Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Müller, Matthias; Ludwig, Horst-Michael; Ehrhardt, Dirk | Frost-Tausalz-Angriff auf Beton - Mechanismen und Schadensmodelle | Beton- und Stahlbetonbau | 6/2019 | 392-400 | Fachthemen |
KurzfassungWiederholte Frost-Tau-Wechsel können in Zusammenhang mit der Einwirkung von Feuchtigkeit und Tausalzen eine Schädigung der Betonoberfläche durch Abwitterungen verursachen. Der Frost-Tausalz-Widerstand von Beton wird momentan vorwiegend über deskriptive Ansätze gewährleistet, also indirekt über Vorgaben zur Betonzusammensetzung und Nachbehandlung. Infolge des stetigen Wandels von Baustoffen und Bauweisen und dem damit verbundenen Verlust des Erfahrungshintergrunds wird mittelfristig das Performancekonzept auf der Basis genormter Prüfverfahren das deskriptive Konzept ablösen. Es ist zu erwarten, dass darüber hinaus auch für den Bereich des Frost-Tausalz-Angriffes probabilistische Modelle für eine Lebensdauerbemessung notwendig werden. Unverzichtbare Basis dafür ist ein tiefergreifendes Verständnis für den zugrunde liegenden Schadensmechanismus. x | |||||
Palecki, Susanne | Veränderung des Frost- und Frost-Tausalzwiderstands von Hochleistungsbeton in Abhängigkeit vom Betonalter - Einfluss der Alterung und der Umgebungsbedingungen | Beton- und Stahlbetonbau | 6/2019 | 401-408 | Fachthemen |
KurzfassungBeton ist in der Praxis verschiedenen Umwelteinflüssen wie z. B. einem Frost-Tausalzangriff ausgesetzt, der je nach Zusammensetzung die Dauerhaftigkeit unterschiedlich stark beeinflussen kann. Für eine entsprechende Überprüfung der Eignung einer Betonmischung vor deren Einsatz in der Praxis stehen verschiedene Laborprüfverfahren zur Verfügung, die aus Konformitätsgründen ein Prüfalter von 28 Tagen vorschreiben, obwohl in der Praxis Bauteile häufig erst zu einem späteren Zeitpunkt Frost-Tau-Wechseln ausgesetzt sind. Die Erfahrungen zeigen, dass besonders bei Betonen mit Zusatzstoffen, wie sie bei hochfesten Betonen eingesetzt werden, eine Beeinflussung der Prüfergebnisse vom Zeitpunkt der Frost-Tausalzprüfung gegeben ist. Hier wird sowohl die innere als auch äußere Schädigung mit zunehmendem Prüfalter negativ verändert. Als Ursache können in erster Linie Änderungen innerhalb der Gefügestruktur sowie der gefrierbaren Wassermenge genannt werden. x | |||||
Baumgartner, Alexander; Fraundorfer, Andreas; Dauberschmidt, Christoph; Kustermann, Andrea | Veränderung der mechanischen Kenngrößen von Betonstabstählen durch chloridinduzierte Korrosion | Beton- und Stahlbetonbau | 6/2019 | 409-418 | Fachthemen |
KurzfassungDie Dauerhaftigkeit chloridexponierter Stahlbetonbauteile wird maßgeblich durch das Korrosionsverhalten des Bewehrungsstahls bestimmt. Hat ein Eintrag von Chloriden in kritischer Konzentration in das Bauteil stattgefunden, kann eine Lochfraßkorrosion initiiert werden. Die durch die Korrosion auftretenden, sehr lokalen Materialabträge können in kurzer Zeit zu hohen Querschnittsverlusten der Bewehrung führen. x | |||||
Mielich, Oliver; Reinhardt, Hans-Wolf; Özkan, Hasan | Kriechen und mechanische Eigenschaften von Straßenbetonen nach AKR-provozierender Lagerung | Beton- und Stahlbetonbau | 6/2019 | 419-429 | Fachthemen |
KurzfassungVier Straßenbetone wurden mit der am F.A. Finger-Institut für Baustoffkunde der Bauhaus-Universität Weimar entwickelten FIB-Klimawechsellagerung einer AKR-provozierenden Lagerung unterzogen. Es wurden Dehnungen, Druckfestigkeit, Elastizitätsmodul, Kriechen und Schwinden bestimmt. Die Ergebnisse zeigen, dass der AKR-bedingte Schädigungsprozess wie folgt beschrieben werden kann: AKR-verursachte Mikrorissbildung in der Zementmatrix ist für die Druckfestigkeit des Betons eher nebensächlich. Löseprozesse und Rissbildungen in der Gesteinskörnung setzen die Steifigkeit des Betons (E-Modul) herab, nicht jedoch die Druckfestigkeit. Die Risse, die bei langsam reagierenden Gesteinskörnungen ihren Ursprung im Gesteinskorn haben, setzen sich in die Matrix fort. Bei größerem Matrixvolumen und vermehrter Rissbildung wird das Kriechen vergrößert. Ungeschädigter Beton zeigt, wenn auch nur marginal, unter Einfluss einer Natriumchloridlösung (NaCl-Lösung) ein erhöhtes Kriechen, was auf einen chemischen Einfluss der Matrix hinweist. x | |||||
Dietz, Jörg | Besonderheiten bei der Ausführung semi-integraler Großbrücken am Beispiel der Wehretalbrücke | Beton- und Stahlbetonbau | 6/2019 | 430-439 | Berichte |
