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Tunnel Construction (tunnel + construction)
Selected AbstractsThe interaction of ground, TBM and segment lining with closed shield machines / . Interaktion Untergrund, Tunnelvortriebsmaschine und Tübbingausbau bei geschlossenen SchildmaschinenGEOMECHANICS AND TUNNELLING, Issue 5 2010Dipl.-Ing. Mechanised tunnelling - Maschineller Vortrieb Abstract The article explains the interaction of the overall system of ground, TBM and segment lining based on recent experience of projects using TBMs with active face support in Austria and abroad. The alternating dependencies and their consequences for tunnel construction are discussed in more detail. Of particular interest is the influence of the support medium and how it functions at the face and the tunnel side walls. The interaction of support pressure, thrust force and the centre of gravity of the TBM and its effect on steering behaviour are also considered. The effects of the compression of the segment tube by the TBM (prestress) are considered in relation to the improvement of the bedding and the problem of floating. Der Beitrag beleuchtet die Interaktion des Gesamtsystems "Untergrund , Tunnelvortriebsmaschine , Tübbingausbau" basierend auf aktuellen Erfahrungen zuletzt realisierter Projekte im In- und Ausland bei TVM-Einsätzen mit aktiver Ortsbruststützung. Dabei wird insbesondere auf die wechselweisen Abhängigkeiten und deren Auswirkungen auf die Tunnelherstellung eingegangen. Ein Schwerpunkt liegt beim Einfluss des Stützmediums und der zugehörigen Wirkungsweise an der Ortsbrust und der Tunnellaibung. Berücksichtigung findet die Wechselwirkung von Stützdruck, Vortriebskraft und der Schwerpunktlage der TVM auf deren Steuerverhalten. Die Auswirkung des Zusammendrückens der Tübbingröhre durch die TVM (Vorspannung) wird in Bezug auf die Bettungsverbesserung und die Problematik des Aufschwimmens betrachtet. [source] Requirements for the observational approach in deep tunnelling.GEOMECHANICS AND TUNNELLING, Issue 1 2010Anforderungen an die Beobachtungsmethode bei tiefliegenden Tunneln General; Structural analysis; Allgemeines; Statik Abstract The author shortly reviews the requirements of the Eurocode 7 regarding the Observational Method for use during tunnel construction. The particularities and problems of applying the Observational Method at deep tunnels are listed. A recommendation is given to improve the situation and to bring the approaches used in normal ground engineering problems and deep tunnels closer together. Zunächst werden die Anforderungen des Eurocodes 7 hinsichtlich der Anwendung der Beobachtungsmethode im Tunnelbau kurzbetrachtet. Anschließend werden die Besonderheiten und Probleme bei deren Anwendung bei tiefliegenden Tunneln analysiert. Dabei zeigen sich wesentliche Unterschiede zu anderen bodenmechanischen Anwendungen. Schließlich werden Empfehlungen gegeben, wie die Anwendung der Beobachtungsmethode verbessert und die Vorgangsweisen vereinheitlicht werden können. [source] Numerical modelling of compensation grouting above shallow tunnelsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2005C. Wisser Abstract This paper describes the development of a numerical model for compensation grouting which is a useful technique for the protection of surface structures from the potentially damaging movements arising from tunnel construction. Pipes are inserted into the ground between the tunnel and the overlaying structure from an access shaft. Buildings on the surface are instrumented and movements are carefully monitored. Once the deformations exceed a certain Trigger Level, grout is injected into the ground to prevent damage. In the finite element model described here, compensation grouting is modelled by applying an internal pressure to zero-thickness interface elements embedded in the mesh. An ,observational algorithm' is used, where the deformations of the surface are monitored and used to control the injection process. Example analyses of compensation grouting are given for three-dimensional tunnel construction underneath a greenfield site. Different strategies are used to control the injection process and their effectiveness in preventing surface movement is assessed. The numerical model is shown to replicate general behaviour expected in the field and is capable of modelling the control of ground surface movements at a greenfield site. Copyright © 2005 John Wiley & Sons, Ltd. [source] Three-dimensional finite element analysis of lined tunnelsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 3 2001C. E. Augarde Abstract This paper describes finite element procedures that have been developed to model the ground movements that occur when a shallow tunnel is installed in a clay soil. This study is part of a wider project concerned with the development of new methods to predict the likely extent of damage to surface structures caused by nearby shallow tunnelling. This particular paper, however, is concerned only with the numerical model of tunnel installation. The structural liner is an important component of this tunnel installation model; two different ways of modelling the liner (based on continuum elements and shell elements) are discussed in the paper. A test problem consisting of the installation of a lined tunnel in an elastic continuum is used to investigate the merits of these different approaches. When continuum elements are used to model the liner, the numerical results agree well with an analytical solution to the problem. When shell elements are used to model the