• Journal of Conservation Science
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• v.28 no.4
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• pp.329-341
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• 2012

Magai Wareiishi Jizo (Buddhist statue carved on rock surface) is close to shoreline and a part of rock block is periodically immersed by seawater. Rock material of the Wareiishi-jizo statue is composed mainly of medium or coarse-grained biotite granite and very durable. However, physical properties of the rock have been changed according to the complex interactions of the salt solution and surrounding environment. Exfoliation of the rock surface is a serious condition by salt crystallization. Exfoliation (14.6%) is concentrated on the upper part of the rock block with mainly boundary of seawater as the center. On the other hand, lower part of the rock block show black layers by contaminants deposition. In addition, brown discoloration and biological contaminants is overlapped. Rock surface show high discoloration rate of 50.5% (black discoloration, 29.2% > yellow discoloration, 14.1% > brown discoloration, 4.4% > green discoloration, 2.9%). Upper part of the rock block had a lot of change in the physical properties than lower part that is immersed by seawater. In particular, surface properties of the rock block was very weak state at the boundary surface of seawater permeation.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.227-236
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• 2003

The evaluation of the reliable strength and deformation characteristics of weathered granite masses is very important for the design of geotechnical structure under working stress conditions. Various types of laboratory test such as triaxial compression test can be performed to determine the strength parameters. However, it is very difficult to obtain the representative undisturbed samples on the site and also the rock specimen cannot represent rock mass including discontinuities, fracture zone, etc. This study aims to investigate the strength and deformation characteristics of granite masses corresponding to its weathering and develop a practical strength parameter evaluation method using the results of PMT. To predict weathering intensity and strength parameters of the weathered granite masess in the field, various laboratory tests and in-situ tests including field triaxial test and PMT are carried out. Based on the results of weathering index tests, the classification method is proposed to identify the weathering degree in three groups for the weathered granite masses. Using the analytical method based on the Mohr-Coulomb failure criteria and the cavity expansion theory, the strength parameters of rock masses were evaluated from the results of PMT. It shows that weathering intensity increases with decreasing the strength parameters exponentially. The strength parameters evaluated with the results of PM almost coincide with the results of field triaxial test.

• Proceedings of the KGS Conference
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• 2004.11a
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• pp.43-43
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• 2004

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.1-7
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• 2007

The property of weathered soil cannot but have a possibility of having a limit when its precise approaching due to the various weathering environment, and the peculiarity of its conduct affected by the weathering degree and effect factors. Especially most domestic or international researches are concentrated on the sedimentary soil, trying to analyze the mechanical behavior of weathered soil from the viewpoint of sedimentary soil. Therefore, it's difficult to judge if those results meet the actual conduct of weathered soil. This study suggested a way of weathering degree changing experiment as an early stage in an experiment of artificially changing weathering degree. In order to find out the property of strength change by the change of weathering degree, indoor mechanical experiment was made using soil sample after freezing and thawing. Under the weathering degree, characteristic change is watched by country rock and region of weathered granite soil.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.67-81
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• 1993

This dissertation is a basic research on the degradation of rocks and aims at clarifying the relations between the progression of degree of weathering and the variation of chemical composition. The author wants to make clear the degradation of rocks and the process of formation of sedimentary rocks from a standpoint of elucidation of migration of elements. This study is considered to be significant not only as a part of research on the distribution of earth crust materials but as the petrogenesis of rocks. The chemical studies on the weathered rocks have been started relatively early and there are not a few researches on them: Goldich, 1938; Harris, et al., 1966; Ruxton, 1968; Berner, et al., 1982; Kanuss, 1983; Lasaga, 1984; Siagel, 1984. The degree of migration of elements in weathering is the composite result of various factors. Because, at the present time, it is difficult to clarify the individual and composite effects of each factor theoretically and quanititatively, we must accumulate empirical data and use them relatively. In such consideration the author acquired some data of chemical weathering from the chemical analysis of granitic and basaltic rocks in and around Fukuoka city, Japan and granitic rocks in and around Chonju and Iri cities, Korea. Because both rock types studied can be considered as representative materials of acidic and basic rocks compsing the earth crust, it is significant to examine the phenomena of weathering of both rock types. The following results are obtained from the analysis and examinations of chemical compositions of the original and weathered rocks. The loss rate of major elements has no uniformity, but the following relation holds in general; Ca, Na> K, Si> Mg> Fe, Al. As weathering proceeds, the ratio of $Al_2O_3/CaO$ shows increasing phenomena, and that of $Na_2O/CaO$ decreasing. The range of migration of composition is broad in basaltic rocks but narrow in granitic rocks. The reason is that the chemical weathering of basaltic rocks progresses more easily than that of granitic rocks. The chemical weathering potenitial index of basaltic rocks in larger than that of granitic rocks. The reason is that the chemical weathering of basaltic rocks proceeds more easily than that of granitic rocks. In weathering, the decrease of mobile cations such as $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$ and the increase of $H_2O$ in basaltic rocks are more obvious than in granitic rocks.

