• Explosives and Blasting
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• v.8 no.4
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• pp.30-43
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• 1990

본고는 현존하는 암석과 암반의 풍화분류방법에 대한 고찰 및 이러한 방법들을 실제로 우리나라의 토목현장에 적용할 경우 발생되는 여러 가지 문제점을 서술하고, 이에 따른 문제점 극복을 위해 우리나라의 여건에 맞도록 암석 및 암반의 풍화상태를 조사 기술하므로서 각종 토목공사에서 보다 유용하게 사용할 수 있는 풍화분류방법을 제시한다.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.355-364
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• 2004

A study on the weathering grade classification has been performed for granite and granite gneiss in Korea. The qualitative classification criteria of weathering were reviewed and then modified with field studies for the weathered rock masses. The thin section observations and XRD analyses for the different weathering grades rock samples showed the petrographical and petrophysical difference with respect to the weathering : the proportion of weathering-resistant minerals suck at quartz and orthoclase has a tendency to increase with the development of weathering, but that of weathering-sensible minerals such as anorthite and biotite is decreased. The ranges of physical and mechanical rock properties for different weathering grades were obtained from the laboratory rock tests and field tests for the studied rocks. And then, along with $RDI_{sq}$(Fookes et al., 1988), the weathering index $I_{a}$, (Woo, 2003) has been developed in this study to demarcate the weathering grade. Those two indices rely mainly on the water absorption ratio of rock and on the different rock strength. The range of these weathering indices have been determined with the physical and mechanical rock properties that can be obtained from simple field or laboratory tests in 4 grades $I_{a}$＞ 7 for F, 3.5 ＜ $I_{a}$ ＜ 10 for SW, 1.0 $I_{a}$＜ 6.0 for MW and $I_{a}$＜ 2.5 for HW. Consequently, the weathering index could be utilized to classify quantitatively the rock weathering grade, especially for the studied granites and the granite gneiss in Korea.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.127-140
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• 1999

In this study, decomposed granite soil samples were taken from 16 different regions and their weathering properties were investigated by testing their physical and chemical properties. According to the results, the Chemical Weathering Index (CWI) ranges from 15.5 to 30 in general and 12 out of the 16 regions show over 20 in CWI. The 12 regions are categorized into complete granite soil areas by Sueoka's classification. CWI, Li. $SiO_2,\; \DeltaS/S$ and SAR are all correlated significantly and used as indicators by which the degree of weathering can be judged. The degree of weathering can be measured especially through Li or $SiO_2$ which is considered as an easy approach of geotechnical classification. Also, the relationship between the value of N and Li is regarded as a good indicator in estimating the degree of weathering.

• Proceedings of the KSEG Conference
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• 2004.03a
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• pp.12001-12049
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• 2004

암석의 풍화과정은 화학적인 변질, 물리적인 분해 및 생물학적인 작용으로 나뉘어 진다. 풍화에 영향을 주는 요소는 기후, 조성광물의 종류 및 구조, 절리와 단층, 열수변질작용과 광화작용, 염기성 및 산성암맥과 지형 등이다. 또한 암석의 풍화는 성인에 따라 다양한 양상으로 진행되는데 이는 암석을 이루고 있는 각각 광물들이 열역학적인 반응경로가 서로 다르고, 이에 수반되는 물리적인 풍화진행속도가 차이가 있으며, 암석의 균질성, 투수성 등이 암종별로 다양하기 때문이다. 현장에서 암석의 풍화정도는 조성광물의 변질과 분해정도를 육안 등으로 정성적으로 판단하고 분류하는 것이 일반적이다. (중략)

• 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.

• Journal of The Geomorphological Association of Korea
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• v.20 no.4
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• pp.37-50
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• 2013

This study analyzes results of published studies of weathering pits in Korea focusing on tafoni and gnamma and it suggests new types of weathering pits and next subjects through the analysis. 34 papers, published between 1978 and February 2012, have been analyzed and the following are details of the analysis. In terms of the study results, weathering pits are commonly developed on coarse-grained rocks such as granite, but also found on various rocks. Multiple reasons including mechanical, chemical and salt weathering create weathering pits and they are closely related to the geological structure. Weathering pits are classified as tafoni and gnamma but the forms have not been verified. In the future, quantitative analysis must be conducted find the factors influencing creation, forms and development of weathering pits.

• Explosives and Blasting
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• v.22 no.2
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• pp.33-43
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• 2004

The six grades weathering system is normally used in weathered rock classification. In this study. fresh and weathered rock block of grade I to V were sampled in Jang-soo ana but samples of the grade VI was omitted from this study. The variation quantities of chemical weathering indices with weathering degree are smaller than those of physical and mechanical properties. Increase of Weathering degree is well indicated by physical and mechanical properties such as strength, hardness, ultrasonic velocity and slake durability result. Especially, absorption and porosity ratio is a good indicator. As weathering proceeds. a number of the cracks affect the rock deformation. Therefore, stress-strain curves of weathered rocks in unconfined state are quite different from ones of fresh rocks.

• 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 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.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.583-596
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• 2022

The rock surface of Bangudae petroglyphs is mainly dark brown hornfelsified shales by contact metamorphism. The surface form a weathered layer of a invariable depth, and there is a difference with mineral and chemical composition between weathered and non-weathered layers. Surface of the petroglyphs has been discolored to light brown over the face due to biological and chemical weathering. As the measuring chromaticity based on the non-weathered layer, the whiteness and yellowness increased in the weathered layer, and the color difference (ΔE) was 5.54 to 36.89 (mean 17.26). In the weathered layer of the petroglyph surface, the CaO content was reduced by about 90% compared to the non-weathered layer, and Sr also showed the same trend. In particular, the mean porosity of the non-weathered layer was 0.4%, but it was estimated as 25.0% in the weathered layer. This is interpreted as the fact that calcite reacts with water, and forms a weathered layer from the surface as it is eluted. Based on the weathering depth modeling of the petroglyphs using the penetration characteristics of X-rays, the weathering depth of rock faces was found to be 1 to 2mm. However, the area classified as 2mm or more estimated to be a maximum of 3 to 4mm, considering the weathering depth around the petroglyphs surface.