• Title/Summary/Keyword: buried tunnel

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Analytical solution for steady seepage and groundwater inflow into an underwater tunnel

  • Zou, Jin-feng;Wei, An;Liang, Li
    • Geomechanics and Engineering
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    • v.20 no.3
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    • pp.267-273
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    • 2020
  • Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

Analysis of the Structural Behaviors of Tunnel Linings in Joomunjin Standard Sand by Centrifugal Model Tests (원심모형실험에 의한 사질토 지반내 터널 복공의 역학적 거동에 관한 연구)

  • 김택곤;김영근;박중배;이희근
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.161-168
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    • 1999
  • A series of centrifuge model tests were performed in order to investigate the behaviors of various tunnel linings. A 1/100-scaled aluminum and hydrostone horseshoe tunnel linings with a radius km, height km were buried in a depth of C/D=3 with dry Joomunjin standard sand, the relative density of which was 86%. Bending moments and thrusts along the tunnel circumference were measured by 12 strain gages. Earth pressures in soil and on lining were estimated by pressure transducers, ground surface settlements at center and edges by using LVDTs. Average Ko(coefficient of earth pressure at rest) was 0.39 for the model sand. The structural behaviors of lining depended on its damaged conditions. But, as a rule, on the crown, the tensile circumferential strain of lining occurred at the inner surface, and the compressive at the outer surface, then positive bending moment was created at the crown. The circumferential strain of the inner surface on the springline was tensile, and the outer compressive, so negative bending moment was measured at the springline. For hydrostone linings, cracks initiated at the inner surface on the crown, and the outer on the springline over average 40g.

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A Study on the Application of Convergence Measurement System to Inverse Calculation of Tunnel Lining Sectional Forces (터널 라이닝 단면력 역산을 위한 유지관리 내공변위계측시스템 적용 연구)

  • 이대혁;김기선;한일영;박연준;유광호
    • Tunnel and Underground Space
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    • v.11 no.2
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    • pp.146-155
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    • 2001
  • An inverse calculation method to obtain sectional forces, axial force and flexural moment of a tunnel concrete lining was developed by utilizing convergence measurements acquired at the maintenance stage. To monitor the behavior of the lining, DOCS system was applied to a subway tunnel section. The method was proved to be effective, yielding the same results as measured forces of buried instruments. Many effects such as vibration of sensors, vibration due to test train operation, the variation of temperature and high voltage were checked and a new management scheme for tunnel maintenance was proposed.

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Numerical Analysis of Peak Uplift Resistance of Buried Pipeline in Sand and Soft Clay (연약 점토와 사질토에 묻힌 파이프라인의 극한 인발저항력 산정)

  • Kwon, Dae-Hean;Seo, Young-Kyo
    • Journal of Ocean Engineering and Technology
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    • v.31 no.3
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    • pp.227-232
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    • 2017
  • Subsea pipelines are one of the most important structures used to transport fluids such as oil and natural gas in offshore environments. The uplift behavior of the pipeline caused by earthquakes and buoyancy can result in a pipeline failure. The objective of this study is to examine the peak uplift resistance through parametric studies with numerical modeling by PLAXIS 3D Tunnel. The effects of the embedment ratio and pipe diameter were first examined for uplift resistance in sand and soft clay conditions. Then the length of geogrid layers and the number of geogrid layers were examined in terms of ability to resist uplift behavior.

Numerical Analysis of Peak Uplift Resistance for Pipelines Buried In Sand

  • Kwon, Dae-Hean;Seo, Young-Kyo
    • Journal of Advanced Research in Ocean Engineering
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    • v.3 no.4
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    • pp.158-164
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    • 2017
  • A pipeline is one of the most important structures for the transportation of fluids such as oil, natural gas, and wastewater. The uplift behavior of pipelines caused by earthquakes and buoyancy is one of the reasons for the failure of pipelines. The objective of this study is to examine the peak uplift resistance using parametric studies with numerical modeling of PLAXIS 3D Tunnel. The effects of burial depth and pipe diameter on the uplift resistance of loose and dense sand were first examined. Subsequently, the effects of the length of geogrid layers and the number of geogrid layers were examined to prevent uplift behavior.

A Study on Fire Safety Measure for Korean Utility Tunnels Based on Analysis of Fire Safety Performance for Utility Tunnel in Advanced Countries (해외 공동구의 방재성능분석을 통한 국내 공동구에 적합한 방재대책에 관한 연구)

  • 박형주;김상욱
    • Fire Science and Engineering
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    • v.15 no.4
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    • pp.71-77
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    • 2001
  • The pipes and cables buried below ground which may have helped to improved city landscapes is becoming direct and indirect cause for various disaster in Korea due to potential possibility of fire. Various types of fire in utility tunnels should be analysed in order to improve its fire safety level, therefore mail problems and shortcomings are checked out as a result of this analysis. By performing both tunnel fire risk analysis and fire safety level comparison in advanced countries, effective measure and approach to required standardization may be presented to bath tunnel structure and its containing cables in order to diminished up to a desirable rate in a near future.

