• The Journal of Engineering Geology
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• v.13 no.3
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• pp.335-344
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• 2003

This study is focused to the physical and shear strength properties of the weathered limestone soils distributed in Changsung and Hwasun area, Chonnam province. Disturbed soil was used as soil samples. To grasp the physical and shear strength properties of weathered limestone soil, specific gravity test, atterberg limit, grain size distribution and direct shear test were conducted in the laboratory. The physical and shear strength properties of the weathered limestone soil in the study areas are as follows. The range of specific gravity (Gs) is 2.78 to 2.80, liquid limits (LL) 37 to 38 (%), plasticity index (PI) 13.7 to 15.4, and soil classification CL. The range of strength parameters by direct shear test (vd, $1.5t/\textrm{m}^3$) is 3.07 to 4.4 ($t/\textrm{m}^2$) of cohesion and 34.8 to $42.4^{\circ}$ of internal friction angle in unsaturated soils. As a result of comparing with the weathered granite soils (Yang, 1997: Mun, 1998: Park, 1998), it is considered that physical properties of the weathered limestone soils in this study are different from the weathered granite soils. On the other hand, internal friction angle of shear parameters is found to be similar.

• Korean Journal of Soil Science and Fertilizer
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• v.31
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• pp.36-44
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• 1998

우리 나라에서 토양의 점토광물에 관한 최초의 연구는 1958년 김제지방의 답 토양에 관한 연구로 (Dewan, 1958)시작되었다. 1960년대 시작하여 1970년대 까지는 주로 토양점토광물의 동정이 이루어 졌다. 점토광물의 동정(同定)에 사용된 잔적토(殘積土)(Residual Soil)로는 화강암(花崗岩), 화강편마암(花崗片麻岩), 현무암(玄武岩), 석회암(石灰岩), 혈암(頁岩), 제(第)3기층(紀層), 홍적층(洪積層) 유래 토양과 토양종류별(土壤種類別)로는 과부식회색토(寡腐植灰色土), 염류토(鹽類土), 충적토(沖積土), 적황색토(赤黃色土), 화산회토(火山灰土), 퇴적토(堆積土), 갈색토(褐色土), 암쇄토(岩碎土), 저위생산답(低位生産畓)이였으며, 토양점토광물(土壤粘土鑛物)과 작물수량성(作物收量性) 관계에 관한 연구가 실시되었다. 1980년대에 들어와서는 토양중의 1차광물과 점토광물의 풍화에 대한 안정도와 1차광물의 동정이 행해졌으며, 이밖에 Kaolinite 입자의 전하에 관한 연구등 점토광물의 흡착과 활성 연구, 점토광물의 토양개량재로서의 흡착과 화학적 특성 변화 연구와 점토광물의 토양개량 시용효과에 관한 연구가 행해졌다. 1990년대에 들어와서는 토양 중의 1차광물과 점토광물의 정량에 대한 자료가 축척되었고, 토양의 풍화에 대한 안정성과 생성기작, Zeolite와 새로운 광물이 합성되었다. 또한 합성광물을 이용한 농업과 산업광물로의 응용성 환경 산업에서의 적용가능성에 대한 평가가 시도되었다. 토양의 점토광물의 조성에 관한 연구는 토양 모재를 중심으로 이루어졌는데, 화강암(花崗岩)에서는 Halloysite, 화강편마암(花崗片麻岩)에서는 Kaolinite, Metahalloysite, Illite, 산성암(酸性岩)에서는 Kaolinite, Venrmiculite와 Chlorite의 중간광물, 현무암(玄武岩)에서는 Illite, Kaolinite, Vermiculite, 석회암(石灰岩)에서는 Vermiculite-Chlorite 중간광물, Kaolinite와 Illite, 혈암(頁岩)에서는 Kaolinite, Halloysite, Illite 외 Vermiculite-Chlorite, 화산회토(火山灰土)에서는 Allophane이 주광물이었다. Soil Taxonomy와 토양광물과의 관계에서, 답 토양에서는 Entisols의 주점토광물은 2:1형과 1:1형 광물이지만 Inceptisols와 Alfisols에서는 Halloysite가 대부분이다. 밭 토양의 경우는 Alfisols의 주점토광물은 Vermiculite, Illite, Kaolinite이었고, Ultisols에서는 Vermiculite-Chlorite 중간광물이었다. 산림토양에서는 Inceptisols중에서 Andept는 Allophane, Alfisols에서는 2:1 광물이지만, Ultisols에서는 Halloysite이다. 모재별 조암 광물의 풍화와 점토광물의 생성과정에서 화강암(花崗岩)과 화강편마암(花崗片麻岩)의 장석류(長石類)는 kaoline광물로, 이 밖의 운모광물(雲母鑛物), 녹니석(綠泥石), 각섬석(角閃石), 휘석(輝石)으로부터 생성된 illite, chlorite, vermiculite는 풍화중간에 혼층단계(混層段階)를 거쳐서 kaoline 광물로 풍화된다. 석회암(石灰岩) 토양의 smectite가 Mg농도가 높은 토양용액으로부터 침전되어 생성되었거나 운모 또는 chlorite에서 유래된 vermiculite의 변성작용에 의해 생성되고, 혈암(頁岩)토양의 점토에 illite가 주로 풍화에 저항성이 큰 미립자의 함수백운모(含水白雲母)로부터 유래되며, 현무암(玄武岩) 중의 장석류(長石類)는 kaoline광물로, 휘석(輝石)은 chlorite${\rightarrow}$illite의 풍화과정을 거친다. Zeolite, 함불석 Bentonite, Bentonite 등 우량점토 광물이 분포과 광물조성, 이화학적 특성이 조사되었고, 토양의 물리적, 화학적 성질의 개선을 필요로 하는 토양의 개량을 위해서 Bentonite, Zeolite, Vermiculite 등의 토양 개량재(改良材)로서의 기초연구와 이들 개량재 시용효과에 관한 연구 등이 주로 논토양에서 수행되었다. 점토광물과 수량관계를 보면 Montmorillonite를 주점토광물로 함유된 답 토양의 수도수량이 1:1 광물을 주점토광물로 함유하고 있는 토양에서의 수도수량 보다 높았다. 토양광물에 관한 기초연구(基礎硏究)로서 양이온교환능과 포화이온의 영향, 입자의 전기화학적 성질, 흡탈착 성질, 표면적과 등전점, 해성점토에 대한 압밀점토(壓密粘土)의 변형율(變形率)의 추정 등이 주로 연구되었다. 부가가치가 낮거나 폐기되는 광물을 이용하여 토양개량재 혹은 흡착제를 형성하는 연구가 알카리 처리에 의한 Zeolite 합성에 집중되었다.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.9-17
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• 2005

