• 한국토양비료학회지
• /
• 제6권1호
• /
• pp.61-65
• /
• 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.

• 한국농공학회논문집
• /
• 제52권3호
• /
• pp.89-95
• /
• 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
• /
• 제6권3호
• /
• pp.90-94
• /
• 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
• /
• 제34권4호
• /
• pp.425-435
• /
• 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.

• 한국토양비료학회지
• /
• 제16권2호
• /
• pp.92-97
• /
• 1983

하해혼함식양질답(河海混咸埴壤質畓)에서 수도수량(水稻收量)을 향상(向上)시킬 수 있는 토양물리성(土壤物理性) 개량방법(改良方法)을 구명(究明)하기 위하여 심토파쇄 및 혼층처리후(混層處理後) 수도생육(水稻生育)과 토양물리성(土壤物理性)을 조사(調査)한 시험결과(試驗結果)는 다음과 같다. 1. 심토파쇄와 혼층처리(混層處理)에 의(依)하여 가비중(假比重), 경도(硬度), 공극률(孔隙率) 및 투수성등(透水性等) 토양물리성(土壤物理性)이 현저(顯著)히 개선(改善)되었다. 2. 토양(土壤)의 물리성(物理性)과 수도(水稻)의 근(根) 발달 및 수량간(收量間)에는 유의성(有意性)있는 상관관계가 성립(成立)되었다. 3. 토양물리성개선(土壤物理性改善)에 의(依)한 수도(水稻)의 증수효과는 약(約) 10%로써 배수효과 5%보다 훨씬 높았다. 4. 토양물리성개선효과는 4년차(年次)까지 지속(持續)되었으며 혼층(混層)이 심토파쇄(深土破碎)보다는 효과가 좋았으나 심토파쇄가 중기계(重機械)를 이용(利用)하여 편리(便利)한 작업(作業)이 가능(可能)하므로 가장 효율적인 개선방법(改善方法)이라고 판단된다. 5. 혼층처리시에 생고시용(生藁施用)은 무시용(無施用)에 비(比)하여 수도수량(水稻收量)이 2~3% 증수되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.480-488
• /
• 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.

• 한국지반공학회논문집
• /
• 제16권2호
• /
• pp.79-89
• /
• 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
• /
• 제13권6호
• /
• pp.963-975
• /
• 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
• /
• 제36권4호
• /
• pp.329-341
• /
• 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.

• 한국자원식물학회지
• /
• 제20권1호
• /
• pp.93-98
• /
• 2007

석탄회의 시용은 토양의 pH를 증가시키는 경향을 보였으며, 무연탄회 보다는 유연탄회에서 그 효과가 더 현저하였다. 석탄회 시용에 의한 토양 pH 교정효과는 토양중 유효인산의 함량을 증대시켰으나 공시토양의 높은 pH와 고온, 건조한 환경으로 인하여 석탄회의 시용량이 증가하여 토양 중의 인산함량이 높을수록 식물체에 함유된 인산의 함량이 오히려 낮아지는 경향을 보였다. 토마토의 수량은 식물체내의 인산함량이 높은 처리구에서 많아 식물체 중의 인산 함량의 증가가 식물의 수량을 증가시키는 요인이 된 것으로 생각된다. 수확기별로 보면 모든 처리구에서 제 2과방의 주된 수확시기인 7월 21일에서 7월 30일 사이에 주당 수확된 과실의 수가 많았고, 과실의 개별 무게가 무거워 수량이 가장 많았다. 결론적으로 석탄회의 시용은 토양의 물리화학성을 개량시키는데 기여하는 것으로 생각된다.