Journal articles
Author(s) | Title | Journal | Issue | Page | Category |
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Stockinger, Georg; Thuro, Kurosch; Moeck, Inga; Straubinger, Robert | The rock mass as the governing factor for successfully developing deep geothermal systems in Southern Germany | Geomechanics and Tunnelling | 1/2022 | 37-47 | Topics |
AbstractIn Southern Germany, geothermal wells target Upper Jurassic carbonates, formerly referred to as Malm, below the Northern Alpine Foreland Basin (NAFB). In the northern, shallower carbonates (3000 m depth), e.g., in the Munich area, hydrothermal systems prevail, and wells yield proper flow rates. Deeper carbonates (> 4000 m) towards the south indicate a petrothermal system due to a decline in porosity and permeability. Inexplicably, fractures only contribute poorly to larger flow rates. This sets the goal for the project Dolomitkluft to analyse the rock mass for options countering low flow rates in two geothermal wells at Geretsried, Bavaria. Therefore, 20 m drill cores from 4600 to 4715 m total vertical depth (TVD) depict the initial structure of the rock mass: the rock parameters, the discontinuity network, and the in situ stresses. Alternating homogeneous, micritic, strong, to inhomogeneous, porous, weak limestones and massive, crystalline dolostones define the stratigraphy. Five joint sets from the cores can be distinguished into the bedding, two paleo anti- and synthetic normal faults and two recent strike-slip faults. The latter, in combination with core disking, allows exclusively a strike-slip (SS) stress regime and delimits the ratio to at least SH : Sv : Sh = 1.7 : 1.0 : 0.7. According to the results, including dilatation- and slip-tendencies, drill trajectories of prosperous geothermal wells should head ESE/WNW, perpendicular to SS-faults, and avoid the presence of normal faults. x | |||||
Rioseco, Ernesto Meneses; Dussel, Michael; Moeck, Inga S. | 3D thermo-hydro-mechanical simulation of the behaviour of a naturally fractured petrothermal reservoir in deep Upper Jurassic carbonates of the Bavarian Molasse Basin - Case study Geretsried | Geomechanics and Tunnelling | 1/2022 | 48-57 | Topics |
AbstractBased on multi-scale and multi-disciplinary measured data, gathered at the Geretsried geothermal site, a 3D reservoir model of the deep and fracture-controlled Upper Jurassic carbonates in the North Alpine Foreland Basin is generated in this work. An efficient methodology is developed to numerically simulate the coupled reservoir processes of fluid flow, heat transport and thermoporoelastic stresses resulting from possible geothermal doublet operating schemes with cold fluid injection and production profiles in an enhanced naturally fractured reservoir. A variety of numerical experiments is conducted to study the reactivation potential and dilation tendency of the fracture and fault system. Simulation results show the spatiotemporal evolution of the thermoporoelastic stresses and the zone affected after 50 years of geothermal doublet operation. From these simulations, the thermoelastic response of a geothermal doublet operating with 60 °C fluid injection temperature and 20 l/s flow rate translates into a maximum induced thermal stress of around 49.4 MPa near the injection well. In terms of a long-term reservoir performance and fault and fracture reactivation potential, the findings reveal a negligible risk to a sustainable geothermal doublet operation. x | |||||
Backers, Tobias; Kahnt, René; Stockinger, Georg | Structural dominated geothermal reservoir reaction during proppant emplacement in Geretsried, Bavaria / Strukturdominierte Reaktion des geothermischen Reservoirs während Stützmitteleintrag in Geretsried, Bayern | Geomechanics and Tunnelling | 1/2022 | 58-64 | Topics |
AbstractAs a source of sustainable, renewable, and clean energy, deep geothermal systems increasingly gain importance for the energy transition. In Germany, the North Alpine Foreland Basin is the success story for hydrothermal systems. Besides successful projects in the Munich area, recent attempts to establish successfully operating geothermal wells southwards, e.g., in Geretsried, failed due to a lack of permeability of the rock mass. Subsequent research in Geretsried found that all existing discontinuities are low to non-productive. The current project ZoKrateS, rethinking the Geretsried reservoir being a petrothermal play, bypasses these limitations by stimulating the existing fractures, and trying to keep them conductive by embedding proppants