• Geomechanics and Engineering
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• v.31 no.2
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• pp.149-158
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• 2022

Ladle furnace (LF) slag, waste from the steel-making process, was incorporated to improve the compressive strength of soil cement. LF slag was mixed to replace the cement in the soil-cement samples with wt% ratio 20:0, 15:5, and 10:10 of cement and slag, respectively. LF slag in the range of 5, 10, and 20 wt% was also separately added to the 20-wt% cement-treated soil samples. The soil-cement mixed LF slag samples were incubated in a plastic wrapping for 7, 14, and 28 days. The strength of soil cement was highly developed to be higher than the standard acceptable value (0.6 MPa) after incorporating slag into soil cement. The mixing of LF slag resulted in more hydration products for bonding soil particles, and hence improved the strength of soil cement. With the LF slag mixing either a replacement or additive materials in soil cement, the LF slag to cement ratio is considered to be less than 1, while the cement content should be more than 10 wt%. This is to promote a predominant effect of cement hydration by preventing the partially absorbed water on slag particles and keeping sufficient water content for the cement hydration in soil cement.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.231-235
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• 2004

To investigate removal effects of nutrients in stormwater runoff by soil of riparian protection zone, soil column experiment was conducted for 20 months. Artificial stormwater runoff containing phosphate and nitrate was applied on the surface of soil column twice a week, and phosphate and nitrate concentrations were measured from the leached water. Soil of riparian protection zone reduced the released amount of infiltrated water to the surrounding water. After infiltration of 1m depth of soil column, average removal rates of phosphate and nitrate were 97.7 % and 74.7 %, respectively. As main mechanisms of phosphate are adsorption to soil particle and utilization by plants, periodical replacement of soil and harvesting of plant at the end of growing season are required. For the removal of nutrients in stormwater runoff by the soil layer, soil of riparian protection zone has higher hydraulic conductivity to infiltrate stormwater. Sandy soil having hydraulic conductivity of about $1{\times}10^{-2}cm/s$ range might be appropriate for this purpose.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.305-314
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• 2018

Purpose: Dynamic Replacement Method currently lacks of sufficient research, implementation cases, and case histories, compared with other comparable methods, such as Dynamic Compaction Method. Method: In this study, for Dynamic Replacement Method, the effective improvement depth and improved strength were analyzed for silty clayey soils. Results: Testbed test was performed to verify the effectiveness of Dynamic Replacement Method followed by the main dynamic replacement implementation on real construction site. Conclusion: A The effects of changes of soft ground depth, dynamic replacements' diameter, depth, spacing, and applied energy on dynamic replacement efficiency in silty clays were assessed and the followings were found: Empirical coefficient for soil $n_R$ of Dynamic Replacement Method was within the range of 0.14~0.32 and its ${\sqrt{WH}}$ is recommended to be 1.25~2.5 times of those from Dynamic Compaction Method.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.485-495
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• 2016

To reinforce and improve the soft ground under a breakwater while using materials efficiently, the replacement ratio and leaving periods of surcharge load are optimized probabilistically. The results of Bayesian updating of the random variables using prior information decrease uncertainty by up to 39.8%, and using prior information with more samples results in a sharp decrease in uncertainty. Replacement ratios of 15%-40% are analyzed using First Order Reliability Method and Monte Carlo simulation to optimize the replacement ratio. The results show that replacement ratios of 20% and 25% are acceptable at the column jet grouting area and the granular compaction pile area, respectively. Life cycle costs are also compared to optimize the replacement ratios within allowable ranges. The results show that a range of 20%-30% is the most economical during the total life cycle. This means that initial construction cost, maintenance cost and failure loss cost are minimized during total life cycle. Probabilistic analysis for leaving periods of shows that three months acceptable. Design optimization with respect to life cycle cost is important to minimize maintenance costs and retain the performance of the structures for the required period. Therefore, more case studies that consider the maintenance costs of soil structures are necessary to establish relevant design codes.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.443-450
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• 2001

This paper shows the reduction effect of tile earthquake-induced liquefaction potential of soils that improved by Vibro-Replacement Stone Columns. The Vibro-Replacement Stone Columns method transforms soft cohesive soils into a composite mass of compacted granular or crushed stone columns by using vibrating equipment and water jets. This study investigated and analyzed the behavior of the stone columns and composite ground using the results of in situ test and measurement at the job-site. This paper shows the evaluation of the earthquake-induced liquefaction potential of soils using in situ test. There are different types of in situ test used in the evaluation the liquefaction potential. In the particular study the Standard penetration test, and Cone penetration test were used. The N value of Standard Penetration test has been used all over for a very long time. The evaluation of the liquefaction of soil was performed using the worldwide renewed Cone penetration test

