• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.827-832
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• 2003

This study presented the reinforcing effect of sands by using newly devised 3D Tirecell. Plate loading tests for sand were conducted for different relative density and number of reinforced layers. From the tests, the ultimate bearing capacity of reinforced sand increased with increasing relative densities. The effect of reinforced layers with 0.4B interval is limited to 2 layers and further reinforcing effects can not be obtained beyond 3 layers. Especially the bearing capacity increased remarkably at 1 layer of Tirecell reinforcement and the degree of increase was small for 1 layer to 2 layers increase of reinforcement. Test results show that the reinforcing effect of Tirecell is prominent compared with commercial geocell in the literature.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.411-416
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• 2003

As rapid industrialization continues in these days, construction in the down town areas increases. Since constructions are performed around old and existing structures, the need to provide reinforcements to protect the existing structures from collapse and damage arises. Furthermore, if the construction is to take place in the down town area, difficult work space and damage caused by noise, vibration and collapse of structure can't be ignored. Among the remedial measures available today, micropile reinforcement is considered the best method to remedy these problems. But up to the present the characteristics of micropiles and ground behaviour has not been proven and no standard design is not yet available. Therefore, most design are performed based on previous experiences. In this study, the difference in the bearing capacity with changing reinforcement angle, space and sphere around foundation was monitored. These results were induced to broaden heighten the limits of micropile application.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.283-286
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• 2007

지반을 보강 또는 지하수를 차단하기 위해 실시되는 그라우팅과 같은 공법이 제대로 효과를 발휘하기 위해서는 bulging 또는 sheet 형태의 그라우트체 형상의 조절이 필수적이다. 본 논문에서는 이러한 그라우트체 형상에 영향을 끼치는 인자를 찾기 위해 포화된 사질토지반에서의 그라우트 실험을 다수 실시하였다. 그라우트의 주입속도와 점성의 크기, 사질토의 상대밀도와 입도크기의 인자를 사용하여 실험을 사용한 결과, 비교적 느린 주입속도와 작은 상대밀도, 그라우트의 점성과 입자가 클수록 bulging 형상의 그라우트체가 형성이 되었다. 이와는 반대로 빠른 주입속도와 높은 상대밀도, 그리고 그라우트의 점성과 흙 입자가 작을수록 sheet 형상의 그라우트체가 형성이 됨을 확인하였다.

• 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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• 1999.10a
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• pp.201-208
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• 1999

The NATM(New Austrian Tunnelling Method) has been used for tunnelling since 1980's. But Collapses of tunnel under construction take place frequently, especially at urban areas because of adjacent buildings, underground conduits and traffic loads. This paper is a case study on the reinforcement method of subway tunnel at urban areas. In this study, ground inspection, geological investigation, laboratory test and numerical analysis by means of FDM program were carried out. The tunnel excavation was stopped because of over excessive brake of tunnel crown and shotcrete was installed to prevent deformation of adjacent ground as the temporary method. From the result of field survey and geological investigation, it is found that the soft weathered soil was distributed to the ground of tunnel invert unlike original investigation. The results of the analysis and the study show that the SGR(Space Grouting Rocket) method and Umbrella method can be applied for the stability of tunnel excavation and in addition the reinforcement of concrete lining is required for long-term stability of tunnel.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.441-448
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• 2000

While the Grouting has been used to reinforce the foundation of structures in wide range of application, there need complementary measures against problems such as pollution, durability, influence on the adjacent structures. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. In this paper, on the basis of the case history constructed in this year, a study has been performed to analyze the basic mechanism of the Compaction Grouting, Also, the effectiveness of the ground improvement and the bearing capacity of the Compaction Pile has been verified by the S.P.T and core strength.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.247-267
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• 2005

이암층 역암층 그리고 화산암층과 같은 특수지질 불량구간에서 터널과 암반사면의 합리적인 시공을 달성하기 위해서는 먼저 대상지질에 대한 지질조건과 암반특성을 정확히 이해하는 것이 필요하며, 이를 바탕으로 지반특성에 적합한 보강대책을 수립하도록 하여야 한다. 본 고에서는 포항지역과 경주지역에서의 미고결 이암 및 역암층 그리고 제주도 화산암층에서의 암반 구조물에 대한 설계 및 시공사례를 검토하고 전형적인 미고결 지층으로 알려진 신생대 지층에서의 터널과 암반과 같은 암반구조물에 대한 설계 및 시공상의 제반 문제점을 고찰하므로서 이에 대한 합리적인 대책을 수립하고자 하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.499-509
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• 2005

We have many foundations which were constructed on the karstic areas where solution cavities and fractured zone may form under, or close to foundations. The fact that the ground under the pier foundations was reinforced with the three axial high pressure jet grouting is confirmed through out about two hundred design reports. It is necessary that evaluation of a simple application of high pressure jet grouting method on the karstic areas containing solution cavities. In this study, the improved situation and reinforcing methods of the ground under the pier foundations are proposed based on the evaluation of design reports for the express highway and No.38 national roads.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.327-334
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• 2008

This paper presents the results of investigation on the influencing factors for GESC(Geogrid-Encased Stone Column) method in soft ground. A parametric study was then conducted on the influencing factors such as replacement ratio, geogrid stiffness and thickness of soft ground using stress-porepressure coupled analysis. The results indicate that the relationship between these parameters and settlement ratio, and the relationship between these parameters and stress concentration factor can be identified.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.480-488
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• 2010

The CGS method is non-discharge replacement method improving ground stiffness by the effect of static compaction with injecting very low slump mortar into ground, and is applied for increasing bearing capacity and filling ground cavity by lifting or restoring differential settled structures and preventing differential settlement. This paper suggests design of ground improvement and construction case history for civil engineering structures by CGS method. This method can be used for reinforcing soft ground and liquefaction of loose sandy soil. This method was used in SongDo area in Incheon Economic Free Zone due to its low vibration of ground while it can improve the soft soil where underground structures(subway and box culvert) are already existed.