• Geotechnical Engineering
• /
• v.12 no.6
• /
• pp.139-152
• /
• 1996

In order to treat flow problems for unsaturated soils, it is necessary to obtain the soil-water characteristic curves which show nonlinear relationship between metric suction and volumetric water content. With two different pleasuring devices, measurements of the matric suction were taken for Jumoonjin sand, Hangang sand, and weathered granite soils with different fined. Experimental parameters which can describe experimental formulas for the soil-water characteristics were determined by using the data obtained from the experiment. Among experimental formulas of previous researchers, that of van Genuchten(1980) agreed well with the results of experiments. For weathered granite soils, the parameters increased with the increase of fine contents, Therefore, the soil-water characteristic for a weathered soil can be estimated by using Parameters corresponding to its fine contents.

• Tunnel and Underground Space
• /
• v.7 no.2
• /
• pp.91-99
• /
• 1997

To stabilize the energy price, the more storage facilities of energy are required and among the storage methods of LPG and LNG, the method of storage at low temperature under normal confining pressure is considered. It is needed to understand the mechanical and thermal characteristics of rock under temperature variation so that the behaviors of rock can be predicted. In this paper, the variation of the rock charateristics of the Hwangdeung granite and the Boryung sandstone is studied at low temperature. The mechanical characteristics of rock under low temperatures are that as temperature decreased, unaxial compression strength and Young's modulus increased for Hwangdeung granite; strength and Young's modulus in wet condition were greater than those in dry condition. In the case of Boryung sandstone, as temperature decreases unaxial compression strength and Young's modulus increase but decrease below -10$0^{\circ}C$ in dry condition and below -16$0^{\circ}C$ in wet condtion. The mechanical characteristics of rock after cooling to previous temperature and thawing are that uniaxial compression strength and Young's modulus decrease as temperature decreases. Uniaxial compression strength and Young's modulus in wet conditon decrease more than those in dry condition. Brazilian tension strength decreases as temperature decreases.

• Tunnel and Underground Space
• /
• v.5 no.4
• /
• pp.336-346
• /
• 1995

Geotechnical Information System (GTIS) for efficient management of three dimensional borehole data has been developed. Some problems were raised during the input process of borehole data, and alternative solutions were sought. According to the previous geotechnical reports, there is no unified weathering classification scheme. A criterion, 100 times/30cm from SPT, was turned out inappropriate to the discrimination of weathered rock from weathered soil. It has also been suggested that weathered soil, weathered rock, soft rock, and hard rock should be defined as CW, HW, MW, and SW~fresh condition. For better comparison of RQD, the use of NX size coring is recommended for the whole area although BX size coring has been used in excavated area. The limit of drilling depth up to 1 m from the top of surface of hard rock should be extended to avoid possible wrong interpretation of rock head due to the existence of corestone. The input data were analysed by geostatistical methods. It is found that the range in semivariogram is about 300m, and the variance of gneiss is greater than that of granite. It is because the granite data analysed came from almost single uniform rock mass(i.e.Seoul granite), but gneiss data came from the rock mass(i.e. Gyeonggi gneiss complex experienced several metamorphic metamorphic processes.

• Economic and Environmental Geology
• /
• v.28 no.2
• /
• pp.139-145
• /
• 1995

Tungsten skarn mineralization of the Sangdong mine is localized in the interbedded limestone layers of the Myobong Slate Formation and in the limestone of the Pungchon Limestone Formation of Cambrian age. Fluid inclusion, gas composition and Nd-Sr isotope for granites and skarns have been investigated. Gas compositions show $CO_2$ rich in the Sangdong granite and CH, rich in the Nonggeori and Eopyeong granites. The initial $^{87}Sr/^{86}Sr$ and $^{143}Nd/^{144}Nd$ ratios of the Sangdong granites have 0.714~0.716(${\varepsilon}_{Sr}$=138~162) and 0.51173~0.51178(${\varepsilon}_{Nd}$=-14.4~15.5), respectively. And their two stage model ages range from 1687 to 1764 Ma. The granite characterized by high strontium initial ratios and negative eNd value could have originated from the old continental crust source. Low homogenization temperature of the Sangdong granite having $203{\sim}296^{\circ}C$ with 1.9~9.2 NaCl equiv. wt% indicates the post-magmatic hydrothermal alteration temperature. Skarn ore fluid responsible for tungsten mineralization has been evolved from CH, rich fluid of early pyroxene garnet skarn to $CO_2$ rich later quartz-mica skarn.

• Journal of Conservation Science
• /
• v.36 no.1
• /
• pp.60-72
• /
• 2020

The Inscribed stones of Hanyangdoseong has been weathered for a long time because of external environment and living organisms. To establish a long-term conservation-management strategy for the inscription stones, the material characteristics of the inscription stones of Naksan Mountain Area were identified, and its deterioration state was diagnosed. Consequently, it was confirmed that the Inscription stones of Naksan Mountain Area mainly comprised coarse-to medium-grained pinkish granite and biotite granite, and, in part, comprised reddish granite, quartz porphyry, and aplite. Presently, the Inscription stones of Naksan Mountain Area, Hanyangdoseong, is undergoing a considerable decrease in physical properties because of physical, chemical, and biological weathering. Moreover, it has been confirmed that the type of damage, such as blistering, soiling, and dicolouration, on the surface shows a significantly high deterioration rate, and that conservation treatment might be required in future. In addition, because the possibility of damage recurrence is high even after the treatment, the conservation state must be regularly monitored.