that prevent full closure. Four detached sections of the well GEN-1ST-A1 were subject to individual stages of stimulation. These four sections have been stimulated by placing proppants at injection pressures below the in-situ least principal stress at no microseismic activity. After injection the communication between well and formation appeared to be increased. Although data processing is still ongoing, linear correlations between cumulative injected volume and quasi-static pressure may be interpreted as channel flow within highly disturbed rock masses at intersections of faults. The high elasticity of these sections enables even low pressure to cause discontinuity opening below the least principal stress. x | |||||
Stoxreiter, Thomas; Galler, Robert | Results of the EU H2020 project ThermoDrill - Contribution of rock mechanics to the utilization of geothermal energy / Ergebnisse aus dem EU-H2020-Projekt ThermoDrill - Ein Beitrag der Felsmechanik zur effizienteren Gewinnung geothermischer Energie | Geomechanics and Tunnelling | 1/2022 | 65-73 | Topics |
AbstractThe urgent need to speed up the process of reducing CO2 emissions, as well as to stimulate the production and use of renewable energy demands sophisticated technologies to reach these goals. By developing an advanced drilling technology, the EU H2020 project ThermoDrill set itself the target to make the utilization of geothermal energy more economical. The new drilling technology is based on the combination of rotary drilling and high-pressure fluid jetting. Rock mechanics largely contributes to the achievement of the common purpose of the project. Especially the investigation of the rock destruction process due to the combined hydraulic and mechanical impact plays a major role. The results are based on extensive experimental research concerning rock fracture under varying conditions. Additionally, various methods of crack detection are applied to identify the underlying mechanisms of the drilling technology. As a result, the specifications of the developed prototypes are to a considerable amount based on the rock mechanical findings. The huge potential of the advanced drilling technology is supported by the results of laboratory tests and field tests. x | |||||
Hahn, Simon; Polat, Berker; Jamali, Shahin; Wittig, Volker; Bracke, Rolf | Water jet drilling technology for application in geothermal environments / Erschließung geothermischer Lagerstätten mittels Hochdruck-Wasserstrahl Bohrtechnik | Geomechanics and Tunnelling | 1/2022 | 74-81 | Topics |
AbstractHigh-pressure water jet drilling technologies are widely used in the drilling industry. Especially in geothermal and hard rock applications, jet drilling is, however, confronted with several limitations like lateral length, hole size, steerability and jetability of the reservoir rock. The application of jet drilling technologies in the field can only be estimated based on the experience of the operator and surface experiments imitating downhole conditions. To predict a successful jetting operation in the field, a modelling framework has been developed, which considers operational and technical parameters as well as reservoir rock specifications. The framework consists of calibrated models describing downhole hydraulics and mechanics during the jetting operation and estimates the required technical equipment to successfully penetrate the reservoir rock and the maximum achievable lateral length for various hole configurations. The modelling framework is applied on a theoretical case study. x | |||||
Bücken, Daniel; Meier, Tobias; Backers, Tobias | Geomechanical effects of seasonal heat storage in abandoned mines / Geomechanische Auswirkungen saisonaler Wärmespeicherung in stillgelegten Bergwerken | Geomechanics and Tunnelling | 1/2022 | 82-90 | Topics |
AbstractFor the transition to sustainable heat sources, storage infrastructure is required to provide heat evenly throughout the year. Solar heat is typically produced in the summer and can be stored in underground heat reservoirs for the winter. Flooded coal mines, e.g., are potential heat reservoirs. To assess whether the geomechanical integrity of a colliery and the surrounding rock mass are affected by seasonally stored heat, a numerical case study was performed at “Zeche Dannenbaum” in the Ruhr valley, Germany. During summer, hot water was injected into level 8 of the colliery while cold water was produced from level 4. This process was reversed in winter. Detailed subsurface models of the colliery, rock mass and tectonic faults were used to numerically simulate the cyclical changes in pore pressure and temperature and the resulting stress changes. The displacement of the land surface, and geomechanically critical regions in the rock mass were derived. Moreover, the reactivation potential of the fault zones and the risk of induced seismicity were evaluated. The high injection temperatures induce strong thermoelastic effects, which could potentially lead to fault reactivation and induced seismicity. Surface displacements, however, are negligeable. x | |||||
