• 레미콘
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• no.9 s.21
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• pp.98-105
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• 1989

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.705-712
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• 2005

Among soft ground treatment methods with granular soil used in domestic, the sand compaction pile method has been utilized greatly, but, as a result of exhaustion of sand and increase of unit cost, a necessity of an alternative method is suggested. In this study, the static load tests for group crushed-stone compaction piles which were constructed at in-situ site were performed. Pile diameter was 700mm and area of loading plates were changed. The static load tests of single and group piles were performed for area replacement ratio of 20, 30 and 40%. Based on test results, bearing capacity of group crushed-stone compaction pile were estimated. The more both single pile and group pile increase, the more yield bearing capacity tended to increase. Also, the yield bearing capacity of a group pile is about 50% less than the yield bearing capacity of a single pile. If the ground reinforced with the crushed-stone compaction pile is replacement ratio of $20{\sim}40%$, RIYB of both single pile and group pile increases qualitative tendency of linear more than original ground

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.5-11
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• 2007

Among soft ground improvement methods by using granular material, the sand compaction pile method has been widely utilized in Korea, but, as a result of shortage and increase of unit price of sand, a necessity of an alternative method has been required. In this study, a series of in-situ static load tests for crushed-stone compaction piles were performed. Pile diameter was fixed to 700mm and areas of loading plates were changed. The static load tests were performed for area replacement ratios of 20, 30 and 40% respectively. Based on the test results, bearing capacity of single crushed-stone compaction pile was estimated. It showed that the settlement decreases as the replacement ratio increases. Also, a yielding capacity equation of the crushed-stone compaction pile considering replacement ratio was suggested.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.103-111
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• 2012

In this study, the full-scale laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use an alternative material of sand in soft ground is performed. The settlement and pore water pressure were measured to evaluate the discharge capacity and filed application, and the results were compared and analyzed through the finite element method. The measured and estimated settlement in all vertical drain materials decreases gradually with the load increase. The measured settlement 6.55~8.63 mm, and the estimated by the Hyperbolic model was 7.45~7.92 mm. So the model used for the analysis can be applied to the settlement estimation of the actual field. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. The pore water pressure was similarity to that of sand after rapid drawdown. Therefore, it was applicable to the field because discharge capacity was enough to be an alternative material to the sand which had been being used as the vertical drains.

• Advances in nano research
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• v.15 no.6
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• pp.533-539
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• 2023

This study aims to examine four machine learning (ML)-based models for their potential to estimate the splitting tensile strength (STS) of manufactured sand concrete (MSC). The ML models were trained and tested based on 310 experimental data points. Stone nanopowder content (SNPC), curing age (CA), and water-to-cement (W/C) ratio were also studied for their impacts on the STS of MSC. According to the results, the support vector regression (SVR) model had the highest correlation with experimental data. Still, all of the optimized ML models showed promise in estimating the STS of MSC. Both ML and laboratory results showed that MSC with 10% SNPC improved the STS of MSC.

• KCID journal
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• v.19 no.1
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• pp.3-18
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• 2012

In recent years, as environmental problems have become great concerns among many people, th loss of beach sand has become one of the highly controversial issue. Major reasons for the beach erosion within the cases of West Coast can be classified as: 1) erosion at Unyeo, Baeksajang beaches are caused by the wave refraction according to the large-scale sand dredging, 2) erosion at Kkotji, Baeksajang, and Unyeo beaches are caused by large-scale embankment construction and the coastal road construction, and 3) erosion at Chollipo and Hakampo beaches are caused by construction of small ports. Erosion in the west coast of Korea coast beach erosion control measures, include groin, zeotube, terraced stone, jetty groin, and beach nourishment. Erosion control measures initially installed to prevent erosion showed a positive effect. However, if there is no continuous source of sand, the effect of measures is fewness.

• Journal of Technologic Dentistry
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• v.32 no.2
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• pp.57-63
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• 2010

Purpose : This study aimed to find out the effects of treatments on the surface of Zirconia. Methods : To this end, we selected six treatments that have been used widely: steam cleaning, 2bar & 6bar sand blasting, grinding by green stone point, grinding by diamond bur, and grinding by diamond bur with water spray. Results : The results of our study showed that monoclinic rate increased from all six treatments. Monoclinic rate varied by treatments, ranged from 0.6% (steam cleaning) to 6.5% (6bar sand blasting). These values from all six treatments were below ISO 13356 standard, which is 25%. Also, we found that two treatments (green stone point and diamond bur) increased roughness of surface of Zirconia. Conclusion : This study concluded that phase changes of Zirconia were not significant by using six treatments we employed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.6
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• pp.81-90
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• 2008

Recently, geofiber(polyester) reinforced soil was added on soil-seed mixture spray to control erosion and to improve vegetation growth on rocky slope sites. This research was conducted to compare vegetation effects and soil hardness on three types of soil-seed mixture spray on stone gabion river bank [A type : soil-seed mixture spray underlying 30cm thick sand with geofiber(geofiber reinforced soil system), B type : soil-seed mixture spray underlying 30cm thick sand without geofiber, C type : soil-seed mixture spray]. Evaluation were made concerning vegetation coverage, soil hardness and moisture content. The results of this study showed that A type system was effective for the growth of vegetation and soil hardness when compareed to B type and C type. A type and B type showed higher covering rate than C type on stone gabion river bank, and especially A type showed the highest covering rate. Soil hardness and water content were high on A type vegetation system compared to B type and C type. We noted that high soil hardness and high moisture content with geofiber(geofiber reinforced soil system) were effective both to control erosion from water current impact and to be high coverage and species of vegetation on stone gabion river bank.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.107-114
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• 2003

Among soft ground treatment methods with granular soil used in domestic, the sand compaction pile method has been utilized greatly, but, as a result of exhaustion of sand and increase of unit cost, the necessity of an alternative method is suggested. In this study, the static load tests for crushed-stone compaction piles which were constructed on test field were performed. Based on test results, stress concentration ratios between the crushed-stone compaction pile and the soft ground were investigated and estimated. At loading pressure, settlement showed decreasing tendency as replacement rate increases. At replacement rate of 20%, yield pressure was smaller but, at replacement rates of 30% and 40%, settlement and yield pressure were similar. The stress concentration ratio was within the range of 1.7 to 3.0 and it was higher as replacement rate increased.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.567-581
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• 2023

Enhanced vertical load capacity of the ground reinforced with the stone columns drew great attention by the researchers as it deals with many of the geotechnical difficulties associated with the weak ground. Recently, it has been found that the stone columns are also prone to fail under the shear load when employed beneath the embankments or the foundations susceptible to lateral loads. In this study, the effect of various encasement conditions on the lateral deflection of stone columns is investigated. A method of dual layers of encasement has been introduced and its the effect on lateral load capacity of the stone columns has been compared with those of the single encased stone column and the un-encased stone columns. Large shear box tests were utilised to generate the shear deformation on the soil system under various normal pressure conditions. The stiffness of the soil-stone column combined system has been compared for various cases of encasement conditions with different diameters. When subjected to lateral deformation, the encased columns outperformed the un-encased stone columns installed in loose sand. Shear stress resistance is up to 1.7 times greater in dual-layered, encased columns than in unencased columns. Similarly, the secant modulus increases as the condition changes from an unencased stone column to single-layer encasement and then to dual-layer encasement, indicating an improvement in the overall soil-stone column system.