• 제목/요약/키워드: Retaining structures

검색결과 259건 처리시간 0.025초

Damage rate assessment of cantilever RC walls with backfill soil using coupled Lagrangian-Eulerian simulation

  • Javad Tahamtan;Majid Gholhaki;Iman Najjarbashi;Abdullah Hossaini;Hamid Pirmoghan
    • Geomechanics and Engineering
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    • 제36권3호
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    • pp.231-245
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    • 2024
  • In recent decades, the protection and vulnerability of civil structures under explosion loads became a critical issue in terms of security, which may cause loss of lives and structural damage. Concrete retaining walls also restrict soils and slopes from displacements; meanwhile, intensive temporary loading may cause massive damage. In the current study, the modified Johnson-Holmquist (also known as J-H2) material model is implemented for concrete materials to model damages into the ABAQUS through user-subroutines to predict the blasting-induced concrete damages and volume strains. For this purpose, a 3D finite-element model of the concrete retaining wall was conducted in coupled Eulerian-Lagrangian simulation. Subsequently, a blast load equal to 500 kg of TNT was considered in three different positions due to UFC 3-340-02. Influences of the critical parameters in smooth blastings, such as distance from a free face, position, and effective blasting time, on concrete damage rate and destroy patterns, are explored. According to the simulation results, the concrete penetration pattern at the same distance is significantly influenced by the density of the progress environment. The result reveals that the progress of waves and the intensity of damages in free-air blasting is entirely different from those that progress in a dense surrounding atmosphere such as soil. Half-damaged elements in air blasts are more than those of embedded explosions, but dense environments such as soil impose much more pressure in a limited zone and cause more destruction in retaining walls.

벽체 허용변위와 양상을 고려한 사질토지반에서 수동측토압 제안 (Proposal of Mobilized Passive Earth Pressure to Allowable Wall Displacement and Movement Types in Sandy Soil)

  • 윤영호;김태형;김태오;우민석
    • 한국지반공학회논문집
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    • 제39권7호
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    • pp.5-15
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    • 2023
  • 수평방향의 토압에 저항하는 흙막이 구조물(옹벽, 가시설 등) 설계에서 수동토압(Passive earth pressure) 산정은 중요한 요소이다. 토압이론에서 주동토압과 수동토압은 벽체 변위가 충분히 발생하여 한계변위에 도달한 한계상태에서의 토압이다. 흙막이 구조물설계에서 수동토압은 저항력으로 고려되는데, 이때, 수동토압이 발생하는 한계변위는 주동토압이 발생하는 한계변위의 10배 이상으로 이 변위를 수동토압산정에 적용하는 것은 비합리적이다. 그러므로 한계변위의 수동토압(Passive earth pressure)이 아닌 임의 크기의 수평변위에서 발생되는 임의 수동토압을 발현수동측토압(Mobilized passive earth pressure)으로 정의하고 흙막이 구조물의 안정성 검토에 발현수동측토압을 적용하는 것이 현실적으로 필요하다고 판단하였다. 본 연구에서는 모래지반에 대하여 문헌조사를 통해 흙막이 구조물의 안정성 확보가 가능한 허용수평변위를 0.002H(H:굴착깊이)로 제안하였으며, 임의수평변위에서 발생되는 발현수동측토압을 산정할 수 있는 반경험식을 사용하였다. 그리고 사질토 지반에서 구해진 발현수동측토압 자료를 바탕으로 실무에서 간단하게 적용할 수 있도록 벽체의 거동양상에 따른 Rankine의 수동토압에 적용 가능한 감소계수를 제안하였다.

Investigation of Field Construction and Economic Efficiency for Steel Plate-Concrete Structures with Application of Parking Building

  • Han, Kwon-Gyu;Park, Ho-Young;Han, Kyung-Bo;Choi, Byong-Jeong
    • 한국건축시공학회지
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    • 제14권1호
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    • pp.1-10
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    • 2014
  • The SC structure can have relatively liberal sectional surfaces, and allows modularization for pre-forming in factories and structural stability. It can be used for the shear walls in the core of general buildings or the structural members for parking buildings. In the future, it could be applied to moving large bus terminals, and widely used for general industrial structures as it can expedite the process compared to other methods. This study examined the applicability of SC structures to the retaining walls of a parking building and reviewed its economic value by comparing its construction term, quality control benefits, and cost compared to RC structures. It was found that SC structures are about 1.6-1.7 times more expensive than RC structures in terms of the cost of fabrication and installation. However, the construction term can be reduced by 27% to save indirect costs for constructors, as well as the cost of removing molds and material loss required when installing RC structures.

도심지 흙막이 굴착시 손상거동에 대한 대책공법사례 (Case Study of Damage Behavior in Urban Excavation)

  • 김만하;채영수;김학문
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2005년도 지반공학 공동 학술발표회
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    • pp.330-335
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    • 2005
  • Reliable predictions of the movement of earth retaining structures and the ground adjacent to braced walls in urban excavation are often difficult due to many variable factors. The ground settlement and the damage of adjacent structures in urban excavation has been an important issue. Therefore, the stability of the adjacent structures must be secured with the excavation support and research on the protection of adjacent structure is necessary. This study showed a countermeasure method for case of damage behavior in urban excavation.

