• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.51-60
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• 2004

In Korea there are recently many attempts to expand a temporary soil nailing system into a permanent soil nailing system since the first construction in 1993. In the soil nailing system, the rigid facing walls act on restraining the deformation of the ground. These are purposed to minimize the damage of adjacent buildings or underground structures. In Korea, to minimize the relaxation of the ground, the soil nailing system in the downtown area is often used experientially together with braced cuts, sheet pile walls, soil cement walls (SCW), or jet grouting walls. However, for the conservative design, the confining effects by the stiff facing have been ignored because the proper design approach of considering the facing stiffness has not been proposed. In this study, various laboratory model tests are carried out to examining the influence the rigidity of facings on the global safety of soil nailing system. Also, the parametric studies using the numerical technique as shear-strength reduction technique are carried out. In the parametric study, the thickness of concrete facing walls is changed to identify the effects of the facing wall stiffness.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.3
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• pp.77-85
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• 2007

Assessment of soil erosion is a cost and time-consuming task. There are many models developed to predict soil erosion from an area, but Universal Soil Loss Equation (USLE) is most widely used empirical equation for estimating annual soil erosion. Soil erosion depends upon-rainfall intensity, type of soil, land cover and land use, slope degree, slope length and soil conservation practice. All these parameters are have spatial distribution and hence satellite remote sensing and Geographic Information System (GIS) are applicable in the assessment of the influence on soil erosion. GIS has been integrated with the USLE (Universal Soil Loss Equation) model in identification of rainfall-based erosion to the Bocheong River which is the representative basin of IHP due to Typhoon Rusa. Similar studies are available in literature, ranging from those that use a simple model such as USLE to others of a more sophisticated nature.

• Journal of Biosystems Engineering
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• v.34 no.6
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• pp.434-438
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• 2009

This study was conducted to design an cone penetrometer type impedance sensor that can measure soil water content in realtime. The best width between electrical probe was determined by 5 mm. For optimization about realtime application device, linear regression analysis was applied between soil water content and impedance signal. It was concluded that proper combination of excitation frequency, impedance parameter, and model would provide acceptible performance of a soil waler content sensoe. Best model was obatained at a 36.5 MHz with |Z| as a predictor variable, with a coefficient of determination of 0.96 (RMSE=1.35, RPD=4.98).

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.245-252
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• 2000

Model tests on free standing pile groups and piled footings with varying a pile spacing in two layered soils are carried out. The influence of pile cap on the behaviors of end bearing pile groups is analyzed by comparing the bearing behavior in piled footings with those in a single pile, a shallow footing(cap alone) and free standing pile groups. From the test results, it is found that the bearing characteristics of cap-soil-pile system are related with load levels and pile spacings. Before yield, the bearing resistance by cap is not fully mobilized, however, as the applied load increases, the bearing resistance of cap approaches to that of cap alone and settlement hardening occurs after yield due to the compaction caused by the contact pressure between cap and soil. By the cap-soil-pile interaction, shaft friction and point resistance of piles considerably increase with dependency of pile spacings. In two layered soil, the increasing effect of dilatancy in dense sandy soil adjacent to pile tips, increases the point resistance of pile.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.77-86
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• 2005

In urban areas, new tunnel construction work is often taking place adjacent to existing piled foundations. In this case, careful assessment for the pile-soil-tunnel interaction is required. However, research on this topic has not been much reported, and currently only limited information is available. In this study, the complex pile-soil-tunnel interaction is investigated using the upper and lower bound methods based on kinematically possible failure mechanism and statically admissible stress field respectively. It is believed that the limit theorem is useful in understanding the complicated interaction behaviour mechanism and applicable to the pile-soil-tunnel interaction problem. The results are compared with numerical analysis. The material deformation patterns and strain data from the FE output are shown to compare well with the equivalent physical model tests. Admissible stress fields and the failure mechanisms are presented and used to develop upper and lower bound solutions to assess minimum support pressures within the tunnel.

• Interaction and multiscale mechanics
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• v.6 no.1
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• pp.51-81
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• 2013

A wide literature review on Static Soil-Structure-Interaction (SSI) is done to highlight the key impacts of soil complexity on structural members of framed structures. Attention is paid to the developed approaches, i.e., conventional and Finite Element Method (FEM), to emphasize on deficiencies and merits of the proposed methods according to their applicability, accuracy and power to model and idealization of the superstructures as well as the soil continuum. Proposed hypothesis are much deeply discussed herein for better understanding which is normally neglected in literature review papers due to the large number of references and limit of space.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.117-123
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• 2000

Using the modified DEM (Discrete Element Method), which we proposed in order to improve the accuracy of the simulation, soil behavior and reaction by lugs of rotating wheel and a soil cutting process by a high speed blade were calculated and compared with experimental data. The DEM is one of computational mechanics, where the object body is supposed as an assembly of small particles called elements and not a continuum as in the case of FEM. We can easily treat some discrete phenomena such as cracking, separating and sliding by the DEM. We had to modify the original mechanical model, which induced too free movement of elements, adding a tension spring, which would display the role of soil adhesion. The results of DEM simulations were successful from both the soil behavior and reaction points of view.

• Journal of environmental and Sanitary engineering
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• v.17 no.1
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• pp.52-56
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• 2002

The study was carried out to evaluate the characteristics of biodegradation by Pseudomonas putida G7 in soil column. The reactor system was used to investigate mass transfer of VOCs as Toluene in a column of unsaturated soil. Determination of the fate of VOCs in unsaturated soil is necessary to evaluate the feasibility of natural attenuation as a VOCs remediation strategy. The objective of this study was to develop a mechanistically based mathematical model that would consider the interdependence of VOC transport, microbial activity, and sorptive interactions in a moist, unsaturated soil. Because the focus of the model was on description of natural attenuation, the advective VOCs transport that is induced in engineered remediation processes such as vapor extraction was not considered. It can be concluded that the coefficient for gas liquid mass-transfer was found to be a key parameter controlling the ability of bacteria to VOCs. Finally, it appeared that bioremediation technology of VOCs which are difficult to be decomposed by chemical methods.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.1
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• pp.11-20
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• 2009

Flow pump technique was used in order to determine the soil-water characteristic curve of weathered granite soils in Pocheon area. This technique enables measurement to be more convenient and accurate as it is based on the CU condition of triaxial compression test. Besides, it is also able to measure dry and moisture curves continuously since the test is controled by means of a computer automatically. In this study, not only a hydraulic conductivity of weathered granite soils at fully saturated state in Pocheon area, but also a soil-water characteristic curve throughout unsaturate flow tests were determined. In addition, Brooks and Corey's model and Genuchten's model were used to simulate the soil-water characteristic curve. On the basis of the simulation an unsaturate hydraulic conductivity was predicted.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.423-428
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• 2005

If the load of constructing vehicles during the construction work acts on the road or the ground surface on the soft ground, due to the excess stresses in soils the trafficability of the vehicles influences the constructing efficiency, constructing period and so on. Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research represents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer for its vertical and horizontal stress in (1)homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stress turn out to be different in the value of theoretical and actual measurement after the trial examination of model.