• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.425-428
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• 2005

To resolve land demand by the development of various industries and the cityward tendency of population, the construction of ultra-soft ground that is unused in the past has been progressing with activity. The ultra-soft ground has very small shear strength and large deformation, so leads to many problems in ground improvement in construction. In order to dispose of these problems, it is necessary to develope the chemical materials that can be applied to the surface stabilization of ultra-soft ground. In this study, the new ground treatment that is using cement and SCS is compared, analyzed with existing ground treatment. In addition, through the laboratory tests that check the characteristic of congealment and strength, the application of SCS in field is affirmed.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.918-927
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• 2008

The problems associated with constructing high-speed concrete track embankments over soft compressible soil has lead to the development and/or extensive use of many of the ground improvement techniques used today. Drains, surcharge loading, and geosynthetic reinforcement, have all been used to solve the settlement and embankment stability issues associated with construction on soft soils. Geosynthetic-reinforced embankment supporting piles method consist of vertical columns that are designed to transfer the load of the embankment through the soft compressible soil layer to a firm foundation and one or more layers of geosynthetic reinforcement placed between the top of the columns and the bottom of the embankment. In the paper, the evaluations of a seismic performance of geosynthetic-reinforced embankment piles for a ultra soft ground during earthquake were studied. the equivalent linear analysis was performed by SHAKE for soft ground. A seismic performance analysis of Piles was performed by GROUP PILE and PLAXIS for geosynthetic-reinforced embankment piles. Guidelines is required for pile displacement during earthquake. Conclusions of the studies come up with a idea for soil stiffness, conditions of pile cap, pile length and span.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.731-738
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• 2002

Recently, as large constructions on the coast are performed frequently, surface layer stabilization method which Is one of the improvement methods for dredged soft clay has been applied. However, there have been few studies about the surface layer stabilization method. The purpose of this study is to clarify characteristics of ultra-soft marine clay and hardening agent. Also, optimal mixture ratio of hardening agent was verified through the laboratory tests such as statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil and standard mixing tables of hardening agent were determined according to ground conditions through statistical analysis. Also, applicability of surface layer stabilization method to field was verified by pilot tests. From the results of the tests, it was found that hardening agent materials such as cement, slag, fly-ash, inorganic salts, arwin, gypsum etc. affect on the appearing compressive strength. It was defined optimal mixture ratio which satisfies the required compressive strength from the statistical analysis. Also, It was compared the effect of ground improvement by cements and hardening agents through the pilot tests. This study will serve as data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• Geotechnical Engineering
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• v.23 no.9
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• pp.10-20
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• 2007

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.80-90
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• 1998

The EPS construction method-one kind of the load reducing methods-utilizes the EPS blocks, ultra-light materials whose unit weight is about 1/100 of soils and has been applied to many soft ground sites. It needed 3,000 days to get the 90% degree of the consolidation for the case of 12m high soil embankments on the 30m thick soft clayey foundations. The N value of SPT at this deposit was less than 5. The pack drain was installed to promote the radial consolidations. Although staged embankments were planned, designers failed to get a sufficient stability of the foundation ground. Therefore, the EPS fill method was selected to reduce the load and the construction period. EPS blocks(D-20 model) replaced the upper part of the soil embankments. These complex embankments reduced the ground settlement and the construction period. The possibility of lateral movements of the bridge abutments was checked and the design scheme was reviewed.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.33-43
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• 2002

Recently, as large constructions on the coast increase, an application of a surface layer stabilization method which is one of the improvement methods for dredged soft clay has increased. However, there are few studies about this. The purpose of this study is clarifying characteristics of ultra-soft marine clay and hardening agent. Also, it is verifying an optimal mixture ratio of hardening agent through the laboratory tests according to designed experiments and proving by statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil in accordance with the design of experiments. Regression equations between hardening agents materials and unconfined compressive strength were derived from the tests. The applicability of regression equations were also verified by pilot tests. From the test results, it was found that hardening agent materials(cement, slag, fly-ash, inorganic salts, arwin, gypsum etc.) have some effect upon compressive strength. The optimal mixture ratio which satisfies the required compressive strength was derived from the statistical analysis. The effect of ground improvement by cements and hardening agents was confirmed through the pilot tests. This study will suggest data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• Journal of the Korean Professional Engineers Association
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• v.34 no.2
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• pp.42-45
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• 2001

This Grand Sorae Bridge was built in order to lead to balanced reigoonal development by linking the 2nd Seoul - Inchon Highway to WestCiast Highway and it will contribute to develop the economy of the region and traffic of its vicinities by helping ease traffic in and around Inchon. It extends 470 meter across Sorae port by using 10 continuous steel box griders under benoto(all casing) system considering ultra soft ground condition of the site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.269-275
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• 2019

As the national industry is developing gradually due to the expansion of the economic scale, the construction of large and super high-rise structures for building social infrastructure has been increasing, and studies have been conducted actively to transmit the large loads at the upper portion to the lower bedrock. In this study, the PHC was extended to an ultra-high strength PHC, which increased the concrete compressive strength of the PHC from the conventional 80 MPa to 110 MPa, and the PHC, which extended the tip of the pile. After construction with the driving method and injected pile method, the tendency of the bearing capacity was tested through a load test. Measurements of the bearing capacity of the extended PHC using the pile driving method revealed the main surface friction force to be smaller than that of the general PHC, and the stet-up effect was also insignificant. On the other hand, the effect of the friction force on the ground surface when the injected pile method was applied is expected to increase the bearing capacity when the gap between the main surface and the ground is wide and the cement paste is filled tightly. In addition, the ultrahigh strength PHC showed higher bearing capacity than the conventional PHC, and the permissible pile stress was less than 60%. Therefore, it is possible to reduce the number of piles and reduce the construction cost and effect of shortening the length of the pile by designing the tip of the pile on the ground with the intensity of soft rock as a method for utilizing the increased strength of the ultra-high strength PHC.

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.29-37
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• 2009

Examining the mechanical characteristic of the bamboo net structure is necessary in order to evaluate the influence of bending rigidity of bamboo on bearing capacity, however, there is no equipment to examine such mechanical behavior of the bamboo net structure in the world. In this study, a specific equipment to examine stress-strain behavior characteristics of the structure of bamboo net is developed. In comparison with Bamboo's stress-strain behavior characteristic and vertical stress caused by various dozer equipments, the case of estimating minimum embedded depth considering ground settlement is analyzed.