• Title/Summary/Keyword: temporary wall

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Parametric Study for Seismic Design of Temporary Retaining Structure in a Deep Excavation by Dynamic Numerical Analysis (동적수치해석을 이용한 대심도 흙막이 가시설 내진설계 변수연구)

  • Yang, Eui-Kyu;Yu, Sang-Hwa;Kim, Dongchan;Kim, Jongkwan;Ha, Ik-Soo;Han, Jin-Tae
    • Journal of the Korean Geotechnical Society
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    • v.38 no.12
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    • pp.45-65
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    • 2022
  • In this paper, a diaphragm wall that supports soils and rock was modeled using FLAC, a finite difference analysis program, to evaluate the seismic behavior of temporary retaining structures in a deep excavation. The appropriateness of the numerical model was verified by comparing its results with those of the centrifuge test performed in a similar condition. The bending moment distribution along the diaphragm wall shows a very similar tendency, and the maximum acceleration obtained at the backfill and top of the wall shows a difference within 5%. Based on the developed model, a parametric study was conducted in various input earthquake, ground, and excavation conditions. The maximum structural forces and bending moment under earthquake loading were compared with the maximum values during excavation, from which the critical condition that requires a seismic design was roughly sorted out. The maximum bending moment of a wall that retains soil layers increased 17%. Particularly, the axial force of struts located in loose soils increased 32% under 100 years return period of an earthquake event, which strongly is estimated to require seismic design for structural safety.

A Case Study on the Self-Supported Earth Retaining Wall with Different Formations (다양한 형태의 2열 자립식 흙막이 공법 시공사례 연구)

  • Sim, Jae-Uk;Kim, Kyoung-Chul;Son, Sung-Gon;Park, Young-Jin;Im, Jong-Chul
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.1039-1049
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    • 2010
  • Excavation support systems are the temporary earth retaining structures that can prevent the lateral movement of soils. The systems are initially performed before other construction operations and have a great impact on the entire construction period. The temporary support system in Korea have been carried out generally along with installing supports, which are struts, tiebacks, and rakers. However, most of existing support systems in application relatively have limitations such as cost increase, construction configuration, and displacement occurred with support systems. Thus, a new retaining support system (referred to as the SSR, New Construction Technology No. 533) was developed to solve the aforementioned problems. This study introduces the design, construction, and maintenance of the SSR system under the different construction conditions. The behavior and characteristics of the SSR system were identified based on the case studies.

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POLYMERIZATION SHRINKAGE, HYGROSCOPIC EXPANSION AND MICROLEAKAGE OF RESIN-BASED TEMPORARY FILLING MATERIALS (레진계 임시수복재의 중합수축, 수화팽창과 미세누출)

  • Cho, Nak-Yeon;Lee, In-Bog
    • Restorative Dentistry and Endodontics
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    • v.33 no.2
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    • pp.115-124
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    • 2008
  • The purpose of this study was to measure the polymerization shrinkage and hygroscopic expansion of resin-based temporary filling materials and to evaluate microleakage at the interface between the materials and cavity wall. Five resin-based temporary filing materials were investigated: Fermit (Vivadent), Quicks (Dentkist), Provifil (Promedica), Spacer (Vericom), Clip (Voco). Caviton (GC) was also included for comparison. Polymerization shrinkage of five resin-based temporary filling materials was measured using the bonded disc method. For the measurement of hygroscopic expansion, the discs of six cured temporary filling materials were immersed in saline and a LVDT displacement sensor was used to measure the expansion for 7 days. For estimating of microleakage, Class I cavities were prepared on 120 extracted human molars and randomly assigned to 6 groups of 20 each. The cavities in each group were filled with six temporary filling materials. All specimens were submitted to 1000 thermocycles, with temperature varying from $5^{\circ}C/55^{\circ}C$. Microleakage was determined using a dye penetration test. The results were as follows: 1. Fermit had significantly less polymerization shrinkage than the other resin-based temporary fill ing materials. Fermit (0.22%) < Spacer (0.38%) < Quicks (0.64%), Provifil (0.67%), Clip (0.67%) 2. Resin-based temporary filling materials showed 0.43-1.1% expansion in 7 days. 3. Fermit showed the greatest leakage, while Quicks exhibited the least leakage. 4. There are no correlation between polymerization shrinkage or hygroscopic expansion and microleakage of resin-based temporary filling materials.

