• Journal of the Korean Geosynthetics Society
• /
• v.7 no.4
• /
• pp.9-18
• /
• 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
• /
• v.10 no.4
• /
• pp.25-31
• /
• 2009

In this study, the problem of existing soil pavement is a long-term durability lack and crack occurrence. It complements in order to develop the environmental soil pavement material which composites readily blended mineral binder of liquid and decomposed granite soils. It was estimated optimal mixture proportion for unconfined compressive strength, permeability, $Cr^{6+}$detection test, SEM test with age, freezing and thawing test. It resulted mixture proportion of powder types mineral binder for rates of cement : fly ash : plaster was optimal rates of 50 : 33 : 7, and $Cr^{6+}$detection test as a result was a slight production. SEM test with 3days as a result was made Ettringite. It was found that this material was early development of early-strength for chemical. This study indicated that it will execute field appliciability Evaluation test, examination of soil pavement method with decomposed granite soils and mineral binder.

• Korean Journal of Plant Resources
• /
• v.32 no.4
• /
• pp.290-295
• /
• 2019

This study was carried out to select the optimal condition for prothallus propagation and sporophyte formation of Leptogramma pozoi (Lag.) Ching subsp. mollissima (Fisch. ex Kunze) Nakaike and to provide basic data for mass production system. In the propagation, 300 mg of prothallus were inoculated in different kinds of medium [1/4, 1/2, Murashige and Skoog (MS), Knop], sucrose (0, 1, 2, 3, 4%), and cultured for 8 weeks. Sporophyte formation studies were carried out by inoculating blended prothallus into artificial soils. The soils were mixed with horticultural substrate, peatmoss, perlite, and decomposed granite at different ratios or only with the horticultural substrate. Then the prothallus was cultivated for 12 weeks to figure out the formation and growth of the sporophytes. The growth and development of prothalli were excellent on MS medium. According to medium components, prothallus growth was favorable in all treatments except 0% sucrose treatment and the highest in 2% sucrose. In the experiment of soil mixtures, sporophyte formation was the highest in the horticultural substrate:perlite 2:1 (v:v) and horticultural substrate:decomposed granite 2:1 (v:v) treatment, and the overall growth was good in the horticultural substrate:decomposed granite 2:1 (v:v) mixed soil.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.5 no.1
• /
• pp.206-217
• /
• 2001

The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows ; 1) The relationships among Nc, Li and CEC, Li>6%, CEC>14 corresponds to Nc=2~30, and 4%${\phi}$)increases at a standard pressure. 3) And Nc=0~50 corresponds to $27{\sim}50^{\circ}$ of internal fiction angle and to 12~49kPa of cohesion. That is to say, internal friction angle(${\phi}$)corresponds better than cohesion(c). In conclusion, this study suggests that in simplified dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a completely weathering soil. It also appears that CEC increases as Li increases while Nc decreases.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.7 no.6
• /
• pp.84-93
• /
• 2004

This study was carried out to select proper species for early stage replantation in granite forest roads cut-slope. From two to sixteen year elapsed forest roads in four regional areas of Gangwon-do, sample plots were selected, and their vegetations and environmental factors were investigated. Soil organic matter, total nitrogen, soil moisture content, and bulk density in the decomposed granite soils were below 1.32%, 0.08%, 10.0%, and above 1.24g/$cm^3$, respectively. The result indicated that the soil was not good for plant growth. The environmental factors affecting distribution of species in the granite forest roads were the elapsed year, cut-slope, elevation, and cut-slope aspect. Species with high frequency in the granite forest road cut-slope ordered Lespedeza bicolor, Rubus crataegifolius, Pinus densiflora, Lysimachia clethroides, Amorpha fruticosa, Dactylis glomerata, Lespedeza cyrtobotrya, Festuca arundinacea, Spodiopogon sibiricus, Artemisia stolonifera, and Weigela subsessilis. Herbs seeded in earth stage such as Dactylis glomerata, Lolium perenne, and Festuca arundinacea had changed into perennial herbs such as Carex lanceolata, Poa sphondylodes, Patrinia villosa, Artemisia princeps var. orientalis, Spodiopogon sibiricus, Melica onoei, Artemisia keiskeana, Artemisia stolonifera, Astilbe chinensis var. davidii, Spodiopogon sibiricus, and those had changed into shrubs such as Rubus crataegifolius and Weigela subsessilis, and those had changed into trees such as Salix hulteni, Salix koreensis, and Fraxinus rhyncholhylla according to elapsed year of forest roads. Legumes such as Lespedeza sp., Pueraria thunbergiana, Amorpha fruticosa, etc., herbs such as Artemisia keiskeana, Artemisia princeps var. orientalis, Artemisia stolonifera, Astilbe chinensis var. davidii, Spodiopogon sibiricus, Miscanthus sinensis, etc., and woody plants such as Pinus densiflora, Rubus crataegifolius, Weigela subsessilis, Zanthoxylum schinifolium, Rhododendron mucronulatum, etc., with foreign herbs were considered as proper species for replantation in granite forest road cut-slope.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.5
• /
• pp.48-58
• /
• 2003

