• Journal of the Mineralogical Society of Korea
• /
• v.13 no.3
• /
• pp.147-163
• /
• 2000

The mineralogy and chemical composition of reddish to brownish yellow residual soils, so called "Hwangto" have been examined according to representative host rocks. The result of the study indicates that Hwangto consists of 40-80% clay minerals and various minerals such as quartz, feldspar, hornblende, goethite, and gibbsite. Clay minerals include kaolinite, halloysite, illite, hydroxy interlayered vermiculite (HIV), mica/vermiculite interstratifield mineral and chlorite. The mineralogical constituents and contents of Hwangto were different depending on the types of host rocks. Moreover, the Jurassic granitic rocks contain relatively more kaolin minerals, whereas the Cretaceous granitic rocks contain more HIV and illite. In addition, reddish Hwangto contains relatively more kaolinite and HIV, and yellowish Hwangto contains more illite and halloysite. It is suggested that feldspars and micas of host rocks were chemically weathered into illite, halloysite, illite/vermiculite interstratified minerals, and HIV, and finally into kaolinite. Compared with their host rocks, the major chemical compositions of Hwangto tend to contain more $Al_2O_3,\;Fe_2O_3,\;H_2O$ in amount and less Ca, Mg, and Na. Hwangto contains relatively high amount of trace elements, P, S, Zr, Sr, Ba, Rb, and Ce including considerable amount of Li, V, Cr, Zn, Co, Ni, Cu, Y, Nb, La, Nd, Pb, Th in excess of 10 ppm. Relatively high amount of most trace elements were detected in the Hwangto. The major and minor chemical compositions of the Hwangto were different depending on the types of host rocks. However, their difference was in the similar range compared with the compositions of host rocks.

• Economic and Environmental Geology
• /
• v.30 no.4
• /
• pp.327-340
• /
• 1997

Geochemical characteristics of groundwater, based on chemical analyses of 54 water samples, differ among main rocks of Haman formation, Panyawoel formation, andesite and granite in Daegu area in relation to mineralogical and chemical compositions of the rocks. Concentrations of most solutes are higher in groundwaters of Haman and Panyawoel formations than in those of andesite and granite. High concentrations of $Ca^{2+}$ and $Mg^{2+}$ in groundwaters of the sedimentary rocks result mainly from reaction of $CO_2$-charged water with calcite and weathered feldspars. Average groundwaters in the sedimentary rocks are oversaturated with respect to calcite. Major types of groundwaters are hard $Ca(HCO_3)_2$ and $CaSO_2-CaCl_2$ with hardness of 442 mg/l for Haman formation and 275 mg/l for Panyawoel formation whereas they are soft $Ca(HCO_3)_2$ with hardness 35 mg/I for andesite and 39 mg/I for granite. $Ca(HCO_3)_2$ type results mainly from calcite-dissolution and $CaSO_4-CaCl_2$ from pyrite and partly from domestic pollutants. $CaSO_4-CaCl_2$ type may indicate that groundwaters in the sedimentary rocks are more evolved geochemically than those in the igneous rocks, but it is not obvious because the type might be affected by pyrie dissolution and domestic pollutions. Acid rain is buffered by active calcite in the sedimentary rocks. In the igneous rocks acid rain might react with gibbsite and other forms of $Al(OH)_3$ that might have accumulated as weathering products of primary silicates, and is buffered.

• Korean Journal of Environment and Ecology
• /
• v.12 no.1
• /
• pp.22-29
• /
• 1998

This study is investigated for the trace element concentration in the soils derived from different parent rocks, which are serpentinites, metamorphic rocks and black shales, and the absorption of the trace element by Pinus rigida in Hongseong and Keumsan, Chungnam, respectively. The concentrations of nickel, chrominium and cobalt are high in the serpentinites, whereas the concentrations of zinc, molybdenium and iron are high in the metamorphic rocks. These elements in black shale are lower than those in serpentinites and metamorphic rocks. The serpentine soils show high nickel, chrominium and cobalt content, while zinc and iron content are high in the mixed soils(serpentinites + metamorphic rocks) and black shales. Comparing with parent rocks, all of trace elements in their weathered soils are low. The pH of serpentine soil is high, 7.73~9.55 and that of black shale soil in 5.61. In serpentine area, the absorptions of chrominium by P. rigida is lower than its in the soils. The absorption of zinc by P. rigida is high relative to zinc concentration in soils. The Co/Ni and Fe/Ni quotient in P. rigida over serpentine soils are considerably lower than those growing over other soils tpes.

• Journal of the Korean Geotechnical Society
• /
• v.35 no.11
• /
• pp.75-95
• /
• 2019

The numerical analysis on PHC piles socketed into weathered rocks through sandy soil layers was conducted to propose the table solution or the chart solution to obtain the mobilization capacity. The mobilization capacity was determined at the settlement of 5% pile diameter and applied a safety factor of 3.0. In order to utilize the excellent compressive strength of the PHC pile effectively, it is recommended that the allowable bearing capacity of ground would be designed to be more than the long-term allowable compressive pile load. A procedure for determining an allowable pile capacity for PHC piles socketed into weathered rocks through sandy soil layers is given by the sum of the allowable skin friction of the sandy soil layer and the weathered rock layer and the allowable end bearing capacity of the weathered rock layer. The design efficiency of the PHC pile is about 85% at the reasonable design stage in the verification of the newly proposed method. Thus, long-term allowable compressive load (P_all) level of PHC piles can be utilized in the optimal design stage.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.2
• /
• pp.135-145
• /
• 2015

In order to predict the deterioration of stone monument due to acid fog, an artificial fog test using pH4.0 and pH5.6 was applied to the Gyeongju Namsan granite, decite and marble. After the test had weathered Gyeongju Namsan granite a larger weight reduction due to acid fog than fresh one. Decite has shown the most significant changes among the tested rocks with about 0.005 % of weight reduction. Decite and weathered granite will have considerable weight reduction due to acid rain than the acid fog, whereas the marble was expected to show a weight reduction regardless of the phase of water. The porosity and water absorption rate of weathered granite had significantly increased. This result means that the weathered rock is predicted to be more susceptible to acid fog than the fresh rock. The absorption rate of the marble after the test had shown approximately 50 % increase. The color of the samples had slightly changed towards yellow, such tendency was greater shown in weathered rocks. The marble reacted with acid fog had an increased whiteness. A large amount of cation in the samples is caused mainly by the dissociation of minerals through the reaction with acid fog.

