• Economic and Environmental Geology
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• v.55 no.5
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• pp.429-438
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• 2022

This study evaluated the effect of the degree of weathering on the particle size distribution and the amount of fine particles generated in the aggregate production process during the crushing of igneous rock. Rock samples were collected from three areas with differences in strength from the Schmith hammer measurement at the aggregate quarry in Geochang, Gyeongsangbuk-do. After crushing with a jaw crusher under the same conditions in laboratory, particle size analysis, mineral analysis, chemical analysis, and weathering index were calculated. The Schmidt hammer measurements were 56, 28, and <10, and the CIA and CIW values of weathering index were also different, so the rock samples were classified into hard rock, soft rock, and weathered rock according to the weathering degree. It shows a smaller particle size distribution toward weathered rocks under the microscope, and the proportion of altered clay minerals such as sericite increased. The composition of feldspar and quartz was high for hard rock, and the ratio of muscovite and kaolinite was low. As a result of the crushing of the jaw crusher, hard rock produced a lot of coarse crushed material (13.2mm), while soft rock and weathered rock produced fine crushed material (4.75mm). The former showed the characteristics of the beta distribution curve, and the latter showed the bimodal distribution curve. The production of fine rock particles (based on 0.71mm of sieve, wt. %) increased to 13%<21%<22% in hard rock, soft rock, and weathered rock, and the greater the degree of weathering, the more fine rock particles were generated. The fine particles are recovered by the operation of the sand unit in the wet aggregate production process. Therefore, in order to minimize the amount of sludge generated in the aggregate production process, it was judged that a study on the optimal operation of cyclones could be necessary.

• Economic and Environmental Geology
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• v.40 no.1 s.182
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• pp.47-66
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• 2007

The Sitting Buddha Carved on Rockcliff (National treasure No. 201) in Bukjiri consists of porphyritic biotite granite, which was fractured by three joint sets of NE-SW, EW and NS directions. They produced a physical weathering that broke many parts of the Buddha and background. The chemical index of alteration is 59 to 61 from the major elements in the granite that was weathered into producing kaolin minerals from alteration of feldspars and biotite. With weathering degree, major element compositions increase in $SiO_2$ and MnO, whereas decrease in $TiO_2,\;{Fe_2O_3}^t,\;MgO,\;CaO\;and\;K_2O$. Change proporations of trace elements to $Al_2O_3$ increase in all transition elements, Rb and Y, whereas decrease in Li, Sr and Ba. REE pattern increases only in HREE. Particularly, a decrease in CaO, $K_2O$, Sr and Ba results in what they are effluxed to dissolve from feldspars by groundwater. The Buddha image has been deteriorated into joints, color changes, brown rusts, granular decay, microorganic smears by the such weathering causes as deformation, moisture, temperature variation and microorganic living. The moisture, which leaks along the joints in the granite, not only dissolve to decompose minerals but also grows many microorganism and is frozen over during winter. NE-SW and NS joint sets affect to seep in water during rainy days to deteriorate the image because they extend outward.

• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.1-11
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• 2020

A CIA analysis (A-CN-K and A-CNK-FM ternary diagram) indicates that, unlike the general granitic hills of the Korean Peninsula, the chemical weathering of the granitic grus (sandy regolith) in the eastern Jincheon basin is variable in geomorphic site except the Chuncheon basin. In the study area, there are three types of hills, such as; inner hills, linear isolated hills, and outer hills. The weathered mantles of the outer hills and linear isolated hills are weakly altered, whereas the inner hill, the Bonghyeon profile, shows a stronger chemical loss of the compositions approximating saprolite. There are small differences between the outer hills and linear isolated hills. The Geumwang site is considered fresh rock due to a low lever of alteration, although its sampling profile shows sandy weathering mantles. In the profiles of the Masan and Mugeuks sites, the lower part of weathering mantles has not experienced a significant level of component loss, but the upper regoliths have substantially been modified. The alteration of the hills occurs by chemical loss of CaO and Na₂O. K₂O exhibited little variation at all sampling suites and it has not changed into saprolite.

• Geotechnical Engineering
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• v.11 no.4
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• pp.63-74
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• 1995

Much of Taegu and Kyungpook areas are composed of sedimentary rocks. This paper is concerned with the engineering characteristi os of weathered shale soils and mudstone soils. In this study, the engineering characteristics of weathered shale soils and mudstone soils are investigated by performing tests such as compaction, gradation, CBR permeability and crushability according to compaction energy and water content. The experiments were carried out to obtain the relationships of the ratio of surface area(Sw'/Sw) and the indez of crushing(IC) The results are found as follows : (1) Weathered shale soils are larger than weathered mudstone soils in maximun dry den sixty, but weathered shale soils are smaller than weathered mudstone soils in OMC. (2) Minimum permeability is found in OMC's 1~2% wet side, and the more compaction energy is high, the more the change's range of permeability becomes narrow. (3) There is linear correlation between the ratio of surface area and the indez of crushing. IC : 14.286sw'/Sw -8.429(r=0.9937) (4) Soaked CBR value becomes maximum in OMC's dry side, and it decreases as the water content increases. Whereas the more compaction energy is high the more unsoaked and soaked CBR values are high in OMC's dry side, unsoaked and soaked CBR values are opposed to that in OMC's wet side.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.517-523
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• 2007

