• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.207-213
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• 1976

In order to obtain the prediction of the maximum dry density and the optimum moisture content of soil without soil moisture test, compaction test results from 157 different places either under construction or already completed were analyzed. The analyzed results were as follow The relationship between the maximum dry density and the optimum moisture content of the soil showing a correlation coefficient of 0.96 indicated that there was a high correlation between them. From the above relationship we obtained the equation, ${\gamma}_{dmax.}={\frac{1}{0.4193+0.00937W_{opt.}}$ Equation between the optimum moisture content and the maximum wet density of the soil was $W_{opt.}={\frac{0.4193{\gamma}_{tmax.}}{0.937_{\gamma}_{tmax.}-0.01}$, and the values of the optimum moisture content being predicted with the maximum wet density of the soil showed a little difference between those and tested values. The values of the maximum dry density being predicted with the moisture content estimated by the maximum wet density of the soil were within the range of ${\pm}5%$ of its tested values. The relationship between the dry density and the void ratio showed a high correlation between them (${\gamma}=0.9706$). From the above relationship, we obtained the equation, ${\gamma}_{dmax.}={\frac{1}{0.3938+0.3426e}}$.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.61-72
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• 2001

A barrier liner system is placed at the bottom and side slope in landfill to protect a leaking of leachate that the hydraulic conductivity of this system should be less than It 107cm/sec. In this study, the soil-bentonite mixture for the bottom liner system was evaluated in two point of views : changing characteristics of the hydraulic conductivity according to the different mixing ratio of soil-bentonite with the effect of bentonite swelling and the difference method (A & D type) of compaction on the hydraulic conductivity. As the results, maximum dry density (${\gamma}$$_{dmax}$) of SC group mixture was higher than of CL group mixture. However, the result of optimum moisture contents(OMC) of both groups were the contrary. In case of ${\gamma}$$_{dmax}$ by different compaction method, D type was higher than A. But the OMC were the contrary. The difference of ${\gamma}$$_{dmax}$ according to the Compaction energy, “SC” group mixture W3S higher than the “CL” group. In case of OMC of “CL” group was higher than “SC” group. The effecting of swelling was a little bit different on the two factors. According to the result of compaction test, the use of site soil only could not meet the criteria on hydraulic conductivity, but could find a solution for the mixing ratio of bentonite mixture were satisfied to the standard of barriation. The increased in bentonite mixing ratio and degree of swelling, the values of hydraulic conductivity were decreased. Especially the “CL” group with “D” type compaction measured the lowest value with the same conditions. Also, the bentonite mixing ratio has more influenced on the hydraulic conductivity compare with swelling effect. The “SC” group mixture with “A” typo compaction got a big difference from others. The evaluation of economic for the construction cost on the two cases, the lower bentonite mixing ratio of soil-bentonite mixed soil is more economically because of bentonite cost.

• Geotechnical Engineering
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• v.11 no.4
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• pp.37-48
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• 1995

The dynamic behavior of dry sand under different vibration conditions is studied through laboratory experiments. Sinusoidal and random vibration experiments of sand are carried out in vertical direction under various surcharge loads. Five different sand samples are selected for the azperiment. They are composed of four different -size samples of particles and one sample which is simulated the field condition. In case of sinusoidal vibration, the change in relative density is measured with acceleration levels. To produce an acceleration, the vibration amplitude is maintained within the range of 0.4mm~0.6mm and the vibration frequency is changed within the range of 3Hz~40Hz. In case of random vibration, the combined sinusoidal acceleration is produced by a random vibration generator and the change in relative density is measured by an accelerometer. Based on the experimental results, it is found that the sandy soil is compacted to 94%~99% of relative density by vertical acceleration and the peak acceleration producing the maximum relative density is proportional to the difference between maximum and minimum void ratios. It is also found that the effect of surcharge loading : the greater the surcharge loading, the larger the change in relative density and the greater the acceleration required to change the relative density.

• Journal of the Korean Geotechnical Society
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• v.38 no.10
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• pp.41-48
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• 2022

The mass density of the medium (ρ) used to calculate the maximum shear modulus (G_max) of the saturated ground based on the shear wave velocity is unclear. Therefore, to determine the mass density, a verification formula and five scenarios were established. Laboratory tests were conducted, and the obtained results were compared. The mass density of the medium was assumed to be saturated (ρ_sat), wet (ρ_t), dry (ρ_dry), and submerged conditions (ρ_sub), and the V_s ratios of saturated to dry condition were obtained from each case. Assuming the saturated density (ρ_sat), the V_s ratio was consistent with the value from the resonant column test (RCT) results, and the value from the bender element test results was consistent with the wet density assumption (ρ_t). Considering the frequency range of earthquakes, it is concluded that applying the saturated density (ρ_sat) is reasonable as in the RCT results.