Investigation of Seismic Response for Deep Temporary Excavation Retaining Wall Using Dynamic Centrifuge Test (동적원심모형실험을 통한 대심도 가설 흙막이 벽체 지진 시 거동 연구)

  • Yun, Jong Seok;Han, Jin-Tae;Kim, Jong-Kwan;Kim, Dongchan;Kim, Dookie;Choo, Yun Wook
    • Journal of the Korean Geotechnical Society
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    • v.38 no.11
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    • pp.119-135
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    • 2022
  • This paper used dynamic centrifuge tests to examine the seismic response for a deep temporary retaining wall with four input motions of 100, 1,000, and 2,400 years of return periods. The centrifuge model was designed based on an actual deep excavation design with a 50 m maximum excavation depth. The model backfill was prepared with dry silica sand at a relative density of 55%, and the retaining wall was modeled as a 24.8 m height diaphragm wall supported by struts. Acceleration response was amplified at the backfill surface, top of the wall, and near bedrock. However, in the middle of the model, input motion was de-amplified. The member forces of the wall and strut induced by the seismic load, which excited, were compared with the member force at rest condition. The wall's maximum negative and positive moments were increased to 36% and 10% compared to the maximum moment at rest. The maximum axial force increases to 70% of the at rest axial force on the bottom strut. The equivalent static analysis using Mononobe-Okabe (M-O) and Seed-Whitman (S-W) seismic earth pressures were compared to the centrifuge results. Considering the bending moment, the analysis results with the M-O theory underestimates but that with the S-W theory overestimates.

Study on Development of CWS (buried wale Continuous Wall System) Method (CWS공법(buried wale Continuous Wall System)의 개발에 관한 연구)

  • Lee Jeong-Bae;Lim In-Sig;Chun Sung-Chul;Oh Boh-Wan;Ha In-Ho;Rhim Hong-Chul
    • Journal of the Korea Institute of Building Construction
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    • v.6 no.2 s.20
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    • pp.81-89
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    • 2006
  • A down construction method is frequently used in these days to reduce popular discontent and to assure sufficient working space at early stage in downtown area. There are two main problems in the existing down construction method. One is a confliction between frame works and excavation works, and the other is a cold joint in retaining wall which is unavoidable due to a sequence of concrete placement and induces a water leakage. Therefore, a new method is needed to overcome these problems. The CWS (buried wale Continuous Wall System) method was developed by authors. By replacing RC perimeter beam with embedded steel wale, the steel frame works of substructure can be simplified and the water leakage can be prevented using continuous retaining wall. Consequently, the improved qualify and reduction of construction period can be obtained from CWS method.

APPLICATION OF WIRELESS INCLINOMETER FOR DISPLACEMENT MEASUREMENT OF TEMPORARY EARTH RETAINING PILE

  • Chi Hun In;Hong Chul Rhim
    • International conference on construction engineering and project management
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    • 2009.05a
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    • pp.218-223
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    • 2009
  • During the process of excavation for substructures of buildings, precise and constant measurements of retaining wall displacement is crucial for construction to be complete and safe. Currently an inclinometer is used to measure displacement around the perimeter of an excavation site. The existing inclinometer system requires an instrument to be placed inside pre-bored holes for each measurement with an typical interval of two weeks. This makes it difficult to obtain continuous displacement data, especially during a critical time such as rainy season in summer. Also, the existing inclinometer is placed at certain distance away from the retaining wall system itself. Thus, exact measurement of retaining wall movement is compromised because of the distance between the retaining wall and the inclinometer. This paper presents the development of wireless inclinometer system for the displacement measurement of retaining walls by being attached directly to the retaining wall. The result of the application of the developed systems are provided with advanced ubiquitous sensor network (USN) system features. The USN technique incorporated into the system enables users to monitor movement data from wherever possible and convenient such as construction manager's office on site or any other places connected through internet. The research work presented in this paper will provide a basis to save construction time and cost by preventing safe-related unexpected delay of construction due to the failure or collapse of retaining walls.

