• 제목/요약/키워드: tunnel behavior

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Evaluation of Tunnel Face Stability with the Consideration of Seepage Forces (침투력을 고려한 토사터널 막장의 안정성 평가방법에 대한 고찰)

  • 남석우;이인모
    • Proceedings of the Korean Geotechical Society Conference
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    • 한국지반공학회 1999년도 가을 학술발표회 논문집
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    • pp.193-200
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    • 1999
  • Since Broms and Bennermark(1967) suggested the face stability criterion based on laboratory extrusion tests and field observations, the face stability of a tunnel driven in cohesive material has been studied by several authors. And recently, more general solution for the tunnel front is given by Leca and Panet(1988). They adopted a limit state design concept to evaluate the face stability of a shallow tunnel driven into cohesionless material and showed that the calculated upper bound solution represented the actual behavior reasonably well. In this study, two factors are simultaneously considered for assessing tunnel face stability: One is the effective stress acting on the tunnel front calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady state ground water flow. The model tests were performed to evaluate the seepage force acting on the tunnel front and these results were compared with results of numerical analysis. Consequently, the methodology to evaluate the stability of a tunnel face including limit analysis and seepage analysis is suggested under the condition of steady state ground water flow.

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Analysis on the behavior of a old tunnel supporting system by enlargement (노후터널 확대시 기존터널 지보재 응력 변화에 대한 분석)

  • Baek, Ki-Hyun;Kim, Woong-Ku;Seo, Kyoung-Won
    • Proceedings of the Korean Geotechical Society Conference
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    • 한국지반공학회 2010년도 춘계 학술발표회
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    • pp.1382-1387
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    • 2010
  • A 3D FEM numerical analysis was performed to observe the changes of supporting system of a old 1-lane tunnel when it is enlarged to 2-lane, 3-lane and 4-lane. The standard Type-III supporting pattern was applied to the new tunnel because the ground was assumed as Type-III. The observation was carried out at the middle supporting system of the old 1-lane tunnel alignment. The results shows that the changes of old tunnel supporting system began when the new tunnel was excavated at 2D(D is the equivalent diameter of 1-lane tunnel) behind of the observation place and became very rapid from 1D.

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Structural stability evaluation of TBM tunnels using numerical analysis approach

  • Dohyun Kim
    • Geomechanics and Engineering
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    • 제38권6호
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    • pp.583-591
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    • 2024
  • To properly simulate the excavation process and evaluate the structural stability of the tunnel, rigorous large deformation analysis method is necessary. This study applies two most widely used numerical approaches capable of modelling and considering the large deformations behavior during excavation process to analyze and evaluate the structural stability of circular tunnel based on tunnel boring machine (TBM) excavation. By comparing and combining the results from two numerical approaches, the deformation of the excavated ground will be analyzed. The stability of the circular tunnel from TBM tunneling was assessed based on the maximum deformation occurred during the excavation process. From the numerical computation it was concluded that although the range of the damage on the ground done during excavation was found to be larger under hard rock condition, maximum deformation within the circular tunnel structure was larger under weak ground conditions and deeper tunnel depths.

Behavior of the tunnel under the influence of a existing building during the adjacent ground excavation (근접굴착 시 기존건물의 영향을 받는 터널의 거동)

  • Lee, Jong-Min
    • Journal of Korean Tunnelling and Underground Space Association
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    • 제20권3호
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    • pp.609-623
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    • 2018
  • If the ground is excavated in a depth which is deeper than the adjacent existing tunnel, the behavior of the braced wall is known to be greatly affected by the presence of the tunnel. By the way it is expected to be also affected by the structure on the ground surface, There are not many examples of studies which are conducted on this subject. As a result, largel scale model tests and analysis were conducted, to measure the behavior of the tunnel under the building whose location on the ground surface was varied during the adjacent ground excavation. For this purpose, the location of a building load was varied in 0 m, 1D, 2D on ground surface. In this paper, the behaviors of braced wall and adjacent tunnel was studied. Model tests in 1 : 10 scale were performed in real construction sequences. The size of test pit was 2.0m(width)×6.0m(height)×4.0m(length) in dimension. As a result, it was found that the stability of the existing tunnel under the influence of the building load on the ground surface adjacent to the braced wall.

Effects of Excavation Methods on Tunnel Deformation Behavior - A Numerical Investigation (굴착공법이 터널변위 거동에 미치는 영향 - 수치해석 연구)

  • Yoo, Chung-Sik;Kim, Joo-Mi;Kim, Sun-Bin
    • Journal of Korean Tunnelling and Underground Space Association
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    • 제8권4호
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    • pp.289-305
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    • 2006
  • This paper presents the effect of excavating methods on tunnel behavior. As part of this study, it is preliminarily focused on the comparison of two different excavation methods, center diaphram (CD) method and ringcut (RC) method. Especially, the purpose of this research is to study the behavioral mechanism of two tunnels which share the same construction environment but different excavating method. Two numerical analysis models with the same tunnel section and material properties are compared in this study, and they are analyzed by 3D finite element analysis. In each model, face stability, crown displacement, ground settlement, and shotcrete-lining stress are computed, then the general behavior of CD method and RC method is studied. The results indicate that the CD method tends to be effective in controlling tunnel displacement while the RC method is more effective in controlling ground settlement. Design implications of the findings from this study are discussed.

