• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.41-47
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• 2006

This paper introduces stress monitoring system for buried gas pipeline in poor ground. During the six months of improvement construction of poor ground, maximum settlement of gas pipeline is about 40 cm. This value represents relative small compared to the initial settlement estimation of ground improvement construction plan, 90 cm. Also, this paper includes the result of finite element analysis of gas pipeline to confirm safety of pipelines in poor ground. The stress monitoring system for gas pipeline was developed to guarantee the safety of buried gas pipeline in poor ground. Eventually, the ground improvement workings are ended safely and it is proved that the pipeline has no safety problem.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.165-173
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• 2018

Purpose: The area such as historic sites where distributed in the hills surrounded by the mountains in the past, if heavy rains occur, soil that distributed in the substructure of a sedimentary layer's permeability decreases therefore, water do not smoothly drainage and increases surface structures' moisture content. Therefore, many phenomena occur such as the muddy ground. This experiment tried to figure out the cause of poor drainage, predicting poor drainage system when rainfall occur. So not only the base of cultural properties distributed in the historic site, but also have big influences on the upper structure. Method: We are going to propose an improvement plan through the various sites exploration and the field permeability test. In addition, analyze interrelationship to figure out the cause of the poor drainage through monitoring under ground water. Conclusion: As the result of the experiment, the cause of the poor drainage system formed on shallow depth of ground level inside of a land. We can see that soil of surface and fill deposit permeability was in poor condition. Therefore, it was in very inappropriate hydrogeological condition when surface water permeate into the underground when rainfall occurs.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.96-97
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• 2016

As coal fly ash emissions have increased due to additional constructions of domestic heat power plants, the amount of embedded reject ash (Rj henceforth) is increasing as well. Most Rj is embedded, so if it is used as an alternative admixture instead of cement, embedded quantities will decrease, leading to economic and environmentally positive effects. Therefore this study conducted an experiment to contemplate the usability of Rj ground in the Los Angeles abraser, and what effects ground Rj has on the engineering properties of poor-mix mortar. The result was that as the number of grinding turns increased, liquidity, air quantity and intensity were improved, proving Rj a possible alternative admixture to cement.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.829-834
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• 2009

Alluvial soil is one of the most difficult grounds for tunneling works due to the insufficient ground strength and excessive ground water inflow. Dduk island in Seoul has a wide alluvium developed by two rivers, Han and Jung-Ryang. Subway tunnel of $\bigcirc\bigcirc$ line planed across Dduk island has highly poor ground conditions due to small cover and deeply developed alluvium. Moreover, much part of this tunnel is located parallel to the bridge foundations of another railway with a small horizontal distance. Original design was done in 2002 and construction has been in progress. During the construction, tunnel design has been partly changed and adjusted for the complex ground condition and the demand from related organizations. This paper intend to introduce the urban tunnel design and construction in alluvial soils. This line could be divided three sections(A, B, C) according to ground and adjacent conditions. Section A is featured by mixed tunnel faces consisted with alluvial soils and weathered or weak rocks. The feature of section B is that tunnel underpasses near the bridge foundations of another subway. Lastly, section C with a very short length is the most difficult construction conditions due to the small cover, poor ground, obstacles on and underneath ground surface.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.6 s.113
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• pp.40-50
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• 2006

This study was carried out to examine the tree-ring growth characteristics of Zelkova serrata Makino after replanting, for the built-up planting founds for stability of landscaped trees in the reclaimed land from the sea. the factors, many affecting the growths of Zelkova serrata Makino, were the replanting stress and drought. The growth reduction due to replanting and drought occurred in the replanting year and the following year. The mean sensitivity(year-to-year variation) and the coefficient of variation(tree-to-tree variation in a certain year) in tree rings of Zelkova serrate Makino, were higher in the poor soil sites than in the favourable soil ones. And the poor soil sites were the filled ground of improve soil and the covered ground of improve soil and the top ground of big mounding than mounding ground sites, especially soil hardness, alkali soil, high $Na^+\;and\;K^+,\;low\;Ca^{++}\;and\;Mg^{++}$ and T-C were the most crucial. We suggest technique development of the built-up planting ground for stability in the reclaimed land from the sea. The built-up planting grounds in reclaimed land from the sea, should be considered for the use of fair soil with the physical and chemical soil properties, -high level foundation of planting ground, and the prevention of disturbed soil-.