KurzfassungDie aktuelle Tendenz im Brückenneubau weist eine zunehmende Anzahl semi-integraler Großbrücken auf. Die Vorteile geringerer Wartung und höherer Robustheit erfordern zusätzliche Überlegungen in der technischen Bearbeitung. Die Wehretalbrücke ist aufgrund ihrer Schlankheit und komplexen Geometrie gut geeignet, um die Besonderheiten integraler Brücken bei der Planung und Ausführung exemplarisch aufzuzeigen. Das Bauwerk wurde semi-integral als Rahmen mit vier Stielen ausgeführt. Die Abhängigkeiten zwischen Bau- und Endzustand machen frühe Abstimmungen zwischen Planer, Baugrundsachverständigem, Baufirma und Bauherr notwendig, damit ein reibungsloser Bauablauf gewährleistet werden kann. x | |||||
Beton- und Stahlbetonbau aktuell 6/2019 | Beton- und Stahlbetonbau | 6/2019 | 441-445 | Beton- und Stahlbetonbau aktuell | |
KurzfassungPersönliches: x | |||||
Kongresse - Symposien - Seminare - Messen | Beton- und Stahlbetonbau | 6/2019 | 446 | Veranstaltungskalender | |
ATC2-Sympoisum | Geomechanics and Tunnelling | 6/2019 | Cover Pictures | ||
KurzfassungThe Dywi Drill Hollow Bar system from DSI Underground is a versatile support element, which can be used as a micropile, soil or rock nail, grouted anchor, spile or grouting lance in mining and tunnelling as well as for geotechnical tasks such as foundations. Recently, DSI got an approval for the Dywi Drill Hollow Bar as a temporary micropile and as a permanent pile, according to which a service life of 100 years can be achieved for a permanent pile (photo: DSI Underground). x | |||||
Content: Geomechanics and Tunnelling 6/2019 | Geomechanics and Tunnelling | 6/2019 | Contents | ||
Marcher, Thomas; Galler, Robert | Austrian Tunnel Competence Center - ATC2 | Geomechanics and Tunnelling | 6/2019 | 616 | Editorials |
News: Geomechanics and Tunnelling 6/2019 | Geomechanics and Tunnelling | 6/2019 | 618-627 | News | |
KurzfassungBreakthrough at the Sydney Metro - Durchschläge bei der Metro Sydney x | |||||
Bacher, Michael; Nipitsch, Gernot; Fruhwirt, Daniel; Sturm, Peter | Semmering Base Tunnel - Keeping shafts free of ice through the example of the Fröschnitz 2 supply shaft / Semmering-Basistunnel - Eisfreihaltung von Schächten am Beispiel des Versorgungsschachts Fröschnitz 2 | Geomechanics and Tunnelling | 6/2019 | 631-637 | Topics |
KurzfassungThe Fröschnitz 1 and Fröschnitz 2 supply shafts of the Semmering Base Tunnel are used for the ventilation of the tunnel drives, transport of personnel, materials and machinery and as escape and rescue routes. Until the final completion of the concrete inner lining in the shafts, water still emerges repeatedly at the surface at a few locations of the shotcrete support layer. This led above all for the Fröschnitz 2 shaft to ice formation during longer periods with outside air temperatures below the freezing point of water with simultaneous operation of the fresh air supply. The effectiveness of warm air supply was investigated with thermodynamic and aerodynamic investigations and then the cost-effectiveness of two selected systems to provide warm air were considered. The aerodynamic simulations showed that in particular the entry angle of the warm fresh air flow is decisive for the magnitude of the warm air losses. x | |||||
Cordes, Tobias; Weifner, Tassilo; Unteregger, David; Bergmeister, Konrad | Interaction between deep tunnel drives and an existing tunnel in fault zones - Modelling against reality / Wechselwirkungen zwischen tiefliegendem Tunnelvortrieb und bestehendem Tunnel im Bereich von Störzonen - Modellierung versus Realität | Geomechanics and Tunnelling | 6/2019 | 641-650 | Topics |
KurzfassungThe influence of a tunnel drive on an existing tunnel is primarily the result of the tunnel geometries, the relative location of the two tunnels, the geological-geomechanical conditions and the associated primary stress state. During construction of the Brenner Base Tunnel, there are constructionally relevant interactions in some places between the running tunnels and the exploratory tunnel (EKS) running centrally and 12 m deeper. The rock mass stress as a result of driving the running tunnels here leads to deformations of the previously driven exploratory tunnel. Due to the high loading on the outer linings of deep tunnels and the high stiffness of the already hardened shotcrete support, slight deformation can cause local cracking in the support layer. This article compares the observed deformations in a fault zone intersecting at a flat angle with numerical simulations, which enables investigation of the geomechanical problems. Comparison of the calculation results with the real deformation behaviour permits the validation of the numerical simulations and the reliability and limits of such analyses. x | |||||
