• Tunnel and Underground Space
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• v.10 no.3
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• pp.378-386
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• 2000

This paper presents groundwater flow characteristics in discontinuous rock mass using fracture network program(NAPSAC) by statistical approach. Equivalent permeability coefficients are estimated from borehole data around Mabuk test tunnel site and fracture map on the arch of the tunnel. The reliability of fracture network model is obtained from determination of input data for statistical fracture network analysis from the real data(data of fracture network, data of hydraulic tests). The variation of permeability and mean anisotropic permeability coefficients are calculated from the realized model by increasing the size. As a result of analysis, a strong anisotropy of permeability is observed according to the direction of the fracture sets around the test tunnel.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.234-243
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• 2007

In this paper, it was aimed to enhance core processes required in establishing hydrogeological models constructed using borehole investigation results. Water Conducting Feature(WCF) information was extracted from borehole investigation, and HydroDFN model was constructed based on the WCF information. The HydroDFN model was sub-divided by cubic blocks, and equivalent permeability of each sub-divided block was calculated and compared with the results of hydraulic test at the borehole. Through these analysis processes, suggestion for identifying and prescribing WCF parameters in the construction of HydroDFN model was made.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.675-682
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• 2013

In this study, to enhance the quality of concrete surface by removing the surplus water, permeable liner attached the euroform was applied for manufacturing concrete specimens. Various kinds of concrete mixtures with different water to binder ratios were applied and the strength properties of the hardened concrete surfaces were evaluated at different heights. Experimental results showed that the rebound values by schmidt hammer test and the compressive strengths on the surfaces of concrete specimens were increased as proportion to the amount of mixture water which is dependent on the water to binder ratio of each concrete mixture, and more enhancements were observed on the middle and lower specimen surfaces than the upper region. SEM analysis also showed that much denser hydrate structures were observed on the specimen surfaces by the application of the permeable liner while similar hydrate formations were occurred regardless of surface treatment conditions. From the MIP test results of the concrete surfaces, it was observed that, by the application of permeable liner, the pore volume below $0.01{\mu}m$ was decreased with a maximum of 50% resulting in the densification of pore structures.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.1-10
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• 2019

This study was intended to evaluate the water permeability and structure for calcium bentonite-sand mixtures to utilize calcium bentonite as a liner. This study conducted physico-chemical properties tests, compaction tests, permeability test and Scanning Electron Microscopy analysis (SEM) analysis. It was found the higher the ratio of calcium bentonite, the lower the dry density with coefficient of permeability, and the higher the optimum moisture content. In particular, SEM analysis was found the higher the ratio of calcium bentonite, the higher the area of the montmorillonite particles. In conclusion, the optimum coefficient of permeability that finds the landfill liner condition (must be less than $1{\times}10^{-7}cm/sec$) was obtained when the ratio of calcium bentonite was 40% or higher. These findings may improve the understanding of the calcium bentonite as a liner. Calcium bentonite shows a similar permeability to sodium bentonite 7% when mixed at 40% or more. Therefore, it is considered that calcium bentonite can be utilized as a liner.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.47-55
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• 2009

As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a vertical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully applied to analyzing slug test results to estimate the hydraulic conductivity of vertical cutoff walls. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method has been modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1253-1257
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• 2010

그라우팅은 건설공사에서 지반의 갈라진 틈이나 공동, 공극 등에 적절한 충전재를 압력을 이용하여 주입하는 것으로, 굴착공사 시 누수방지와 불안정한 지반의 보강을 위하여 광범위하게 사용되고 있다. 가장 많이 사용되고 있는 그라우팅 주입재의 재료로는 물유리계를 주재료로 사용하는 약액주입공법이 많이 사용되어지고 있다. 기존의 물유리계 재료를 사용할 경우 발생하는 용출현상 및 강도저하를 보완하기 위하여 가소성을 부과한 무기질계 재료ECG(Eco Clean Grouting)를 사용하여, 강도 및 내구성이 우수하고 주입재의 용출 현상이 발생하지 않아 환경오염 문제가 거의 없는 영구적인 차수 및 보강에 적합한지와 친환경적 특성을 확인한다. 본 연구는 가소성 무기질계 재료인 ECG(Eco Clean Grouting)재료를 사용하여 현재 많이 사용되는 재료인 물유리계 재료로 일축압축강도, 체적변화, 내구성 평가, 투수시험, 어독성 시험, 용탈시험등을 수행하여 비교 분석 하였다. 일축압축 시험결과 재령 28일 강도는 ECG가 물유리재료에 비해 크게 발현되었고, 내화학성시험 결과 ECG의 길이변화율이 거의 없는 것으로 내화학성에서 강점을 보였다.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.110-116
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• 2016

