• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.481-489
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• 2006

Two dimensional diffusion model test was conducted to investigate the sedimentation properties and consolidation process of reclaimed ground using dredging coarse soil which is composed of passing amount 20 percentage and 45 percentage of #200 sieve size respectively. The passing amount of #200 sieve size affected on sedimentation properties. The coarse soil which is passing amount of 20 percent showed that the sedimentation structure was layered type and passing amount of 45 percentage was wall-partition type according diffusion distance. Furthermore, the water content of surface and section, and distribution of fine soil were changed according to diffusion distance. and the change amount of pore water pressure and strength property when soil is diffused, segregated and accumulated can be applied efficiently in design of dredging and reclamation.

• Steel and Composite Structures
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• v.49 no.2
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• pp.231-244
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• 2023

Many of the recent investigations in the field of geotechnical engineering focused on the bearing capacity theories of multilayered soil. A number of factors affect the bearing capacity of the soil, such as soil properties, applied overburden stress, soil layer thickness beneath the footing, and type of design analysis. An extensive number of finite element model (FEM) simulation was performed on a prototype slope with various abovementioned terms. Furthermore, several non-linear artificial intelligence (AI) models are developed, and the best possible neural network system is presented. The data set is from 3443 measured full-scale finite element modeling (FEM) results of a circular shallow footing analysis placed on layered cohesionless soil. The result is used for both training (75% selected randomly) and testing (25% selected randomly) the models. The results from the predicted models are evaluated and compared using different statistical indices (R² and RMSE) and the most accurate model BBO (R²=0.9481, RMSE=4.71878 for training and R²=0.94355, RMSE=5.1338 for testing) and TLBO (R²=0.948, RMSE=4.70822 for training and R²=0.94341, RMSE=5.13991 for testing) are presented as a simple, applicable formula.

• Geomechanics and Engineering
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• v.10 no.3
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• pp.335-355
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• 2016

Most laboratory test research has focused on grouting efficiency in homogeneous reconstituted soft clay. However, the natural sedimentary soils generally behave differently from reconstituted soils due to the effect of soil structure. A series of laboratory grouting tests were conducted to research the effect of soil structure on the performance of compensation grouting. The effects of grouting volume, overlying load and grouting location on the performance of compensation grouting under different soil structures were also studied. Reconstituted soil was altered with added cement to simulate artificial structured soil. The results showed that the final grouting efficiency was positive and significantly increased with the increase of stress ratio within a certain range when grouting in normally consolidated structured clay. However, in the same low yield stress situation, the artificial structured soil had a lower final grouting efficiency than the overconsolidated reconstituted soil. The larger of normalized grouting volume could increase the final grouting efficiency for both reconstituted and artificial structured soils. Whereas, the effect of the overlying load on final grouting efficiencies was unfavourable, and was independent of the stress ratio. As for the layered soil specimens, grouting in the artificial structured soil layer was the most efficient. In addition, the peak grouting pressure was affected by the stress ratio and the overlying load, and it could be predicted with an empirical equation when the overlying load was less than the yield stress. The end time of primary consolidation and the proportion of secondary consolidation settlement varied with the different soil structures, grouting volumes, overlying loads and grouting locations.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.117-129
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• 2009

Several researches have been done to estimate the earth pressure on a vertical circular shaft considering three dimensional arching effect and verified them by conducting model tests. However, any equation suggested so far is not applicable in case of multi-layered soils and/or C-${\phi}$ soils. In this study, new equation for estimating the earth pressure acting on the vertical shaft in c-${\phi}$ soils is proposed. A parametric study is performed to investigate the significance of the cohesion when estimating the coefficient of earth pressure in C-${\phi}$ soils and estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. This paper is Part I of companion papers focusing on the theoretical aspect of model developments; the experimental verification will be made in Part II.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.91-96
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• 2009

Layered double hydroxide is synthesized and used in the arsenate adsorption experiments. The shapes of two materials analyzed by TEM showed that unheated material is amorphous in shape, micro-sized while heat treated material showed more crystallized in shape and nano-sized. X-ray diffraction showed this result more obvious. $N_2$ adsorption-desorption results showed that the materials are mesoporous and the specific surface area of the heated material is more than two times larger than the unheated material. Adsorption of As(V) is expected to be more in the heated material than the unheated material. Kinetic test of arsenate adsorption showed very fast reaction. The reactivity of Fe with As(V) might be the main factor for this result. The reaction kinetic of the heated and the unheated materials were similar and even the adsorption isotherms showed similar results for both materials. Both materials are found to be useful in remediation of soil and groundwater polluted by waste mine tailings consist of high concentration of As(V).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.759-768
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• 2015

The ground motions of large dimensional structures such as long span bridges at different stations during an earthquake, are inevitably different, which is known as the ground motion spatial variation effect. There are many causes that may result in the spatial variability in seismic ground motion, e.g., the wave passage effect due to the different arrival times of waves at different locations; the loss of coherency due to seismic waves scattering in the heterogeneous medium of the ground; the site amplification effect owing to different local soil properties. In previous researches, the site amplification effects have not been considered or considered by a single-layered soil model only. In this study, however, the ground motion amplification and filtering effects are evaluated by multi-layered soil model. Spatially varying ground motion at the sites with different number of layers, depths, and soil characteristics are generated and the variation characteristics of ground motion time histories according to the correlation of coherency loss function and soil conditions are evaluated. For the bridge system composed of two unit bridges, seismic behavior characteristics are analyzed using the generated seismic waves as input ground motion. Especially, relative displacement due to coherency loss and site effect which can cause the unseating and pounding between girders are evaluated. As a result, considering the soil conditions of each site are always important and should not be neglected for an accurate structural response analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1017-1025
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• 2013