A set of soil samples were picked up from a failed slope formed by rainfall in limestone zone in Jangseong-gun, Jeonnam, Korea, to find out its physical and mechanical characteristics for this study, and variation of safety factor depending on slope inclination was defined by analysing slope stability affected by rainfall. Decomposed limestone soil in the research area is composed of quartz, orthoclase, gibbsite, geothite, etc., with specific gravity of 2.73, and this soil is included in SC by unified soil classification system. Calcium ingredient decreased remarkably during weathering at its mother rock. Coefficient of permeability is 2.56×10/sup -4/ cm/ sec, similar to its value of silty clay. Cohesion decreases remarkably from 3.0 t/ ㎡ to 0.72 t/ ㎡, and Φ value of internal friction angle tends to decrease as it turns to be saturated soil from partial saturated soil in the shear test. To analyze slope stability affected by rainfall, it is reasonable to seek seepage depth with reference to rainfall＊ intensity. In the slope stability analysis, when the seepage depth is the larger, its safety factor is the less, which makes the slope unstable. Comparing with minimum safety factor, 1.5 of cut slope in consideration of the seep-age line, safety factor is found to be satisfactory only when inclination of cut slope of decomposed limestone soil is more than 1：1.2 slope at least considering rainfall. It is also found that decrease of cohesion has great effect on decline of safety factor of slope while partial saturated soil turns to be saturated soil.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.427-438
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• 2023

