• Title/Summary/Keyword: secondary lining

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A secondary development based on the Hoek-Brown criterion for rapid numerical simulation prediction of mountainous tunnels in China

  • Jian Zhou;Xinan Yang;Zhi Ding
    • Geomechanics and Engineering
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    • v.34 no.1
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    • pp.69-86
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    • 2023
  • To overcome the dilemma of the [BQ] method's inability to predict mountain tunnel support loads, this study is based on the Hoek-Brown criterion and previous results to obtain the connection equations from GSI scores to each parameter of the Hoek-Brown criterion and the link between the [BQ] scores and the GSI system. The equations were embedded in the Hoek-Brown criterion of FLAC6.0 software to obtain tunnel construction forecasts without destroying the in-situ stratigraphy. The feasibility of the secondary development of the Hoek-Brown criterion was verified through comparative analysis with field engineering measurements. If GSI > 45 with a confining pressure of less than 10 MPa, GSI has little effect on the critical softening factor while we should pay attention to the parameter of confining pressure when GSI < 45. The design values for each parameter are closer to the FLAC3D simulation results and the secondary development of the Hoek-Brown criterion meets the design objectives. If the Class V surrounding rock is thinned with shotcrete or the secondary lining is installed earlier, the secondary lining may act as the main load-bearing structure. The study may provide ideas for rapid prediction of mountainous tunnels in China.

Development of Knowledge-based Study on Optimized NATM Lining Design System (지식기반형 NATM 라이닝 최적 설계 시스템 개발)

  • Song, Ju-Sang;Yoo, Chung-sik
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.251-265
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    • 2018
  • This paper concerns the development of an optimized NATM secondary lining design system for a subsea tunnel. The subsea tunnel is normally laid down under the sea water and submarine ground which consists of soil or rock. The design system is the series of process which can predict lining member forces by ANN (artificial neural network system), analyze suitable section for the designated ground, construction and tunnel conditions. Finally, this lining design system aims to be connected for designing the subsea tunnel automatically. The lining member forces are predicted based on the ANN which was calculated by a FEM (finite element analysis) and it helps designers determine its lining dimension easily without any further FEM calculations.

Behavior of double lining due to long-term hydraulic deterioration of drainage system

  • Shin, Jong-Ho;Lee, In-Keun;Joo, Eun-Jung
    • Structural Engineering and Mechanics
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    • v.52 no.6
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    • pp.1257-1271
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    • 2014
  • The hydraulic deterioration of the drainage system in tunnel linings is one of the main factors governing long-term lining-ground interactions during the lifetime of tunnels. Thus, in the design procedure of a tunnel below the groundwater table, the possible detrimental effects associated with the hydraulic deterioration should be addressed. Hydraulic deterioration in double-lined tunnels can occur because of reasons such as clogging of the drainage layer and drain-pipe blockings. In this study, the coupled mechanical and hydraulic interactions between linings due to drain-pipe blockings are investigated using the finite-element method. A double-lined structural model incorporating hydraulic behavior is developed to represent the coupled structural and hydraulic behavior between the linings and drainage system. It is found that hydraulic deterioration hinders flow into the tunnel, causing asymmetric development of pore-water pressure and consequent detrimental effects to the secondary lining.

A Study on failure mechanism and load-bearing capacity of single-shell tunnel lining (싱글쉘 터널 라이닝의 파괴 메카니즘 및 지보성능에 관한 연구)

  • Shin, Hyu-Soung;Kim, Dong-Gyou;Chang, Soo-Ho;Bae, Gyu-jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.3
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    • pp.273-287
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    • 2006
  • This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

A Study on Field Change Case of Tunnel Concrete Lining Designs Using GLI(Ground Lining Interaction) Model (GLI(Ground-Lining Interaction)모델을 이용한 터널 콘크리트라이닝의 현장 설계변경 사례에 대한 연구)

  • Chang, Seok-Bue;Lee, Soo-Yul;Suh, Young-Ho;Yun, Ki-Hang;Park, Yeon-Jun;Kim, Su-Man
    • Tunnel and Underground Space
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    • v.20 no.1
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    • pp.58-64
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    • 2010
  • GLI model was verified to consider the interaction between a ground and a tunnel lining and to rationally reduce the ground load acting on the secondary lining(concrete lining) of a tunnel. In this study, the economy and the construction condition of tunnel concrete linings designed by a conventional frame model at Lot O of OO line were highly enhanced through a field design change using GLI model. For a few safe considerations, not only about 50% saving of reinforcing steel could reduce the material cost but also the wide space between bars could make it easy to pour concrete mix without voids. There was large saving effect of reinforcing steel for poor ground conditions because Terzaghi's load used in the conventional frame model produces too much high loads for those conditions.

