• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6C
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• pp.431-443
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• 2006

As part of a fundamental characterization for subsurface layers in Korea, the weathering degree and shear wave velocity ($V_S$) were evaluated from the X-ray fluorescence analyses and the site investigations containing boring and in-situ seismic tests, respectively, for decomposed granite layer in Hongsung. The subsurface layers at Hongsung were composed of 10 to 40 m thickness of weathered layer in most sites. According to the results of weathering degree analyses in Hongsung, it was examined that three chemical weathering indexes such as MWPI, VR and WIP generally increased with decreasing depth. From the in-situ seismic tests, the $V_S$ was determined as the range between 200 and 500 m/s in weathered layer. Based on the $V_S$ and N value at borehole seismic testing sites, N-$V_S$ correlations were established for weathered layer. Furthermore, the relationships of three representative weathering indexes with the $V_S$ and N value indicated that the MWPI, WIP and 100/VR increased linearly as increasing $V_S$ and exponentially as increasing N value.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.587-598
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• 2023

To assess the distribution and temporal changes in radon concentration within a region in Yeonpung-myeon, Goesan-gun, known for elevated groundwater radon levels, we conducted a series of analyses, measuring radon concentration and DTW (Depth to water table) at 2-month intervals over 12 cycles. The investigation covered 10 groundwater wells and one stream within the designated area. The groundwater in the central part of the region exhibited high radon concentrations, ranging from 37.0 to 2,675.2 Bq/L. Conversely, the peripheral zones displayed comparatively lower radon concentrations, ranging from 10.6 to 37.9 Bq/L. This variation is attributed to the presence of granite porphyry that intruded into the Okcheon Formation, forming a fracture zone and contributing to elevated radon levels in the central part. In contrast, the peripheral locations, located within the Okcheon Formation and away from the granite porphyry intrusion, demonstrated lower radon concentrations. The observed significant fluctuation in radon concentration in the central area is associated with its low-lying topography. The pronounced seasonal changes in groundwater levels contribute to the migration of shallow, low-radon groundwater into areas with higher radon concentrations, explaining the observed variations in radon levels within the central part of the studied area.

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.196-212
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• 2023

This study identifies the origin of stone remains (pavement and banister stones) excavated from the first burial site of King Jeongjo through petro-mineralogical analysis in a quarry and examines the relationship with the stone remains from Geolleung (King Jeongjo's Tomb). The excavated stones from the first burial site of King Jeongjo are all light gray fine-grained biotite granite, and mainly contain quartz, feldspar, and biotite. The magnetic susceptibility of the stones ranges from 5.55 to 12.10 (average 7.00) (SI unit). According to old documents, the quarrying sites of the stones were Mts. Aengbong and Yeogisan (Godeung-dong District, Suwon), and we found a fine-grained biotite granite outcrop behind Mr. Aengbong (currently the site of Yeonggwang Apartment) with a geological survey, and it was petrologically similar to the stone remains from the first burial site. The magnetic susceptibility of the outcrop rocks was 5.15 to 7.24 (SI unit), and their petro-mineral and geochemical characteristics were found to be the same as those of the first buried site and Geolleung Tomb. It was confirmed that most of the stone elements in the first burial site were reused to build Geolleung Tomb while moving the grave. Only the pavement and banister stones seem to have been discarded in the first grave site without being transferred. This is because the size of the new burial mound became larger than the first grave during construction because Queen Hyoui (the consort of King Jeongjo) died and was buried together with the king in the same tomb, and the stone blocks did not fit a grave that size. With these research results, it was possible to compare and examine the old records and scientific analysis data, and they are expected to be used as basic source material in related research.

• Economic and Environmental Geology
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• v.57 no.5
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• pp.609-632
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• 2024

Magnesian granitoids, ranging from quartz-syenite to granodiorites of varied mineralogical composition, are poorly studied in metamorphosed terrains of Proterozoic eon, unlike their ferroan variety. Geochemical traits of magnesian granitoids in southwest Nigeria's Precambrian basement are investigated to understand their chemistry and evolutionary origins, such as continental collision events and tectonic settings. Four intrusive units based on their mineralogical compositions were identified as quartz syenite, porphyritic granodiorite, tonalite-trondhemite-graniodiorite (TTG) component of the high-grade migmatite gneiss, and charnockite (with granodioritic compositions). These rocks contain alkali feldspar, plagioclase, quartz, and biotite, the main mineral phases that are common to them. Pyroxene and garnet were observed in the quartz-syenite and charnockite, while hornblende crystals were found in quartz syenite, porphyritic granodiorite, and TTG. Geochemical analysis showed average silica and alumina concentrations accordingly: quartz syenite (59.28% SiO₂, 13.28% Al₂O₃), porphyritic granodiorite (58.80% SiO₂, 16.59% Al₂O₃), TTG (59.07% SiO₂, 15.56% Al₂O₃), and charnockite (53.43% SiO₂, 18.06% Al₂O₃). The average Fe/Mg ratios were 1.14 (quartz syenite), 1.78 (porphyritic granodiorite), 1.66 (TTG), and 1.80 (charnockite), and total alkali values were 9.98% (quartz syenite), 7.79% (porphyritic granodiorite), 9.11% (TTG), and 6.56% (charnockite). Based on their Fe/Mg ratio, alumina saturation index (ASI) (0.63-0.88), and Modified Alkali Lime Index (MALI) these rocks were characterised as metaluminous magnesian with alkali-calcic to alkalic nature. Variable LREE enrichment and europium anomalies were observed, with the quartz-syenite having the highest LREE enrichment and lowest Eu/Eu* (av.0.67). The plot of Rb vs Y+Nb showed that these intrusives are post-collision plutons, with the quartz syenite samples plotting in the syn-collision granite (syn-COLG) field while the porphyritic granodiorite and the charnockite plotted in the volcanic arc granite (VAG) field. These rocks must have been derived from partially melting the upper continental crust and deeper crust of possible mantle materials and emplaced as Pan-African post-orogenic plutons. The tectonic discrimination diagram for the granitoids implied late orogenic to post-collision uplift, collision arc events, and granite magmatism as the dominant events which characterised the Pan-African orogeny.

