• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.493-500
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• 1999

In 1990's, two types of land consolidation has been widely carried out to enforce competativeness of rice production in Korea. One is so called large-scale land consolidation for resizing paddy field and farm road, the other is general land consolidation for changing both size and shape of field, water channel and farm road. This study was conducted to evaluate how much effect on fm mechanization the land consolidation had. To evaluate the influence of the land consolidation, theoretical analysis and surveys were accomplished. Land consolidation was analyzed to increase field efficiency by 180 to 670% depending on the type of land consolidation and machine selection. Also, land consolidation brought increment of real working time ratio by reducing traveling time on farm road. Trends of large scale mechanization and increment of custom work were observed to be accelerated by land consolidation. It also gave effect on the pattern of machine troubles. Farmers were conscious of the influence of land consolidation on machine utilization, however, in plains level of satisfaction was shown to be low.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.678-683
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• 2004

The most popular consolidation tester is a standard consolidatiion tester, which performs consolidation using the step load weight. However this apparatus is used to obtain only the vertical consolidation coefficient. Therefore the purpose of this study is to develope the horizontal consolidation cell for a horizaontal consolidation coefficient. Various size of tests have been peroformed to investigate the effect of scale effect. From the test results, it has turned out that this horizontal consolidation cell has a good function for a horizontal consolidation coefficient.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.4
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• pp.4242-4250
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• 1976

The determination of the pre-consolidation load known to have a great effect on the consolidation characteristics of the soil have been researched and discussed in detail by many other researchers. A study was undertaken to investigate and compare the effect of pre-consolidation loads on the coefficient of permeability and the consolidation characterisics of soil through the consolidation test on the three types of soil samples. The results of this study are follows; 1. Large compression index is dependent on initial void ratio of the sample being used and the pressure-void ratio curve shows a curved linear relationship in over-consolidated area but a linear relationship in normally consolidated area.2. Settlement-time curve is S-shaped where the pressure is larger than pre-consolidation load and regardless of over-burden pressure, it is a similar straight line respectively in the secondary consolidation area. 3. Primary consolidation ratio of the sample increases almost linearly with the increase of over-burden pressure but the coefficient of volume compressibility decreases linearly with the increase of it. 4. Time factor of a certain degree of consolidation increases with over-burden pressure but the coefficient of consolidation decreases with it in over-consolidated area. There is a linear relationship between them in normally consolidated area. 5. The void ratio of completion point of primary consolidation decreases linearly with over-burden pressure. 6. The coefficient of permeability of sample decreases linearly with over-burden pressure in normally consolidated area, also it increases linearly with increment of the void ratio of the sample.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.93-100
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• 2000

This research is to investigate the self-weight consolidation settlement and desiccation shrinkage settlement of soft marine dredging clay by performing numerical and experimental works. Large column test were carried out investigate the consolidation settlement considering effect of the self-weight and desiccation shrinkage, and centrifuge model test was also carried out investigate self-weight consolidation settlement. Results of centrifuge model and large column experiments about changes of settlement with time were analyzed by using the numerical technique of explicit finite difference method considering effect of the self-weight and desiccation based on the finite strain consolidation theory. Centrifuge model test results were in relatively good agreements with analyzed results in terms of self-weight consolidation settlement with time. Large column test results showed quite different values from the numerically estimated one, carried by experimental conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.504-510
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• 2009

Dredging and Reclamation which have been conducted steadily for creation of new coastal area have demerit that takes a long time. Hence, a lot of researches on acceleration of self-weight consolidation is proceeding continuously. In this paper, 30 cases of laboratory self-weight consolidation tests were conducted to understand application of PDF method, one of the self-weight consolidation acceleration methods, to domestic dredged soils. Acceleration effect of self-weight consolidation was confirmed through comparison and analysis on completion time and settlement of self-weight consolidation for none installed case and 4 kinds of common used PBD installed cases.