Burger, Ulrich; Geisler, Thomas; Lehner, Florian; Cordes, Tobias; Marcher, Thomas | Sectional discharges as geothermal potentials of deep tunnels / Teilströme als geothermisches Potential bei tiefliegenden Tunneln | Geomechanics and Tunnelling | 1/2022 | 92-103 | Topics |
AbstractDeep tunnels are long tunnel systems which cross different hydrogeological environments as a drainage. Thus, their water inflows have very different characteristics. The tunnel water discharges formed from these water inflows, which drain individual sections of the tunnel system, also have different properties. These discharges from individual tunnel sections - so-called sectional discharges - are important for determining the geothermal potential of deep tunnels. Knowledge of the origins of sectional discharges and their properties allows optimising the usage of the geothermal potential of the water by provision of adequate tunnel water management. By monitoring sectional discharges, the most effective “mixing scenarios” can be calculated and thus an optimization of the geothermal output can be achieved. The concept of sectional discharges for the geothermal evaluation of deep tunnels is presented based on data from the Brenner Base Tunnel (BBT). x | |||||
Stemmle, Ruben; Menberg, Kathrin; Rybach, Ladislaus; Blum, Philipp | Tunnel geothermics - A review / Tunnelgeothermie - Ein Ãœberblick | Geomechanics and Tunnelling | 1/2022 | 104-111 | Topics |
AbstractTunnel geothermal systems hold the potential to promote decarbonization of the building heating and cooling sector. They can be integrated into existing infrastructure, resulting in low additional costs. In addition, these systems have large contact areas with the ground leading to larger heat fluxes. However, tunnel geothermics is relatively unknown and rarely used. Thus, the objective of this study is to provide an overview of the two primary tunnel geothermal system types as well as their application and potential. Open hydrothermal systems use the tunnel drainage water as a heat source, whereas closed absorber systems harness the heat flux from the subsoil and the warm tunnel interior via heat exchangers. The evaluation of the global application of existing and planned tunnel geothermal systems shows that all open systems are currently located in mountainous regions with a thick rock overburden. In contrast, closed absorber systems are mostly installed in urban tunnel infrastructures. The spatial distribution of geothermal tunnel systems has a focus in central Europe with Switzerland, Germany and Austria being the countries with the highest number of installed systems. Finally, this study also presents a brief summary of existing methods to determine the geothermal potential of tunnels. x | |||||
Carstens, Volker; Ilg, Ludwig; Pospisil, Petr | Rock heat input of ventilated tunnel structures / Felswärmeeintrag belüfteter Tunnelbauwerke | Geomechanics and Tunnelling | 1/2022 | 112-120 | Topics |
AbstractPredicting the heat input from rock is particularly important for climatic conditions in long tunnels during the construction phase because, although other heat sources are present, this often has the greatest impact on the amount of heat transferred to the air in tunnels with a high rock overburden. Correctly predicting the time-dependent rate at which the excavated tunnel tube cools is of fundamental importance, as this determines the amount of cooling power required to maintain the working climate. Two different rock heat calculation methods will be presented here: an analytical method based on a series development and a method based on solving the heat conduction equation using a numerical method. x | |||||
Todaro, Carmine; Martinelli, Daniele; Boscaro, Alessandro; Carigi, Andrea; Saltarin, Simone; Peila, Daniele | Characteristics and testing of two-component grout in tunnelling applications | Geomechanics and Tunnelling | 1/2022 | 121-131 | Topics |
