• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.293-300
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• 1999

The maintenance for the stability of tunnel, especially on downtown area, careful check must be considered during construction stage and after. Moreover we have to achieve the stability of tunnel by ground improvement and reinforcement when ground condition is bad or tunnel failures under the various ground conditions. In this paper, it is presented the case of tunnel failure and the state of restoration by ground reinforcements at seoul subway $\bigcirc$-$\bigcirc$ construction site. For the purpose of ground reinforcement, first, curtain wall was established by chemical grouting. Secondly, cement milk grouting was carried by upper part of tunnel crown. Also Boreholes loading test and tunnel monitoring were carried by in failure site for the long term stability of tunnel.

• Tunnel and Underground Space
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• v.25 no.3
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• pp.244-254
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• 2015

The tunnel is excavated through the alluvial layer composed of sand and gravel with groundwater deposited on rock. A portion of upper part of the tunnel is located in the alluvial layer and there are several buildings just above the curved section of the tunnel. It is necessary to prevent from sand-flowing into the tunnel due to low strength of the alluvial, high groundwater level and shallow depth of the tunnel from the ground surface. For this, the alluvial around the tunnel is pre-reinforced by umbrella arch method with multi-stage grouting through large diameter steel pipes or jet grouting before excavating the tunnel. The effect of the pre-reinforcement of the tunnel and the safety of the buildings are monitored by measurement of ground deformation occurred during tunnelling.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.579-584
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• 2003

In this study, anisotopic yield function is proposed for the numerical analysis of reinforced tunnel ground with grouting. For this, material properties of the reinforced ground both by equilibrium as well as kinematic condition along the interface and by the mean field theory of Eshelby (1957) and Zhao (1990) are compared with each other and, as a result, the advantage/disadvantage of the proposed models are summarized. Finally, reinforced ground around tunnel with grouting is analyzed numerically. A new anisotropic yield function model is shown to be more reliable than the previous one and the predicted result is agreeable with the experimental data available.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.405-411
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• 2008

The pressurized grouting soil nailing method using rubber membrane packer system was developed for recycling materials to minimize environmental pollution and reducing construction costs. For this purpose, field pull-out tests were performed to evaluate the characteristics of soil nailing by measuring tensile stresses and axial displacements.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.437-440
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• 2008

This paper discussed the relationship between existing flowability test method and rheology test, and rheological flowable behaviour of Non Shrinkage Grouting Mortar(NSGM) based on rheological aspect. Five different grouting products are chosen and W/P are conformed to recommendation proposed by product company to meet KS F 4044. For rheological properties of NSGM, flowable behaviour can be explained by the assumption of Binghan model. Also, relationship between flowability test and rheology index of NSGM is confirmed based on this test. Increase of funneling time and decrease of flow led to increase rheology index.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.149-158
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• 2017

Permeating injection is commonly known as an ideal type of injection in grouting reservoir embankment, yet often-combined permeating and fracturing injection grouting operation can disturb the original soil. A grouting method has been regarded as effective and developed to ameliorate the possible disturbance problem. It involves compaction grouting with low expansive pressure near the injection hole and repetitive injection and compaction with grout material that allows ideal permeating injection. This thesis develops Hybrid Grout (ie. HG grout) that allows various application in any ground condition combined together, has high fineness and low viscosity, and expands permeation injection to silty sand. It researches on the injection effect of permeable compaction grout which is done with PC packer and is a combination of HG grout and expansion agent to obtain permeation compaction effect on the area near grout injection spot by developing Permeable Compaction Type Packer(ie. PC packer). As the developed PC packer, HG grout, and and expansion agent (HI-E) are applied to reservoir embankment reinforcement grouting, possibile permeation compaction effect that satisfies reservoir embankment grouting standard is confirmed according to the research.

• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.19-30
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• 2023

Underground structures, such as compacted sand piles applied as soft ground countermeasures, are analyzed for settlement and stability by the composite ground design method. The basic principle of the composite ground design method is the arching effect. The reinforcing effect of the pile is evaluated as the stress-distribution ratio. When applying grouting piles with elastic properties using the ground reinforcement method, the existing stress-distribution ratio was only considered when the pile was installed. This study shows that the method of applying the stress-distribution ratio applied in previous studies should be changed when the ground reinforcement pile is installed at an arbitrary location in the ground without raising it to the ground surface. When high strength jet routing is applied, the stress-distribution ratio (n) to the in-situ ground generally ranges from 30 to 50. However, if the pile is located far from the surface and the depth goes down to the boundary depth of the stress sphere, the stress-distribution effect rapidly decreases, and the stress-distribution ratio converges to 1.5.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.103-110
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• 1998

Several soil improvement methods are applied to stabilize soft ground. But their improvement effects are known to be reduced in view of strength under poor conditions such as marine clay. The purpose of this paper is to investigate the strength increase effects of super injection grouting on the marine clay, A series of laboratory tests and chemical analysis tests has been peformed. Through this study, the causes of strength inferiority of treated soil was analyzed and soil improvement effects of grouted soil was presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.424-433
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• 2006

This paper studies the field applicability of the Special Chemical grouting Method(SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure$(981\sim9,810kPa)$ to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through use of the environmentally friendly injection material, and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.25-31
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• 2006

This paper studies the field applicability of the Special Chemical grouting Method (SCM) in reinforcing and reducing permeability of the back of an existing continuous wall. SCM uses double rod which imposes intermediate pressure ($981{\sim}9,810kPa$) to disturb, cut, discharge, and mix the ground. It is observed that a bulb is formed by using cement paste and environmentally friendly injection materials with minimal alkali leaching. Uniaxial compression tests, test for chemical properties and fish poison test are performed. Test results indicate that the method results in higher durability, less leaching through the use of the environmentally friendly injection material and faster mobilization of the strength. In addition, field tests confirm the formation of the bulb and the seepage cutoff wall.