• Journal of Ginseng Research
• /
• v.29 no.4
• /
• pp.192-205
• /
• 2005

This study is for geochemical relationships between ginsengs and soils from three representative soil types from Keumsan, shale, phyllite and granite areas. For this study, ginsengs (2, 3 and 4 years), with the soils and their host rock, are collected and are analysed for the transitional elements. In the weathered soils, the shale area is high in the most of elements, but low in the granite area. High correlation relationships are shown in the shale area. In the field soils, the shale area is mainly high, but low in the granite area. Comparing with ages, most of elements are high in the 2 year soils, but low in the 4 year soils. Regardless of the localities, positive and negative correlations are dominant in the shale area. In the host rocks, high element contents are shown in the phyllite and shale areas. Positive and negative correlations are found in the shale and phyllite areas for large numbers of the element pairs. In the ginsengs, differences of the element contents with ages are not clear, but show high element contents in the 2 year ginsengs of the shale and phyllite areas, and low contents in the 4 year ginsengs of the granite area. Positive correlations are shown in the Cu-Zn pair in the shale and phyllite areas, and Co-Cu pair in the granite area. In the relative ratios(weathered soil/field soil), most of elements from the shale area are high, above I, suggesting high element contents in the weathered soils of the shale area relative to the granite and phyllite areas. In the relative ratios(weathered soil/host rock), most of elements are above 1, suggesting the high element contents in the weathered soils relative to the host rocks. Relative ratios (soil/ginseng) of the element contents are several to ten times. Regardless of the areas, big differences of the relative ratios are found in the Co and small differences are in the Cu and Zn, which suggest that differences between soils and ginsengs are big in the Co contents and small in the Cu and Zn contents. Regardless of the ages, differences among relative ratios are small in granite area relative to the shale area, which suggest more similar contents between ginsengs and soils in the granite areas.

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

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.486-493
• /
• 2006

This paper deals with the procedure and the results on the dynamic loading tests of two large diameter - long drilled shafts (diameter=2.0m, length=75m) which were embedded into weathered rocks through thick soft marine clays and sandy gravels. Prior to the real dynamic loading test, the numerical simulation for the test procedure was performed to check the structural stability of the main pile body using equivalent static elastic analysis and the application of the hammer system using WEAP (Wave Equation Analysis of Pile Driving). Through these preliminary analyses the dynamic loading tests on large diameter - long drilled shafts have been successfully achieved.

• Journal of Industrial Technology
• /
• v.26 no.A
• /
• pp.109-117
• /
• 2006

This study is an numerical study of predicting the behavior of anchor embedded in weathered rocks, subjected to uplift loads, about ultimate pullout capacity and the failure mechanism. Factors influencing the behavior of anchors were investigated by reviewing the data about in-situ anchor tests performing numerical modelling with changing the bondage length of anchor, diameter of anchor body and diameter of tenden, and by Correlations between those factors were evaluated to apply them to predict the behavior of anchors. As results of numerical analysis, a linear relationship between bondage length, diameter of anchor body and diameter of tenden with ultimate pullout capacity was obtained on the one hand, from the result of numerical analysis changing the Young's modulus of weathered rock, this parameter was found to inflence to load-displacement and ultimate pullout capacity within the range of 10%, which was mot so significant to affect.

• Journal of Korean Society of Forest Science
• /
• v.104 no.4
• /
• pp.588-597
• /
• 2015

This study was carried out to identify the reasons of the landslide by land creeping in South Korea in order to provide basic information for establishing the management plan for prevention. Total 29 sites of landslide areas caused by land creeping were observed in South Korea. Among them, the soil-composition of most frequent landslide areas occurred by land creeping was colluvium landslide as 75.9% (22 sites), followed by clay soil landslide as 10.3% (3 sites), bedrock landslide as 6.9% (2 sites), and weathered rock landslide as 6.9% (2 sites). According to the types of parental rocks, the investigated landslide areas were divided into 3 types: 1) metamorphic rocks including schist, phylite, migmatitic gneiss, quartz schist, pophyroblastic gneiss, leucocratic granite, mica schst, banded gneiss and granitic gneiss, 2) sedimentary rocks including limestone, sandstone or shale and mudstone, 3) igneous rocks such as granite, andesite, rhyolite and masanite. As a result, it was noticed that the landslides occurred mostly at the metamorphic rocks areas (13 sites; 44.8%), followed by sedimentary rock areas (12 sites; 41.4%), and igneous rock areas (4 sites; 13.8%). Looking at the direct causes of the landslide, the anthropological activities (71%) such as cut slopes for quarrying, construction of country house, plant, and road, farming of mountain top, and reservoir construction were the biggest causes of the landslides, followed by the land creeping landslides (22%) caused by geological or naturally occurred (22%), and cliff erosions (7%) by caving of rivers and valleys.