• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.74-74
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• 1999

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1014-1023
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• 2006

Soil nailing is a reinforcement method used for stabilizing excavated wall or slope. Due to its many advantages such as ease of construction and economical efficiency, use of soil nailing is increased. However, the soil nail can't trespass on the neighbor private land, which pays rent for use. For this reason, removable soil nailing system was developed. However, the removal rate of this system is just about $50\sim70%$. To solve this, the Fiber Reinforced Polymer (FRP) soil nailing system, which does not need to be removed and allows for the trespass on the private land, is developed. In this paper, through theoretical and experimental studies in laboratory and field, we evaluate the stability and behavior characteristics of the FRP nail system. Besides, numerical analyses using FLAC2D were performed for various soil conditions, where the simulations for pullout tests were carried out. As a result, compared with the conventional removable soil nailing system, the FRP soil nailing systems show similar behavior characteristics.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.152-152
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• 2018

Soil moisture is a important factor in hydrologic analysis. So, if we have spatially distributed soil moisture data, it can help to study much research in a various field. Recently, there are a lot of satellite derived soil moisture data, and it can be served through web freely. Especially, NASA (National Aeronautics and Space Administration) launched the Soil Moisture Aperture Passive (SMAP) satellite for mapping global soil moisture on 31 January 2015. SMAP data have many advantages for study, for example, SMAP data has higher spatial resolution than other satellited derived data. However, becuase many satellited derived soil moisture data have a limitation to data accuracy, if we have ancillary materials for improving data accuracy, it can be used. So, in this study, after applying the alogorithm, which is data assimilation methods, applicability of satellite derived soil moisture data was analyzed. Among the various data assimilation methods, in this study, Model Output Statistics (MOS) technique was used for improving satellite derived soil moisture data. Model Output Statistics (MOS) is a type of statistical post-processing, a class of techniques used to improve numerical weather models' ability to forecast by relating model outputs to observational or additional model data.

• Journal of Biosystems Engineering
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• v.43 no.3
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• pp.161-172
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• 2018

Purpose: During tillage operations, the selection of a working machine (tool) depends on the soil conditions as well as the type of tillage operation to be performed. The goal of this research was to ascertain the effects of varying working machine parameters of a compact disc harrow on tillage operations under various soil moisture content (SMC) conditions. Methods: The working machine parameters were the disc spacing and machine speed. The tillage parameters under investigation were the soil inversion ratio (SIR), tillage cutting depth (TCD), and soil clod breakage ratio (SCB). To determine the SIR, the areas of the white regions before and after tillage were obtained. The ratio of the difference of the areas of the white regions before and after tillage to the area of the white regions before tillage was considered as the SIR. The SCB was obtained as the ratio of the weight of soil clods after sieving with a mesh size of <0.02 m to the total weight of the soil clods before sieving. The soil TCD was measured using a tape measure at random points after the tillage operation. The resulting data were statistically analyzed in a one-way analysis of variance. Results: The highest soil inversion was achieved when the machine speed was 0.2 m/s with the disc spaced at 0.2 m in the 16.5% SMC. At a 0.4-m/s machine speed and 0.3-m disc spacing the highest soil breakage was achieved in the 26.5% SMC. The highest TCD was achieved at a 0.2-m/s machine speed and 0.2-m disc spacing in the 16.5% SMC. Conclusions: It was concluded that varying the working machine parameters, such as the disc spacing and machine speed, could significantly affect the soil inversion and soil clod breakage; however, it had no significant impact on the TCD.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.527-532
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• 2010

Soil-cement has been broadly used for eco friendly pavement, slope protection and soft soil improvement since it used for the increase of soil strength with cement. Recently, additional agents are mixed with existing soil-cement so as to improve specific properties or functions such as strength, color and permeability of it. This study aims at figuring out the physical and mechanical properties of a soil-cement mixed with crashed oyster shell and loess. The study is specially focused on the applicability of oyster shell as an alternative material for sands. To have his objective achieved a series of uniaxial compression tests were conducted. As a result, it appears that usage of oyster shell may have effect on strength improvement of mixed soils.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.940-950
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• 2010