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Catastrophe analysis of active-passive mechanisms for shallow tunnels with settlement

  • Yang, X.L.;Wang, H.Y.
    • Geomechanics and Engineering
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    • v.15 no.1
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    • pp.621-630
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    • 2018
  • In the note a comprehensive and optimal passive-active mode for describing the limit failure of circular shallow tunnel with settlement is put forward to predict the catastrophic stability during the geotechnical construction. Since the surrounding soil mass around tunnel roof is not homogeneous, with tools of variation calculus, several different curve functions which depict several failure shapes in different soil layers are obtained using virtual work formulae. By making reference to the simple-form of Power-law failure criteria based on numerous experiments, a numerical procedure with consideration of combination of upper bound theorem and stochastic medium theory is applied to the optimal analysis of shallow-buried tunnel failure. With help of functional catastrophe theory, this work presented a more accurate and optimal failure profile compared with previous work. Lastly the note discusses different effects of parameters in new yield rule and soil mechanical coefficients on failure mechanisms. The scope of failure block becomes smaller with increase of the parameter A and the range of failure soil mass tends to decrease with decrease of unit weight of the soil and tunnel radius, which verifies the geomechanics and practical case in engineering.

A fundamental study on the development of feasibility assessment system for utility tunnel by urban patterns (도심지 유형별 공동구 설치 타당성 평가시스템 개발에 관한 기초 연구)

  • Lee, Seong-Won;Sim, Young-Jong;Na, Gwi-Tae
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.1
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    • pp.11-27
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    • 2017
  • The road network system of major domestic urban areas such as city of Seoul was rapidly developed and regionally expanded. In addition, many kinds of life-lines such as electrical cables, telephone cables, water&sewerage lines, heat&cold conduits and gas lines were needed in order for urban residents to live comfortably. Therefore, most of the life-lines were individually buried in underground and individually managed. The utility tunnel is defined as the urban planning facilities for commonly installing life-lines in the National Land Planning Act. Expectation effectiveness of urban utility tunnels is reducing repeated excavation of roads, improvement of urban landscape; road pavement durability; driving performance and traffic flow. It can also be expected that ensuring disaster safety for earthquakes and sinkholes, smart-grind and electric vehicle supply, rapid response to changes in future living environment and etc. Therefore, necessity of urban utility tunnels has recently increased. However, all of the constructed utility tunnels are cut-and-cover tunnels domestically, which is included in development of new-town areas. Since urban areas can not accommodate all buried life-lines, it is necessary to study the feasibility assessment system for utility tunnel by urban patterns and capacity optimization for urban utility tunnels. In this study, we break away from the new-town utility tunnels and suggest a quantitative assessment model based on the evaluation index for urban areas. In addition, we also develop a program that can implement a quantitative evaluation system by subdividing the feasibility assessment system of urban patterns. Ultimately, this study can contribute to be activated the urban utility tunnel.

Analysis of the Structural Behaviours of Aluminum Tunnel Lining in Joomunjin Standard Soil by Centrifugal Model Tests (원심모형실험을 이용한 주문진 표준사 지반내 알루미늄 모형 터널 복공의 역학적 거동에 관한 연구)

  • 김택곤;김영근;박중배;이희근
    • Tunnel and Underground Space
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    • v.9 no.2
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    • pp.114-130
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    • 1999
  • It is very important to study on the structural behaviors of structurally damaged tunnel linings. A series of centrifuge model tests were performed in order to investigate different behaviors of tunnel linings. A 1/100-scaled aluminum horseshoe tunnel linings with a radius 5 cm, height 8 cm were buried in a depth with dry Joomunjin standard sand, the relative density of which was 86%. Such sectional forces as bending moments and thrusts along the tunnel circumference were measured by twelve strain gages. Earth pressures in soil mass and on the outside of lining model were estimated by pressure transducers, ground surface settlements at a center and edges by using LVDTs.

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A Study on the Electric Railroad Grounding System of Tunnels and Bridges (전기철도 시스템에서의 터널, 교량구간 접지방안 연구)

  • 윤응규;오광해;오기봉
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.559-565
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    • 2002
  • This paper presents a standard grounding scheme for bridge and tunnel areas where earthing wires cannot be easily buried. Specially, a new grounding method in which structure grounding devices are used shows good grounding effects like the earthing-wire grounding scheme. The proposed method can be a measure for equal potential in case earthing cables are disconnected.

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