• The Journal of Engineering Geology
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• 제12권1호
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• pp.23-34
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• 2002

Borehole image analysis has been carried out to obtain the detailed geological data by approach of direct observation. Direct application of borehole image analysis inevitably gives rise to a few of restriction of data acquisition due to the limited information within narrow borehole space. Considering the apparent dip of discontinuity surface depending upon the direction, the visualized program of two-dimensional subsurface discontinuities is coded. Borehole image analysis can compensate the distribution of subsurface discontinuity extending into the expected area of investigation. In order to draw subsurface profile in the proposed area of subsurface construction, visualized program is coded as a window GUI (Graphic User Interface) using Fortran and Visual Basic Programming languages. It is to open publicly for the usage of whoever is in want. Discontinuity distribution map is visualized along the Proposed line of tunnel in the Janggye-ri area, Jangsu-gun. Using the visualized program, the limited information from borehole spatially applies into analysis of overall subsurface structures, and the distributional characteristics of discontinuity anticipate at the proposed area. In addition, spacing and extension of joint and depth of discontinuity effecting tunnel safety can be visualized along the direction of the proposed tunnel. These lines of visualization apply design and construction of fundanmental structures.

• The Journal of Engineering Geology
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• 제22권1호
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• pp.1-13
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• 2012

The purpose of this work is to gain a better understanding of the interrelationships between geological structures and slope failure in sedimentary rocks. In the studied slopes, construction-related slope failure could only be observed on the south-dipping slopes. This indicates that slope stability may be dependent on the angular relationships between the dip direction of bedding and the orientation of the slope. Slope failure continued, post-construction, around large fault zones in the studied outcrop; these fault damage zones are, however, not easily recognized in the field. Here we suggest a new method that uses accumulated fracture density to precisely identify fault damage zones. Multiple-faced slopes are now increasingly being exposed during large-scale construction projects in South Korea. This multiple-faced slope analysis indicates that the stability of a slope should be evaluated by identifying domains, through the analysis of possible slopes and their angular relationships with bedding and other discontinuities, prior to construction. Therefore, careful consideration of geological structures such as bedding and other discontinuities, and their angular relationships during the design of cuttings through sedimentary rocks, will increase the efficiency of construction and enable the safe construction of more stable slopes that will retain their stability after construction.

• The Journal of Engineering Geology
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• 제12권4호
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• pp.405-419
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• 2002

Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

• Journal of the Korean Geographical Society
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• 제47권6호
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• pp.809-824
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• 2012

Stone cultural heritages quantitatively as well as qualitatively occupy a large proportion in the designated heritages in Korea. The Stone Buddha statue in the Gulbulsa temple site, designated as the No. 121 treasure in 1935, is located in the southwestern slope of Mt. Sogeumgang, Dongcheon-dong, Gyeongju-si, Gyeongbuk Province and Buddhist images are sculptured on four sides of a 3.5m-tall gigantic rock. The damage states result from the weathering degree and indicate high correlation with the water contents. The water contents in the Stone Buddha of Gulbulsa temple site are highest at the east side and then decrease in order of north, south and west sides. These are proportional to the durations of sunshine. Moreover, the Stone Buddha of Gulbulsa temple site with dense joints, repaired areas and vegetated areas by lichens shows high water contents and damage states.

• The Journal of the Petrological Society of Korea
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• 제24권2호
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• pp.91-105
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• 2015

Jungtaesan and Galpyeongji intrusions in the northeastern Cheongsong occur as laccolith and stock which intrude Gasongdong Formation and Dogyedong Formation, respectively. Cheongsong dike swarm, intruding the Dogyedong Formation, is closely associated with this stock. The dike swarm is more radial to focus into Galpyeongji and its outline is oval. The dikes of the dike swarm are only rhyolite dikes with flow banded, spherulitic and rare stony structures, and represents a single intrusive phase of magma. It can be interpretated that orientation of the dikes is controlled by stress states. Therefore, the dikes display a radial pattern through occupying vertical joints that have been generally attributed to radial fractures formed during doming of the sedimentary rocks by the intrusion of the Galpyeongji stock. The dike pattern could sufficiently account for dike injections into these joints.

• The Journal of the Petrological Society of Korea
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• 제1권1호
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• pp.34-41
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• 1992

The Precambrian granitic gneisses are widely distributed in the Danyang-Yecheon area, eastern part of Korea, where the Ryeongnam massif borders the Ogcheon fold belt. They are composed of migmatitic, biotite granitic, garnet-bearing and granoblastic granitic gneisses. The common joint sets of the granitic gneiss are NE and NS directions, which are probably related to the effects of Daebo orogeny and Bulgugsa disturbance, respectively. Mineral assemblages of the banded gneiss xenolith in the garnet-bearing granitic gneiss are quartz-plagioc1ase-biotite-mus-covite-orthoclase and quartz-plagioc1ase-biotite-garnet, belonging to the amphibolite facies. The granoblastic granitic gneiss is felsic, metaluminous, and granitic, and shows subalkaline trend. The garnet-biotite geothermometry of garnet-bearing granitic gneiss yields 640$^{\circ}$-708$^{\circ}C$ at pressure of 4 kb.

