• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.1-9
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• 2020

This paper presents the results of experimental investigation on the effect of degree of saturation of soil on the pullout behavior of a geogrid. Different test variables were taken into account while performing the experiment including the soil physical conditions based on water content and external loading applied. The soil used was locally available weathered granite soil. The tests included variations in saturation of about 90%, 80%, 70% and 45% (optimum moisture content). The pullout tests were performed according to ASTM standard D 6706-01. The results indicate that increasing the degree of saturation in the soil decreases the pull-out capacity, which in turn decreases the interface friction angle and interaction coefficient. The decrease in the pullout interface coefficient was observed to be around 12.50% to 33.33% depending on the normal load and degree of saturation of the soil. The test results demonstrated the detrimental effect of increasing the degree of saturation within the reinforce soil on the pullout behavior of reinforcement, thus on the internal stability. The practical inferences of the outcomes are analyzed in detail.

• Geotechnical Engineering
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• v.13 no.6
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• pp.13-24
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• 1997

In Korea, granite is abundant and occupies around two-thirds of the country's ground. Bven though weathered granite residual soils are widely distributed, undisturbed sampling of this soil is extremely difficult because of the particultate structure. This difficulty has kept away the researchers from investigating !he deformational characteristics of weathered granite residual soil. Thus, a special undisturbed sampling device was developed and undisturbed samples were prepared for triaxial compression (TX), resonant column(RC), and torsional shear (75) tests. Local deformation transducer (LDT) was fabricated for internal strain measurements during TX tests. Both undisturbed samples and statically compacted samples of same density were tested by using TX with LDT, RC, and 75 test equipments. The behaviour of statically compacted specimens was almost the same as that of undisturbed samples in the strain ranges below 1 percent. The stiffness and strength decreased with increasing degree of weathering. In case of undisturbed specimens, strains at failure are widely varied from 2 percent to 11 percent, and planes of failure are irrelevant to the angle of internal friction due to the inhomogeneous nature.

• Journal of the Mineralogical Society of Korea
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• v.14 no.1
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• pp.58-72
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• 2001

The Cretaceous granite, andesite and sedimentary rocks are widely distributed in the northern Pusan area. The present study investigates mineralogical and geochemical charateristics of residual and cultivated soils derived from these rocks. The soils of granite area contain a large amount of quartz relative to clay minerals, whereas the soils of the andesite area contain more clay minerals than quartz. Clay minerals consist mainly of kaolin minerals illite hydroxy interlayered vermiculite interstratified mica/vermiculite and chlorite. Kaolin minerals are abundant in paddy soils while illite is abundant in less weathered soils. Si and K are major elements in the soils of granite area while Fe and Al in the soils of andesite area. In all the soils Ca, Mg and Na were generally depleted in comparison to those in parent rocks. Analysis data of trace element show that the enrichment pattern in soils depends on parent rock type with high oncentration of some elements over 100 ppm: Ba and Rb in granite area Zn, Bn, and V in andesite area, and Ba and V in sedimentary rock. In granite area, Rb and Th were greatly enriched in soil than in parent rocks. However, Cr, Ni and Sr commonly decrease, whereas Pb increases in all the soils. Exchangeable cation capacity(CEC) is relatively high in the soils of andesite are including abundant clay minerals. Collective evidences prove that the mineralogical and chemical compositions of soils are strongly dependent on the parent rock type. The mineralogy and chemistry of long cultivated soils are not significantly different from those of residual soils.

• Geotechnical Engineering
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• v.13 no.4
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• pp.177-198
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• 1997

Since decomposed granite soil shows various characteristics of shear behavior dependent on initial conditions such as weathering degree and grain breakage, it is nacessary to invert ligate stress -strain relationship and changes of shear characteristics for different initial conditions. Associated with abovefnentioned view, direct shear tests, and triaxial compression tutsts(Ef, CD) were carried out in this study for undisturbed and disturbed compacted weathered granite samples obtained from 4 construction work sites with the various weathering degree and components of parent rocks. The deformation behavior of undisturbed samples under small confining stress shows hardening to softening, which is similar to that of over nsolidated clay whereas disturbed weathered granite soils do hardeningfonstant regardless of weathering degree, which is also similar to sedimentary clay. Conventional direct shear-tests for undisturbed samples show a tendency to overestimate cohesion. It is possidle to approximate stress ratio(q/p') and volumetric increment ratio(dv/ds) in the triaxital compression tests by an equation, ($dv/d\varepsilon,=\alpha(M-\eta))$ irrespective of moisture content, weathering degree and disturbance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2C
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• pp.117-123
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• 2008