The rapid expansion of buildings and paved roads increases the risk of flood disaster in an urban area. One of the solutions can be the use of permeable pavements. This study evaluated the permeability of permeable blocks used for the roadway pavement. Joint fillers and mat sands of the investigated blocks met the corresponding standards. The flexural strength of the blocks was 5.29 MPa to meet these standards. Based on interior permeability test results after pollution, the four products evaluated were categorized into the following three levels: One for the $1^{st}$ level, one for the $2^{nd}$ level and two for the $3^{rd}$ level. From the field permeability test and pervious concrete infiltration test results nine months after their construction, all the products except one passed the quality standards of 0.1 mm/s.

• The Journal of Engineering Geology
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• v.9 no.3
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• pp.187-206
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• 1999

A computer program to numerically predict the permeability tensor of fractured rocks is developed using information on discontinuities which Borehole Televiewer and Borehole Image Processing System (BIPS) provide. It uses orientation and thickness of a large number of discontinuities as input data, and calculates relative values of the 9 elements consisting of the permeability tensor by the formulation based on the EPM model, which regards a fractured rock as a homogeneous, anisotropic porous medium. In order to assess feasibility of the program on field sites, the numerically calculated tensor was obtained using BIPS logs and compared to the results of pumping test conducted in the boreholes of the study area. The degree of horizontal anisotropy and the direction of maximum horizontal permeability are 2.8 and $N77^{\circ}CE$, respectively, determined from the pumping test data, while 3.0 and $N63^{\circ}CE$ from the numerical analysis by the developed program. Disagreement between two analyses, especially for the principal direction of anisotropy, seems to be caused by problems in analyzing the pumping test data, in applicability of the EPM model and the cubic law, and in simplified relationship between the crack size and aperture. Aside from these problems, consideration of hydraulic parameters characterizing roughness of cracks and infilling materials seems to be required to improve feasibility of the proposed program. Three-dimensional assessment of its feasibility on field sites can be accomplished by conducting a series of cross-hole packer tests consisting of an injecting well and a monitoring well at close distance.

• The Journal of Engineering Geology
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• v.16 no.1 s.47
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• pp.15-21
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• 2006

Sandy soils obtained from the field were examined by the way of particle analyses. The hydraulic conductivity values of the disturbed soil samples were measured by the falling head method. Then the correlations between the hydraulic conductivity and particle distribution were defined. The soil which was a product of the weathering of the granitic rocks belonged to sand and loamy sand area in a sand-silt-clay triangular diagram. The measurements of hydraulic conductivity were $1.15X10^{-5}\sim7.31X10^{-4}cm/sec$ which is the range of sand and silt. It was clearly observed that the hydraulic conductivity measurements of the sandy soils showed stronger correlations with the particle variances rather than the mean grain sizes. The larger the variances, the smaller the hydraulic conductivity measurements. The sandy soil which was a product of weathered granite and whose mean grain size was $0.38\sim1.97mm$ showed regression curves of $y=6.0E-5x^{-1.4}$ in a correlations between hydraulic conductivity and particle variances. Accordingly, it is clearly concluded that making estimates with-out any consideration about particle variances can produce serious errors.

• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.239-245
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• 2009

To verify the reinforcing effect of grouting materials composed of colloid cement and ordinary portland cement on the water leakage region in a small scale dike, we performed a tubecasing method and applied surface electrical resistivity survey including electrical resistivity tomography (ERT) to find resistivity variation before and after grouting. Hydraulic conductivities after grouting show 10 times lower than those of before grouting. These variation indicates that the cement grout blocks the leakage pathway effectively. As the results of dipole-dipole resistivity survey along the dike, resistivity distribution after grouting did not represent noticeable spatial variation in time. Resistivity monitoring results at the dike with vertical electrical sounding (VES) showed that the region of decreasing apparent resistivity was occupied by the grout after grouting. Predicted resistivities from the inversion of ERT data well matched with results of VES at the same regions. From the ERT using check holes to inspect the effect of grouting, we could find that the ERT is quite effective to identify spatially the grout region in a dike.