• Journal of Conservation Science
• /
• v.2 no.2 s.2
• /
• pp.31-62
• /
• 1993

Stone -monuments, distributed in this area, have been investigated and studied in geological and conservational points of view. They are seemed to have been mainly built from the Shilla to Koryeo Kingdom, although more systematic studies are needed. The used rocks in these monuments are mainly biotite granite and hornblende-biotite granite of Jurassic age. The rock phases are nearly identical to those which are distributed in the area. The two rock phases are nearly same in the characteristics of minevalogy and texture except the amount of hornblende. However, hornblende-biotite granite characteristically contains aggregates of mafic minerals which are frequently observable in the monuments. They are mainly influenced by chemical weathering due to warm, abundant rainfall, and salty moisture because of being adjacent to the sea. Some cracks are secondarily developed which may be due to strong chemical weathering and influence of sculpturing. For conservation, it must be scientifically considered based on characteristics and kind of rock phase, factors on weathering process, situation and protection.

• Geotechnical Engineering
• /
• v.9 no.3
• /
• pp.5-22
• /
• 1993

A series of laboratory tests (physical and mechanical index and engineering design) were conducted on undisturbed granite soils of CW and RS weathering grades in Korea. From these testes it can be concluded that most of physical and mechanical index values are very sensitive to change in weathering grade from CW to RS. Engineering design tests indicate that the unconfined compressive strength and the shear strength parameters are significantly reduced and that the soil becomes ductile and plastic with increasing weathering and saturation. It was found that weathered granite soils have the special characteristics when water saturated: (i) they significantly lose their shear strength(especially cohesion) and unconfined compressive strength, (ii) they are fragile and their grains break down in water as observed in grain size analysis.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.501-503
• /
• 2003

Soil-gas radon level and other atmospheric factors have been measured at residual soil profiles that overlie granite bedrock which consists of major geology in Korea for 6 months from November, 2000 to April, 2001. Seasonal variations of soil-gas radon concentration are generally of greater magnitude than day-to-day fluctuations. The highest radon concentrations of 5,131 pCi/L measured during winter season and the lowest radon concentrations of 107 pCi/L during spring season. Two study areas, Bongcheon-dong(granite bedrock) and Seongnam-Yongin(gneiss bedrock) were investigated to assess the radon potential according to their field survey and emanation tests. The mean values of radon decrease in sequentially from Suji-A(813 pCi/L)>Suji-B(757 pCi/L)>Bundang-B(691 pCi/L)>Bundang-A(643 pCi/L)>Bongcheon-dong(513 pCi/L). Estimated soil-gas radon potential using maximum radon emanation ratios of each study area decreases in the order of Bongcheondong(950 pCi/L)>Suji-B(524 pCi/L)>Bundang-A(437 pCi/)>Bundang-B(259 pCi/L)>Suji-A(230 pCi/L) areas. The values of indoor radon and its daughter product concentrations in Bongcheon-dong area show that indoor basement rooms in poor ventilation condition could be classified as extremely high radon risk location of more than 4 pCi/L Rn and 0.02 WL.

• Economic and Environmental Geology
• /
• v.1 no.1
• /
• pp.9-34
• /
• 1968

Manganese ore deposits of the Samhan Changgun Properties are located at the valley of west-lope-side of Changgun-bong (1132m) occupied over the Myon border between Sochon-myon and Jaesan-myon Pongwha-gun, Kyongsang-Pukdo. Geology of the more property and it's vicinity consists of Wonnan formation and Yulri formation of pre-Cambrain and Changgun limestone formation, Mica-schist formation, quartizite formation and Jaesan formation (containing coal bearing zone the unknown age. And granites and dykes were intruded into the above formation later. 1. Management deposits is embedded the formation of Janggun limestone especially Contact zone in the contact zone to of Chunyang Granite limestone enclosed by Granite, and Maginal zone of fault line in the limestone. Therefore, Chunyang Granite is Closely related to ore deposit. Pegmatite which is near by ore deposit was intruded before mineralization and it seems to be a channelway of ore solution. The most important ore deposits of property grouped into south deposit, east deposit, east-Gachon deposit, South-Gachon deposit, Durimgok deposit and West deposit, out-crops at several place. Besides these deposits there also are several prospects on outcrop scathered. Hydrothermal alteration take place strongly in the well rock and it's sequence are Characterized as following; 1) Dolomitization 2) Carbonization 3) Mamgamotozation 4) Pyritization 5) Silicification 6) Oxidation 2. The grade of manganese dioxide is up to Mn 45% in Maximum, but generally, averaging Mn 30~35% of high grade ore and averaging Mn 30~32% of manganese carbonates are mined in his property.

• Tunnel and Underground Space
• /
• v.10 no.3
• /
• pp.309-315
• /
• 2000

For proper sampling of a rock and preparation of specimens, the representative elementary volume (REV) should be determined in rock mechanical test and numerical analysis. Mechanical properties of a rock, in general, would be strongly affected by mineral composition. In this reason REV of Youngju granite is determined by using stereoscopic microscope observation and homogenization numerical analysis. As the area of analysis model exceeds approximately 702$\textrm{mm}^2$(900 elements), the change of the mineral composition is not observed. The calculated results indicate that Young's modulus is fluctuated with increase of the number of elements in homogenization numerical analysis mesh. However, as the number of elements exceeds 1156 (area of about 900$\textrm{mm}^2$), Young's modulus does not change apparently.