• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1415-1426
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• 2008

Stone columns, locally called "GCP (granular compaction pile)" can be used to improve strength and resistance against lateral movement of a foundation soil like rigid piles and piers. Also installation of such a discrete column facilitates drainage, and densifies and reinforces the soil in the sense of ground improvement. The integrity of the GCP has been indirectly controlled with the records of each batch including depth and the quantity of stone filled. An integrity testing was attempted using crosshole S-wave logging. The method is conceptionally same as the crosshole sonic logging (CSL) for drilled piers. The only and critical difference is that S-wave should be used in the logging, because P-wave velocity of the stone column is less than that of ground water. The crosshole sonic logger does not have the capability to measure S-wave propagating through the skeleton of crushed stone. An electro-mechanical source, which can generate either P- or SH-waves, and a 1-D geophone were used to measure SH-waves. Two 76mm diameter cased boreholes were installed 1 meter apart across the nominal 700mm diameter stone column. At every 10cm of depth, shear wave was measured across the stone column. One more borehole was also installed 1 meter outward from the one of the above boreholes to measure the shear wave profile of the surrounding soil. The diametric variation of the stone column with respect to depth was evaluated from the shear wave arrival times across the stone column, and shear wave velocities of crushed stone and surrounding soil. The volume calculated with these variational diameters is very close to the actual quantity of the stone filled.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.1-9
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• 2019

In this study, the effect of ground improvement was to be verified by granular compaction pile from the ground reclaimed with Fly Ash landfill site. The depth and strength parameters of the Fly ash layer was determined using the ground investigation and cone penetration test. And the STONE C program was used to predict the strength parameter, bearing capacity and settlement of the improved ground. As a result of the plate bearing test, the bearing capacity of improvement ground was higher than the design load and the settlement was smaller than the reference value. After the construction, the improvement effect by the cone penetration test was confirmed. The cone penetration resistance value($q_c$) increased by 250% to 500% and the effect was excellent.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.255-261
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• 1998

The recent greenhouses are extremely light-weight structures and easily damaged by the strong winds due to the lack of uplift capacity of pile foundations. The uplift capacity of pile foundations are subject to the shape of the pile surface, diameter, weight, and embedded depths. etc. So, it is very important to figure out the most appropriate conditions on shape of the pile surface and it's embedding depths. to improve wind proof capability of pipe greenhouses. In this study, plane and corrugated pile surfaces were examined on their uplift capacity with 30 to 50 cm of embedding depths. The diameters of tested piles were 10 cm, 15 cm, and 20 cm, respectively. Compaction ratio of the tested soil was 80%. Each test run was repeated three times for the respective treatment. Obtained results are as follows; In all cases, as the diameter and the embedding depth were increased, the ultimate uplift capacity of the pile was also increased. And it was clear that the ultimate uplift capacity of corrugated pile was approximately two times as big as that of plain piles under same conditions.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.176-181
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• 2003

Damages by vibration and noise due to the construction performance are increasing. The rise of construction demand and enlargement of equipments are major reasons of this damage. As a result, the enmity of the people is provoked and this appears to be an obstacle of construction work. Especially, in case of ground improvement construction. Casing pipe is inserted into the Sand Drain, Sand Compaction Pile and Vibrated Crushed-stone Pile by vibration power when carrying out. Hence, a pillar is formed and it creates vibration and noise. This causes a lot of restrictions to construction condition. The low Vibration and low noise construction equipments uses earth auger and hydrulic cylinder for insertion and chopping operation instead of vibro hammer, which is the source of vibration and noise. This minimize ground disturbanceand decrease vibration and noise successfully, but increase chopping effect greatly. Thus, this new equipment is not only suitable for environment but also excellent engineering method of construction.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.264-271
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• 2005