• Geophysics and Geophysical Exploration
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• v.2 no.1
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• pp.1-7
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• 1999

We investigated the weathering characteristics of On-Yang gneiss by means of geological survey and Ground Penetrating Radar(GPR). The results of geological survey and boring show the two sets of vertical joint and horizontal joint developed by foliation which is composed of salic and melanic layers. GPR section evidently shows foliation direction and differential weathering due to discontinuity and mineral composition of metamorphic rock. The GPR section for instantaneous phase attribute based on complex trace analysis evidently shows continuity and foliation direction of metamorphic rock. The strong reflection amplitude which is derived from the banded structure of weathered rock can be incorrectly interpreted as a reflection of bedrock. The depth of rock basement should be estimated from the overall exploration result such as boring, seismic method, and electrical resistivity method.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.69-79
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• 2008

Dokdo is a volcano edifice originating from an oceanic island that was formed around 3 million to 2.2 million years ago, and it consists of Dongdo(eastern island) and Seodo(western island). Even though Dokdo is a small volcanic island, Dokdo has infinite potential value and significant economic, social, scientific, and technical aspects due to its resources, ecological and territorial value. In addition, it is of national interest with regards to the dispute with Japan over the dominium of Dokdo. A need to evaluate the ground stability of Dokdo, especially in Dongdo, has been seriously raised recently due to the various cracks caused by the progressive weathering and corrosion. This study dealt with the geology and geological layers of Dokdo and identified the status of ground cracks as the previous research to evaluate the ground stability of zones of concern in Dongdo. Also, this study analyzed the relationships between physical and mechanical properties with rock types. The results showed that the values of rock properties in Dokdo are lower contrary to the general rocks in Korea, and tuff was especially affected by the weathering and corrosion.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.1-12
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• 2010

This study examined geological characteristics of a wetland in Mountain Geumjeong in Busan Metropolitan City. Field survey and laboratory tests were performed to identify topographic features, geological and structural geological characteristics, rock strength along the distance from the wetland, soil profile in the wetland, and chemical property of the wetland soil. The bedrock of the wetland consists of hornblende granite. Hornblende granite and rhyolitic rock around the wetland have the joints with strikes of N-S, E-W, and NE-SW directions and with higher dips greater than $60^{\circ}$. Lower rock strength and higher weathering grades take place towards the wetlands. According to X-ray diffraction analysis of wetland soil samples, kaolinite, montmorillonite, and gibbsite appear which demonstrate weathered products of feldspars in the hornblende granite. The soil profile in the wetland comprises O, A, B, and C horizons from the land surface. The contents of the organic matters decrease from shallow parts to deeper parts of the soil profile. In addition, $K^+$ and $Na^+$ originating from the weathering of feldspars are dominant components among inorganic ions in the wetland soil.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.617-626
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• 2019

In this study, we investigated the petrographic characteristics and physical property of the Rock-carved Seated Buddha at Bugmireugam hermitage of Daeheungsa temple in Haenam. The Buddha Statue was carved on micrographic granite, and the rock was composed of the fine quartz encircled by orthoclase. The results of diagnosis for deterioration evaluation have shown a highly damage rate of black contaminants (8.4%) and crack index (6.6). The ultrasonic velocity have detected SW (slightly weathered) grade of weathering coefficient (mean 0.18). Various weathering factor on the surface of the Buddha Statue was affected by precious shelter, and physical property with ultrasonic was directly influenced by the structural characteristics and fissure of host rock.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.527-534
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• 2000

136 cut slopes which extends from Namyangju to Chunchon city along the 46th national highway were investigated to analyze the influence factors affecting slope instability. Geologic and geotechnical conditions were examined and the detailed investigation were carried out for fifty five failed slopes. failure mode (wedge failure, planar failure, circular failure, sheet eroison and rock falls) are examined with respect to slope inclination, rock type, weathering grade and discontinuity patterns. It is suggested that the failure modes and their dimensions have relations to the morphology and geologic conditions of the slopes. Wedge failure has highest is the most frequent failure mode and falls, sheet erosions, planar failures and circular in descending order of failure percentage. Wedge failure is most dominant failure type over all lithology except quartzite formation. In slopes of well foliated and banded gneiss, failure ratio of wedge is up to 50% ca. Failure ratio(number of rock fall/number of total failure) of rock fall increases with increase fo slope inclinations and decrease of weathering grade. Dimension analyses of failed slopes shows wedge and circular failure has higher value of D/L and D/H than planar failure and sheet erosion.