This study was carried out to select proper species for early stage replantation in granite forest road cut-slope. From one to thirteen year elapsed forest roads in five regional areas of Chungcheong-do and Kyungsangbuk-do, sample plots were selected, and their vegetations and environmental factors were investigated. Soil organic matter, total nitrogen, soil moisture content, and bulk density in the granite weathering soils were below 0.5%, 0.02%, 10%, and above 1.2g/$cm^3$, respectively. The environmental factors affecting distribution of species in the granite forest road were the elapsed year, elevation, cut-slope aspect, and cut-slope. Sowing plants of Dactylis glomerata, Lolium perenne, and Eragrostis curvula were found in the early stage of forest road-cut. Annual herbs of Youngia denticulata, Erigeron annuus, etc. were found in the 2-3 years elasped forest road-cut. Perennial herbs of Artemisia princeps var. orientalis, Miscanthus sinensis, etc., parachute woody plants of Weigela subsessilis, Pinus densiflora, etc., and gravitative trees of Prunus sargentii, Lindera obtusiloba, Quercus sp., etc. were found in the forest road cut-slope after 3 years of road-cut. Leguma of Lespedeza cureata, Amorpha fruticosa, Lespedeza bicolor, Pueraria thunbergiana, Albizzia julibrissin, etc., herbs of Artemisia keiskeana, Artemisia princeps var. orientalis, Miscanthus sinensis, etc., and woody plants of Rubus crataegifolius, Weigela subsessilis, Zanthoxylum schinifolium, Pinus densiflora, etc. were considered as proper species for replantation in granite forest road cut-slope.

• Geotechnical Engineering
• /
• v.10 no.3
• /
• pp.55-78
• /
• 1994

Decomposed granite soil is a Granitic Gneiss, and it is a c Korean peninsula. It is known a changed significantly when it is aim of this study is to evaluat utility of the constitutive laws. Firstly, triaxial tests were pe sites prepared by the laborato scrutinized the characteristics results were analysed and the p evaluated. Finally, the predicted Even though the origins of slight difference in the angle of pression line( A) : both soils show In the effective mean normal uniqueness of the Normal Compr The relationships between the the decomposed granite soil tier OCR is larger than 2, the stress stress(MDS) or. even thous moved below the theoretical Ros was found to coincide with the (NC) soils, the pore pressure parameter, A,, increased up to 1.3. This phenomenon might be mainly due to the effect of the particle crushing during shearing, When the OCR value approaches 7, the negative pore pressure is developed in undrained tests and the dilatancy is observed in drained tests. The predicted and the observed behavior of drained tests showed relatively good fitting with the Cam-Clay model.