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Bioinspired Nanoengineering of Multifunctional Superhydrophobic Surfaces

  • Choi, Chang-Hwan
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2015년도 추계학술대회 논문집
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    • pp.102-133
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    • 2015
  • Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. Especially, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing. Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing.

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Safety Classification of Systems, Structures, and Components for Pool-Type Research Reactors

  • Kim, Tae-Ryong
    • Nuclear Engineering and Technology
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    • 제48권4호
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    • pp.1015-1021
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    • 2016
  • Structures, systems, and components (SSCs) important to safety of nuclear facilities shall be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions. Although SSC classification guidelines for nuclear power plants have been well established and applied, those for research reactors have been only recently established by the International Atomic Energy Agency (IAEA). Korea has operated a pool-type research reactor (the High Flux Advanced Neutron Application Reactor) and has recently exported another pool-type reactor (Jordan Research and Training Reactor), which is being built in Jordan. Korea also has a plan to build one more pool-type reactor, the Kijang Research Reactor, in Kijang, Busan. The safety classification of SSCs for pool-type research reactors is proposed in this paper based on the IAEA methodology. The proposal recommends that the SSCs of pool-type research reactors be categorized and classified on basis of their safety functions and safety significance. Because the SSCs in pool-type research reactors are not the pressure-retaining components, codes and standards for design of the SSCs following the safety classification can be selected in a graded approach.

지하구조물 역타공법 PRD공정이 삭제된 대안공법 제시 (Downward Method of Underground Structures)

  • 이왕희;이일재;임시내;맹은주;정욱성
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2013년도 추계 학술논문 발표대회
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    • pp.4-7
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    • 2013
  • In recent downtown high land due to an increase in the utilization of land from the property line to maximize the proximity of the construction and use of underground structures has increased. The nature of urban underground retaining structure construction safety, environmental management, and civil contrast situations, construction periodt perspective, this method is widely used in the backhand. Recent Patents DP method and the method of the DBS method than in the SPS process is deleted according to the PRD process cost savings are generated. The workability and safety study of two kinds of method, such as air speed, and considering the reduction of indirect costs in terms of economic efficiency is considered to be a superior method.

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절리가 형성된 암반지층에서 발생된 토압의 크기 및 분포특성 (Characteristics of the Earth Pressure Magnitude and Distribution in Jointed Rockmass)

  • 손무락;윤철원
    • 대한토목학회논문집
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    • 제31권6C호
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    • pp.203-212
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    • 2011
  • 본 논문은 암반지층에 설치되는 굴착벽체의 안전하고 경제적인 설계 및 시공을 위해 절리가 형성된 암반지층에서 발생하는 토압의 크기 및 분포특성을 조사한 것이다. 이러한 목표를 위해, 먼저 기존 선행연구의 한계성 및 문제점을 파악하고 이를 극복하기 위해 암반지층의 다양한 절리특성 등을 고려할 수 있는 개별요소법(DEM)에 근거한 불연속체 수치해석적 매개변수 연구를 수행하였다. 매개변수로는 암반종류 및 절리상태(절리면의 전단강도 및 절리경사각)가 고려되었으며, 지반과 굴착벽체의 상호작용을 반영하면서 각 요소의 영향이 고려된 토압크기 및 분포특성이 파악되었다. 뿐만 아니라, 암반지층에서 발생된 토압과 토사지반에서의 경험토압인 Peck토압과의 상호 비교가 이루어졌다. 비교결과 절리가 형성된 암반지층에서 발생된 토압의 크기 및 분포는 암반의 종류 및 절리상태에 따라서 크게 영향을 받은 것으로 나타났고 토사지반에 있어서 Peck의 경험토압과 비교하여 서로 다른 특징을 나타내었다. 이와 같이 조사된 결과는 향후 절리가 형성된 암반지층에서의 굴착벽체 설계를 위한 토압산정에 필요한 정보 및 기초자료로서 활용될 것이다.

도심지 지하굴착의 문제점과 개선방향 (SOME PROBLEMS AND REMEDIAL MEASARES OF BRACED EXCAVATION IN URBAN AREAS)

  • 김학문
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 1994년도 가을 학술발표회 논문집
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    • pp.158-168
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    • 1994
  • This report describes aspects of recent braced excavation constructed in built up areas where adjacent buildings or underground utilities are likely to be subjected to settlement and damages. Trends and choice of earth retaining structures for deep excavation are present, and some desigen and construction techniques are introduced in order to minimise possible adverse effects to the urban environment. Some problems in design and construction of braced excavation in urban area are closely examined and remedial measrures are proposed.

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임시구조물로서 분리형 보강토 옹벽의 적용사레 (The Application of KOESWall System as a Temporary Structure)

  • 김영윤
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2000년도 토목섬유 특별세미나
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    • pp.53-58
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    • 2000
  • The KOESWall system that minimizes the horizontal deformation of reinforced wall effectively was developed bt E&S Eng. Co., Ltd. in 1999. Due to its systematical feature i.e. isolated construction method. KOESWall system is able to use as temporary structures more economically without the facing block. In this report, it is shown that the case history of KOESWall as a temporary soil retaining structure and the field measuremnets.

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