• Journal of the Korean earth science society
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• v.38 no.6
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• pp.421-426
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• 2017

In this study, we selected three representative granite samples and conducted petrological observation to establish the Korean geostandards. Samples were taken from the two Jurassic (KJG-1, KJG-2) and one Cretaceous (KCG-1) granites in South Korea. The powder samples were prepared by the standard pulverization process, and glass beads were made for geochemical analysis using X-ray fluorescence (XRF) method, and finally, major element contents of the samples were acquired. The analytical data are shown with mean, standard deviation and relative standard deviation. The accuracy of the analysis was confirmed within an estimated error range of about 5% by comparing the recommended true values of the USGS and GSJ geostandards. Also, we checked the analytical precision by calculating a relative standard deviation of about 3% from the XRF analytical results for the three samples.

• Tunnel and Underground Space
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• v.18 no.5
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• pp.386-392
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• 2008

Recently, an earthquake-resistant has become essential to the large-scale structures at Gyeonggi and Gyeongsangnam province in Korea, but it is generally compared the measured data with foreign references because of the lack of the research data. It will be presented the characteristics of suitable dynamic elastic modulus in Korean geology, which characteristics are characterized the seismic wave velocities($V_p,\;V_s$) and correlation with dynamic elastic modulus($E_d,\;G_d\;K_d$) by each rock type of Korean granite, because it is very different between the values of foreign references and Korean geological characteristics.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.2 s.13
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• pp.19-27
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• 2004

The interest in the dynamic properties of soils has increased strongly because of earthquake, heavy traffic, and foundations undergo high amplitude of vibrations. Most of soils in Korean peninsula are composed of granite soils, especially the decomposed mudstone soils are widely spread in Pohang areas, Kyong-buk province. Therefore, it is very important to investigate the dynamic properties of these types of soils. The most important soil parameters under dynamic loadings are shear modulus and material dampings. Furthermore, few definitive data exist that can evaluate the behavior of unsaturated decomposed mudstone soils under dynamic loading conditions. The investigations described in this paper is designed to identify the shear modulus and damping ratio due to a surface tension for the unsaturated decomposed mudstone soils under low and high strain amplitude. For this purpose, the resonant column test and the cyclic triaxial test were performed. Test results and data have shown that the optimum saturated degree of decomposed mudstone soils under low and strain amplitude is $32{\sim}37%$ which is higher than that of decomposed granite due to the amount of fine particles as well as the type and proportion of chief rock-forming minerals.

• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.9-18
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• 2008

Shallow slope failures in residual soil during periods of prolonged infiltration are common in Korea. This study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method. Approximate method which is based on the Green-Ampt model have been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods. Pradel & Raad method which is devised to predict the depth of wetting front to decomposed granite soil slopes having measured soil-water characteristic curves. To compare the results with those obtained from the Pradel & Raad method, a series of numerical analysis using SEEP/W were carried out. It was found that the stability analysis of unsaturated soils calculated by using the soil-water characteristic curve of decomposed granite soils was found to be a proper analysis for shallow slope failures due to rainfall.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.5-14
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• 2010

This study was aimed to suggest reliable information of shear strength characteristics due to change of saturation in the landfills or slopes during rainfall infiltration. According to the Mohr-Coulomb failure criteria, the characteristics of shear strength due to change of saturation were analyzed for the weathered residual soils which were sampled in the road construction site of Daejeon city. From the direct shear strength tests, the cohesions and the shear resistance angles were showed maximum values in the condition of optimum moisture content, and then decreased in the condition of wet side compaction. In this study, the cohesions were decreased more than 50% according to increasing saturation by infiltration for the compaction soils. But the reductions of the shear resistance angles were about $1{\sim}2^{\circ}$ which was small value, and thus the changes of the saturation were not nearly influenced the shear resistance angle. The influences of the saturation were seemed to very small for the residual strength parameters according to Mohr-Coulomb failure criteria.

• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.379-385
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• 2013

In this study, partial drilled shafts (Bottom Cast-in-place Concrete pile) were applied to the pilot test site to ensure the bearing capacity; we used the skin friction force in the IGM to analyze the feasibility of the application of IGM theory. The soil characteristics were analyzed in cohesive, non-smear, and smooth conditions for the application of the IGM theory via geotechnical investigation and measurement of the disturbance and surface roughness. Static load and load transfer tests were conducted to calculate the allowable bearing capacity and the skin friction force by depth. The skin friction force increased with increase in the depth and standard settlement, showing a very high correlation. In addition, because the unconfined strength ($q_u$), which is the most important parameter in the cohesive IGM, cannot be measured in a weathered granite area, the static load and load transfer test results and the N value were used to obtain $q_u$.