The monolithically coupled finite element analysis for a deformable unsaturated soil slope is performed to investigate matric suction distribution on a soil slope subjected to rainfall infiltration, which can consider the hydraulic-mechanical characteristics for the analysis. The soil-water characteristic curves (SWCC) are experimentally determined to estimate three types of hydraulic properties of domestic areas. Based on the physical properties, the distribution of matric suction is investigated by considering the major factors, such as soil conditions, rainfall intensities, and slope angles. It is found from the results of this study that the matric suction rapidly decreases with an increase in rainfall intensity, regardless a slope angle. The slope surface is more easily saturated when its saturated hydraulic conductivity is smaller than rainfall intensity, and for the case of multi-layered soil slope, hydraulic characteristics of slope surface has a significant influence on matric suction distribution.

• Korean Journal of Environment and Ecology
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• v.25 no.2
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• pp.211-226
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• 2011

The purpose of this paper was to ensure the basis for effective management of Tricholoma matsutake mountain province, to perform biotope mapping of Pinus densiflora based on growth environment of Tricholoma matsutake, target a cluster of Yangyang-gun, Kang Won-do. Study Methods were to review on growth and environmental characteristics of Tricholoma matsutake through internal and external documents and to identify vegetational structure and soil characteristics. This paper studied growth structure and soil environment of Pinus densiflora forest where a farm of production area for Tricholoma matsutake of in order to set the standard of Pinus densiflora biotope. Mapping standards were derived by separating of landform conditions, soil conditions, vegetation conditions. Biotope types were divided into possible production area for Tricholoma matsutake and potential production area for Tricholoma matsutake, possible production area for Tricholoma matsutake were Pinus densiflora biotope in landform and soil structure that enables Tricholoma matsutake production and Single-layered Pinus densiflora biotope of less than 30cm(DBH)-Tree species that other shrub is dominant in shrub layer, Multi-layered Pinus densiflora biotope that Pinus densiflora forest was predominant in understrory layer. Potential production area for Tricholoma matsutake were single-layered Pinus densiflora biotope of more than 30cm(DBH) in landform that enables Tricholoma matsutake production, Pinus densiflora biotope with Quercus predominant in the understrory layer, single-layered Pinus densiflora biotope with Quercus predominant in shrub layer, inappropriate vegetation structure area that the induction of production of Tricholoma matsutake was possible through future vegetation management. According to the research results, Pinus densiflora forest were divided into 16 types; 6 types of possible Tricholoma matsutake production areas, 9 potential Tricholoma matsutake production areas and 16 types of areas where Tricholoma matsutake production was impossible. Possible production areas account for 15.48%, or $9.8km^2$ out of the total Pinus densiflora forest while potential production areas take up 32.42%, or $20.52km^2$, and areas where Tricholoma matsutake production was impossible was 52.10%, or $32.97km^2$.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.6
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• pp.45-56
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• 2006

The finite element method is a practical tool to compute the response of the irregularly layered soil deposit to the base-rock motions. The method is useful not only in estimating the interaction between the structure and the surrounding soil as a whole and the local behavior of the contacting area in detail, but also in predicting the resulting behavior of the superstructure affected by such soil-structure interactions. However, the computation of finite element analysis is marched in the time domain (TD), while the site response analysis has been carried out mostly in the frequency domain (FD) with equivalent linear analysis. This study is intended to compare the results of the TD and FD analysis with focus on the peak response accelerations and the predominant frequencies, and thus to evaluate the applicability and the validity of the finite element analysis in the site response analysis. The comparison shows that one can obtain the results very close to that of FD analysis, from the finite element analysis by including sufficiently large width of foundation in the model and further by applying partial mode superposition. The finite element analysis turned out to be well agreeing with FD analysis in their computed results of the peak acceleration and the acceleration response spectra, especially at the surface layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.78-89
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• 2007

Two design examples of deep foundations for high-rise buildings on soft ground are introduced in this paper. The first one is a 54-story building in Ho-Chi-Minh city, Vietnam, which was designed to be founded on $2.8m{\times}1.0m$ barrette foundations with approximately 60m to 75m depth. Based on a number of design guides and existing load test data from the construction sites in Ho-Chi-Minh city, the capacity of a barrette foundation in sand or clay layered ground was calculated to be 17.2MN to 27.8MN depending on the installing depth. The second one is a 40-story building in Baku city, Azerbaijan, which was designed to be supported by 2.0m diameter bored pile foundations with approximately 23m depth. As analytical or empirical guides for the local ground conditions were very limited, the design procedure from the SNiP Code, one of Russian specifications, was adopted and used to calculate the pile capacity. The capacity of bored pile foundation in highly weathered soil was expected to be 14.8MN to 15.5MN depending on the boring depth.