Diernhofer, Florian; Schneider, Klaus; Steiner, Helmut | Challenge of maintaining the Koralm Tunnel - Balancing operational availability and increasing railway equipment / Herausforderung Instandhaltung Koralmtunnel im Spannungsfeld betrieblicher Verfügbarkeit und Anlagenmehrung | Geomechanics and Tunnelling | 6/2019 | 652-660 | Topics |
KurzfassungThe Koralm Tunnel (length 33 km) crossing the eastern Alps is part of the Koralmbahn line and one of the longest rail tunnels in the world. The installation of railway equipment in the tunnel is due to start soon and it is particularly important to now make current decisions considerung future developments and demands. In particular the conflicting goals of the scheduling horizon of the construction permit process nearly 20 years ago, the 150-year design horizon and the rapid development of electronics, data processing and telematics have to be considered. Experience of operation of long rail tunnels confirms that despite all logistical efforts, the maintenance of railway equipment leads to a great expense of time and finance and also to restrictions of the line availability for operations. x | |||||
Geißler, Hendrik; Lassnig, Herbert | Dewatering of sludges from aggregate production / Entwässerung von Schlämmen aus der Produktion mineralischer Zuschlagstoffe | Geomechanics and Tunnelling | 6/2019 | 661-666 | Topics |
KurzfassungIn order to implement construction projects responsibly and at the same time efficiently, intelligent, multi-project material flow management is becoming ever more important. At the Brenner Base Tunnel, material excavated from the tunnel and geogenic fill was processed for use as concrete aggregates. One part of this processing was the separation of the finest grains by washing the material. This however produced a considerable quantity of sludge, which was to be dewatered immediately after the washing. The article describes the sludge dewatering in geotextile tubes. In addition to the application example from the construction of the Brenner Base Tunnel, the findings from this project have also been applied to optimise dewatering systems in the original application area of cleaning up waterways. Finally there is a brief outlook of current research results regarding the use of the dewatering system for used bentonite suspensions in specialised civil engineering. x | |||||
Gschwandtner, Gunter Gernot; Lenz, Gerold; Wagner, Oliver Kai | Collapses in the vicinity of fault zones - Geotechnical causes and identification / Nachbrüche im Nahbereich von Störungen - Geotechnische Ursachen und Identifikation | Geomechanics and Tunnelling | 6/2019 | 667-673 | Topics |
KurzfassungThe Semmering Base Tunnel with a total length of 27.3 km is being excavated from the Gloggnitz portal as well as from three intermediate faces at Göstritz, Fröschnitzgraben and Grautschenhof. The geological conditions of the project are characterized by tectonically extremely complex rock formations with difficult geotechnical conditions. The excavation passes through numerous fault zones with deep overburden. During the excavation works, some large-volume collapses occurred. In this article, the collapse events are reconstructed from the available geological and geotechnical information. The reconstruction of the observed system behaviour is based on analytical and numerical calculations. The aim is to identify the respective failure mechanisms. x | |||||
Kessler, Gernot; Klais, Frank; Reiterer, Markus | Site facilities on contract SBT 3.1 / Die Bauinstallationen im Baulos SBT 3.1 | Geomechanics and Tunnelling | 6/2019 | 674-680 | Topics |
KurzfassungOn contract SBT3.1 of the Semmering Base Tunnel, the intermediate access point at Grautschenhof had to be relocated late in the tender design phase due to new geological findings. One consequence of this was the limited space available on the new construction site area. A number of complementary measures were considered by the client in the tender. Supplemented by innovative technical solutions from the SBT 3.1 Grautschenhof joint venture, it was possible to establish a functioning logistics system for four conventional excavations in the tightest of spaces. x | |||||
Klaffenböck, Thomas; Gertl, Reinhard | Automatic fire-fighting systems in tunnels / Automatische Brandbekämpfungsanlagen in untertägigen Bauwerken | Geomechanics and Tunnelling | 6/2019 | 681-689 | Topics |
KurzfassungA fire can occur in many areas of a transport system. Detecting fires at an early stage and rapid automated fire-fighting can significantly minimize or completely prevent damage to rolling stock and infrastructure. In addition to effective fire-fighting, people should be safeguarded, the systems should be economical, and activation should cause a minimum of damage. Despite the positive effects of using automatic fire-fighting systems in terms of building protection and reducing the fire load, there may be negative effects on escaping persons during the escape phase. Different systems such as the high-pressure water mist system and the deluge system are investigated by CFD simulation and evaluated with regard to their use during the escape and external rescue phases. x | |||||