liner, however, the results were found to be significantly influenced by the particular formulation adopted for the shell elements. Example analyses, involving incremental tunnel construction in a clay soil where the soil is modelled using a kinematic hardening plasticity model, are described. These analyses confirm that a thin layer of continuum elements may be used, satisfactorily, to model tunnel linings in a soil,structure interaction analysis of this sort. Copyright © 2001 John Wiley & Sons, Ltd. [source] Zeolites in fissures of granites and gneisses of the Central AlpsJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2010T. WEISENBERGER Abstract Six different Ca-zeolite minerals are widespread in various assemblages in late fissures and fractures in granites and gneisses of the Swiss Alps. The zeolites formed as a result of water,rock interaction at relatively low temperatures (<250 °C) in the continental upper crust. The zeolites typically overgrow earlier minerals of the fissure assemblages, but zeolites also occur as monomineralic fissure fillings. They represent the youngest fissure minerals formed during uplift and exhumation of the Alpine orogen. A systematic study of zeolite samples showed that the majority of finds originate from three regions particularity rich in zeolite-bearing fissures: (i) in the central and eastern part of the Aar- and Gotthard Massifs; (2) Gibelsbach/Fiesch, in a fissure breccia located at the boundary of Aar Massif and Permian sedimentary rocks; and (3) in Penninic gneisses of the Simano nappe at Arvigo (Val Calanca). Rail and road tunnel construction across the Aar- and Gotthard Massif provided excellent data on zeolite frequency in Alpine fissures. It was found that 32% (Gotthard NEAT rail base tunnel, Amsteg section) and 18% (Gotthard road tunnel) of all studied fissures are filled with zeolites. The number of different zeolites is limited to six species: laumontite, stilbite and scolecite are abundant and common, whereas heulandite, chabazite and epistilbite occur occasionally. Calcium is the dominant extra-framework cation, with minor K and Na. Heulandite and chabazite contain Sr up to 29 and 10 mol.% extra-framework cations respectively. Na and K contents in zeolites tend to increase during growth as a result of changes in fluid composition and/or temperature. The K enrichment of stilbite found in surface outcrops compared to subsurface samples may indicate late stage cation exchange with surface water. Texture data, relative age sequences derived from fissure assemblages and equilibrium calculations show that the Ca-dominated zeolites precipitated from fluid with decreasing temperature in the order (old to young = hot to cold): scolecite, laumontite, heulandite, chabazite and stilbite. The necessary components for zeolite formation are derived from dissolving primary granite and gneiss minerals. The nature of these minerals depends, among other factors, on the metamorphic history of the host rock. Zeolites in the Aar Massif derived from the dissolution of epidote, secondary calcite and albite that were originally formed during Alpine greenschist metamorphism from primary granite and gneiss assemblages. Zeolite fissures occur in areas of H2O-dominated fluids. This is consistent with equilibrium calculations that predict a low CO2 tolerance of zeolite assemblages, particularly at low temperature. [source] Survivorship, tunneling and feeding behaviors of Coptotermes formosanus (Isoptera: Rhinotermitidae) in response to 2,-acetonaphthone-treated sandPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2004Sanaa A Ibrahim Abstract In laboratory tests, 2,-acetonaphthone was incorporated into sand at different concentrations (4.16,200 mg kg,1) and evaluated for survivorship, feeding and tunneling effects on the Formosan subterranean termite, Coptotermes formosanus Shiraki. 2,-Acetonaphthone at 8.33 mg kg,1 sand significantly reduced survivorship (89,94%), tunnel area (68,91%) and food consumption (84,100%) compared with the control. Most of the dead workers were found at the release point and a few had traveled to the surface of the treated sand. Malformed workers (,27%) with an unexpected symptom of molting failure were observed, particularly at the lowest concentration tested (4.16 mg kg,1). In choice assays, threshold concentration for significant reduction in survivorship, tunnel construction in treated sand and food consumption in the treated-sand side was 8.33 mg kg,1 with termites collected from New Orleans, LA and 35.0 mg kg,1 for those from Lake Charles, LA. Termites actively fed and tunneled in the untreated sand, whereas 2,-acetonaphthone at 140 mg kg,1 completely inhibited consumption of food placed on the treated sand. Copyright © 2004 Society of Chemical Industry [source] A Simulation Model for Shield Tunnelling and its Interactions with Partially Saturated SoilPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Felix Nagel The design of shield supported tunnel construction in urban areas requires the reliable determination of the expected time-variant ground response and the prognosis of possible critical conditions endangering the soil stability. In partially saturated soil the response of the surrounding underground depends strongly on the interactions between the construction process and the surrounding underground and its constituents. The paper gives an overview on a Finite Element model for the simulation of shield supported tunnel advance in partially saturated soil that is capable of accounting for these interactions. Special emphasis is laid on the description of the surrounding underground, modelled as a three phase continuum within the Theory of Porous Media (TPM). Applicability of the simulation model is discussed by results obtained from the simulation of compressed air application for the heading face support. