• Economic and Environmental Geology
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• v.9 no.1
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• pp.13-26
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• 1976

The basic rocks distributed in the Okchon paleogeosynclinal zone have been previously considered as intrusive in majority, but as sedimentary parensis in few variety. The present study is to find out some clues to conclude otherwise, if any, by clarifying 1) the nature and characteristics of the rocks, 2) type of the associated sedimentary rocks if any, and 3) their occurrence in related to regional geologic structure. The finding are as follows: 1) The basic rocks are identified and classified to hornblende gabbro, amphibolite, basalt and andesite (in part metamorphosed to meta-volcanics), green schist and peridotite(which appears in separate locality from the others). 2) Associated sedimentary rocks which appear to overlie the basic rocks are known as Kunjasan and Baekwhasan formations. The two formations are probably same, but been used differently by different authers at different localities. The rocks is exclusively consisted of cherty looking siliceous quartzite and some localitis it shows very calcarious nature. The formation seems to indicate a sort of pelagic siliceous sediments although it contain some pebbles. 3) The basic rock suites are always underlain by the same continuous, great thrust, which separates the Okchon paleogeosyncline zone from the neogeosynclinal zone in the area studied. The comparison of Okchon basic rocks suite to the ophiolite suites in other parts of the world indicates some similarity with which the writers suggested the probalility of Okchon basic rocks being ophiolites that occur along ancient geosuture line now represented by the great thrust.

• Explosives and Blasting
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• v.22 no.2
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• pp.13-20
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• 2004

도심지 굴착과 같은 환경적 제약과 사회적 문제가 존재하는 현장에 대하여. 암반제거작업에 있어서 가장 경제적이고 효율적인 발파공법을 적용하기 위해서, 본 연구는 기존의 발파방진기술인 Line Drilling과 Presplitting의 상점을 살리면서, 단점을 보안한 새로운 발파방진 기술인 NPS(New Presplitting)발파법의 효과에 대하여 연구하였다. NPS 발파법의 분석은 안산암과 화강암, 화강편마암의 3종류의 암반을 대상으로 NPS 발파법의 열수를 1열, 2열, 3열, 4열을 적용하여 발파로 인한 진동을 NPS 발파법의 적용전과 후의 발파진동값을 기준으로 NPS 발파법의 전, 후 진동감쇠 효과를 비교하고, 동일 조건을 가정한 경제성을 살펴보았다. 그 결과 NPS 발파법의 3가지 암석에 대한 현장적용 결과 암종에 따른 NPS 발파공법의 진동감쇠효과의 변화보다, NPS 발파법의 적용 pattern에 대한 진동감쇠효과의 변화가 크게 나타났으며 NPS 발파공열이 2열일 때 감쇠범위는 40％∼80％로 가장 효율적으로 나타났으며 3열과 4열의 경우에도 진동감쇠효과는 있으나 그 효율이 크게 향상되지 않을 뿐 아니라 2열에 비하여 경제적으로 불리함을 알 수 있었다. 또한 NPS 발파법은 보안물과의 거리가 가까울수록 더 경제성이 큰 것으로 분석되었다.

• Tunnel and Underground Space
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• v.13 no.2
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• pp.108-116
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• 2003

Measured convergence data of a tunnel were investigated by means of statistical and regression analysis, where the rock mass were mainly composed of andesite and granite. The rock mass around tunnel were classified by RMR method into five different ratings, and then convergence data which belong to individual ratings were statistically processed to find out the appropriate regression equations. Exponential equations were better coincided with measured data than logarithmic equations. As the number of rock mass rating was increased, the magnitude and standard deviation of convergence were increased. Final convergence data were also investigated to study the relevance with both maximum displacement rate and early measured convergence. Some brief results of their relevance are presented. For instance, the regression coefficient between final convergence and maximum displacement rate was turned out to be 0.87 for this studied tunnel.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.1-11
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• 1999

In the last decade, the supply of natural aggregates has been continuously increased due to the other types of aggregates. In general, aggregates constitute 70-80% of the total volume of concrete, so the quality of aggregates is main factor controlling physical characteristics of concrete. For this reason, physical properties of aggregate according to different rock types were studied. The majority of crushed aggregates is taken out of granite, gneiss, sandstone, andesite, basalt and so forth. The physical properties of these rock types were tested and most of them fell within the acceptable limit on the base of Korean standard regulation. The major lithology of the crushed aggregates is granite and gneiss, both of which are marked for more than 50% of total lithology thpes in Korea. A to the physical properties of granite, the high specific gravity coincides with low porosity, low absorption ratio, while the abrasion and soundness index show, in general, no specific trend. It has been assumed that slight differences of the physical properties of granite aggregates are related with those of the mineral composition, grain size, and so on. In comparison to granite, the physical properties of gneiss have little correlation one after another. This trend is related to different mineral composition, grain size and typical sheet fractures typically prevailing in the texture of gneiss. Spatial pattern of physical properties shows that high specific gravity of granite coincides only with low porosity and absorption ratio in all provinces except Cheolla province, and high specific gravity of gneiss coincides with low porosity and absorption ratio only in Cheolla and Gandwon provinces.

