• 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 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.13 no.11
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• pp.69-79
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• 2012

This pre-supported nail method is able to decrease ground displacements more than NATM because this method reinforces ground with grouted steels before tunnel excavation. Therefore this method has advantage of being able to increase the stability and workability. This study presents applicability of pre-supported nail method with case of site measurement for shallow tunnel composed with high groundwater level and unconsolidated soil, performs this research the mechanism of new supporting system is compared with the conventional existing supporting system in terms of soil reinforcement. NATM has characteristics that construction stage displacement of the apparent height difference is observed in the step of divided excavation processing. Otherwise it is analyzed that pre-supported nail method is not sensitive in the displacement problem of excavation processing in comparison to NATM. It is found that this method is very applicable in shallow depth tunnel such as portal area, tunnel in soil and weak zone without arching effect.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.203-210
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• 1997

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.13-23
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• 2017

This paper discusses about the reinforcement materials and construction method in order to cope with roadbed settlement in operating railway. In Korea, concrete tracks have been introduced to urban railways, high-speed railways, and general railways, but some recently constructed concrete tracks have experienced roadbed settlements. Reinforcement of the railway roadbed is urgent task for safe operation of railway, but it is difficult to reinforce the roadbed and there are no case history of reinforcing railway roadbed under an operating railroad track. Therefore, in this study, the target performance level for roadbed reinforcement was determined, and infiltration and solidity injection efficiency were investigated for selected reinforcement materials. As a result of the study, it was found that the generally used reinforcement materials and methods for geotechnical works need to be improved for applying in railway roadbed reinforcement.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.85-95
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• 2012

The method of using organic acid is more environment-friendly for it improves the strength of the ground. The method of proliferating microbes makes soil particle bonded, finally improves the strength of the ground and decreasing permeability. Although there has been the research on the effect of strength increasing, there has never been a research on the evaluation of field application. In this paper, through the light drop weight test, the dynamic cone penetration test, the field density test, the variation of strength was investigated in the mixed ground with organic acid for 56 days. As the results of the field test, it was found that the strength and stiffness of the ground increased with organic acid, and that through SEM-EDS, the precipitation of calcium carbonate made by specified microbe obviously increased with organic acid material and so the ground was improved. Therefore, the sustainable development of this method needs to be analysed more in the future.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.6
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• pp.135-142
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• 2001

Laboratory experiment was performed to evaluate the influence of mixing conditions to the strength of solidified sandy soils with cement. The major physical factors considered in this experiment were the fine particles content(<$\sharp200%$), cement content(%) and water-cement ratio, and unconfined compressive strength test was performed on the samples at 7 and 28 cured day. The results of tests shows that when the cement content is relatively low (7~10 percents) the fine content in the sandy soils is very important, but when cement content is high the water-cement ratio became more important. It was appeared that in the range of the cement content of 7~10 percents, about 20~30 percents of fine content to the total sample weight is the optimum condition to get the maximum strength. In the case of the cement content of 13 percents, the strength of sample was considerably affected by the water-cement ratio rather than the fine content. In this paper, empirical equations were also developed and evaluated to verify the relationship among three factors by the multi-regression analysis.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.107-122
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• 2009

Insufficient reinforcement for maximizing payability and benefits in mining cavities causes subsidence problems and it threatens residents' lives and properties. So many reinforcement management methods are developed and now various methods are being applied in the field. Among them, a filling method which sends reinforcement materials in the cavities is used extensively. However, domestic geological condition and coal mining methods are so complicate that make many steep cavities. Because of those problems, it is difficult to apply foreign methods directly, which is valid for horizontal cavities. In this study, the injection volume of quick setting grouting material which is developed for filling cavities in domestic condition and the shape of consolidated bodies are investigated. And a programming method for estimating proper injection amounts of filling materials is proposed. The results are verified by numerical analysis using UDEC.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.113-119
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• 2006

Recently, the ground injection method using water glasses as one of the main resources and the products of these constructions have basic problems in terms of the method of constructions for the permanent foundation reinforcement and stopping leakage of water because they have some serious problems such as durability, compressive strength, injectant eluviation and so forth even though they are still used to stop leakage of water in the temporary structures. The purpose of this study is to demonstrate the strength characteristic and environment friendliness of NDS method by unconfined compressive strenth test, permeability test, length change test, leaching test, and assessment of environmental impact in comparison water glass type material. The test results show that NDS method has significant improvement of strength, permeability, volume change, and leaching. An assessment of environmental impact also demonstrates that the NDS material is environmentally friendly.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.23-29
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• 2019

In general, pipe laying works are performed by constructing underground facilities such as pipes and then refilling the rest of the area with sand or soil. However, there are many problems in the compaction process such as difficulties in tampering around the underground facility and low compaction efficiency. Such problems cause deformation and damage to the underground pipes during refilling work and ultimately cause road sinks. Construction methods using CLSM are one of the typical methods to solve these issues, and recently, studies on CLSM using coal ash, which has similar engineering properties as sand, have been actively performed to protect environment and recycle resources. While many studies have been conducted to recycle fly ash in many ways, the demand for recycling bottom ash is increasing as most of the bottom ash is not recycled and reclaimed at ash disposal sites. Therefore, in order to find bottom ash applications using eco-friendly soil binders that are environmentally beneficial and conform with CLSM standards, this study investigated flow characteristics and strength change characteristics of eco-friendly soil binders, weathered granite soil, a typical site-generated soil, bottom ash, and fly ash mixed soil and evaluated the soil pollution to present CLSM application methods using bottom ash.