^{(R)}\;40\;EC)$, methamidophos $(Tamaron^{(R)}\;60\;SL)$, phosphamidon $(Dimecron^{(R)}\;50\;EC)$, monocrorotophos $(Nuvacron^{(R)}\;24\;EC)$, dimethoate $(Rogor^{(R)}\;50\;EC)$, and phosalone$(Rubitox^{(R)})$ were evaluated for the control of the pine gall midges(Thecodiplosis japonensis Uchida et Inouye). Except phosalone, all the insecticides tested in this experiment were very effective for the suppression of the gall incidence by the insects. There was no significant difference in effectiveness between the conventional drilling and improved Mauget methods, and trunk-implantation of the insecticides by the improved Mauget method seemed to be much more feasible in practical view points of the labor cost saving the recovery of the holes drilled.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.43-54
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• 2002

As construction cases of structure are increasing in the soft ground, the necessity of ground improvement is also increasing. Granular pile is one of the improvement methods for soft ground and for loose sandy soil. In domestic, SCP(Sand Compaction Pile) method using sand material has been mainly used to improve soft ground, but Granular pile with crushed-stone was not used much. However, alternative material such as crushed-stone is needed to substitute for sand due to the environmental and economical problems. In this study, staged load test and consolidation test were performed in the laboratory to observe the behavior of soft ground improved by Granular pile. In order to evaluate the characteristics such as bearing capacity, drainage, md settlement, sand and crushed-stone were applied as each pile material. The test results show that crushed-stone has higher bearing capacity and less settlement than those of sand under similar fore water pressure condition. Therefore, crushed-stone is determined to be appropriate as the substitute for sand.

• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.5-17
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• 2023

In this study, a classification and uniaxial compression test of soil was conducted on 15 collapsed sites to use ground improvement with excellent protection effect owing to the increase of localized heavy rain in Korea. The Casagrande method and fall cone test were performed on the field soil to derive an expression for comparing liquid limit and plastic limit values, soil classification, and correlation between each other. By deriving the optimal mixing ratio of the ground improvement agent using uniaxial compressive strength for each soil classification, the classification of the fine-grained soil was not clear owing to the proficiency difference and test error. However, after classifying using the fall cone test, it was possible to suggest a clear optimal mixing ratio.

• Journal of the Korean Geotechnical Society
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• v.26 no.8
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• pp.59-66
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• 2010

In this study, an applicability by using the FEM was investigated for the prediction of both the depth of improvement and the vibration effect when dynamic compaction method is applied. The region was modelled by the field conditions applying dynamic compaction method and the rigid body force was applied to the dynamic load model. Predicted depth of improvement calculated by the vertical peak particle acceleration was compared and analyzed with an existing empirical equation, and the effect of groundwave by deducing the peak particle velocity from vibration sources was compared and analyzed with the results of another existing empirical equation. The results showed that the prediction of the depth of improvement has similar tendency to practice, and the vibration effect has some differences in a particular section from existing equation, but it could predict the safety distance to some degree. The analyzed results are expected to be basic data for the development of reliability of dynamic compaction design with existing empirical method.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.99-104
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• 2007

The deep soil mixing, on ground modification technique, has been used for many diverse applications including building and bridge foundations, port and harbor foundations, retaining structures, liquefaction mitigation, temporary support of excavation and water control. This method has the basic objective of finding the most efficient and economical method for mixing cement with soil to secure settlements through improvement of stability on soft ground. In this research, the experiments were conducted on a laboratory scale with the various test conditions of mixing method; the angle of mixing wing, mixing speed. Strength and shapes of improved soil of these test conditions of deep mixing method were analysed. From the study, it was found that the mixing conditions affect remarkably to the strength and shapes of improved soils.