• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.71-82
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• 1995

The weathered two-mica granite is widely distributed in Korea and called a kind of ground rock for kaolin. The major minerla compositions are consist of this quartz, feldspar, mica and clay mineral. At present, only a small portion of this granite is used as the material for the low-grade tile industry due to the low S.K. value and the high contents of impurities such as Fe2O3 and FeO. The low S.K. value is caused by feldspars not weathered to clay minerals. The refinement of this thus has been required for the recent shortage of the resources of high-grade one. This paper concerns an optimum hydrothermal treatment condition to refine the low-grade weathered two-mica granite of which impurities are feldspar mineral and Fe2O3. FeO components in using for the main material of ceramic industry. And then, from this result, we tried to fine out the basic formation mechanism of clay mineral from feldspar etc and develope the effectual utilization method of this.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.415-426
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• 2010

Post-grouting for the drilled shaft is known to increase the end bearing capacity of pile 2~3 times higher by consolidating and reinforcing the disturbed ground containing slime around the pile end. However, the general design guideline for post-grouting has not been established yet in Korea. Especially in the domestic application, the post-grouting is employed just for repairing the pile with the unacceptable resistance rather than for increasing the design resistance of pile. Therefore, little is reported about the effect of post-grouting on the pile resistance itself. In this study, the effect of post-grouting on the resistance of drilled shafts installed in the weathered rock in Korea was estimated by performing the bi-directional load tests on the piles with and without the post-grouting. The test results presented that the initial slope of end bearing-base displacement curve in the pile with post-grouting was 4 times higher than that without post-grouting. At the acceptable settlement (1% of pile diameter), the end bearing capacities of piles with and without the post-grouting were estimated to be 12.0 MPa and 7.0 MPa, respectively, indicating that the post-grouting could increase the end bearing resistance of pile in weathered rock more than 70%.

• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.15-23
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• 2023

In this study, the infiltration behavior of slopes composed of mixed soils with clay contents of 0%, 5%, and 10% in weathered Gneiss soil, which is a representative weathered soil in Korea, was investigated, and the stability of unsaturated slopes due to rainfall infiltration was examined. For this, in this study, the soil water characteristic curve was obtained through the water retention test, and the strength constant was obtained through the triaxial compression test. Based on the obtained results, the influence of clay content and antecedent rainfall effect (i.e., initial suction) on the formation of saturated zone (i.e., wetting band) and slope stability due to rainfall infiltration was examined through infiltration and stability analyses. As a result, it was found that the hig her the initial suction, the slower the formation of the saturated zone on the slope. In addition, it was found that as the clay content increases, the shear strength of the ground increases and the resistance to rainfall infiltration increases, and eventually the slope stability is greatly improved.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.85-92
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• 2003

Generally, ordinary portland cement(OPC) is widely used for grouting to reduce permeability of ground under the foundations of structures. But, it is hard to be injected into the microscopic voids, fissures and crevices in soil or rock formation for the OPC material. Therefore new method what is called MSG(Micro Silica Grouting) has been developed recently to improve the weak point of the OPC material. In this case study, in order to verify performance of the MSG's water cut-off, trial injections were performed in rear of CIP(Cast in Place Pile) on the site A(weathered soil) and B(alluvial soil) that are constructed for the subway No. 9 nowadays. To take the proper grouting method of the MSG in the trial injecting, the injections are carried out for grouting types(constant pressure or fixed Quantity) and grouting methods(1.5shot or 2.0shot) and to confirm the effects of water cut-off and the injection range of the MSG, the tests of permeability and indicator(phenolphthalein) response were performed before and after the injection. Through the tests results, we could affirm the effects of water cut-off of the MSG and the injection range for the weathered and alluvial soil layers near the Han River. Finally we could make sure the application of the MSG method in actual construction under the layers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.33-38
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• 2009

An experiment for uranium sorption onto fresh and weathered biotites was performed. After centrifugation, concentrations of uranium in the supernatants were analyzed using ICP-MS, and biotite samples were investigated using XRD and SEM. With powdered biotites (<3 mm in size), we have conducted uranium sorption experiments about fresh and weathered biotites to obtain uranium sorption amounts in various pH conditions. The uranium sorption was not high at a low pH (e.g., pH 3), but increased with increasing pH. There were lower uranium sorption by the weathered biotites than by the fresh ones, and the difference was much larger at higher pH (e.g., pH 11). The lower sorption values of uranium by the weathered biotites may be caused by a change of mineral surfaces and a chemical behavior of surrounding dissolved elements. It seems that the uranium-mineral interaction has been diminished, especially, in the weathered biotite by a destruction and dissolution of preferential sorption sites on the mineral surfaces and by the colloidal formation from dissolved elements.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.38-41
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• 2009

