• Title/Summary/Keyword: Foundations

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Bearing Capacity Analyses of Shallow Foundations in Reinforced Slopes

  • Kim, Hong-Taek;Choi, In-Sik;Sim, Young-Jong
    • Geotechnical Engineering
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    • v.12 no.3
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    • pp.127-148
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    • 1996
  • Recently, foundations of heavy structures such as bridge abutments have been built on slopes or near the crest of slopes at an increasing rate. Because the bearing capacity of such foundations is considerably lower than the bearing capacity of the same soil on a level ground, deep footings such as piles and caissons are often used. However, the costs of such methods are generally very high. One of the new techniques to overcome the problem is to place reinforcing members such as geosynthetics or metal strips horizontally at some depths beneath the footings. Rational methods of analysis to predict the bearing capacity of footings in reinforced slopes are therefore needed. This paper proposes an analytical method for estimating the increase in bearing capacity gained from the included horizontal strips or ties of tensile reinforcing in the foundation soil below the footing built near the crest of a slope. A failure mechanism, including the concept of'wide slab effect', adopted in the present study for analyzing the bearing capacity of foundations in reinforced slopes, is established through the observed model test behaviors described by Binquet SE Lee and Huang et al, and the Boussinesq solutions. The analytical results are then compared with the experimental data described in the paper by Huang et al. Also in order to properly evaluate the soil reinforcement interaction, typical pullout test values of the apparent friction coefficient, which usually vary with depths owing to both the increase of the shearing volume and the increase in local stress caused by soil dilatancy, are analyzed and related functionally. Furthermore, analytical parametric studies are carried out to investigate the effect and significance of various pertinent parameters associated with design of reinforced slope foundations. Keywords : Bearing capacity, Reinforced slope, Slab effect, Friction coefficient.

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The Influence of Suction Foundation Models for Offshore Wind Turbine (해상풍력발전 석션기초의 강성산정 방법에 따른 영향 분석)

  • Jang, Hwa Sub;Nam, Hyun Woo;Kwak, Yeon Min;Yoon, Se Woong;Kim, Ho Sun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.5
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    • pp.339-344
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    • 2015
  • Suction piles have been widely used as foundations and anchor systems in offshore industry, and recently, it have been tried to be used as foundations for offshore wind turbines. Many researches have shown that stiffness of a foundation could effect dynamic responses of a offshore wind turbine so that appropriate modeling application of wind turbine foundations is recommended. In this paper, we calculate a stiffness matrix of a suction foundation through 3D FEM analysis and compare the results with the ones calculated by conventional formula for estimating stiffness of shallow foundations. And then we carry out integrated load analysis for the evaluation of dynamic responses and natural frequencies of the structure using the calculated stiffness matrix. The results shows that the effect of load in the mudline is not large, but in the case of assuming the foundation as a fixed support, the natural frequency is over-estimated up to 10%. Therefore, considering stiffness of foundations is recommended when you evaluate the natural frequencies of wind turbine structures.

The Characteristic Studies of Powder Coating System in Wet Slurry Processing Powder Foundation (습식공정 파우더 파운데이션에서 파우더 코팅 시스템의 특성 연구)

  • Lee, Chan-Ki;Lee, Su-Jin;Choi, Jae-Wook;Choi, Yeong-Jin;Han, Shang-Hoon
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.36 no.3
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    • pp.227-231
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    • 2010
  • Among various make-up products, foundations are widely used to express clear and flawless skin. Foundations can be classified by its formula to 3 types, liquid foundation, powder foundation, and oil dispersion foundation. Powder foundations are easy to carry and use, so it is commonly possessed. In the R&D point of view, the developing method of powder foundations can be classified again to 3 types. Dry-process, baked-process, and the wet slurry-process. The fact that the wet slurry-process goes through either the back injection method or the front injection method is previously known. The front injection process is used as the main method in this study. We observed the quality dependence on the kind of solvent and the powder coating system. In brief, when water was used as the main solvent, the hardness increased than when volatile silicones or hydrocarbons were used. And the sensory results were shown to prefer volatile solvents (silicones or hydrocarbons) over water. Similarly, when the amino acid-coating system was applied, the hardness was shown to increase, when silicone-coating system shown no specific change. By these results, tailor-made powder foundations targeting specific customer grades can be easily produced.

Optimization of Reinforcement Effect of Large-diameter Drilled Deep Foundation (보강형 현장타설말뚝의 최적보강효과 분석)

  • 남대승;김수일;이준환;윤경식
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.207-216
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    • 2003
  • Drilled deep foundations of large diameter are often used for foundations of transmission towers. As tower structures become larger in modern society, there is a need of more efficient and economical design of large-diameter drilled deep foundations. Reinforced drilled deep foundations are popular in Japan for the foundation of tower structures. Stiffeners attached to the shaft of the foundation are used to increase the shaft resistance. This study aims at analyzing the effect of reinforcement with large-diameter drilled deep foundations based on numerical analysis of the representative soil and rock conditions in Korea. The numerical analyses are conducted to analyze the reinforcement effect of various stiffener conditions of number, inclination, location and length. Regarding to number of stiffeners, the effect of reinforcement for weathered and soft rocks increases proportionally as the number of stiffeners increases. For weathered soil, however, the effect of reinforcement increases at a lower rate. The effect of stiffener location is nearly negligible for axially loading cases, while it is significant for laterally loading cases. For the laterally loading cases, upper locations of stiffener give greater reinforcement effect than that of lower location. For stiffener inclinations of axial loading cases, a stiffener inclination equal to 60$^{\circ}$ gives the greatest reinforcement effect.

A Study on the Improvement Measures for Training of Special Security Guard (특수경비원 교육훈련의 개선방안에 관한 연구)

  • Choi, Eun-Ha;Yoo, Young-Jae;Lee, Sang-Bin
    • Korean Security Journal
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    • no.16
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    • pp.357-371
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    • 2008
  • Currently, the security operations in nation's key foundations in Korea are performed by private police and special security guard in accordance with the Private Police Act and Security Business Act, respectively. In 1960s, The Korean Government introduced the private police system in terms of the national security issues, but it was just a hurriedly-set plan on the basis of Japanese Sunsa system as by that time there was no such system revitalized. However, the special security guards could offer wider range of security services including those of the private police with the enactment and revision of the Security Business Act 1976 and April 2001, respectively. Moreover, the expectations and interests rose over the special security guards in nation's key foundations after 9.11Terror Event in the U. S. 2001. However, as we investigated the current education/training system for the special security guard, we found that such education/training which is not activating the specialty of special security guard will not respond to the social demands. Special security guard owns its own characteristics other than those of general security guard as they are in service in nation's key foundations. Thus, the effcient management and training for the special security guard is the most important matter for the safety and security of nation's key foundations. Therefore, the well-educated special security guard through the reorganized and specialized education/training for the protection of nation's key foundations is expected to offer qualitatively improved security services.

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