• Journal of the Korean Geotechnical Society
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• v.29 no.4
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• pp.13-22
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• 2013

To simulate the soft ground improved by vertical drain method and to investigate the effect of overlapping smear on subsequent consolidation behavior, a series of consolidation tests with a large consolidation chamber and mandrel insertion device were conducted. Based on the test result, numerical analysis was also performed to analyze the efficiency of the vertical drain method. Laboratory test and numerical analysis results showed that the effect of smear zone increased consolidation settlement but the overlapping smear zone decreased the consolidation settlement. In addition, vertical drain accelerated consolidation rate but narrowing the drain spacing did not affect the consolidation rate because of the effect of smear. The efficiency of consolidation rather decreased substantially when the smear zone was overlapped.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.3
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• pp.63-70
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• 2018

In this study, a simple probabilistic approach using equivalent coefficient of consolidation ($c_e$) was proposed to consider the spatial variability of coefficient of vertical consolidation ($c_v$), and the effect of the probability distribution of coefficient of consolidation on degree of consolidation in heterogeneous soil was investigated. The statistical characteristics of consolidation coefficient were estimated from 1,226 field data, and four probability distributions (Normal, Log-normal, Gamma, and Weibull) were applied to consider the effect of probability distribution. The random fields of coefficient of consolidation were generated based on Karhunen-Loeve expansion. Then, the equivalent coefficient of consolidation was calculated from the random field and used as the input value of consolidation analysis. As a result, the probabilistic analysis can be performed effectively by separating random field and numerical analysis, and probabilistic analysis was performed using a Latin hypercube Monte Carlo simulation. The results showed that the statistical properties of $c_e$ were changed by the probability distribution and spatial variability of $c_v$, and the probability distribution of $c_v$ has considerable effects on the probabilistic results. There was a large difference of failure probability depend on the probability distribution when the autocorrelation distance was small (i.e., highly heterogeneous soil). Therefore, the selection of a suitable probability distribution of $c_v$ is very important for reliable probabilistic analysis of consolidation.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.109-118
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• 2004

The consolidation of clay occurs with time lag, and this kind of lag can be separated into plastic lag and hydraulic lag. In this study, CRS tests were performed to research the effect of original secondary consolidation of the clay with respect to the characteristics of consolidation. Test results showed that plastic time lag was one of the key factors to get the preconsolidation pressure, and suggested the formula of the Quasi-preconsolidation pressure obtained from the relationship between consolidation time lag and consolidation pressures. In addition though the characteristics of coefficient of consolidation show a wide range of values, after passing the double preconsolidation point, it showed the tendency to converge into the constant value. The coefficient of permeability in normally consolidated state is related to its void ratio, and the permeability variables, n and $C_1$ were determined by the test results using the equation suggested by Samarasinghe. et. al. And then the equation was compared with the Kozeny-Carman's equation. Because of delayed compression caused by consolidation time lag, aging effect could be also found in the relationship between coefficient of permeability and void ratio.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.141-146
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• 2010

To investigate the effect of drainage spacing and smear on the rate of consolidation, a large consolidation chamber and mandrel insertion device were developed. After the occurrence of smear by installation of sand drain, model ground was consolidated in either overconsolidated or normally consolidated state. As smear effect increases and thus drain spacing decreases, total settlement increase in overconsolidated state but has no effect in normally consolidated state. Efficiency of vertical drain decreases and consequently consolidation time increases in all tests as smear effect becomes significant.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.916-923
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• 2005

In this study, to observe aging effect of undrained shear behavior for Nak-Dong River sand, undrained static and cyclic triaxial tests were performed with changing relative density ($D_r$), consolidation stress ratio($K_c$) and consolidation time. As a result of the test, the modulus of elasticity to all samples estimated within elastic zone by the micro strain of about 0.05% in case of static shear behavior increased with the lapse of consolidation time significantly, so aging effect was shown largely. Also strength of phase transformation point(S_{PT}$) and strength of critical stress ratio point($S_{CSR}$) increased with the lapse of consolidation time. Undrained cyclic shear strength($R_f$) obtained from the failure strain 5% increased in proportion to relative density($D_r$) and initial static shear stress($q_{st}$), $R_f$ of consolidated sample for 1,000 minutes increased about 10.6% compared to that for 10 minutes at the loose sand, and $R_f$ increased about 7.0% at the medium sand. In situ application range of $R_f$ to the magnitude of earthquake for Nak-Dong River sand was proposed by using a increasing rate of $R_f$ as being aging effect shown from this test result.