Results from the most recent decade of Mars' missions to Mars highlight a liquid water and water-ice sculpted landscape. Evidence includes layered sedimentary sequences with weathered outcrops, debris flows, fluvial valleys, alluvial fans, deltas, glacial and periglacial landscapes, and geochemical/mineralogical signatures of aqueous activity, including the formation of sulfates and clays, and the leaching and deposition of elements such as potassium, thorium,and iron. Such evidence indicates weathered zones and possible paleosols in stratigraphic sequences, transport of water and rock materials to sedimentary basins, and the possible formation of extensive transient lakes and possibly transient oceans on Mars. This new evidence is consistent with Viking-era geologic investigations that reported magmatic-driven flooding, ponding to form large water bodies in the northern plains, and transient (tens of thousand of years) hydrological cycles. It may even indicate aqueous activity at present. Both endogenic (magmatic driven) and exogenic (both impact cratering and changes in orbital parameters) have influenced paleohydrologic and environmental change on Mars. Abundance of water and dynamic activity would be decisively important for the possibility of past and present life on Mars.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.999-1008
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• 2009

A series of sedimentary rocks which are formed in the Tertiary are distributed around Samcheok(Samcheok-Pukpyoung basin), Younghae(Younghae basin), Pohang(Pohang basin), Gyeongju(Yangnam basin), Ulsan(Ulsan basin), Jeju(Seogyuipo formation) in the southern region of the Korean Peninsula. This study concerned with geological, geophysical, geotechnical properties of the unconsolidated rocks in the Pohang area. A consolidated rocks are classified as hard rock - soft rock - weathered rock - residual soil follows in degree of weathering. But unconsolidated rocks has soil properties as well as rock's at the same time. The results of field excursion, boring, borehole-logging, rock testing, geophysical survey, laboratory test are soft rock range, but the durability of the rock until the residual soil from the weathered rock. We accomplished the rock mass classification of the unconsolidated rocks.

• Explosives and Blasting
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• v.23 no.1
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• pp.9-17
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• 2005

This study is to clarify the comparative relationship and mechanical anisotropy of granite distributed in the Nam-weon on the subject of weathered rock mass sea water surroundings. Artificial weathering test is defined as a test, which controls the weathering rate and agents by controlling the weathering rate and agents by artificial environmental of salt water. Increased weathering degree is large indicated by weathering salt water, such as apparent specific gravity, absorption, porosity, uniaxial compression strength, P-wave velocity, slake durability, shore hardness, indirect tensile strength(brazilian test) and cohesion were measured. As the Weathering salt water proceeds, cracks develope increasingly. A number the cracks affect the rock deformation. Therefore, stress-strain curve of weathered salt water rock in one confined state are quite differ from weathered fresh water rock those. A reason of their deformation type is the formation of micro-cracks and potential porosity caused by artificial weathering test.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.13-22
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• 2011

In this study, features of correlation between S-velocity and N value are derived from 9 suspension PS layers in Chungcheong Buk-do. S-velocity to be measured on Chungcheong Buk-do is classified into 5 as conditions of stratum that are ; cohesive soil layer, sandy soil layer, gravel layer, weathering soil layer, weathered rock layer. Each correlation formulas between N value by SPT and S-velocity is proposed from these classifications. And correlation formula for whole soil body except weathered rock layer also is proposed for reference. Corelation formulas developed this study formed square expression considering existing formulas produced internationally. Strength parameter converted to linear if N value is more than 50. Features of proposed formula which came up with comparative analysis of international result of cohesive soil layer and sandy soil layer and gravel layer show similar to existing ones. But there is deference that result of correlation formula for weathered rock layer is a little smaller than domestic formula's one. Because correlations of weathered rock layer above the N value of 50 is converted into a linear formation.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.4
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• pp.284-289
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• 2014

Farmers in highlands in South Korea pile up 20 to 30 cm of saprolites, mostly granite- or granite-gneiss-weathered materials, on surface of arable lands every three to five years to compensate eroded soil and sometimes to discontinue soil-borne diseases. Immediate increases of infiltration and percolation rates are expected with coarse textured saprolites while soil drainage becomes poorer in a long-term. In this study, we analyzed mineralogical characteristics and micro-morphology of plow pan to investigate processes making impermeable layers. Soil samples were collected from plow pan, usually located at approximately 20 cm soil depth and at the lower part of piled saprolites, in arable lands in Hoenggye 5-ri, Daekwanryeong-myeon, Gangwon-do (N37.7, E128.7) in which saprolites were added 2, 4, and 8 years ago; saprolites were transported from similar areas. The saturated hydraulic conductivity decreased over time. Based on soil thin section pedography, quartz and feldspar accounted for a majority of minerals. The size of feldspar decreased and macropores became filled with clay or silt particles over time, which implies that macropores were packed with particles weathered from feldspar. The X-ray diffraction (XRD) analysis indicated that intensity of feldspar decreased over time and the reverse was true for kaolinite and illite, indicating that feldspar and mica weathering induced formation of kaolinite and illite. Conclusively, deteriorated drainage by formation of impermeable layers in farms with piled saprolites was caused by accumulation of clay minerals such as kaolinite and illite in macropores; illite and kaolinite can be formed by weathering of mica and feldspar, respectively.