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Safety Management of the Retaining Wall Using USN Sonar Sensors (USN 초음파 센서를 활용한 흙막이 안전관리)

  • Moon, Sung-Woo;Choi, Eun-Gi;Hyun, Ji-Hun
    • Korean Journal of Construction Engineering and Management
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    • v.12 no.6
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    • pp.22-30
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    • 2011
  • In the construction operation, foundation work should be done in advance for the building structure to be installed. This foundation work include a number of activities such as excavation, ground water prevention, piling, wale installation, etc. Caution should be taken in the operation because the dynamics of earth movement can cause a significant failure in the temporary structure. The temporary structure, therefore, should be constantly monitored to understand its behavior. This paper introduces the USN-based monitoring system to automatically identify the behavior of the temporary structure in addition to visual inspection. The autonomous capability of the monitoring system can increase the safety in the construction operation by providing the detailed structural changes of temporary structures.

Design Optimization of Earth Retaining Walls Using the Taguchi Method (다구찌 기법을 활용한 흙막이 가설공법 최적설계 방안)

  • Moon, Sungwoo;Kim, Sungbu
    • Korean Journal of Construction Engineering and Management
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    • v.18 no.1
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    • pp.83-89
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    • 2017
  • Temporary structures provide the accessible working area when building a permanent building structure in the construction operation. Executed in a natural environment, the temporary structure is prone to the external influence factors of underground water, soil conditions, etc. These factors should be carefully considered in designing the temporary structure. The objective of this study is to apply the external influence factors in designing a more reliable earth retaining wall. The research methodology is based on the Taguchi method that has been studied to improve product quality in the industry. An orthogonal array was developed to analyze the interaction between the external influence factors and the internal influence factors. A sample case study demonstrated that the Taguchi method can be used in planning a more reliable temporary structure for earth retaining walls.

A Study on the Evaluation of the Availability of Sign System in Temporary Space -Focused on COVID-19 Vaccination Spaces- (임시공간의 사인 시스템 가용성 평가에 관한 연구 -COVID-19 백신 접종 공간을 중심으로-)

  • Li, Yi-Han;Zhang, Hui
    • Journal of Digital Convergence
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    • v.20 no.5
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    • pp.323-329
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    • 2022
  • In this study, users of the display system designed for the conference hall were evaluated as an example of a temporary space marking system for vaccination at a COVID-19 vaccination center in Chuncheon, Gangwon Province.Unlike ordinary space, temporary space display systems organize space on a limited schedule, so it is necessary to properly place and communicate information about space and processes in the display design to users. Therefore, a paper description manual, a wall display panel, and a floor path tape were provided and deployed to users of the inoculation session. The results of user evaluations show that for specific users over 60 years of age, a file (information display system) that conveys the overall information about the space and process is effective for vaccination. This result is expected to serve as a reference to how and how the display system will be installed in a temporary space in the future.

The Design and Construction of the Anchorage of Yi Sun-Sin Grand Bridge (이순신대교 앵커리지 설계-시공사례)

  • An, Ik-Kyun;Kim, Kyung-Taek;Seo, Young-Hwa
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.14-25
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    • 2010
  • The Yi Sun-Sin grand bridge is the suspension bridge which connects Myodo and Gwangyang. It is over the main navigation channel of Gwangyang Harbor. South anchorage(AN1, Myodo side) of the bridge is designed as rock anchored type. It sustains using the resistance of the underground rock's mass in Myodo. As this type of anchorage can minimize the exposure of the structure, It is economically efficient and environmentally friendly. North anchorage (AN2, Gwangyang side) is designed as the gravity type. This anchorage is 68 meters in diameter and use its own weight to support. Instead of normal rectangular diaphragm wall, the circular shape diaphragm wall is adopted to the north anchorage. It doesn't need to use internal temporary facilities, so it can significantly improve the constructability of the structure.

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