• Horticultural Science & Technology
• /
• v.35 no.4
• /
• pp.480-489
• /
• 2017

We investigated a suitable method for in vitro germination of spores, propagation of prothalli, and the formation of sporophytes in the fern Dryopteris nipponensis Koidz. Spore germination rate was relatively high regardless of culture medium. Prothallus development was faster in Knop medium than in Murashige and Skoog (MS) media. Prothalli used in all experiments were obtained from germinated spores, and were cultivated in different concentrations of media components. The active formation of sexual organs such as antheridium made 1MS medium suitable for prothallus propagation, although there was a lower propagation ratio compared to Knop medium. Growth and morphogenesis of prothalli were most effective on 1MS medium containing 2% sucrose, and 60 mM of total nitrogen source with 20:40 mM ratio of $NH_4{^+}:NO_3{^-}$. To select a suitable soil composition for sporophyte formation, ground prothalli were cultivated on single and mixed soils using bed soil, peat moss, perlite, and decomposed granite for 14 weeks. Bed soil promoted sporophyte formation and growth regardless of single or mixed use. In particular, a mixture of bed soil and decomposed granite in a 2:1 ratio (v:v) led to accelerated sporophyte formation ($0.83/cm^2$).

• Journal of Korean Society of Forest Science
• /
• v.86 no.2
• /
• pp.186-199
• /
• 1997

The soils derived from granite gneiss occupy almost one third of the land area in Korea. The soils under forest vegetation, formed on granite gneiss, in Sun chon-shi, Chollanam-do in southern part of Korea, were studied to evaluate the weathering and the transformation of primary minerals into secondary minerals, clay minerals. The studied soils contained large amounts of ferromagnesian minerals, weathered biotites and were well weathered, strongly acid and low in organic matters and in ration exchange capacity. The clay contents in the Bt horizon were almost two times higher than those in the C horizon. The O horizon had a thin layer which consisted of a little decomposed plant components with a granic fabric and high porosity, and showed the micromorphological characteristics of moder humus. The related distribution pattern of the E horizon were enaulic and large amounts of silts and small amounts of sand grains were another characteristics of the E horizon. The most striking micromorphological features were multilaminated clay coating and infillings in the voids in the Bt and C horizons, and generally limpid ferriargillans ejected from the biotites and imparted red color to the soils in the Bt horizon. High clay contents in the Bt horizon was not only due to clay translocation, but also due to intensive in situ mineral weathering in this horizon. The most significant pedogenic process, revealed by the petrographic microscope and SEM, was the formation of iron oxides from biotites, the formation of tubular halloysites and the weathering models of biotites; wedge weathering and layer weathering. The thick coating on the weathering biotites showed the characteristics of the weathering process and the synthetic hematites were revealed in clays by TEM. Total chemical analysis of clays revealed extensive loss of Ca, and Na and the concentration of Fe and Al. Mineralogical studies of clays by XRD showed that micas were almost completely weathered to kaolinite, vermiculite-kaolinite intergrade, hematite, gibbsite, while halloysites from other primary minerals. Some dioctahedral mica appeared to be resistant in the soils. Parent rock of the soils contained a considerable amounts of biotites and this forest soils showed especially a dominant characteristics of biotite weathering.

• Proceedings of the KSR Conference
• /
• 2001.05a
• /
• pp.451-458
• /
• 2001

The purpose of this study was to evaluate shear parameters on cutting slope of weathered granite soils by using small dynamic cone penetration test on the very moment of its cutting. The results were : On the relations among N$\_$c/, Li, and CEC, the condition of Li＞6%, CEC＞14(meq/100g) corresponds to that of N$\_$c/ values of 2∼30, and 3＜CEC＜14(meq/100g) to N$\_$c/=30∼50. Comparing the smallest penetration depth from two small dynamic cone penetration tests done at 5m below from the top of the slope on April 15th, October 31t. there was a l0cm difference. So we could find out the degree of weathering on the slope. And dividing the difference by 190 days (the whole testing time), we could know it's being weathered 0.052mm each day. The more N. value increases, the more shear parameters(internal friction angle ; $\phi$, cohesion : c) increase at a standard pressure($\sigma$＞32㎪). So the condition of N$\_$c/=2∼50 corresponds to that of $\phi$=27∼50, c=12∼49㎪. From the above testing results, the N$\_$c/ values more correspond to $\phi$ values than c values. In conclusion, this study suggests that on small dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a strong weathering soil. It also shows that as Li increases CEC increases as well, while N$\_$c/ decreases.