We carried out a geological survey to classify the types of mass movement in Danyang Geopark (where various rock types are distributed) and analyzed the mechanical and hydraulic characteristics of landslide materials using a series of laboratory tests. Debris flows occurred in areas of limestone/marble, shale, and porphyroblastic gneiss, and limestone/marble landslides were distinguished from the others through the presence of karren topography. Soil tests showed that soil derived from weathered gneiss, which has a higher proportion of coarse grains, has a higher friction angle, lower cohesion, and larger hydraulic conductivity than soils from areas of limestone/marble, and shale. Rock failure mass movements occurred in areas of phyllite, sandstone, and conglomerate and were subdivided into plane failure, block-fall, and boulder-fall types in areas of phyllite, sandstone, and conglomerate, respectively. The shear strength of phyllite is much lower than that of the other types of rock, which have similar rock quality. The slake durability index of the conglomerate is similar to that of the other rock types, which have similar degrees of weathering, but differential weathering of the matrix and clasts was clearly observed when comparing the samples before and after the test. This study can help establish appropriate reinforcement and disaster prevention measures, which depend on the type of mass movement expected given the geological characteristics of an area.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.1-17
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• 2014

This study analyzed characteristics of landform relieves on 12 bedrock whole(W) areas and 24 mountain(M) and valley(V) areas. Based on this result, characteristics and relations between bedrocks and landform relief were classified as follows. 1) gneiss-height M and granite-height W, M, V areas show active stream incision for uplift. However these areas have relatively low relief and grade compared to high altitude, because effect of denudation don't pass on whole slope. 2) gneiss-height W, V, gneiss-mid M, schist M, granite-mid M, volcanic rock W, M, sedimentary rock-height(conglomerate) W, M, V, sedimentary rock-mid (sandstone and shale) M, limestone W, M areas have active stream erosion and mass movement, but landform relieves are on the high side, because these have resistant bedrock and geological structure against weathering and erosion. 3) gneiss-mid W, V, schist W, V, granite-mid W, V, volcanic rock V, sedimentary rock-mid W, V, sedimentary rock-low(shale) M, limestone V areas landform relieves are on the low side, because these have weak resistance and active weathering, mass movement, erosion, transportation and deposit. 4) gneiss-low W, M, V, granite-low W, M, V, sedimentary rock-low W, V areas landform relieves are very low, because these don't have active erosion and mass movement as costal area with low altitude.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.414-419
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• 1998

The contribution of soil organic matter on the soil surface charge characteristic of paddy and upland soils weathered from granite or limestone was evaluated. The surface charge characteristics of the soils with and without soil organic matter by pre-treatment with hydrogen peroxide was determined at pH 3.5~9.0 range using the ion adsorption method. Regardless of soil organic matter removal, the soil surface negative charge increased linearly by the increase of pH with high statistical significance at all kinds of soils. Here, the differential increasement of soil surface negative charge by pH inclease, dCEC/dpH, was proposed as the parameter of pH dependency of the soil surface charge. The dCEC/dpH of soils with organic matter was in the range of 0.91~4.59, while it was dramatically decreased to the range 0.16~1.91 by the removal of organic matter. The soil surface charge derived from soil organic matter ranged from 15% to 82% to the total amount of surface charge. The magnitude of surface charge carried by 1% of soil organic matter showed considerable differences between soils from 0.22 to $5.03cmol^+\;kg^{-1}$. The effect of soil organic matte on the dCEC/dpH was higher in paddy soils with high oxalic acid extractable Fe than upland soils.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.35-52
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• 1973

Red Yellow Soils occur very commonly in Korea and constitute the important upland soils of the country which are either presently being cultivated or are suitable for reclaiming and cultivating. These soils are distributed on rolling, moutain foot slopes, and terraces in the southern and western parts of the central districts of Korea, and are derived from granite, granite gneiss, old alluvium and locally from limestone and shale. This report is a summary of the morphology, physical and chemical characteristics of Red Yellow Soils. The data obtained from detailed soil surveys since 1964 are summarized as follows. 1. Red-Yellows Soils have an A, Bt, C profile. The A horizon is dark colored coarse loamy or fine loamy with the thin layer of organic matter. The B horizon is dominantly strong brown, reddish brown or yellowish red, clayey or fine loamy with clay cutans on the soil peds. The C horizon varies with parent materials, and is coarser texture and has a less developed structure than the Bt horizon. Soil depth, varied with relief and parent materials, is predominantly around 100cm. 2. In the physical characteristics, the clay content of surface soil is 18 to 35 percent, and of subsoil is 30 to 90 percent nearly two times higher than the surface soil. Bulk density is 1.2 to 1.3 in the surface soil and 1.3 to 1.5 in the subsoil. The range of 3-phase is mostly narrow with 45 to 50 percent in solid phase, 30 to 45 percent in liquid one, and 5 to 25 percent in gaseous state in the surface soil; and 50 to 60 solid, 35 to 45 percent liquid and less than 15 percent gaseous in the subsoil. Available soil moisture capacity ranges from 10 to 23 percent in the surface soil, and 5 to 16 percent in the subsoil. 3. Chemically, soil reaction is neutral to alkaline in soils derived from limestone or old fluviomarine deposits, and acid to strong acid in other ones. The organic matter content of surface soil varying considerably with vegetation, erosion and cultivation, ranges from 1.0 to 5.0 percent. The cation exchange capacity is 5 to 40 me/100gr soil and closely related to the content of organic matter, clay and silt. Base saturation is low, on the whole, due to the leaching of extractable cations, but is high in soils derived from limestone with high content of lime and magnesium. 4. Most of these soils mainly contain halloysite (a part of kaolin minerals), vermiculite (weathered mica), and illite, including small amount of chlorite, gibbsite, hematite, quartz and feldspar. 5. Characteristically they are similar to Red Yellow Podzolic Soils and a part of Reddish Brown Lateritic Soils of the United States, and Red Yellow Soils of Japan. According to USDA 7th Approximation, they can be classified as Udu Its or Udalfs, and in FAO classification system to Acrisols, Luvisols, and Nitosols.