Disturbed and undisturbed decomposed granite soils with different weathering degrees were extracted and analyzed through a series of tests (CD test, constant P test, etc.) to assess their dilatancy characteristics. Here, dilatancy refers to the volume change that takes place during shearing. As a result, the decomposed granite soil dilatancy impact increased the mean effective stress while concurrently lowering the water content in drained shear tests. In the case of undisturbed decomposed granite soil, which has a lower weathering degree, the water content increased at specific limits during the shearing process. A linear relationship of ${\Delta}V_d/V_1=D{\cdot}(({\sigma}_1-{\sigma}_3)-{\sigma}_c)/{{\sigma}_m}^{\prime}$ forms between shearing-induced volume change and principal stress variance.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.1-12
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• 2016

In this study, the impact of sand and weathered granite soil is analyzed by changing the internal temperature from $20^{\circ}C{\sim}70^{\circ}C$C by installing a heating coil inside the triaxial cell. To check the effect on weathered granite soil due to increase of temperature and number of heating-coiling cycles are analyzed by measuring the temperature by using thermometer installed inside the triaxial cell and due to that deviator stress also occurred during the consolidated undrained test. To analyze the effect of weathered granite soil with change of temperature during undrained testing. The deviator stress and pore pressure is measured. As a result, pore pressure increases and the deviator stress decreases with rise of temperature.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.69-73
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• 2009

In this study, three dimensional numerical analyses were performed with variation of pile spacing (S=3D, 4D, 5D) to compare the behaviour of single pile and pile group with cap in granite soil. In order to compare and analyze the lateral resistance of single pile and pile group by changing pile spacing, the pile group with array of $1{\times}3$ was employed. To reduce the computation time the symmetric boundary condition was used. And Druker-Prager model and elasticity model were used for granite soil and for concrete pile and cap, respectively. Using the analyses results of pile group in granite soil under lateral loading, p-y curve for pile group and single pile with changing pile spacing was drawn. With p-y curve p-multiplier was evaluated. As a result of analysis, the value of p-multiplier was increased with increasing pile spacing under 1.0 due to pile shadow effects.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.4
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• pp.2426-2438
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• 1971

Geology of the Dogdo Quadrangle consissed of metamorphosed sediments and granite. By microscopic observation the writer divided the former rocks into the feldspar quartz schist, biotite gneiss and sericite schist. The Seoul granite, which has intruded in the feldspar quartz schist, is distributed in the west half of the age Dogdo quadrangle. The Seoul granite is believed to have intruded in jurassic period, but the age of the metamorphic rocks is Pre-jurassic, though the schist and gneiss have been correlated to the Yeoncheon System of Precambrian. Soil samples were sampled from the locations where no contamination of other rockes is permitted. Results of mechanical analysis, PH and soil structure of the samples are shown, Soils from metamorphic rocks have been subjected to more weathering than granite soil though some of them have higher sorting coeffcient.

• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.367-375
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• 1990

In order to determine the effects of bedrock, organic matter, calcium and iron oxide on the soil aggregation, this research has performed with soils from bedrock regions of Limestone, Granite and Granite gneiss. This research was also to estimate how organic matter, calcium and iron oxide influence on soil aggregation under different forest conditions in various bedrock regions. And it also had a purpose to rate physical factors relevant to soil aggregation, their characteristics and aggregate diameter which closely relates to stabilities in the process of soil erosion. The following conclusions have been drawn in response to the overall research objectives. The rates of the soil aggregation on different bedrock regions were 21% in Limestone bedrock, 19.8% in Granite bedrock and 9.9% in Granite gneiss bedrock. A main factor in soil aggregation was the orgainc matter content in soils and the rate of soil aggregation increased in the constant proportion with the organic matter content. The relation could be formulated into Y=4.31X-4.37(Y : aggregation ratio X : organic matter content). The soil aggregation ratio under the deciduous forests eras higher than that under the coniferous forests. It was considered that this resulted from differences in organic matter content. Soil aggregates with larger diameter than 0.5mm were found more in Limestone bedrock than other smaller size soil aggregates of 0.25mm diameter were more distributed in Granite gneiss bedrock. Granite bedrock region had normal distribution in soil aggregate sizes with the highest frequency of 0.5mm diameter. Calcium and iron oxides had only partial influences on the soil aggregation in some specific conditions. But in Limestone bedrock region calcium influenced on the soil aggregation with the organic matter content.

• Geotechnical Engineering
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• v.6 no.1
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• pp.35-42
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• 1990

Over the years, most pavement designs based on soil strength and permanent strain are almost independent of soil elasticity. However, it was found that plasticity and elasticity of soil have both effected on the failure of pavement structures. The elasticity of soil, hence, using the resilient modulus is reflected for recent pavement design. Although the current AASHTO specifications(1986) for pavement design had changed the soil support value to the resilient modulus, triaxial devices conducting the resilient modulus test have not been fully equipped in a great majority of laboratories. Thus, in the present work, such a resilient modulus is usually derived(from CBR, K values, etc.) by estimating equations. The purpose of this study is to evaluate the resilient modulus of weathered granite soils sampled from 4 points of the central region of Korea by means of AASHTO T 274-82. According to this, some empirical equations for predicting that of the weathered granite soil are proposed and then, the relationship to convert CBR into the resilient modulus is developed.