• Journal of the Korean Geosynthetics Society
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• v.7 no.3
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• pp.17-24
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• 2008

This study is conducted to investigate the possibility of the utilization of the mixed soil formed by mixing stone sludge, bentonite, and residual soil as a soil sealant sustaining both stability and capacity in the barrier system. A series of tests were performed on the mixed soils to evaluate basic properties such as compaction, compressive strength, permeability and CBR of these materials. The results indicates that as the stone sludge content increases, the optimum moisture content increases a little, but the maximum dry density decreases. The compressive strength and CBR decrease, and the cohesion, internal friction angle and expansion ratio increase. When the bentonite content increases, the maximum dry density decreases, and the optimum moisture content, compressive strength and cohesion, internal friction angle, CBR and expansion ratio increase. Mixing ratio of the mixed soil contained with the stone dust more than 10% and the bentonite less than 10% satisfies the standard of the permeability coefficient as the soil sealant.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.59-66
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• 2007

In order to clarify the influence of gravel content on the mechanical properties of gravel-mixed decompose granite soils, large-scale one-dimensional compression tests were performed. The sample used in the study was a decomposed granite soil from Shimonoseki in Yamaguchi prefecture in Japan. After adjusting the grain size of the said soils, the specimen compacted with a certain level of compaction energy was put to the test. Based on the results obtained, when gravel-mixed decomposed granite soil was compacted at the same energy level, there existed the specific gravel content at which dry density was maximum and which also produced the minimum compression index. Furthermore, from these results, an expression based on a two-phase mixture theory was proposed to quantitatively evaluate the effects of gravel content and initial dry density and the material parameters calculated through the proposed method proved to exactly estimate the actual measuring value.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.231-237
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• 1986

Under the different conditions of planting density and nitrogen level with aromatic tobacco, some agronomic characters of tobacco like plant height, leaf size, LAI, yield and price were investigated in view of aroma volatile acid contents, the main compounds contributing to the aroma of oriental leaf tobacco. The closer a spacing interval became, the smaller the growth of plant and the leaf size with increment of yields, until about 22,000 plants per 10 are. But the leaf size became smaller without increment of yield when the planting density became more than 22,000 plants per 10 are. There were definite trends toward increase in leaf size, LAI and yield with increase in nitrogen rate. Correlation coefficient between aroma volatile and plant height, largest leaf length, one leaf area was -0.49, -0.49 and -0.47, respectively, showing significance at 1 % level. But LAI (r=-0.14) and dry weight of unit leaf area(r=0.25) was not observed to be significantly associated with aroma volatile, respectively. The results suggest that closer spacing is desirable for smaller leaves, higher contents of aroma volatile and for increased yield.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.54-62
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• 1994

The hydraulic properties of domestic natural clay/crushed rock mixture suggested as a candidate backfill material for the low and intermediate level waste repository were investigated. The dry density-water content relationship was studied to define an optimum water content that gives a maximum attainable dry density at constant compaction pressure. The hydraulic conductivities of clay/crushed rock mixture as a function of clay content were also measured. As the clay content decreased, the maximum attainable dry density increased and the optimum water content became more distinct. However the attainable density is not significantly sensitive to water content. The hydraulic conductivities of the mixture increased from 5 $\times$ 10$^{-12}$ m/s to 7 $\times$ 10$^{-10}$ m/s with clay content decreasing from 100 wt.% to 25 wt.% at dry density of 1.2 Mg/㎥. In case of dry density of 1.5 Mg/㎥, they maintain the lower values of 5 $\times$ 10$^{-12}$ m/s even at 25 wt.% clay content. The concept of effective clay dry density was suggested to estimate the hydraulic conductivity of the mixture. It was shown that the effective clay dry density concept can explain welt the hydraulic conductivities of the mixtures with various dry density and crushed rock content.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.169-175
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• 1992

The Maximum Dry Density (${\gamma}_{dmax}$) and the Optimum Moisture Content (${\omega}_{opt}$) of the soil samples are determined from the compaction curve plotted with the laboratory compaction test results. But in this study three reported tests, and tests on the silty clay and the sandy silt samples are reviewed through the interpolation methods using an equation of the Moisture-Density relations induced from Lagrange's Interpolation Formula without drawing the compaction curves. As the results of the study ${\gamma}_{dmax}$ and ${\omega}_{opt}$, were calculated rapidly and simply using the equation and approached to the results from the compaction curves, and also due to the differences of the ${\gamma}_{dmax}$ and ${\omega}_{opt}$, calculated from the equation between the compaction curves were within $0.01g/cm^3$(0.5%) and 0.4% respectively the method in this study be recommended as a simple method determining ${\gamma}_{dmax}$ and ${\omega}_{opt}$, during the laboratory compaction tests.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.69-78
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• 2016

A suction bucket foundation has been considered to be a potential foundation type for offshore wind turbines. A suction bucket foundation is usually installed in soft soil, so the accumulated displacement of the foundation may occur under long-term cyclic loads. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The dry model ground was prepared to have two different soil densities by air-pluviation method. The model tests were performed varying the embedment depth of the suction bucket, the soil density, and the amplitude of cyclic load. A one-way horizontal cyclic load was applied over $10^4$ cycles. Test results showed that the accumulated rotation of the suction bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the suction bucket foundations in dry sandy ground under long-term cyclic horizontal loads.