Pfeffer, Robert; Rohm, Paul; Oppitz, David | Directional drilling on construction section SBT3.1 - the challenge of drilling speed and accuracy / Gerichtete Vollbohrung am Baulos SBT3.1 - Herausforderung Bohrgeschwindigkeit und Richtungsgenauigkeit im Störzonenbereich | Geomechanics and Tunnelling | 6/2019 | 690-694 | Topics |
KurzfassungThe Semmering Base Tunnel is being built by Austrian Federal Railways as part of the upgrading of the southern railway line. On contract SBT3.1, Züblin Spezialtiefbau Ges.m.b.H. was employed to undertake slope stabilization, piles dia. 1,500 mm embedded into the rock, as well as vertical and horizontal boreholes in the fault zones of Semmering. Due to the high requirements on drilling speed and accuracy of the boreholes, they were drilled as directional drilling with a hydraulic down-the-hole hammer. The vertical holes were used to install sleeve pipes for grouting works for the shaft Sommerau 2. The horizontal holes, also planned for the inclusion of sleeve pipes for grouting works, were used after on-site rescheduling during the project for exploration and drainage of the rock mass. The drilling and survey data were subject to continual and thorough review to increase the efficiency of each control operation. x | |||||
Pointner, Peter; Höfer-Öllinger, Giorgio | Geological tests on site / Baubegleitende geologische Untersuchungen | Geomechanics and Tunnelling | 6/2019 | 695-701 | Topics |
KurzfassungIn addition to laboratory analysis, tests can be carried out on site to support the geological underground documentation. They should cover the important parameters on the project and be easy and time-saving to implement. This article describes a selection of methods and their suitability for use on construction sites. The tests comprise determination of water content, grain size distribution as well as the implementation of point load and Cerchar abrasiveness tests. For all these tests, the practical application on the site of the Koralm Tunnel contract KAT 3 and implementation details are explained. For all on-site tests, it is recommended that the results gained should be compared with the experimental procedure and the results of laboratory analyses. x | |||||
Pichler, Moritz; Fürnschuß, Martin; Friedl, Katrin; Schürhuber, Robert; Schmautzer, Ernst | Electrical earthing in sub-surface projects / Elektrische Erdung bei untertägigen Infrastrukturprojekten | Geomechanics and Tunnelling | 6/2019 | 702-707 | Topics |
KurzfassungElectrical earthing (grounding) is necessary for the proper operation of electrical systems, machines and electronic equipment in the event of a fault, for protection against lightning and personal injury, and for reasons of electromagnetic compatibility. Earthing is understood as “making an electrical connection between a given point in a system or in an installation or in equipment and a local earth”. Electrical grounding systems are designed according to national and international standards, with some of these standards occupying a significant place in the legal hierarchy in Austria and being binding. Simple structures are designed using approximate formulas given in the literature and standards; more complex arrangements use programs with analytical or numerical models for the calculation and design of grounding systems. Underground infrastructure projects require additional considerations. Starting with the technical and legal requirements, the typical process steps for the design of electrical grounding systems are shown. x | |||||
Mössmer, Stefan; Sulzbacher, Gerhard; Jedlitschka, Gernot; Holzleitner, Wolfgang | Brenner Base Tunnel - Tunnelling in the immediate vicinity of existing structures on the Tulfes-Pfons contract / Brenner Basistunnel - Vortrieb im unmittelbaren Nahbereich von Bestandsbauwerken im Baulos Tulfes-Pfons | Geomechanics and Tunnelling | 6/2019 | 708-715 | Topics |