In case of uneven surcharge like backfill or embankment after constructing caisson applied on the deep soft marine deposits, lateral deformation of soft soils would happen due to plastic deformation of soil particles by increase of excess pore water pressure. Lateral deformation of soil will result in the caisson displacement which affects soft soil-caisson structure safety. Soft soil was improved by soil compaction pile method, and then gravity caisson was installed. Soil deformations were monitored and analyzed with step by step backfill and embankment behind the caisson. Amount and speed of lateral deformation after the installation of caissons were closely related with the time of backfill and embankment. The relationship between maximum lateral displacement($\Delta_y$) in front of caisson and settlement($\Delta_s$) can be expressed as $\Delta_y=(0.0871)\Delta_s+122.95$. Soft soil depth did not affect the lateral displacement of caisson in this study, which can be explained the soft soil improvement under the caisson by S.C.P. method. Substantially the amount and speed of the lateral deformation of caisson were closely related with the uneven surcharging rate behind caisson.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.201-204
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• 2010

Earthquake load to design a structure has been calculated from a fixed base SDOF model using amplified surface accelerations along soft soil layers. But the method dose not consider a soil-structure interaction. Centrifugal experiments that were consisted of soil, a shallow foundation and a structure were performed to find the effects of soil-structure interaction. The experiments showed that mass and stiffness of the foundation affected a response of the structure and nonlinear behavior of soil near the foundation. And a rocking displacement caused by overturning moment affected the response and increases a damping effect. In this study, the centrifugal experiment was simulated as a two dimensional finite element model. The finite element model was used for nonlinear time domain analysis of the OpenSees program. The numerical model accurately evaluated the behaviors of soil and the foundation, but the rocking effect and the behavior of structure were not described.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.84-91
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• 2005

In case of soil nailing system, there have been many attempts to expand into slope and temporary earth retaining system stabilization method since the first ground excavation earth retaining system construction in 1993. Recently, jointing wall, underground wall of buildings and excavation earth retaining wall, construction were increasingly applied for effective utilization of the limited underground space and land application maximized. However, the application of joining wall into retaining wall or building by temporary soil nailing system and design of permanent wall were performed by using Rankine earth pressure theory without considering the distribution of earth pressure in the soil nailing. In this study was performed to introduce the design case by 'Two-Body Translation mechanism (TBTM)' to be able to consider distribution of earth pressure in the soil nailing when designing the permanent jointing wall using soil nailing system for effective utilization of ground space. Also, this study attempts to evaluate the earth pressure change, decreasing effect of wall displacement and increasing effect of stability when advanced soil nailing system is constructed using $FLAC^{2D}$ ${\nu}er.$ 3.30 program and 'Two-Body Translation mechanism'.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.334-341
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• 2004

The coefficient of permeability is one of the most important properties in unsaturated soils. The permeability varies with change in the water content as the soil water characteristic curve(SWCC) does. Thus the permeability curve of unsaturated soils has the similar shape with the soil-water characteristic curve(SWCC). Therefore, the methodologies have been studied to simply predict the unsaturated permeability from the SWCC. In this study, the experimental tests of SWCC and permeability were carried out for domestic weathered granite soils. The SWCC test results were fitted to Fredlund and Xing's SWCC equation and then it was found that there are some relationships between the parameters of SWCC equation and the basic soil properties. Accordingly we used an ANN(artificial neural network) model to obtain the SWCC parameters from the basic soil properties. Finally, the coefficients of permeability were predicted from these results by a prediction model.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1330-1333
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• 2009

The soil nailing method had used in variable construction field because of construction convenience and reinforcement effect. Especially, the removal soil nailing method is useful support system in vertical excavation. In this study, to develop the wedge type removable soil nailing method for improvement of the removal soil nailing method. Because of the reinforcement materials is most important in soil nailing method, to evaluate the mechanical characteristics during laboratory strength test in this study. To conduct bond strength test of deformed bar combined with a wedged screw inside plastic fixed socket for evaluate the strength characteristics of wedge type removable soil nailing method and evaluate the strength characteristics of fixed socket based on laboratory tests.