• Economic and Environmental Geology
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• v.17 no.2
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• pp.91-100
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• 1984

The Gwangyang gold deposits geologically consist of granitic gneiss, metatectic gneiss and porphyroblastic gneiss which correspond to Jirisan gneiss complex. The formations of Gyeongsang system lies unconformably on these gneisses and are intruded by diorite, porphyritic andesite and Bulgugsa granites. Goheung districts are composed of quartz schist, andesitic rock, tuff and granite. The Gwangyang gold deposits are gold bearing fissure filling veins. The vein thickness varies from 15cm to 40cm and they consist of 7-10 layers in parallel. The Goheung copper deposits are sulphide bearing quartz veln which filled the fracture in andesitic rock and biotite granite. The contact zone of these rocks is partially altered. The mineral paragenesis of the Gwangyang and Goheung districts is pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, galena, sericite, quartz and calcite. The variation trends of FMA and A'KF triangular diagrams and the differentiation index (norm, Q + Or + Ab) versus oxides diagrams is similar to the Gyeonsang basin igneous rocks. From the trace element analysis of 10 samples of country rocks, wall rocks and veins, the distribution of copper and lead contents display a correlative distribution pattern in relation to gold and silver. Homogenization temperature of fluid inclusions range from $200^{\circ}C$ to $270^{\circ}C$ in quartz from the Gwangyang gold vein and the size of fluid inclusion range from 0.01mm to 0.04mm. The fluid inclusions are mainly one or two phase and the filling degree of the inclusions varies from 85 to 95.

• Journal of the Korean Geotechnical Society
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• v.28 no.11
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• pp.87-99
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• 2012

Targeting 9 types of rocks, which have high frequency of excavation, the researcher has analyzed decreasing behaviors of elastic modulus due to water content. The elastic modulus decreasing behaviors have been classified into 5 steps by uniaxial compressive strength. The results indicate that all of 5 sedimentary rocks and andesite show single decreasing behavior and granite, rhyolite, and gneiss demonstrate another decreasing behavior. Moreover, sensitivity of water content in granite, rhyolite, gneiss is almost twice as fast as that of the other rocks and their residual value of elastic modulus is very low.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.966-973
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• 2008

In recent, the collapses of cut-slope is gradually increased due to the heavy rains accompanied by typhoon. Specially, many cut-slope failures and landslides was happened to Goheung, Yeosu, Suncheon region, Jeonranamdo in the middle of September 2007. The slope of investigation is width 20 m, height 22 m, and the circular failure was occurred. The parent rocks of the slope are pyroclastic rock, namely andesite, andesitic tuff et al. and the weathering grade is completely weathered to residual soils owing to rapid weathering process and has the existence of fault zone and mafic dyke. Also, lots of extension cracks are presented and the hydrologic condition is very deteriorated. As a result of the limit equilibrium analysis, the safety factor is 1.09(in dry season) and 0.64(in wet season). For the stabilization of the cut-slope, we decided to use the retaining wall, anchors and drainage apparatus.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.233-241
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• 2020

Alkali-silica reaction (ASR) is among one of the most important damaging mechanisms in concrete, depending primarily on aggregates which contain reactive minerals. However, expansion in concrete may not directly relate to the reactive minerals. This study aims to investigate the influence of ASR and the expansion of mortar bars depending on aggregate type containing various components such as quartz, clay minerals (montmorillonite and kaolinite) and micas (muscovite and biotite). In this study, the accelerated mortar bar tests (AMBT) were performed in two conditions (mortar bars in the same and sole NaOH solutions). Petrographic thin section studies, X-ray diffraction (XRD) analysis (Rietveld method), scanning electron microscopy (SEM) and chemical analyses were carried out. This study showed that quartzite bars led to increase in expansion values of mortar bars in diabase-1 and andesite when these were in the same NaOH solution. However, three samples (basalt, quartzite and claystone) were found having ASR expansion based on the AMBT when the special molds were used for each sample. SEM study revealed that samples which exhibit highest expansions according to AMBT had a generally rough surface and acicular microstructures in or around the micro-cracks. Basalt and quartzite showed more variable in major oxides than those of other samples based on the chemical analyses, SEM studies and AMBT. This study revealed that the highest expansions were observed to source not only from reactive aggregates but also from alteration products (silicification, chloritization, sericitization and argillisation), phyllosilicates (muscovite, biotite and vermiculite) and clays (montmorillonite and kaolinite).

• Journal of the Korean GEO-environmental Society
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• v.7 no.2
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• pp.33-42
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• 2006

Eighteen biotite granites on Andong area and twenty seven igneous rocks(diorite, granite, andesite, rhyolite) on Yeosu area were tested to evaluate the correlations between the uniaxial compressive strength values, as determined by the standard uniaxial compression test, and the corresponding results of the ultrasonic velocity. The variability of test results for each test was evaluated by calculating the coefficient of determination or variation. Results indicate that strong correlations exist between the results of uniaxial compression vs the point load, Schmidt hammer and ultrasonic velocity test. The correlation equations for predicting compressive strength using different methods are presented along with their confidence limits. Ultrasonic velocity test used provide reliable estimates of compressive strength.

• Explosives and Blasting
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• v.24 no.2
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• pp.65-73
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• 2006

Blast vibrations produced by emulsion explosives, controlled explosives and no vibration Kinecker through test blasting have been analyzed. Test area is mainly composed of andesite of which uniaxial compressive strength is $1,260kg/cm^2$. The empirical scaling formula from a logarithmic plot of peak particle velocity versus scaled distance have been determined and particle velocities with scaled distance have been evaluated for each explosive type. Vibration level of no vibracon KINECKER is lower than one of the controlled vibration blasting by about 30.71% and also lowers than one of the blasting of medium by about 50.94%.