KurzfassungThis report deals with tunnelling over and under existing tunnels with unreinforced concrete linings and tunnelling under an existing tunnel only supported with shotcrete. The uppermost task was to avoid damage to the existing tunnel and this could be fulfilled through carefully staged advance steps, technically correct construction by the contractor and a dense observation network. The experience tunnelling over an existing tunnel supported only with shotcrete shows that despite slight deformation, cracks and spalling occurred to the shotcrete support layer of the tunnel beneath. This damage did impair the serviceability of the support layer although the structural safety of the tunnel was never in danger. The impairment of the serviceability was temporary and could be remedied by installing overhead protection. In the long term, repair measures were necessary to the support layer in zones with poor geological conditions. x | |||||
Erharter, Georg H.; Poscher, Gerhard; Sommer, Peter; Sedlacek, Christoph | Geotechnical characteristics of soft rocks of the Inneralpine Molasse - Brenner Base Tunnel access route, Unterangerberg, Tyrol, Austria | Geomechanics and Tunnelling | 6/2019 | 716-720 | Topics |
KurzfassungThe engineering geological investigation for the environmental impact assessment of the more than 20 km long route section Schaftenau-Radfeld in the Lower Inn Valley (Tyrol) was conducted in 2017/18. As a central structure, a nearly 3 km long tunnel will be built through the Unterangerberg. The bedrock of the Unterangerberg consists of turbiditic, marine deposits of the Inneralpine Molasse with interbedded layers of marl, claystone and sandstone. The proximity to the Inntal shearzone and exogeneous effects like several glaciations have softened the surface of the inherently weak bedrock and led to heterogeneous mechanical properties. The monotonous lithology is therefore accompanied by an inhomogeneous rock mass characterization. This paper describes experiences of the geotechnical investigation of this weak rock. It was observed that only a quick transport of samples from the drilling site to the laboratory can guarantee for test results in accordance with the standards. The results, lying in the transitional zone between soft rock and hard soil, are in good accordance with data from other studies. x | |||||
Flora, Matthias; Goliasch, Robert; Strauss, Armin; Atzori, Denis | Hard rock tunnel boring machines - State of the art 2020 / Tunnelbohrmaschinen für Hartgestein - Stand der Technik im Jahr 2020 | Geomechanics and Tunnelling | 6/2019 | 721-729 | Topics |
KurzfassungAt this year's International Planning Design and Construction (IPDC) Workshop of the Unit of Project and Construction Management (i3b) of the University of Innsbruck, a selected group of tunnelling engineers took a closer look at the state of the art of hard rock tunnel boring machines and the challenges of tunnelling systems along the Brenner axis. The three currently active construction contracts using mechanized tunnelling technology at the Brenner Base Tunnel have an intersection of comparable geological/geotechnical conditions (quartz phyllite, schist, gneiss and granite) and yet different machine types were selected: a Gripper TBM for the Tulfes-Pfons exploration tunnel - H33, three Double Shield machines for the Mauls 2/3 contract and four Single Shield machines for contract H51. The focus of this workshop was accordingly: from geology/geotechnics to the key specifications of the TBM as a basis, followed by the consideration of the type-independent TBM parameters, the differences as well as advantages and disadvantages of the three machine types and finally an outlook into the future regarding further developments and need for innovation. This article summarizes the contents of the workshop. x | |||||
Hammer, Anna-Lena; Thewes, Markus; Galler, Robert | Empirical forecasting model to determine the strength development of shotcrete / Empirisches Prognosemodell zur Bestimmung der Festigkeitsentwicklung von Spritzbeton | Geomechanics and Tunnelling | 6/2019 | 730-738 | Topics |
KurzfassungShotcrete is an essential support element in tunnelling. From the start of the hydration of shotcrete, it resists stresses and deformation. Therefore its time-dependent material properties, in particular the strength development and stiffness development, are significant. With time, the early strength can affect the progress of rock pressure and the support resistance. In order to describe its mechanical material properties, there are models, mostly validated with data from dry-mix shotcrete or older shotcrete mix designs. Continuous further development in additive technology has however considerable improved the performance of shotcrete in recent years. In this article, data from more recent test series and from practical projects are evaluated. Building on the evaluation of the strength curves, an empirical forecasting model is presented, which can be used for the qualitative estimation of shotcrete strength development. x |