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.299-306
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• 2001

Crushed Stone Pile(CSP) is one of the ground improvement methods available to loose sand and clayey ground by forming compacted CSP in the weak soil layer. The effects of this method are enhancement of ground bearing capacity, reduction of settlement and prevention of lateral ground movement in cohesive layer, reduction of liquefaction potential in sandy ground. This study performs model tests in 1.0m${\times}$1.0m${\times}$1.0m and 1.5m${\times}$1.5m${\times}$l.2m model tank to observe bearing capacity of CSP treated ground. The area replacement ratio of CSP composite ground varies 20%, 30% and 40% with square grid pattern. After the composite ground was consolidated under pressure of 0.5kg/$\textrm{cm}^2$ and 1.0kg/$\textrm{cm}^2$, load tests were carried out. The results show that ultimate bearing capacity increases with area replacement ratio and the preconsolidation pressure of ground.

• Geomechanics and Engineering
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• v.10 no.5
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• pp.689-707
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• 2016

Soil stabilization is one of the useful method of ground improvement for soil with low bearing capacity and high settlement and unrequired swelling potential. Generally, the stabilization is carried out by adding some solid materials. The main objective of this research was to investigate the feasibility of stabilization of organic soils and sewage sludge to obtain low cost alternative embankment material by the addition of two different slags. Slags were used as a replacement for weak soil at ratios of 0%, 25%, 50%, 75% and 100%, where sewage sludge and organic soil were blended with slags separately. The maximum dry unit weights and the optimum water contents for all soil mixtures were determined. In order to investigate the influence of the slags on the strength of sewage sludge and organic soil, and to obtain the optimal mix design; compaction tests, the California bearing ratio (CBR) test, unconfined compressive strength (UCS) test, hydraulic conductivity test (HCT) and pH tests were carried out on slag-soil specimens. Unconfined compressive tests were performed on non-cured samples and those cured at 7 days. The test results obtained from untreated specimens were compared to tests results obtained from soil samples treated with slag. Laboratory tests results indicated that blending slags with organic soil or sewage sludge improved the engineering properties of organic or sewage sludge. Therefore, it is concluded that slag can be potentially used as a stabilizer to improve the properties of organic soils and sewage sludge.

• Journal of the Korea Furniture Society
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• v.19 no.6
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• pp.452-459
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• 2008

The compressed injection yellow ocher soil is the process-technology by drying the product through sunshine, not by firing like pottery and ceramic ware. It is the technology of development being able to achieve the far infrared ray and humidity adjustment by adding recycling paper, Korean paper and bamboo salt, and it corresponds with the construction enforcement ordinance 2007 as an interior-finishing product which is fire-resistant. In case that the yellow ocher soil would be used as lighting device and interior-finishing material and decoration, it could contribute to an improvement of National Health by avoiding the sick house syndrome and adding humidity adjustment, and it has more efficient economic effect due to using recycle-available additives. Through such developments of the yellow ocher soil products the domestic market of lighting device and construction material can be advanced and the replacement effect of imported goods & also export effect can be expected accordingly.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.156-168
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• 2016

The Korean government is planning to invest a lot of funds for conservation of the soil. Accordingly, it needs quantitative information on the soil. This paper attempts to analyze the total value of soil quantitatively: the total economic value of soil can be divided into use value and non-use value. To this end, we apply a replacement cost method (RCM) and contingent valuation method (CVM). Especially, CVM is most widely used to measure the non-use value such as environment goods. We employed the one-and-one-half-bounded dichotomous choice (OOHBDC) for willingness to pay (WTP) elicitation and a spike model. The monthly mean WTP was estimated to be KRW 3,949 per household for the next 10 years, which is statistically significant at the 1% level. Expanding the value to the relevant population gives us KRW 897.9 billion per year and as of the end of 2015, the non-use value of soil was assessed to be KRW 838.6 billion. Meanwhile, use value is subdivided into direct use value and indirect use value. This value was calculated KRW 3,277 trillion and KRW 51.8 trillion, respectively. As a result, total economic value of soil is estimated to be KRW 3,330 trillion in Korea.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.