Geophysical surveys(seismic refraction, electrical resistivity, and ground penetrating radar) were performed to delineate the weathering zone associated with vadose water in Chojeong area and investigate the fault related fracture zones. On the basis of seismic velocity structures, weathering layer for the southwestern part is interpreted to be deeper than for the northeastern part. The depth to bedrock(i.e., thickness of weathered zone) from seismic refraction data attempted to be correlated with drill-core data and groundwater level. As for the investigation of geological discontinuities such as fault related fracture zone, seismic refraction, electrical resistivity, and ground penetrating data are compositely employed in terms of velocity and resistivity structures for mapping of surface boundary of the discontinuities up to shallow depth. Surface boundaries of fracture zone are well indicated in seismic velocity and electrical resistivity structures. Accurate estimation of weathered zone and fracture zone can be successfully available for mapping of attitude of vadose water layer.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2004.04a
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• pp.167-172
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• 2004

• Journal of Conservation Science
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• v.27 no.1
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• pp.101-114
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• 2011

The rock-carved Buddha statue at Dosolam (Korea Treasure No. 1200) of the Seonunsa temple in Gochang is unique style sculptured on natural rock cliff of 13.0m height. The Buddha statue is composed of volcanic complex with tuff, dacitic tuff breccia, tuff bereccia and lithic tuff. Especially, the Buddha statue is characterized by hydrothermal alteration and fragmentation on the upper and lower part. As a result of damage diagnosis, exfoliation and detachment of physical weathering are high of 11.3% and 9.3%, respectively. Infrared thermography analysis, exfoliation and micro-cracks occurred in the measuring parts that have not been confirmed by naked eyes. Chemical index of alteration and weathering potential index of host rock for the Buddha statue are 55.16 to 64.01 and 6.14 to 9.92 which are represented within highly weathering degree. In surface, dark black, reddish brown and white discoloration are observed prominently in the lower. Brown discoloration 6.9% is highest. According to the P-XRF measurements, high concentration of Fe in common, in part of dark black discoloration was Mn, white and brown discoloration in part of S and Ca content were higher. Biological weathering that yellowish brown and dark gray crustoes lichenes appeared by 20.8% and 13.3%, respectively. Therefore, comprehensive deterioration rate of Buddha statue show physical damage by 21.2%, discoloration for inorganic contaminants by 10.8% and biological damage by 39.4%. Ultrasonic velocity measurement carried out of Buddha statue on the surface by 555 points. Measured value of ultrasonic velocity was about 2,273m/s(1,067 to 3,215m/s, and weathering coefficient is 0.5(0.4 to 0.8) that progress on MW(moderately weathered) to HW(highly weathered) grade of rocks.

• Journal of the Korean GEO-environmental Society
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• v.23 no.3
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• pp.15-22
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• 2022

This study aims to observe the swelling representative rocks in Korea and to suggest improvements in the use of test methods and prior analysis in relation to the weathering of rocks. The swelling test and analysis were performed on the drilling cores obtained for the ground investigation at the domestic highway construction site. For the method of determining the absorption expansion index of rocks, the method proposed in "Standard Methods for Sample Collection and Specimen Preparation" of ISRM and Korean Rock Engineers Standard Rock Test Method was used. The specimen for the measurement of the expansion displacement was cylindrical with a height of 10 cm and a diameter of 5 cm. The existing swelling analysis method evaluates the sensitivity to weathering by using the maximum expansion displacement, but since the classification by bedrock grade is unclear, it is reasonable to use the rate of change of the expansion displacement according to the immersion time. It is necessary to conduct an experiment to distinguish between weathering and fault deterioration. In addition, long-term weathering prediction technology for each cancer type is needed through the expansion displacement analysis of the chemical weathering stage.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.20-29
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• 2001

Final convergence of tunnel crown due to excavation have been well predicted by regression analysis which is expressed as a function of convergence curve on a time and distance dependent. In this study, the validity of the equations for shallow, wide tunnel was investigated by measurement and numerical analysis. Studied tunnel(Sansoo Tunnel) is located at the boundary of downtown and mountain park. Exponential predictions equation was better coincided with measured data than fractional equation for studied tunnel, although the ground was expected to be elasto-plastic. This is because weathered rock ground is changed elasto-plastic ground into elastic ground by multi-steel grouting and forepoling.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.67-76
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• 2009

Statistical analysis was performed using a series of data on RMR, RMR* and crown settlements collected from sites of weathering rock tunnels in Korea. The crown settlements were predicted by recurrence analysis, exponential function, and artificial neural network (ANN) using collected in-situ data. The result of the prediction fitted well compared to the measured settlement in the order of ANN, exponential function, and recurrence analysis. The range of crown settlement predicted by recurrence analysis widely scattered and promised larger settlement than the measured. Also in all method, the predicted value by RMR well matched compared to the measured settlement predicted by RMR*.