• Journal of Korean Society of Forest Science
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• v.54 no.1
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• pp.25-35
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• 1981

Some physical and chemical properties of forest soils in Korea were analyzed for providing the reasonable management methods of forest lands, Among 375 soil series surveyed until 1979, 93 soil series of forest soils were classified and analyzed according to their characteristics. Firstly soil data were classified into 5 categories by weathered products and secondly were classified and analyzed by parent rocks. The results are as follows: 1) In forest soils characterized by weathered products volcanic ash soils were proved to be the most fertile and alluvial soils were turned out to be the most infertile soils. Residual soils on mountain and hill were mostly on the average in all kinds of soil properties analyzed except total soil depth. 2) Igneous rocks developed rather infertile soils containing large amount of organic matter and available $P_2O_5$ with relatively deep soil depth and strong acidity. On the other hand sedimentary rocks produced rather shallow soils containing small amount of organic matter and available $P_2O_5$ but they were relatively fertile with weak acidity. 3) Among igneous rocks basalt and trachyte produced very fertile soils and granite and andesite produced slightly infertile soils. 4) Among sedimentary rocks limestone soils had high fertility neutral in acidity but low amount of available $P_2O_5$ 6) Alluvial sand produced generally very infertile soils with great soil depth comparing with the arable alluvial land with high fertility.

• Journal of Korean Society of Forest Science
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• v.47 no.1
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• pp.52-61
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• 1980

This study is carried out to learn the properties of forest soils in Korea and propose the reasonable management methods of forest land. Among 178 soil series surveyed until now in Korea forest soils include 64 series broken down according to the weathered products into 5 categories such as residual materials on mountain and hill, residual materials on rolling and hill, colluvial materials on local valley and fans, alluvial materials and volcanic ash soils. What discussed in this paper are classification system, parent rocks, texture class and drainage conditions of Korean forest soils. The characteristics of Korean forest soil properties classified in U.S.D.A. soil classification system are as follows: 1. Residual soils on mountain and hill (29 soil series) are almost Lithosols without any distinct soil profile development. They have loamy skeletal (11 series), coarse loamy (5 series), fine loamy (3 series), and fine clayey soils (3 series). Their drainage conditions are somewhat excessively drained in 16 series and well drained in 7 series. 2. Residual soils on rolling and hill (19 series) are Red-Yellow Podzolic soils with well developed soil profiles. They have coarse and fine loamy texture in 12 series and fine clayey texture in 5 series mostly with well drained condition. 3. Colluvial soils on local valley and fans (13 series) include mostly Regosols and some Red-Yellow Podzolic Soils and Acid Brown Forest Soils. They have loamy skeletal (4 series), coarse loamy (3 series), fine loamy (3 series), and fine clayey soils (2 series) with well drained condition. 4. Soil textures of weathered products of parent rocks are as follows: 1) Parent rocks producing coarse texture soils are rhyolite, granite gneiss, schist, shale, sandstone, siltstone, and conglomerate. 2) Parent rocks producing fine and heavy texture soils are limestone, basalt, gabbro, and andesite porphyry. 3) Granite is a parent rock producing various textured soils.