• The Journal of Engineering Geology
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• 제7권2호
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• pp.151-159
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• 1997

Since healed microcracks in quartz grain of grantic rocks within the same mass have identical preferred orientations, the oreintations of granitic cores may be determined if the distinctive feature of healed microcracks can be used.In this study, the possibility of determining orientations of granitic cores using healed microcrack orientations were examined using samples from the borehole drilled to 200 m in depth at the Hongcheon. Eight sections whose core recoveries are 100% were selected. Two to six samples were collected in each section and orientations of healed microcracks in each sample were measured. Healed microcracks in samples from each section show almost identical orientations. The error range for sections with only one preferred orientations is within $\pm$5$^{\circ}$, indicating that correct orientations of core can be determined. However, orientations of cores in sections which have 2 or more healed microcrack orientations should be determined using orientations as well as distribution of peaks of orientations. The error range for this case is lager than former one and is within $\pm$15$^{\circ}$. The orientations of joint which is very impontant factor for designing tunnel and slope stability can be determined using healed microcrack orientation in cores.

• The Journal of the Petrological Society of Korea
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• 제3권2호
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• pp.138-155
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• 1994

Granitic gneiss containing biotite banded gneiss relict around the Daeheung talc deposit are widely distributed which were formed by regional metamorphism of both epidote-amphibolite and iater greenschist facies and granitization. They were derived from same silico-aluminous rocks of sedimentary origin. The mineral assemblages, which are common in the biotite banded gneiss, formed during regional metamorphisms, are survived in the granitic gneiss. The mineral assemblages of the latter greenschist facies may be formed retrogressively from the first epidote-amphibolite facies. The chemical compositions of biotite, muscovite, and chlorite, the important constituents of the gneisses, were controlled by the bulk composition, the chemical composition of the original mineral, and environment of the regional metamorphisms and granitization. The chemical equilibrium between coexisting'minerals, especially biotite and muscovite, is relatively well established, which was controlled mainly by tschermakitic and phengitic substitutions. Cholrite was formed mainly from either biotite or muscovite by retrogressive alteration or granitization, and have nearly similar chemical compositions regardless of the occurrences. The orientation trend of the foliation, joint and quartz vein developed in the gneisses was analyzed by equal area projection which the latter two show nearly identical trend in the strike and dip. This may suggest that the hydrothermal solution was introduced along joint during wet granitization.

• Journal of the Korean GEO-environmental Society
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• 제7권2호
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• pp.67-76
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• 2006

For a hydro power plant project, the headrace tunnel having a finished diameter of 3.3 m was constructed in volcanic rocks with well-developed vertical joint and high groundwater table. The intake facility was located 20.3km upstream of the powerhouse and headrace tunnel of 20km in length and penstock of 440m in height connected the intake and the powerhouse. The typical caldera lake, Lake Toba set the geology at the site the caving of the ground caused tension cracks in the vertical direction to be developed and initial stresses at the ground to be released. High groundwater table(the maximum head of 20bar) in the area of well-connected vertical joints delayed the progress of tunnel excavation severely due to the excessive inflow of groundwater. The excavation of tunnel was made using open-shield type TBM and mucking cars on the rail. High volume of water inflowraised the water level inside tunnel to 70cm, 17% of tunnel diameter (3.9m) and hindered the mucking of spoil under water. To improve the productivity, several adjustments such as modification of TBM and mucking cars and increase in the number of submersible pumps were made forthe excavation of severe water inflow zone. Since the ground condition encountered during excavation turned out to be much worse, it was decided to adopt PC segment lining instead of RC lining. Besides, depending on the conditions of the water inflow, rock mass condition and internal water pressure, one of the invert PC segment lining with in-situ RC lining, RC lining and steel lining was applied to meet the site specific condition. With the adoption of PC segment lining, modification of TBM and other improvement, the excavation of the tunnel under severe groundwater condition was successfully completed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.67-70
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• 2001

터널 굴착에 따른 연구지역내 지하수체의 거동 특성을 파악하기 위하여 터널 굴착시 그라우팅 이전의 초기 유출량과 초기 그라우팅 이후의 구간별 유출량을 측정하였고 단열구조와 비교, 분석하였다. 초기 유출량은 120,990 m$^3$/day이며, 초기 유출이 심했던 구간은 크게 6개 구간으로 세분할 수 있다. 초기 그라우팅 후 지하수 유출이 심했던 구간 역시, 그라우팅 이전과 마찬가지로 6개 구간으로 세분할 수 있다. 그라우팅 전, 후의 유출량을 비교해 보면 그라우팅후의 유출량은 42,844m$^3$/day으로, 그라우팅 전에 비해 많이 감소되었다. 터널 굴착시 터널내로 유출되는 지하수의 대부분은 터널과 직교 혹은 사교하여 관통하고 있는 단층 및 단층 파쇄대와 연장성이 양호한 절리면들을 따라서 유동되고 있다. 터널내의 지하수 유출에 영향을 미치는 단열들은 대체로 4조의 불연속면군으로 분류 할 수 있는데, 주 분포방향은 크게 TSet 1 : N60-85$^{\circ}$W, TSet 3 : N40-50$^{\circ}$E, TSet 3 : N10-20$^{\circ}$E, TSet 4 : N70-80$^{\circ}$E이다.