• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.520-527
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• 2000

In the present study, the analytical approaches of vacuum consolidation with horizontal drains were proposed, For dissipating rapidly pore-water in hydraulic fills, vacuum consolidation method applied vacuum pressure in horizontal drains is developed. In the analytical approaches, the governing equation is based on two-dimensional finite strain consolidation theory and the boundary conditions of horizontal drains are considered in applying negative pore-water pressure occurred by vacuum pressure, Also, parametric studies to vacuum pressure and installation pattern of horizontal drains are carried out.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.59-70
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• 2002

Horizontal drains are sometimes installed on the ground together with vertical drains in order to drain excess pore water. Taking into account the discharge capacity of horizontal drains, a new analytical method is developed in this paper, and then a new formula for the discharge capacity of horizontal drains is proposed. It is known from the analysis that the effect of the rate of surcharge loading is negligible in determining horizontal discharge capacity. This formula is described as the function of coefficient of consolidation, space of vertical drain, compression index, length of horizontal drains, and thickness of the compressible layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.641-648
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• 2000

The horizontal drain method by installing drains horizontally in the ground is often used to expedite the dispersion of pore water and to increase the strength of dredged soft clay under the action of gravity or vacuum. In this study a numerical analysis method is developed to predict the consolidation process of soft ground with horizontal drains. One-dimensional self-weight consolidation theory is extended tn three-dimensions] theory with appropriate boundary conditions of horizontal drains. In the condition of pore water drainage by gravity, the behavior of the dredged clay with horizontal drains is compared with that of the clay without drains. The influence of design factors of drains on consolidation process is also analyzed.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.41-48
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• 2005

The gravitational consolidation behavior of the dredged ground with horizontal drains is analyzed using a finite difference program developed for self-weight consolidation analysis with horizontal drains. The influence of area and direction of horizontal drains on the consolidation time and settlement is analyzed. Various field conditions such as the non-treated ground below horizontal drain installed ground, the accumulation of drained water at the end of horizontal drains, are also included in the analyses. It was found that a slight decrease of consolidation time is resulted in the twice increase of the sectional area of drains. Installing drains vertically can reduce the consolidation time more significantly than installing drains horizontally. The analyses showed quantitatively that the non-treated ground below the horizontal drain installed ground has much influence on long term consolidation settlement, and the accumulation of hydraulic head at the end of horizontal drains results in the increase of consolidation time and insufficient consolidation.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.6
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• pp.111-123
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• 2010

In this study, laboratory model test on utilization of recycled aggregates and crushed stone as horizontal drains to use alternative material of sand in soft ground is practiced. The coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~5.1 times and 2.0~3.3 times greater than sand, respectively. The horizontal coefficient of permeability in case of installing the horizontal perforated drain pipe showed largely 1.9~6.8 times more than the case of not installing. The drainage distance showed 1.7~1.8 times greater than sand. When a degree of consolidation is 90 %, there is no delay of consolidation in SCP and PVD improvement sections. Therefore, it is proven that the field applicability is excellent. Also, the suitable quality management criterion is presented to make use of a horizontal drains in soft ground on the basis of analysis of the physical and environmental characteristics.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.27-39
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• 2005

A finite difference program with 3-D governing equation expanded from 1-D self-weight consolidation is developed to analyze the consolidation behavior of surface dredged soil with horizontal drains. Various boundary conditions with horizontal drains and seepage pressure of pore water infiltrated to the drains are considered in the program. A laboratory soil chamber experiment for the consolidation of dredged soil is performed to validate the program and the measured settlement-time result is compared with the one predicted by the program. The influence of design conditions of horizontal drains such as horizontal installation spacing, installation depth and number of drain layers, on the consolidation is analyzed.

• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.253-260
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• 2013

In this study, laboratory model test carried out to present the suitable range of particle size distribution and clogging behavior of recycled aggregates and crushed stone as horizontal drains in soft ground. The recycled aggregates and crushed stone showed clogging phenomenon because the top fill material and bottom clay inflow into the horizontal drains. The pp mat was the most effective method to minimize clogging phenomenon. The horizontal coefficient of permeability in case of installing the pp mat showed largely 2.1 times more than the case of not installing. When the pp mat is not installing, the thickness of fine grained soil inflow into the horizontal drains showed 6.7~13.3% range in top fill material and 3.3~6.7% range in bottom clay. Overall, the reduction of the discharge capacity by fine grained soil inflow showed small in recycled aggregates and crushed stone. Also, the appropriate criterion range of particle size distribution is presented to make use of a horizontal drains in soft ground on the basis of laboratory test.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.15-25
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• 2003

To evaluate the effect of trapped air bubbles in horizontal drains on discharge capacity, unsaturated discharge capacity tests are carried out for four types of drains selected according to the size of section as well as the shape of core. Unsaturated discharge capacities with the elapse of time, the increase of confining pressures, and hydraulic gradients are examined and are compared with saturated discharge capacities. It is found that the unsaturated discharge capacities at a hydraulic gradient of 0.01 decreased by 17%~80% due to the remained air bubbles in the drains compared with the saturated discharge capacities. It is caused by the fact that the horizontal direction of water flow is not consistent with the direction of movement of floating air bubbles in case of horizontal drains. Especially, far the drain with filament shaped core, discharge capacities decreased significantly due to the difficulty in removing air bubbles.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.557-564
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• 2002

Discharge capacity test is carried out to find out influencing factors on discharge capacity of prefabricated horizontal drains to improve weak dredged clay. Four representative prefabricated horizontal drains are selected based on the size of drain as well as the shape of core. Test is carried out for 10 days at each three level of confining pressure for all drains. Effects of elapsed time, confining pressure, hydraulic gradient and strength of filter and core on discharge capacities are examined. It is found that discharge capacity of drain, which has deformable core or has a possibility of squeezing filter into core, decreases more with time due to its low strength. As confining pressure increases, discharge capacity decreases due to the squeezing of filter into core.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.1
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• pp.39-45
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• 2012

In this study, field test on utilization of recycled aggregates and crushed stone as horizontal drains to use an alternative material of sand in soft ground is practiced. The settlement with time showed similarly ranged from 28.4-30.3 cm in the all horizontal materials. The excess pore water pressure of the recycled aggregates and crushed stone showed smaller than sand. The small the excess pore water pressure becomes faster the consolidation period and it can reduces the amount of residual settlement. Therefore, it was verified as having enough to an alternative materials that the field applicability is excellent. The distribution of earth pressure with time showed similarly in the all horizontal materials. The recycled aggregates and crushed stone was very applicable to practice because there is no mat resistance in the horizontal drains layer. The penetration rate in the SCP and PVD improvement sections did not show large differences as the grain size and the horizontal drainage height increases.