AbstractTwo-component grout is nowadays the most popular backfilling technique, used widely in rock or soil thanks to its versatility and the undoubted advantages for operatives compared to other backfilling technologies. Despite its intensive adoption in shielded tunnelling projects, very poor and often fragmented information is available, especially on the engineering properties used for the mix design calibration (design phase) and secondly on construction sites as the acceptance protocol (operative phase). In this work, starting from real construction sites data, an analysis has been performed in order to determine the intrinsic characteristics of the two-component grout technology. Moreover, the most frequently used engineering parameters have been identified to characterise both component A and the hardened grout, correlated with their usage frequency. The outcomes illustrate that although at the current time different choices are made at different construction sites, a pattern of tests has been recognised, that can be considered as a significant cornerstone for the characterisation of two-component grout. x | |||||
Tschötschel, Marco; Balthaus, Hansgeorg; Beeler, Patrick; Schwalt, Markus; Seith, Oliver | Use of a yielding zone to repair the Gotschna Tunnel / Einsatz einer Knautschzone bei der Sanierung des Gotschnatunnels, Klosters (CH) | Geomechanics and Tunnelling | 1/2022 | 132-140 | Reports |
AbstractDuring the renovation of the Gotschna Tunnel from 2019 to 2020, prefabricated elements made of Compex were used for the first time as a deformable yielding zone in the invert zone. The client, construction management, construction company and supplier of the compressible elements worked closely together to implement the design specifications. Consequently, the expectations of the special building material in terms of the production quality of the prefabricated elements and handling on the construction site were more than met. The parties involved in the construction thus see potential for further applications and further developments of Compex. x | |||||
Site Reports: Geomechanics and Tunnelling 1/2022 | Geomechanics and Tunnelling | 1/2022 | 141-142 | Site Reports | |
AbstractInnovative AT - Pipe Umbrella Systems used in Slovenia's largest construction project - Innovatives AT - Rohrschirmsysteme für Sloweniens größtes Bauprojekt x | |||||
Technical Reports: Geomechanics and Tunnelling 1/2022 | Geomechanics and Tunnelling | 1/2022 | 143-144 | Product Informations | |
AbstractGlass fibre-reinforced diaphragm walls under Munich Central Station - Glasfaserbewehrte Schlitzwände unter Münchner Hauptbahnhof x | |||||
Diary of Events: Geomechanics and Tunnelling 1/2022 | Geomechanics and Tunnelling | 1/2022 | 145-146 | Diary of Events | |
geotechnik: Jahresinhaltsverzeichnis des 44. Jahrgangs 2021 | geotechnik | 1/2022 | Jahresinhaltsverzeichnis | ||
Titelbild: geotechnik 1/2022 | geotechnik | 1/2022 | Titelbild | ||
Abstract
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Inhalt: geotechnik 1/2022 | geotechnik | 1/2022 | Inhalt | ||
Vrettos, Christos | Informationschaos | geotechnik | 1/2022 | 1-2 | Editorials |
Tafili, Merita; Knittel, Lukas; Gauger, Vera | Experimentelle und numerische Untersuchungen zum Kompressionsverhalten von Sand-Schluff-Gemischen | geotechnik | 1/2022 | 3-15 | Aufsätze |
AbstractDie Wahl eines geeigneten Stoffmodells für gemischtkörnige Böden ist für die Nachweisführung einer anspruchsvollen geotechnischen Konstruktion von entscheidender Bedeutung. Für die Entwicklung eines akkuraten Stoffmodells, ist wiederum die experimentelle Untersuchung des Bodens unabdingbar. Anhand von Ödometerversuchen an Mischungen mit unterschiedlichem Feinkornanteil wird das Kompressionsverhalten von Sand-Schluff-Gemischen untersucht. Hierbei zeigt sich, dass mit steigendem Feinkornanteil die Kompressibilität des Materials deutlich zunimmt, die jedoch unabhängig vom Feinkornanteil durch eine exponentielle Beziehung zwischen der äquivalenten Porenzahl e* und der vertikalen Dehnung beschrieben werden kann. Dabei wird das Verformungsgesetz von Ohde (1939) unter Berücksichtigung von e* auf Gemische verallgemeinert. Nachrechnungen mit dem hypoplastischen Stoffmodell für grobkörnige und dem AVISA-Modell für feinkörnige Böden ergeben einen Bedarf für die Kopplung der Vorkonsolidierungsspannung und der Normalkonsolidierungslinie bei einem Verhältnis von 1 : 1 von Sand zu Schluff, abhängig vom Feinkornanteil. x | |||||
Gasser, Daniel; Marte, Roman; Tschuchnigg, Franz | Horizontalverspannung nicht bindiger Böden durch die Rütteldruckverdichtung mit Tiefenrüttler - Experimentelle und numerische Untersuchungen | geotechnik | 1/2022 | 16-30 | Aufsätze |
