• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.128-131
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• 2001

The purpose of this study is to investigate the application of Column Jet Method(CJM) as countermeasure against settlement and slope sliding of existing marine structure due to embankment load behind reclaimed revetment. CJM is to make high-strengthened body by compacting and grouting cement mortar after forming artificial space in the ground with ground relaxition machine or high pressure water jetting. Before the ground was reinforced by CJM, the result of slope stability analysis was not satisfy the allowable safe ratio, but after the ground was reinforced by CJM, the stability of slope was over the allowable safe ratio and stable, Therefor, the application of CJM to restraint settlement and sliding of marine structure was very satisfactory.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.02a
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• pp.14-22
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• 1999

Daylight collapse have been occurred by about 6.$^{0}$ m deep at ground surface which connected to the ground surface and excessive overbreak have been occurred by the space and height of 3.$^1$~6.$^2$m at crown head part of the tunnel during tunnelling of lower-half part after completing upper-half part on tunnelling of a phyllite mountain by NATM method at the construction work of two way-double track national road. This study is a successful illustration case of earth improvement by confirming structural safety of the tunnel in a whole through solving the cause of the tunnel collapse and the work have completed successfully through applying such earth strengthening method as cement mortarㆍcement milk injection, S.G.R, steel pipe reinforced multi-step grouting etc.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1104-1113
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• 2010

In order to reduce negative skin friction uses bitumen most plentifully. But, Bitumen is expensive very of 1.5 or more times of pile material expense. The bitumen will be able to substitute it is nescessary. It was researched that it would be able to bitumen substitutions from in products which is produced from domestic in this study. This was composed with most bentonite, added some cement. When it is used this product in the model test, the reduction ratio appear of 85% or more. In this result, this product as the reduction material is confirmed that has enough ability. Additional research leads, the product according to pile construction method must verify the reduction effect of negativ skin friction in field test.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.866-871
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• 2010

Various design factors should be considered in order to apply the concrete slab track system on the soil/rock roadbed. One of the important factors is the settlement of roadbed. This settlement of concrete track should be supervised under the allowable settlement limit. If the settlement of roadbed under the concrete track exceed the allowable limit, the train serviceability will considerably come down and furthermore the fatal disaster may happen. Therefore, in this paper we introduced a PRCG(pressurized rapid-hardening cement grouting) method as a settlement restoration method that can be suitably adopted to the concrete slab track.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.265-270
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• 2000

AESTRACI: The shmr behior of sawtoothed artrjicial joints grouted with cement milk rm investiguted in the lahotconstant normal stress conditions. Tests were amducted on joints with asperities h i n g inclinations cf 16.7" and 26.6" ,strengths h i n g 15MPa and 47MPa under a given nmge of n o d stresses wrying frcm 0.76 to 1.g MPa md at a freepitching, rolling and dihtmuy. Results show that the gect of asperities on shmr strength increme is signifamt up to as,to grout thidness (t/a) mtio 4 0.3-1.0. Increme of ahesim is the nmn muse cf shmr strength increme in cemmtoothed artificial iointsed artificial ioints

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.389-393
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• 2005

When the high-speed train running on the track, there is a speed limit which track distortion is unusually increased according to condition of track and roadbed. This speed limit is called critical velocity, and physical parameter value increased very greatly. These phenomenon happened as high-speed train were developed, studied regularly through TGV 100 running test in France. As research result until now, the main reason is soft roadbed's capacity. Wave propagation and track support capacity is varied by the site characteristics. This paper achieved theoretical examination about resonance band(speed and frequency) that occurred in roadbed on the base rock in point of geotechnical engineering. The examination of resonance divides with ground response analysis, critical band analysis by the shear wave velocity of roadbed, train critical speed through the ground stratum.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.213-220
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• 2002

Generally it is informed that urethane materials are superior to the others in physical characteristics, durability, ground improvement and the influence to environment . But, the existing urethane methods are too expensive to apply. So this study has analyzed the applicability of TAS method which has developed the existing urethane injection mechanism. From the results, Extending the max-infection distance over l0m from 6m which the existing methods could inject to, TAS method has proved to be economical. Also, the TAS method is obtained quickly to ground improvement effect in various tunnel constructions because rise-time was relatively shorter than that of cement-grouting. Therefore, it is expected that TAS method would be applied a lot for water proof and ground improvement etc. owing to its many advantages mentioned the above.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.361-368
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• 2019

This study aims to evaluate the applicability of a grout material that is mixed with carbon fiber, biogrout, ground granulated blast furnace slag (GGBS) powder and cement. Uniaxial compressive strength tests were performed on homo-gel samples at days of 1, 3, 7, 14 and 28. In addition, the variation of permeability with the mixing ratios was measured. Based on the uniaxial compressive strength test, it was confirmed that the uniaxial compressive strength increased by 1.2times when carbon fiber increased by 1%. In addition, as a result of the permeability test, it was found that when the GGBS increased by 20%, the permeability coefficient decreased by about 1.5times. Therefore, the developed grout material can be used as a cutoff grouting material in the field due to its strength and cut-off effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.122-129
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• 2012

In this study, environmental problems(i.e., pH elevation and $Cr^{6+}$ detection) occurred by using the cement grout made from CA(calcium aluminate) were evaluated using viscosity agents(MC, chelate polymer). Ordinary portland cement and blaste-furnace slag cement were used by main materials and ACC(blended mixture of calcium aluminate) were used by accelerator for hardening of grout. In addition, viscosity agents were used for preventing pH elevation and heavy metal detection from grouting materials. From the results, it was noted that when chelate polymer was used, pH elevation and $Cr^{6+}$ detection were minimized. However, other cases showed higher pH elevation and $Cr^{6+}$ detection. At test 1 day, $Cr^{6+}$ detection with age presented over 97% of total value and, after that, additional increase was not distinct. As a result of this study, it was acknowledged that, to control pH elevation and heavy-metal (like $Cr^{6+}$) detection, the usage of BSC and chelate polymer is a very useful fact.

• Journal of the Korean GEO-environmental Society
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• v.13 no.7
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• pp.31-38
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• 2012

Water glass chemical grouts are primarily used in ground injection projects. Natural and Durable Stabilizer (NDS), Space Grout Rocket (SGR), and other similar materials composing of inorganic accelerating agents with ultra fine cement have been gaining popularity as ground improvement material in South Korea. However, there are questions as to grouting results and environmental issues caused by NDS grout. This study uses the injection method in mudstone embarkment to evaluate the differences in strength, permeability, and optimum injection volume through the use of uniaxial and triaxial compression tests and fish poison tests for NDS and SGR materials. After 28 days, results showed SGR and NDS to have a 50% increase in strength and 50% decrease in permeability with the proper injection rate at 50%.