• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.449-456
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• 2000

Remediation grouting has been widely used for the rehabilitation of various civil works like hydraulic and traffic structures. Recently there were some cases of remediation grouting for repairing old dams in korea. So this study will describe the case of remediation grouting of the concrete dam base located east-northern part of Seoul. We use Lugeon Test and Borehole Image Processing System(BIPS) for estimating the effectiveness of remediation grouting of this project. As the results of this study, we could find the lots of joints between the old concrete body and the weathered rock base. So the about 30% quantity of total cement grouts was injected at the boundary surface between concrete and rock base. And Lugeon Test and BIPS could be compared relatively because BIPS results could be presented quantitatively as well as qualitative analysis. Finally, we could find microfine cement was very effectively injected to the fine fissured concrete body compared with ordinary portland cement, but there was little injectability differences beteween microfine cement and ordinary portland cement at the large cracks or cavities were developed rock base.

• Geomechanics and Engineering
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• v.38 no.5
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• pp.455-466
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• 2024

Ground collapse may occur around the tunnel when the cavity caused by groundwater runoff cannot resist the surcharge load. Any cavities or subsidence must be managed to avoid dangerous situations by stabilizing the ground through appropriate remedial measures. Trench and trenchless grouting methods can generally be used for the cavity restoration. The trench method is difficult to properly control the injection range and may cause environmental problems due to grout leakage and damages to the adjacent structures due to grouting pressure. In this study, Membrane-grouting method (MGM) is proposed, which, can be an appropriate trenchless grouting method that fills the void tightly and effectively controls the injection range. This method can be an alternative to eliminating the influence of adjacent structures and environmental pollution by inserting a membrane into the cavity and filling the membrane with grout. The membrane blocks the outflow of grout. In addition, it is easy to control the injection pressure to avoid heaving failure. This paper investigates the principle and application of the MGM using a theoretical method, model test and numerical analysis.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.45-52
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• 2007

Maintenance of structural and hydrological safety of the superannuated fill dam is very important subject on the viewpoint of disaster prevention. Mainly, the core of the superannuated fill dams have been damaged continuously by the various harmful external forces such as the typhoons, flash floods and earthquake, and these can be connected to the large scaled general dam failure. Therefore, the research on the repair, remediation and reinforcement of dam is necessary. In this study, the permeable grouting method for the remediation of fill dam was examined by the electrical resistivity survey and the change of permeability of core front. As a result, the permeable grouting method can be useful remediation method for the superannuated fill dam, the leakage from the core front decreased greatly before and after the construction of grouting. Furthermore, it can be said that the turbidity of fill dam may not be greatly increased by grouting.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.115-129
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• 2015

The cut-slope of a large-sectional tunnel portal is recognized as a potential area of weakness due to unstable stress distribution and possible permanent displacement. This paper presents a case study of a slope failure and remediation for a large-scale cut-slope at a tunnel portal. Extensive rock-slope brittle failure occurred along discontinuities in the rock mass after 46 mm of rainfall, which caused instability of the upper part of the cut-slope. Based on a geological survey and face mapping, the reason for failure is believed to be the presence of thin clay fill in discontinuities in the weathered rock mass and consequent saturationinduced joint weakening. The granite-gneiss rock mass has a high content of alkali-feldspar, indicating a vulnerability to weathering. Immediately before the slope failure, a sharp increase in displacement rate was indicated by settlement-time histories, and this observation can contribute to the safety management criteria for slope stability. In this case study, emergency remediation was performed to prevent further hazard and to facilitate reconstruction, and counterweight fill and concrete filling of voids were successfully applied. For ultimate remediation, the grid anchor-blocks were used for slope stabilization, and additional rock bolts and grouting were applied inside the tunnel. Limit-equilibrium slope stability analysis and analyses of strereographic projections confirmed the instability of the original slope and the effectiveness of reinforcing methods. After the application of reinforcing measures, instrumental monitoring indicated that the slope and the tunnel remained stable. This case study is expected to serve as a valuable reference for similar engineering cases of large-sectional slope stability.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.293-304
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• 2013

Because the present groundwater law broadly regulates a simple and impractical guideline ignoring aquifer characters and geology, general purpose facilities for protection of groundwater contamination is still considered unsatisfactory to ensure groundwater resources. In recent, there have been growing attempts in the packer development as crucial techniques and devices for groundwater protection. This study investigated the application of packer grouting techniques to contaminated groundwaters of two well sites in the Andong and Yeongi areas, both of which revealed a satisfactory effect with improved water quality: 94% decrease in turbidity at the Andong area and 60% decrease in $NO_3$-N, respectively. Based on aquifer characters including geology, weathering depth, fracture pattern, hydraulic gradient, and the flow path of contaminants, the integrated properties of groundwater contamination should be evaluated and treated with the help of accurate analyses such as bore hole imaging and monitoring data. Packer grouting and casing on well to ensure the useful aquifer free of contaminant are expected to play important role in inhibiting the inflow of contaminants when adequately applied. Therefore it is concluded that these can serve as reliable tools in remediation and protection of contaminated groundwater as well as efficient utilization of groundwater.