• Journal of the Korean Institute of Landscape Architecture
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• v.19 no.3
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• pp.1-15
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• 1991

The current status of evergreen ground-cover plants as of in the winter months in 50 places selected at random in Seoul was assessed to see how they are at the present, and the following matters of evergreen ground-cover plants were observed to be common aspect of them today during the year of 1989 and 1990 and in winter of Seoul. 1. Ground-cover area in 50 different places of Seoul was 36% of the green area, and the evergreen ground-cover area was 3% of total ground-cover area. As the result, most of ground cover plants founded to be zoysia grasses. 2. Total number of evergreen ground-cover plants species was 24, and the species most frequently found were Juniperus chinensis and horizontalis, Buxus koreana, Liriope platyphylla var. nana. Taxus cuspidats, Rhododendron lateritium, Pleioblastus pygmaea, Poa pratensis in that order of the number of plasces assessed, and sere Poa pratensis, Agrostis tennuis, Liriope platyphylla, Buxus koreana, Juniperus chinensis and horizontalis, Taxus cuspidata. var. nana, Rhododendron lateritium in the order of area planted. 3. Woody plants included 9 species and occupied 16% in the area, also introduced plants included 14 species and occupied 79% in the area. As introduced evergreen grasses occupied, almost of evergreen ground-cover herbs, planting of evergreen ground-cover herbs and native plants are thought to be desirable. 4. Flowering plants of 16 species were found to be 16% of the total evergreen ground-cover area. 5. The ratio of topographical difference, such as plain versus slope for planting site, was 82 and 18% respectively, and sunny versus shady and intermediate places were 72, 15 and 13% respectively. 6. Although appearance of plants was generally fair, poor and drying plants were assessed 33% for the number of places planted, and 11% for the area. It seems to be necessary to manage those plants to their growth characteristics, and desiable to introduce various plant species adaptable to the winter climate of Seoul and grow for the winter landscaping purpose. 7. The poor use and lack of evergreen ground-cover plants are regarded to be deficient in the valus and reconization of them, particularly in the landscaping works. It is therefore considered important to bring out pertinent measures against these inadequate situations.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.297-304
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• 2002

This study is about penetrability of Micro Cement(MC) used for ground improvement. In this study, the characteristics of chemical grouting such as solidification, penetrability were analyzed experimentally by changing permeability of ground, grain size and relative density of grout material. For evaluating applicability of grout material, solidification test and penetrability test were performed. From the results of the tests, effective solidification ratio and penetrability ratio of MC was each 75%, 86% to be excellent when ground permeability was in the range of 10$^{-2}$ and 10$^{-4}$ cm/sec. Otherwise, those of Ordinary Portland Cement(OPC) were both lower than 50% to be poor. When penetrability of grout material is needed for improvement of dam foundation and soft ground, application of MC Is much superior to that of the other materials. The results of the grouting tests in the water flowing ground show that solidification effect of long gel-time grout material is excellent as injection pressure increases when groundwater velocity is relatively low. But when groundwater velocity is relatively high, solidification effect of long gel-time grout material is very poor because most grout materials are outflowed. Therefore, as groundwater velocity is high, effective solidification ratio of long gel-time grout material is better than that of short gel-time grout material, also penetration distance of long gel-time grout material is longer than that of short gel-time grout material.

• Geotechnical Engineering
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• v.12 no.2
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• pp.115-132
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• 1996

Several soil improvement methods are applied to stabilize soft ground. But, their improvement effects are known to be reduced in view of strength and durability under poor conditions such as marine clay and the ground with the flow of groundwater. The soil improvement method is generally classified as mixing(high pressure) type and injection type, and in this study, for successflll'applications of gelling methods, first in case that mixing method with cement is applied to marine clay, the causes of strength inferiority of treated soil are analyzed, and the effectiveness of improvement is studied, second in case that injection method with water-glass chemical grouts is applied to the ground with the flow of groundwater, soil improvement effects and durability of grouted soil are studied.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.347-354
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• 2002

In this paper, when structures are constructed in the soft ground with poor bearing capacity at Incheon International Airport(railroad area), as for the grouting columns built In soft ground by high pressure jet grouting with Triple tube rod(super injection grouting), the effects on reinforcement and bearing capacity of ground are investigated. A unconfined compressive strength tests has been performed on the specimens sampled from the grouting columns and a mass plate bearing test has been performed on a grouting column. The test results show that super injection grouting has a sufficient effect on composite ground improved of foundation ground and reatraint of settlement of structure.

• Tunnel and Underground Space
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• v.20 no.1
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• pp.58-64
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• 2010

GLI model was verified to consider the interaction between a ground and a tunnel lining and to rationally reduce the ground load acting on the secondary lining(concrete lining) of a tunnel. In this study, the economy and the construction condition of tunnel concrete linings designed by a conventional frame model at Lot O of OO line were highly enhanced through a field design change using GLI model. For a few safe considerations, not only about 50% saving of reinforcing steel could reduce the material cost but also the wide space between bars could make it easy to pour concrete mix without voids. There was large saving effect of reinforcing steel for poor ground conditions because Terzaghi's load used in the conventional frame model produces too much high loads for those conditions.