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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geoenvironmental Society
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Korean Geo-Environmental Society
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Volume & Issues
Volume 6, Issue 4 - Dec 2005
Volume 6, Issue 3 - Sep 2005
Volume 6, Issue 2 - Jun 2005
Volume 6, Issue 1 - Mar 2005
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Effects of Gas Generation due to Biodegradation on Long-term Landfill Settlement
Ahn, Tae-Bong ; Chin, Han-Gyu ; Han, Woon-Woo ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 5~13
The conventional settlement prediction method is not appropriate to model landfill settlement because it is very complex phenomenon. Biodegradation needs to be considered for long-term settlement since landfills are comprised of various organic materials and soils. As organic materials are decomposed, they directly influences on settlement producing LFG(Landfill Gas). Therefore, mathematical settlement prediction model is proposed based on the generated gas volume. As one of stabilization methods, leachate recycling system is adopted to model tests. Two model tests; one is leachate recycled, the other is non-recycled, are componented with proposed model and analysed regarding gas generation and settlement. The proposed mathematical model requires correction coefficients of 1.4 and 1.7 for non-recycled model and recycled, respectively. The recycled model showed 22% increase of long-term settlement more than the non-recycled model.
The Evaluation on the Environmental Effect of Coal-Ash and Phosphogypsum as the Evapotranspiration Final Cover Material
Yu, Chan ; Yang, Kee-Sok ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 15~21
In this study, the utilization of coal-ash and phosphogypsum was considered as the evapotranspiration final landfill cover(ET cover) material. Cover material considered was the mixture of the weathered granite soil, coal-ash and phosphogypsum and so we sequentially performed the leaching test, column test and field model test to investigate the environmental effects of mixtures of coal-ash and phosphogypsum. In the leaching test, all materials had lower heavy metal concentration than the regulated threshold values. The column test and the review of related regulations were carried out to determine the optimum mixing ratio(OMR) and OMR was soil(4):coal-ash(1): phosphogypsum(1) on the volume base, which was applied to field model test. Field model tests were continued from February to June, 2004 in the soil box that was constructed with cement block. It was verified that coal-ash and phospogypsum mixed with soil was safe environmentally and the mixture of both wastes could improve the water retention capacity of cover materials.
Reclamation and Soil Improvement on Ultra Soft Soil (I) - Reclamation
Na, Yung-Mook ; Hong, Eui ; Han, Jung-Soo ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 23~31
The "Silt Pond" is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Reclamation works in the Silt Pond commenced in the mid of 1990s. A considerable amount of subsurface investigation inclusive of sampling, field vane and density logging tests were carried out prior to the reclamation of the Silt Pond. Since material in the Silt Pond is extremely soft, filling was done by spreading sand with high water content in thin and equal thickness lifts, allowing the stability of the slurry-like foundation. Despite the extreme care taken, failures occurred during the sand spreading phase. A large piece of high strength geotextile measuring
was placed to strengthen the slurry like soil foundation at locations where the ultra-soft soil was found to be exposed. Following the remedial works, the Silt Pond was again reclaimed by sand spreading up to +4.0m CD. The success of the reclamation was confirmed by marine CPT profiling.
Reclamation and Soil Improvement on Ultra Soft Soil (II) - Soil Improvement
Na, Yung-Mook ; Kim, Hee-Hong ; Kwon, Duk-Woo ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 33~44
The 'Silt Pond' is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Soil improvement work in the Silt Pond commenced by installing vertical drains in the mid of 1996, following completion of sand spreading up to +4.0m CD. Prior to soil improvement work in the main area of Silt Pond, experimental tests including laboratory tests with a large diameter consolidation cell and pilot tests were carried out to investigate the deformation behavior of an extremely soft soil. Due to its high compressibility, large strain usually occurred in the initial stage of deformation does not comply with Terzaghi's one dimensional consolidation theory. Taking into consideration experimental test results, the soil improvement works were carried out in main area of Silt Pond containing ultra soft soil. This paper presents the case study on improvement of ultra-soft soil.
A Study on the Distribution of Residual Stress for Drilled Shaft
Kim, Won-Cheul ; Hwang, Young-Cheol ; Ahn, Chang-Yoon ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 45~51
The distribution of shaft resistance is measured by the static load test with the strain gauge or stress gauge, so that the long-term load distribution must be considered for the pile design. However, the measurement by strain gauge generally assumes the 'zero reading', which is the reading taken at 'zero time' with 'zero' load and the residual stress, which is the negative skin friction(or the negative shaft resistance) caused by the pile construction, is neglected. Therefore, the measured value by strain gauge is different from the true load-distribution because residual stresses were neglected. In this study, the three drilled shafts were constructed, and the strain measurements were carried out just after shaft construction. As a result of this study, it is shown that the true load-distribution of drilled shaft is quite different with known load distribution and the true load-distribution of drilled shaft changed from the negative skin friction to the positive skin according to the load increment.
The Long-Term Settlement Behavior Analysis of Multi-layered Refuse Landfill by In-situ Measurement
Chun, Byung-Sik ; Choi, Jung-Hoon ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 53~62
This paper estimates the long-term settlement of Kimpo metropolitan landfill based on measured settlement data from 180 landfill monitors accumulated over a period of 12 years. Comparison of domestic and international settlement records indicate that the domestic compression rate is slightly lower due to greater portion of organic component. Several existing settlement models are used to compare with the observed behavior and also to estimate long-term settlement. The hyperbolic, Gibson & Lo, Bjarngard & Edgers and Power Creep Law models compare well with the measured settlement of the Kimpo metropolitan landfill. The settlement models are further used to estimate long-term settlement. Bjarngard & Edgers and Power Creep Law models result in higher estimates of the long-term settlement compared to the hyperbolic and Gibson & Lo models. Further comparisons indicate that other models, including Sowers and log models, are inapproriate for predicting the long-term settlement of the Kimpo metropolitan landfill.
A Study of the Deformation Characteristics in Limestone Cavity Area by Finite Element Method
Chun, Byung-Sik ; Park, Hyeong-Jun ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 63~72
From the geological and engineering point of view, the limestone is so rigid that it is able to act as a bedrock but if there are some unstable elements which are solubility cavity and cracking zone in the ground, the settlement and bearing capacity of a structure will be required to long-term stability investigations and countermeasures about those problems. When comparing the allowable bearing capacity, the results of Bell's method and the Bowles' method are similar but the results of Hoek-Brown's method are very larger than the others. For weathered limestone, stability is changed by size and depth of the cavity of limestone, but soft and hard rock are stable regardless of size and depth of the cavity.
Slope Stability Analysis Considering Reinforcing Effects of Geosynthetics
Kim, Kyeong-Mo ; Kim, Hong-Tack ; Lee, Hyung-Kyu ;
Journal of the Korean Geoenvironmental Society , volume 6, issue 1, 2005, Pages 73~82
Generally, to evaluate a slope stability of the geosynthetic reinforced soil slope, the modified version of limit equilibrium method can be used. In most cases, resisting effects of reinforcement are dealt with considering an increased shear strength on the potential slip surface. However, it is not clear that the methods satisfy all three equilibrium equations. In this study, the new slope stability analysis method in which not only reinforcing effects of geosynthetics can be considered but also all three equilibrium equation can be satisfied is proposed. A number of illustrative examples, including published load test of large-scale reinforced retaining wall and centrifuge model tests on the geotextile reinforced soil slopes, are also analyzed. As a result, it is shown that the newly suggested method produces a relatively accurate factor of safety.