• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.61-65
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• 1973

Analysis of data in the Official Soil Series Description showed the dominant texture of upland soils is SiL, of which available water range is 21.1% highest among textures. Analyses of data in the N, P, K Trials on Barley in 1964/65-1968/69, and N, P, K and Soil Improvement Trials on upland Crops in 1961-1969 were made to relate fertilizer response to the amount of rainfalls during the growing season. Correlation between nitrogen response and the amount of rainfalls was observed but not between P and K and the amount of rainfalls. Some of physical properties were discussed to seek feasible means for increasing available water.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.89-95
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• 2010

There is the freezing method as one of the ground improvement methods for excavating an underground tunnel, and due to its improved reliability, recently construction cases of applying this method into sandy soil grounds as well as cohesive soil grounds of cities have been reported. But, applying the freezing method into cohesive soil grounds could bring concerns of the expansion of the whole ground and the settlements from thawing of ground. In this study, the deformation strength characteristics of cohesive soil which received freezing and thawing hysteresis were examined using the sample collected from the site of cohesive soil ground applied with the freezing method and its structural characteristics were analyzed using an electronic microscope. And, the test with cohesive soil reconstituted from cohesive soil which received freezing and thawing hysteresis was carried out and its result was analyzed comparatively. The result of this test showed that the structure of natural clay was significantly changed due to freezing and thawing hysteresis.

• International Journal of Railway
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• v.6 no.3
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• pp.90-94
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• 2013

Cement or lime is generally used to improve the strength of soil. However, bacteria were utilized to produce cementation of loose soils in this study. The microo rganism called Bacillus, and $CaCl_2$ was introduced into loose sand and soft silt and $CaCO_3$ in the voids of soil particles were produced, leading to cementation of soil particles. In this study, loose sand and soft silt typically encountered in Korea were bio-treated with 3 types of bacteria concentration. The cementation (or calcite precipitation) in the soil particles induced by the high concentration bacteria treatment was investigated at 7 days after curing. Based on the results of Scanning Electron Microscope (SEM) tests and EDX analyses, high concentration bacteria treatment for loose sand was observed to produce noticeable amount of $CaCO_3$, implying a significant cementation of soil particles. It was observed that higher calcium carbonate depositions were observed in poorly graded distribution as compared to well graded distribution. In addition, effectiveness of biogrouting has also been found to be feasible by bio-treatment without any cementing agent.

• Geomechanics and Engineering
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• v.34 no.4
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• pp.425-435
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• 2023

Granite and marble are widely produced and utilized in the construction industry, resulting in significant waste production. It is essential to manage this waste appropriately and repurpose it in recycling processes to ensure sustainability. The utilization of waste materials such as marble and granite waste (MGW) has become increasingly important in geotechnical engineering to improve the physical and mechanical properties of weak soils. This study investigated the applicability of utilizing MGW and cement (C)-MGW mixtures to improve clayey soil. A series of model plate loading tests were carried out in a specialized circular test tank to assess the influence of MGW and C-MGW mixing ratios on clayey soil samples. The samples were prepared by blending MGW and C-MGW in predetermined proportions. It is found that the bearing capacity of clay soil increased by approximately 71% when using MGW and C additives. Moreover, the consolidated settlement values of the clay soil decreased up to 6 times compared to the additive-free case.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.92-97
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• 1983

This experiment was designed to establish the soil physical improvement practice to increase the rice yields at fine textured fluvio-marine paddy field. After chiseling and trenching the paddy soil, the rice growth and soil physical properties were investigated for 4 years. The results are summarize as follows; 1. The soil physical properties, such as bulk density, hardness, porosity and permeability were prominently improved by trenching and chiseling. 2. There were significant relationships among the soil physical properties, root developments and rice yields. 3. The increasing rates of rice yields by soil physical improvement were about 10%, which is better than 5% of drainage effects. 4. The effects of trenching and chiseling on rice yields were continued to fourth year. Even if trenching effects was better than chiseling the chiseling was considered as a useful treatment for its simple working practice by using a heavy machine. 5. In case of trenching, straw application were increased the rice yields.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.480-488
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• 2010

The CGS method is non-discharge replacement method improving ground stiffness by the effect of static compaction with injecting very low slump mortar into ground, and is applied for increasing bearing capacity and filling ground cavity by lifting or restoring differential settled structures and preventing differential settlement. This paper suggests design of ground improvement and construction case history for civil engineering structures by CGS method. This method can be used for reinforcing soft ground and liquefaction of loose sandy soil. This method was used in SongDo area in Incheon Economic Free Zone due to its low vibration of ground while it can improve the soft soil where underground structures(subway and box culvert) are already existed.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.79-89
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• 2000

The application of stabilization method has increased because of short construction periods, no environmental problems with dumped and replaced soil, assurance of required strength and economical effect with mid to small size construction. The unconfined and triaxial(UU-condition) compression tests were executed with each mixing sample for the study of the improvement effects and the effect of design-parameters by the stabilization methods. Three typical stabilizers, which are representative in Korea, were applied in this study, and three common soils(very soft clay, general weathered soil, common clay), which are common in Korea, were used in this study. In this study, the effect of engineering factors(soils, stabilizers and water contents, etc.) which are important parameters for the improvement effects of mixed ground by stabilizers, was analyzed. As results, the tendencies of design-parameters(unconfined compression strength, deformation modulus and strength parameter) are presented and the criteria of the application of stabilization methods are suggested.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.963-975
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• 2017

Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.

• Geomechanics and Engineering
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• v.36 no.4
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• pp.329-341
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• 2024

Retaining structures are one of the most important elements in the stabilization of excavations and slopes in various engineering projects. Mechanically stabilized earth (MSE) walls are widely used as retaining structures due to their flexibility, easy and economical construction. These benefits are especially prominent for projects built on soft and weak foundation soils, which have relatively low resistance and high compressibility. For high retaining walls on weak foundations, conventional design methods are not cost-effective. Therefore, two alternative solutions for different foundation weakness are proposed in this research: optimized multi-tiered MSE walls and single tier wall with foundation improvement. The cost optimization considers both the construction components and the land price. The results show that the optimal solution depends on several factors, including the foundation strength and more importantly, the land price. For low land price, the optimized multi-tiered wall is more economical, while for high land price (urban areas), the foundation improvement is preferable. As the foundation strength decreases, the foundation improvement becomes inevitable.

• Korean Journal of Plant Resources
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• v.20 no.1
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• pp.93-98
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• 2007

In the present experiment, fly ash application to soil generally improved soil pH condition. The improvement of soil pH was greater with bituminous fly ash than with anthracite fly ash. Treatment of fly ash also made available phosphate content increased. But phosphate content in cultivated tomato plants was in inverse proportion to content in soil due to high pH of experimental soil as well as hot and dry weather. Amount of phosphate in plants had a strong positive effect on the yield of tomato. Number and weight of harvested fruits was greatest from July 21 to July 30, the time considered as peak harvesting period of second fruit truss. In conclusion, the application of fly ash improved physico-chemical properties of experimental soil.