• Economic and Environmental Geology
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• v.26 no.1
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• pp.29-40
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• 1993

Several vermiculite deposits occur as the alteration product from phlogopite in ultramafic rock, in the Hongseong and Cheongyang area, South Korea. Some quarries show well-defined weathering profile. Samples collected from those quarries were examined by XRD and chemistry to define a vertical variations in mineralogy and chemistry of the weathering profile developed on ultramafic rocks. The analysis by X-ray diffractometry showed that mineral compositions changed continuously as depth of profile increasing, the vermiculite-the phlogopite/vermiculite interstratified-the phlogopite. Chemical analysis of bulk samples in altered zone revealed that regardless of composition and kinds of mineral in the rock, there are significant increase of MgO, CaO and $H_2O$, and decrease of K as depth of profile decrease reflecting the characteristics in vermiculitization. Also, there was a tendency that weathering indicies of each sample horizon change gradually with increasing depth. This tendency can be explained as variations of degree of vermiculitization. The regular changes of mineralogical and chemical composition in vertical profile suggest that weathering is the most important process in vermiculitization in this area.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.206-217
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• 2001

The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows ; 1) The relationships among Nc, Li and CEC, Li>6%, CEC>14 corresponds to Nc=2~30, and 4%${\phi}$)increases at a standard pressure. 3) And Nc=0~50 corresponds to $27{\sim}50^{\circ}$ of internal fiction angle and to 12~49kPa of cohesion. That is to say, internal friction angle(${\phi}$)corresponds better than cohesion(c). In conclusion, this study suggests that in simplified dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a completely weathering soil. It also appears that CEC increases as Li increases while Nc decreases.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.87-92
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• 2002

Engineering geological studies were conducted for igneous rocks in southeast Korean peninsula. The purpose of the study is to establish zoning in view of engineering geology in ground construction. For engineering geological implication, lithology, lineament structure and discontinuities were surveyed and analysed. Using constructed data, We compared geological and engineering geological characteristics and made out the detailed engineering geological map. The map responses engineering characteristics such as weathering degrees, discontinuity systems of different rock types.

• Explosives and Blasting
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• v.23 no.1
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• pp.9-17
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• 2005

This study is to clarify the comparative relationship and mechanical anisotropy of granite distributed in the Nam-weon on the subject of weathered rock mass sea water surroundings. Artificial weathering test is defined as a test, which controls the weathering rate and agents by controlling the weathering rate and agents by artificial environmental of salt water. Increased weathering degree is large indicated by weathering salt water, such as apparent specific gravity, absorption, porosity, uniaxial compression strength, P-wave velocity, slake durability, shore hardness, indirect tensile strength(brazilian test) and cohesion were measured. As the Weathering salt water proceeds, cracks develope increasingly. A number the cracks affect the rock deformation. Therefore, stress-strain curve of weathered salt water rock in one confined state are quite differ from weathered fresh water rock those. A reason of their deformation type is the formation of micro-cracks and potential porosity caused by artificial weathering test.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.460-470
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• 2011

Wave velocity was measured to define the weathering characteristics of rock and the strength evaluation of weathered rock on a target of the Aso gravestones with various sizes under the natural environment. As a result, the size correction method which was changed sample of the different size to one of the same size for evaluating wave velocity was proposed, and also suggested the NET (Normalized Elapsed Time) as a new weathering index of rock. In addition, the strength of the weathered rock was estimated from the weathering classification of rock using the NET. Wave velocity of welded tuff was high and didn't show velocity degradation, on the other hand, one of andesite was low and showed velocity degradation. The degree of weathering between rocks of the different size is considered to be comparable, applying the NET based on the on the $V_p/V_o$-NET curve. Furthermore, the classification of rock weathering stages using the NET based on the $S_c/S_o$-NET curve was available, and the estimation of strength for the weathered rock was also possible.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.765-776
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• 2005

As a result of industrial advancement and land development, a number of highway slopes have been gradually formed and numerous problems related to their stability have been frequently caused. Generally, major factors for rock slope stability are lithology, slope inclination, slope height, degree of weathering, precipitation, condition of groundwater and so onl. Many complex factors are mostly involved in the collapse of rock slopes. In this study, a database for 94 collapsed Jungang highway slopes were set up using GIS program through literature search, site investigation, geological map and Korea tectonic province map. The analyses for the collapsed factor including sort of rock(by origin), tectonic province, highway direction, slope gradient and direction, degree of weathering, slope height were carried.