A Study on Geological Factors Affecting Behavior of Sedimentary Rock Tunnel Using Quantification Method Type I (수량화방법 I을 이용한 퇴적암 터널의 지질 인자별 변위 영향도 분석)

  • Yim, Sung-Bin;Seo, Yong-Seok;Kim, Chang-Yong;Kim, Kwang-Yoem
    • The Journal of Engineering Geology
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    • 제17권2호
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    • pp.263-270
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    • 2007
  • Tunnel behavior measured by monitoring during construction is a main item for safety evaluation and it depends widely upon local geological characteristics. To assess in this study how much the geological factors influence on tunnel behavior for each RMR factor, a quantification analysis was carried out using tunnel face maps and measurements as explanatory variables and dependent variables, respectively. The results showed that average significance of the influence of RMR factors - R1, R2, R3, R4 and R5, on tunnel displacements are 17.0%, 20.4%, 20.4%, 11.6% and 30.6%, respectively, and this probably indicates that the groundwater condition played a significant role for the tunnel displacement.

3-Dimentional numerical study on dynamic behavior of connection between vertical shaft and tunnel under earthquake loading (3차원 수치해석을 이용한 지진 시 수직구-터널 접속부 동적 거동 분석)

  • Kim, Jung-Tae;Cho, Gye-Chun;Kang, Seok-Jun;Kim, Ki Jung;Hong, Eun-Soo
    • Journal of Korean Tunnelling and Underground Space Association
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    • 제20권5호
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    • pp.887-897
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    • 2018
  • 3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.

Finite Element Analysis on the Ground Behavior for Tunnel with Pipe-roof (파이프루프공법이 적용된 터널의 지반거동 유한요소 해석)

  • Jo, Seon-Ah;Jin, Kyu-Nam;Sim, Young-Jong
    • Land and Housing Review
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    • 제7권4호
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    • pp.261-269
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    • 2016
  • Pipe-roof method is one of the mostly used method to prevent the ground subsidence during the tunnel construction. As pipe-roof method has made technical advancement and performance improvement, it suggested to utilize pipe-roof to a permanent support system rather than a temporal pre-reinforcing method. Therefore, in this study, pipe-roof method is numerically simulated using finite element method to evaluate effects of pipe-roof on behavior of ground and structure. Analyses are performed considering two major conditions that are with and without the application of pipe-roof and the shape of tunnel cross section. The results are presented with respect to variation of settlement and vertical stress distribution. Based on this results, it is found that ground settlement above the shallow tunnel can be considerably reduced by application of pipe-roof system. Also, the shape of tunnel cross section can influence on the mechanical behavior of ground and structure.

A Study on Instrumentation Results Analysis Using Artificial Neural Network in Tunnel Area (인공신경망을 이용한 터널시공 시 계측결과 분석에 관한 연구)

  • Lee, Jong-Hwi;Han, Dong-Geun;Byun, Yo-Seph;Chun, Byung-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 한국지반공학회 2010년도 추계 학술발표회 2차
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    • pp.21-31
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    • 2010
  • Although it is important to reflect the accurate information of the ground condition in the tunnel design, the analysis and design are conducted by limited information because it is very difficult to get it practically on considering various geography and geotechnical condition. So construction management of information concept is required to manage immediately on the field condition because it is very time-consuming to establish the countermeasure of underground reinforcement and the pattern change of Bo. Therefore, when construction is on tunnel area, examination of accurate safety and prediction of behavior is performed to overcomes the limit of predicting behavior by using Artificial Neural Network(ANN) in this study. Firstly, the field data was secured. Secondly, suitable structure was made on multi-layer perceptrons among the ANN. Thirdly, learning algorithm-propagated applies to ANN. The data for the learn of field application using ANN was used by considering impact factors, which influenced the behavior of tunnel, and performing credibility analysis. crown displacement, spring displacement, subsurfacement, and rock bolt axial force are predicted at the tunnel construction and on-site application was confirmed by using ANN from analyzing and comparing with measurement value of on-site. In this study, the data from Seoul Highway tunnel section was applied to the ANN Theory, and the analysis on the investigate value and the reasoning for the value associated with field application was performed.

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Suggestion of a Modified RMR based on Effect of RMR Parameters on Tunnel Displacement in Sedimentary Rocks (퇴적암 기반 터널에서의 지질인자별 변위 영향도를 고려한 RMR 수정 제안)

  • Seo, Yong-Seok;Yim, Sung-Bin;Na, Jong-Hwa;Park, Si-Hyun
    • The Journal of Engineering Geology
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    • 제18권2호
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    • pp.197-205
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    • 2008
  • Total displacement under non-reinforcement is a quantitative index of rock mass behavior during tunnel excavation and depends widely upon geological characteristics. The primary purpose of this study is to suggest a rock mass evaluation method, well representing tunnel behavior during excavation, according to rock type. A 3-D numerical analysis was carried out, with consideration of the shape of tunnel section, excavation condition and so forth, in a sedimentary rock-based tunnel, and total displacements under non-reinforcement according to rock mass class were calculated. Finally, quantification analysis was carried out to assess correlation of the total displacement with RMR parameters. As the result, a modified RMR system fer quantification of rock mass behavior during tunnel excavation is suggested.