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Bahnsteigerweiterung der U6 unter dem neuen Rathaus in München , Spritzbetonvortrieb mit VereisungBAUTECHNIK, Issue 7 2005Jochen Fillibeck Dr.-Ing. Im Rahmen der Infrastrukturmaßnahmen für den Bau des neuen Fußballstadions in Fröttmaning wurde es erforderlich, die Bahnsteige der U-Bahnlinie U6 unter dem Rathaus in München zu erweitern. Nach dem Entwurf des Baureferats der Landeshauptstadt München wurde hierzu parallel und im direkten Anschluß an die beiden bestehenden Tunnelröhren je ein Tunnel in Spritzbetonbauweise unter atmosphärischen Bedingungen ausgeführt. Die Vortriebe liegen in einem vertikalen Abstand von ca. 10 m zum Münchner Rathaus. Zur Sicherung der Firste und zur Reduzierung der Verformungen wurden im Rahmen eines Sondervorschlags Vereisungsschirme vorgesehen, die von einem über der Firste befindlichen Pilotstollen aus hergestellt wurden. Für die erfolgreiche Umsetzung des Bauvorhabens war es entscheidend, welche Verformungen , Hebungen in der Gefrierphase und Setzungen während des Vortriebs , sich mit dem Baufortschritt einstellen. Dies wurde vorab anhand von Frostversuchen im Labor und mit FE-Berechnungen untersucht. Durch einen Vergleich der Berechnungsergebnisse mit den umfangreichen Kraft- und Verformungsmessungen während des Vortriebs konnte zu jedem Zeitpunkt ein verformungsarmer Tunnelvortrieb mit tolerierbaren Baugrundverformungen sichergestellt werden. Im folgenden Beitrag werden die wesentlichen Berechnungen und Meßergebnisse zu den Baugrundverformungen und zur Wasserhaltung und die Maßnahmen zur Reduzierung der Frosthebungen erläutert. Ferner werden durch einen Vergleich der Bau- und Berechnungsweisen der alten Bestandstunnels mit dem neuen Erweiterungstunnel die mit der Spritzbetonbauweise einhergehenden Entwicklungen im Tunnelbau veranschaulicht. Platform extension of the subway U6 below the historical town hall in Munich , shotcrete method combined with ground freezing. The construction of the new football stadium in Munich-Fröttmaning made it necessary to extend the platform of the subway station U6 "Marienplatz" below the historical town hall of Munich. For this, two new tunnels for pedestrians were driven parallel to the existing subway tunnels. They were planned as shotcrete construction and driven under atmospheric conditions. The tunnels have a vertical distance of approx. 10 m to the foundation of the town hall. Artificial ground freezing was used to guarantee the stability and safety of the tunnel roof and to reduce the deformations. The freezing pipes were implemented in a smaller pilot tube lateral above the tunnels. Both the magnitude of the frost heave displacements and the settlements had to be predicted prior to undertake the construction. Therefore frost heave tests and FE-computations were carried out. During the construction process these results were permanently compared to measurements in order to control and ensure tolerable deformations. In the following contribution the substantial computations and results of measurement relating to the ground deformations and to the lowering of groundwater are described. Furthermore the methods for the reduction of the frost heave are explained. A comparison of the methods of construction and calculation of the old tunnels and the new tunnels illustrates the developments in tunnel construction resulting from the shotcrete method. [source] Hydrogeochemistry of seepage water collected within the Youngcheon diversion tunnel, Korea: source and evolution of SO4 -rich groundwater in sedimentary terrainHYDROLOGICAL PROCESSES, Issue 9 2001Gi-Tak Chae Abstract In the Youngcheon Diversion Tunnel area, South Korea, 46 samples of tunnel seepage water (TSW) and borehole groundwater were collected from areas with sedimentary rocks (mainly sandstone and shale) and were examined for hydrogeochemical characteristics. The measured SO4 concentrations range widely from 7·7 to 942·0 mg/l, and exceed the Korean Drinking Water Standard (200 mg/l) in about half the samples. The TDS (total dissolved solid) content generally is high (171,1461 mg/l) from more shale-rich formations and also reflects varying degrees of water,rock interaction. The water is classified into three groups: Ca SO4 type (61% of the samples collected), Ca SO4 HCO3 type (15%) and Ca HCO3 type (24%). The Ca HCO3 type water (mean concentrations=369 mg/l Ca, 148 mg/l HCO3 and 23 mg/l SO4) reflected the simple reaction between CO2 -recharged water and calcite, whereas the more SO4 -rich nature of Ca SO4 type water (mean concentrations=153 mg/l Ca, 66 mg/l HCO3 and 416 mg/l SO4) reflected the oxidation of pyrite in sedimentary rocks and fracture zones. Pyrite oxidation resulted in precipitation of amorphous iron hydroxide locally within the tunnel as well as in high concentrations of Ca (mean 153 mg/l) and Na (mean 49 mg/l) for TSW, and is associated with calcite dissolution resulting in pH buffering. The pyrite oxidation required for the formation of Ca SO4 type water was enhanced by the diffusion of oxygenated air through the fractures related to the tunnel's construction. The subsequent outgassing of CO2 into the tunnel resulted in precipitation of iron-bearing carbonate. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||