AbstractVibrationsverdichtungsverfahren zur tief reichenden Verbesserung nicht bindiger Böden werden seit den 1930er-Jahren eingesetzt. Verwendet werden entweder Tiefenrüttler oder Aufsatzrüttler. Die Planung der Verdichtungsmaßnahme wie auch die anschließende Qualitätskontrolle erfolgt bis heute fast ausschließlich auf der Grundlage von empirischen Zusammenhängen. Diesbezüglich hat sich der Einsatz von indirekten Untergrunderkundungsmethoden wie z. B. Ramm- oder Drucksondierungen und die arbeitsbegleitende Aufzeichnung von Verfahrensparametern etabliert. x | |||||
Hu, Yifeng; Bayer, Manfred; Sieler, Ulrich | Zu den geomechanischen Parametern von Nürnberger Keupersandstein für den kreuzungsfreien Ausbau des Frankenschnellwegs Nürnberg (Abschnitt Mitte) | geotechnik | 1/2022 | 31-42 | Aufsätze |
AbstractIm Zuge des kreuzungsfreien Ausbaus des Frankenschnellwegs in Nürnberg ist im Abschnitt Mitte ein Tunnel mit tiefer Gradiente in Spritzbetonbauweise geplant. Der Tunnel wird überwiegend im Nürnberger Keupersandstein (Blasensandstein der Kategorie mürb bis mittelhart) aufgefahren. Hierbei werden mehrere kreuzende Bahnlinien mit dem geplanten Tunnel unterfahren. Zur Gewährleistung der Betriebssicherheit stellt die Deutsche Bahn hohe Anforderungen an die Begrenzung der Verformungen bzw. Setzungen der Eisenbahndämme durch den Tunnelvortrieb bei einer Überdeckungshöhe bis ca. 18 m. Zur realitätsnahen Prognose des Verformungs- bzw. Setzungsverhaltens durch Tunnelvortrieb wurden zahlreiche Triaxialversuche an Prüfproben der mürben, mittelharten und harten Sandsteine durchgeführt. Dabei wurden insbesondere die Einflüsse des Seitendrucks und der Ent- bzw. Wiederbelastungsschleifen auf Steifigkeiten untersucht. Der Auswertung der Versuchsergebnisse wurde das Stoffmodell Hardening Soil Model (HSM) zugrunde gelegt. Davon ausgehend wurde die Anwendbarkeit des Stoffmodells HSM für die Nürnberger Keupersandsteine je nach der Kategorie bzw. Druckfestigkeit überprüft, die entsprechenden geomechanischen Parameter ermittelt und zur Bemessung empfohlen. In diesem Aufsatz werden die wesentlichen Ergebnisse dargestellt. x | |||||
Kostkanová, Vladislava; Müller, Kay | Neubaustrecke Dresden-Prag - aktueller Planungsfortschritt mit dem Schwerpunkt Baugrund/Geologie | geotechnik | 1/2022 | 43-50 | Berichte |
AbstractDie DB Netz AG und Správa eleznic planen gemeinsam die neue Hochgeschwindigkeitseisenbahnstrecke zwischen Dresden und Prag. Kernstück des Neubauvorhabens ist ein mindestens 25 km langer Tunnel unter dem Erzgebirge zwischen Heidenau in Deutschland und Stradov bei Ústi nad Labem in Tschechien. Der grenzübergreifende Tunnel wird durch ein gemeinsames Planungsteam der beiden Eisenbahninfrastrukturunternehmen geplant. Dieser Beitrag zeigt die Komplexität des anstehenden Gebirges, die durchgeführten Untersuchungen und gibt einen Ausblick auf die noch anstehenden Untersuchungen (Bearbeitungsstand Juni 2021). x | |||||
Heusermann, Stefan; Kiehl, Johannes R. | Bestimmung von Gebirgsspannungen mit dem Ãœberbohrverfahren - Teil 2: Weggebersonden - Neufassung der Empfehlung Nr. 14 des Arbeitskreises "Versuchstechnik Fels" der DGGT | geotechnik | 1/2022 | 51-62 | Berichte |
AbstractDer Arbeitskreis AK 3.3 “Versuchstechnik Fels” der Deutschen Gesellschaft für Geotechnik e. V. erarbeitet Empfehlungen für felsmechanische Labor- und Feldversuche sowie Messungen im Gebirge und an geotechnischen Bauwerken. Die vorliegende Neufassung der Empfehlung Nr. 14 behandelt Überbohrversuche zur Bestimmung von Gebirgsspannungen und berücksichtigt die Weiterentwicklung der Versuchstechnik seit der Herausgabe der Empfehlung Nr. 14 “Überbohr-Entlastungsversuche zur Bestimmung von Gebirgsspannungen” im Jahre 1990 [1]. Es werden die Anforderungen an die Messgeräte sowie die Vorgehensweise für die Durchführung und Auswertung dieser Versuche festgelegt. Ferner wird auf die Empfehlungen der International Society for Rock Mechanics (ISRM), in denen Überbohrversuche behandelt werden, hingewiesen [2, 3]. Die Empfehlung Nr. 14 ist in zwei Teile gegliedert. Im Teil 1 werden Überbohrversuche mithilfe von Triaxialmesssonden behandelt. Der vorliegende Teil 2 dieser Empfehlung befasst sich mit Überbohrversuchen mittels Weggebersonden. x | |||||
geotechnik Rubriken 1/2022 | geotechnik | 1/2022 | 63-81 | Rubriken | |
AbstractDGGT-Mitteilungen: x | |||||
Termine: geotechnik 1/2022 | geotechnik | 1/2022 | 81-82 | Termine | |
Abstract13. Österreichische Geotechniktagung x |