A Case Study On The Design of Tunnel Type Spillway (터널형 비상여수로의 설계 사례)

  • Baek, Seung-Kyu;Choo, Seok-Yeon;Baek, Un-Il;Park, Hyung-Seop
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.10a
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    • pp.153-160
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    • 2006
  • Tunnel type spillway is rarely constructed in worldwide, and designed secondary in Korea. In this paper we pronounce a case study of tunnel type spillway design. We firstly considered lining concrete abrasiveness and cavitations for tunnel safety. This paper describes the design of tunnel type spillway section, excavation method, blasting, support and concrete lining.

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Study on the optimal construction of a concrete lining in a weathered rock (풍화암지반에 시공되는 콘크리트라이닝의 적정시공에 관한 연구)

  • Kim, Hyeongkeon;Lee, Chul;Lee, Sun-Woo;Park, Jun-Woo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.1
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    • pp.33-47
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    • 2015
  • Concrete lining in tunnel construction is used as secondary support for downward loads when primary support decays. The use of concrete lining varies greatly depending on the intentions of engineer and/or client. An engineer uses much smaller deformation modulus which determines the concrete lining thickness than of a pattern 3, when supporting patterns 4 and 5 are used in a weathered rock and soil. Considering these conditions, this study intends to suggest optimal construction procedures through a back analysis using a computer program(MIDAS-civil). Cases of Seoul Subway System line${\bigcirc}{\bigcirc}$ zone${\bigcirc}{\bigcirc}$ were selected to be examined for this study. The results show that it is possible to reduce the thickness of concrete lining. When results from this study were applied to Seoul Metropolitan subway construction projects, it is expected to bring economic benefits.

Hydraulic and structural interaction of a double-lined tunnel lining due to drainhole blockings (이중구조 라이닝의 배수공 막힘에 따른 수리-역학적 상호작용)

  • Shin, Jong-Ho;Nam, Taek-Soo;Chae, Sung-Eun;Yoon, Jae-Ung
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.11 no.3
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    • pp.243-254
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    • 2009
  • Tunnel problems relate to pore water pressure generally occur due to the restriction of groundwater flow into the tunnel which is generally caused by the deterioration of drainage systems. Previous studies have identified the problem as combined mechanical and hydraulic interaction occasions. In this study, detrimental effects of pore water pressure on the lining were investigated using the finite element method considering deterioration of the drainage system. Particularly, double-lined linings with drain-holes are considered. Deterioration of drainage system is represented as blockages of drain-holes. It is identified that the secondary lining ran be influenced by the deterioration of drainage system. It is shown that a tunnel with all drain-holes blocked moved upward, and unbalanced drain-hole blocking may result in torsional behavior of the tunnel which causes significant damages to the secondary linings.

Groundwater Flow model of Drawdown and Recovery Due to Watertight Tunnel Excavation and Design Example for Lining (터널시공에 따른 지하수위 변화의 모델링과 이를 고려한 완전방수 터널의 라이닝 설계 예)

  • 남기천;이형원;배정식;나경웅
    • Tunnel and Underground Space
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    • v.4 no.1
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    • pp.24-30
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    • 1994
  • Although a dry-system tunnel is not good for reasons fo economy and construction, it has been applied to some tunnels under construction owing to the advantages of good long-term maintenance of tunnel, prevention of consolidation settlement due to the drawdown of groundwater, preservation of the ecosystem, cutailment of operation cost, and so on. The stability of groundwater and the change of the applied water pressure after water proofing were analysed by the finite element method. Using this result, an example of designing the secondary lining for the dry-system tunnel which is to be constructed in low-permeability hard rock was presented.

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A Basic Study for Single Shell Support System of Railway Tunnel (철도 터널의 싱글쉘 지보시스템 적용에 관한 기초 연구)

  • Jung, Daeho;Jeong, Cahnmook
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.1
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    • pp.39-48
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    • 2016
  • In this study, it can be shortened tunnel construction work period by introducing a single-shell tunnel does not placing the secondary concrete lining, a global research trend, reduction of the cost of the lining placement and number of benefits that can ensure the safety of long-term tunnel with a single shell it was to study the tunnel method. First, we analyze the design and construction practices relating to delete lining of the domestic design and construction practices and a comprehensive analysis of the stability study found a rock in good condition interval (1~3 grades), we propose that the lining uninstalled. In the case of domestic changes on the ground floor is very heavy underfoot conditions many so tunneling method by single shell as ground conditions are good and one preferred the water points that apply in less soil, the soil health and poor sections (4~5 grades) reflecting with respect to the concrete lining that is expected reasonable.