Sand pile method, such as sand drain method and sand compaction pile method, has been popularly used as an improvement method for soft clay grounds. The effect of accelerating consolidation of soft clay grounds has been evaluated with Barron's solution. By the way, the consolidation behavior of soft clay ground with sand piles strongly depends on both the nonlinear mechanical interaction between sand piles and surrounding clays and the degradation permeability of clays. In this paper, the method for determining consolidation parameters of soft clay ground with sand drains by using Barron's solution was proposed, through a series of numerical simulations. Through the method, the change in both volume compressibility and permeability during consolidation was reasonably evaluated.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.407-414
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• 1999

Sand drain as a vertical drainage is widely used in soft ground improvement. Recently, sand, the principal source of sand drain, is running out. A laboratory model test was carried out to utilize gravel as a substitute for sand. Though which the characteristics of gravel are compared to those of sand for engineering purpose. According to the test, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel rile explains the result. The clogging effect was not found in gravel column. As a result, it is assumed that gravel is relatively acceptable as a drainage material. Gravel material seems better than sand material in bearing capacity and it is found that bearing capacity is larger when gravel is used as compaction pile than as drain from in-situ test on bearing capacity. Increase of bearing capacity with gravel pile means an effect of composite ground by stiffness of gravel material. It can lie supposed to use gravel pile instead of sand pile in view of consolidation effect and bearing capacity.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.223-233
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• 2003

Sand compaction pile (SCP) is one of the ground improvement techniques which are being used for not only accelerating consolidation but also increasing bearing capacity of loose sands or soft clay grounds. In this study, laboratory model tests and 3-D finite element analyses were performed to investigate the interaction between sand compaction piles and surrounding soft soils. Based on the results obtained, as the area replacement ratio increases, the stress concentration ratio increases at the pile point, the settlement decreases, and the relative displacement between column and soil also decreases. It is also found that numerical study is illustrated by good comparison with model test results, and the numerical analysis revealed slip effects which could not be specifically identified in the model tests.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.4
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• pp.109-119
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• 1998

Recently pipe-framed greenhouses are widely constructed on domestic farm area. These greenhouses are extremely light-weighted structures and so are easily damaged under strong wind due to the lack of uplift resistance of foundation piles. This experiment was carried out by laboratory soil tank to investigate the displacement be haviors of cylindrical pile foundations according to the uplift loads. Tested soils were sampled from two different greenhouse areas. The treatment for each soil type are consisted of 3 different soil moisture conditions, 2 different soil depths, and 3 different soil compaction ratios. Each test was designed to be repeated 2 times and additional tests were carried out when needed. The results are summarized as follows : 1. When the soil moisture content are low and/or pile foundations are buried relatively shallow, ultimate uplift capacity of foundation soil was generated just after begining of uplift displacement. But under the high moisture conditions and/or deeply buried depth, ultimate up-lift capacity of foundation soil was generated before the begining of uplift displacement. 2. For the case of soil S$_1$, the ultimate uplift capacity of piles depending on moisture contents was found to be highest in optimum moisture condition and in the order of air dryed and saturated moisture contents. But for the case of soil S$_2$, the ultimate uplift capacity was found to be highest in optimum moisture condition and in the order of saturated and air dryed moisture contents. 3. Ultimate uplift capacities are varied depending on the pile foundation soil moisture conditions. Under the conditions of optimum soil moisture contents with 60cm soil depth, the ultimate uplift capacity of pile foundation in compaction ratio of 80%, 85%, and 90% for soil 51 are 76kg, 115kg, and 155kg, respectively, and for soil S$_2$are 36kg, 60kg, and 92kg, respectively. But considering that typical greenhouse uplift failure be occurred under saturnted soil moisture content which prevails during high wind storm accompanying heavy rain, pile foundation is required to be designed under the soil condition of saturated moisture content. 4. Approximated safe wind velosities estimated for soil sample S$_1$and S$_2$are 32.92m/s and 26.58m/s respectively under the optimum soil condition of 90% compaction ratio and optimum moisture content. But considering the uplift failure pattern under saturated moisture contents which are typical situations of high wind accompanying heavy rain, the safe wind velosities for soil sample S$_1$and S$_2$are not any higher than 20.33m/s and 22.69m/s respectively.

• 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.