• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.485-496
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• 2020

Recent changes in the disaster environment have greatly increased the possibility of internal erosion in deteriorated reservoirs; thus, countermeasure methods are required to enhance the drainage performance of embankments. Sand filters have been mainly used to prevent internal erosion; however, due to the sand depletion and environmental problems, new alternative materials are required to replace the sand in the filter zone. In this study, crushed stone was used instead of sand as a material that could satisfy permeability, material supply, demanding conditions, and economic efficiency. Although crushed stone has excellent drainage performance, it has a clogging phenomenon due to its high permeability. Accordingly, the materials need to be separated with a geotextile wrapping method. Additionally, the 3D numerical analysis and a large model experiment were conducted to evaluate the seepage characteristics and in-site application of the crushed stone filter. As a result, the crushed stone filter showed an excellent dispersion effect by reducing the pore water pressure by about 9.5 times that of the sand filter. In addition, it was shown that the safety factor for piping increased significantly by reducing internal erosion. When comparing the economics and supply and demand conditions of the material, crushed stone was evaluated as an effective method to reduce the internal erosion of embankments at deteriorated reservoirs.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.969-978
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• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.119-122
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• 2009

The gravel compaction pile method has been used as a soft foundation improvement method because bearing capacity and discharge capacity is excellent. But the discharge capacity decreased when the clogging was generated because the clay penetrate into a void of gravel compaction pile. Accordingly, the purpose of this study is to reduce the clogging generation in gravel compaction pile constructing in the soft ground and take a step to minimize a void of gravel compaction pile. And the proper mixing ratio was determined with the large scale direct shear test performed to get strength and permeability with mixing ratio of crushed stone and sand(100:0, 90:10, 85:15, 80:20, 75:25). As a result of the test, it was showed that internal friction angle was the highest at 85:15 mixing ratio of crushed stone and sand and we can make sure a tendency of internal friction angle's decrease when the mixing ratio of crushed stone and sand passed 15%.

• 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 GEO-environmental Society
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• v.2 no.4
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• pp.63-72
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• 2001

As construction cases on soft ground are increasing, the necessity of ground improvement is also increasing. Granular pile is one of the methods for soft clay and for loose sandy soil. In our country, SCP(Sand Compaction Pile) method using sand material has been mainly used to improve soft ground, but Granular pile with crushed-stone was not used much. However, alternative material such that crushed-stone is needed to substitute for sand due to the environmental and economical problems. In this study, staged load test and consolidation test were performed in the laboratory to observe the behavior of soft ground improved by Granular pile. In order to evaluate the characteristics such as bearing capacity, drainage, and settlement, sand and crushed-stone were applied as each pile material. The test results show that crushed-stone has higher bearing capacity and less settlement than those of sand under similar pore water pressure condition. Therefore, crushed-stone is determined to be appropriate as substitute for sand.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.43-54
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• 2002

As construction cases of structure are increasing in the soft ground, the necessity of ground improvement is also increasing. Granular pile is one of the improvement methods for soft ground and for loose sandy soil. In domestic, SCP(Sand Compaction Pile) method using sand material has been mainly used to improve soft ground, but Granular pile with crushed-stone was not used much. However, alternative material such as crushed-stone is needed to substitute for sand due to the environmental and economical problems. In this study, staged load test and consolidation test were performed in the laboratory to observe the behavior of soft ground improved by Granular pile. In order to evaluate the characteristics such as bearing capacity, drainage, md settlement, sand and crushed-stone were applied as each pile material. The test results show that crushed-stone has higher bearing capacity and less settlement than those of sand under similar fore water pressure condition. Therefore, crushed-stone is determined to be appropriate as the substitute for sand.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.717-724
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• 2003

Although sand compaction pile is applied considerably for increase of hearing capacity in domestic, it is getting more necessary to develope the alternative materials because of exhaustion and increase of unit cost of sand. In this study, stress concentration ratio between crushed-stone pile and soft ground was measured and, a displacement ratio 30, 40 and 50%, variation of stress concentration ratio was analyzed. As an increase displacement ratio, the stress concentration effect of crushed-stone compaction pile doesn't increase proportionally and effect of ground improvement in case of ground was good at displacement ratio 30% or 40%. The stress concentration ratio of crushed-stone compaction pile in group piles is 1.5 times that of crushed-stone compaction pile in single pile.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1378-1382
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• 2009

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. And the mixed soil formed by mixing stone sludge, river sand is conducted to investigate the possibility of recycle. A series of tests were performed on the mixed soil(stone sludge, bentonite, Cement and residual soil) to evaluate basic properties such as compaction, compressive strength, permeability of these materials. and the stone sludge-river sand mixed soil were performed the discharge capacity tests.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1250-1255
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• 2010

In this study, in order to examine the hydraulic characteristics for a crushed stone mat. it was accomplished discharge capacity test and soil-water characteristic curve(SWCC) with the object of the research. From the test result, it produced propriety mixed ratio of the crushed stone which mixes the sand. at the time of crushed stone 100% where it does not mixes the sand it appeared that permeability was biggest. increase of shock and content of the sand showed decrease of air entry value.

• 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.