• Geotechnical Engineering
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• v.13 no.6
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• pp.71-94
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• 1997

It is important to evaluate rock strength in order to check stability of a rock slope or to design a structure built on rock. However, test methods used for the evaluation have some difficulties since rock samples provide various deviation of strength due to micro cracks in the samples and teat errors, Also, reliable data have not been accumulated for the rock strength in Korea. Therefore, simple teat methods that can be used easily for investication of rock strength in field or in laboratory are not provided sufficiently yet. This study is to investigate variation of the rock strength due to the degree of weathering and to evaluate the degree of weathering by types of rocks, by using data that have been obtained for several years. Therefore, it is possible to provide a relationship between several rock strength values by performing tests such as uniaxial compression teat, point load test, schmidt hammer teat, absorption ratio best and slaking durability tests. The equations of relationships that can be used to estimate rock strength by using simple test methods in field and in laboratory are proposed.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.181-194
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• 1999

Both the chemical components and the physical and mechanical properties of the compacted and undisturbed weathered granite soils were estimated to investigate the influences of the degree of weathering and saturation on the shear strength. The weathered granite soils used in this study were taken from six different sites in Korea. The results showed that the shear strength of weathered granite soil decreased with increasing the degree of weathering and saturation. Under the normal stresses less that 40kPa, the shape of Mohr-Coulomb failure envelope followed curved or hyperbolic relationship and a half of cohesion value obtained by the common shear test was observed. Using the Sueoka's method, the values of CWI were ranged from 21.5 to 31.26 which can be characterized as a completely weathered granite soil. Large decrease in shear strength and remarkable variation in dilatancy were observed in saturated granite soil compared to unsaturated soil. It was also found that the shear strength of undisturbed weathered granite soil of Pungam site can be expressed approximately by the equation of ${(\tau)_{sat}= 1.0(\tau)_{unsat}-12.48}$ and this equation can be extended to the other sites considered in this study.

• Journal of Conservation Science
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• v.4 no.1 s.4
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• pp.11-42
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• 1995

Stone-monuments, distributed in this area, have been investigated and studied on the characteristics and the rock phases in the geological and conservational points of view. Most of them may have been built from the end of the Shilla Kingdom to the Koryeo Kingdom, which are based on the typical characteristics of the form. The used rocks in these monuments are mainly biotite granite of the Jurassic age which is widely distributed around the area. Black slate and marbles are also used in some monuments, which may be obtained from other areas. The biotite granite of massive and coarse texture contains often inclusions of biotite aggregates or fragments of dioritic rock phase. However, the biotite granite in the area may be very weak to the chemical weathering so that irregular rock surface shows generally $2\~3mm$ relief. The irregular relief is mainly due to different relative degree on the chemical weathering according to the kind of minerals especially quartz, feldspar and biotite. The chemical weathering is also influenced by organisms. For conservation, they must be scientifically considered based on the characteristics, kind of the rock phase, factors on the weathering process, situation in situ or being transported, and protection.

• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.185-195
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• 1998

Two piston cores (94PC-2 and 95PC-4) taken from the East Sea (Sea of Japan) are studied to evaluate the paleoceanographic changes and its interaction with climatic variation. The bulk geochemistry of the non-biogenic fractions of 54 sediment samples is determined using X-ray fluorescence. Four geochemical stratigraphic units at both core sediments are recognized based on the variations in major element concentration. These chemical stratigraphic units correspond well with the sedimentological and paleontological facies. Source materials are considered as basic and/or intermediate rocks judging from silica content. A distinctive boundary around 11 kyr may correspond to Younger Dryas event. The switch of most major elements at this level and the distinctive changes in concentration of typical terrigenous elements (TiO$_2$ and Al$_2$O$_3$) are the strong evidence for the difference in sources of terrigenous materials. The weathering indices exhibit high degree in Core 94PC-2 and low degree in Core 95PC-4. The changes in weathering degree can be distinguished by the lowest value occurred at 11 kyr in Core 94PC-2 and by a gradual decrease from top to bottom in Core 95PC-4. The profiles of potassium and sodium exhibit specific excursions between the Holocene and the late Pleistocene. This implies that sediments of the two cores originating from different sources with different weathering degrees. The distinct two-group distributions in K$_2$O/CaO vs. Na$_2$O/K$_2$O also support the difference in provenance of aluminosilicate materials at the boundary of 11 kyr. Thus, supply patterns of terrigenous materials are stable in Holocene and more complicated in the last glacial period.