Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Riepler, Franz | Felbertauern rockfall - avalanche gallery: Geological conditions and safety measures / Felssturz Felbertauern - Schildalmgalerie: Geologische Verhältnisse und Sicherungsmaßnahmen | Geomechanics and Tunnelling | 6/2020 | 620-627 | Topics |
KurzfassungOn 14 May 2013 a massive rockfall occurred approximately 1, 100 m south of the Felbertauern Tunnel, which destroyed the avalanche gallery “Schildalm” of the P1 Felbertauernstraße over a length of 130 m. At an elevation of 1,770 m a.s.l. around 10,000 m3 of rock mass dislodged and cascaded down about 190 m of elevation onto the Gallery, which protected the three lane road below. The rock fall debris deposited in the rock fall track, on the road and down to the edge of the valley bottom some 70 m further below the road. As a part of the safety- and remedial measures instable rock masses of approximately 10,000 m3 at the head scarp were removed by blasting. To protect the remaining slopes, rockbolts, steel wire meshes, anchor beams and a rock fall protection barrier were installed. The access to the site was of particular challenge, therefore all tools, machinery and material had to be transported to site by helicopter. x | |||||
Pläsken, Regina; Keuschnig, Markus; Krautblatter, Michael | Permafrost rocks and high-alpine infrastructure: Interrelated, interconnected, interacting | Geomechanics and Tunnelling | 6/2020 | 628-633 | Topics |
KurzfassungOver the last few decades, pronounced changes of mountain environments during exceptionally warm summers have raised strong awareness towards changing cryospheric conditions in high mountain areas. Alpine regions are considered particularly sensitive to climate change, observations as well as projections report a significantly higher temperature rise in comparison to lowland areas. Rising sub-zero temperatures were demonstrated to alter rock- and ice-mechanical strength, namely compressive and tensile intact rock strength, friction, ice creep and fracturing of rock-ice interfaces as well as elastic moduli. So far benchmark studies have only investigated the impact on rock masses irrespective of the interaction with high-alpine infrastructure. This study investigates the interconnection between a high-alpine cable car station and its permafrost-affected surroundings. For engineering applications, the understanding of the state of natural systems is combined with numerical modelling of interactions between constructions and their frozen subsoil. This enables an improved design of high-alpine infrastructures in the long run. x | |||||
Sigl, Oskar | Special construction methods for tunnels with very shallow overburden - Challenge for innovation | Geomechanics and Tunnelling | 6/2020 | 634-640 | Topics |
KurzfassungInfrastructure in large cities is getting denser over time. Therefore, interferences with existing structures and complying to project constraints are fast becoming a very common feature during the implementation process of new projects in urban areas. As a consequence, actual geotechnical challenges often require application of innovative methods of construction in order to minimize potential construction impact or disruption. The paper intends to direct the focus on the application of unusual construction methods and will highlight and discuss some very specific solutions to some major challenges of constructing underground projects in urban environments. This is presented in the form of examples applying unusual construction methods for underground structures related to shallow overburden situations such as passenger linkways, which do not normally stand in the forefront of the attention. The paper is written from the viewpoint of a practitioner, who is deeply involved in the actual design for the implementation of such projects. x | |||||
Gschnitzer, Ernst; Wenger, Julian; Raine, Andy | Woodsmith project - Construction of a 37 km long mineral transport system for the world's largest Polyhalite resource | Geomechanics and Tunnelling | 6/2020 | 643-649 | Topics |
KurzfassungRapidly increasing and urbanized world populations require the use of fertiliser for more efficient food production. Polyhalite provides this by sustainable and low carbon means. The world's largest known high-grade Polyhalite deposit is located under the North York Moors National Park in the north-east of England at a depth of about 1,550 m. In order to protect the national park, the mineral is processed outside the park on the coast near Wilton, Teesside. The mineral is transported there on a conveyor belt running in a 37 km long tunnel between the Woodsmith mine and the portal in Wilton. Strabag was awarded with the design and construction of the 37 km long tunnel, including the mineral transport system. The total contract value amounts to several hundred million Euros with a 100 % share for Strabag. The biggest challenges for this very long tunnel drive are especially the logistics. High safety standards and a tight time schedule, funding issues and contractual changes have resulted in additional challenges. Close cooperation with the Client's team on site has been key for achieving best results for the project. x | |||||
Schürch, Roberto; Perazzelli, Paolo; Moranda, Giuseppe; Spivak, Eldad | The Shazar caverns - Design challenges and construction experience | Geomechanics and Tunnelling | 6/2020 | 650-657 | Topics |
KurzfassungThe Shazar caverns (width 19 m, height of 29 m, length 270 m) are part of the first phase of a larger project called the “Jerusalem Gateway”. They will accommodate a road in the upper level and five parking floors in the lower levels. The geology in the project area is characterized by dolomite and dolomitic limestone, overtopped by decayed rock including significant clay masses and artificial filling. Overall, the rock mass is weathered due to strong karst activity. The peculiarities of the project are the small overburden (7 to 10 m) under poor ground conditions, the close vicinity between the caverns and existing/future buildings (2 to 5 m), the vicinity between the two caverns (3 to 5 m), the intense earthquake activity in the area and the presence of large karstic cavities. The resulting challenges require unique engineering solutions. This paper gives an overview on the project, it presents the adopted design approach and the elaborated design solutions and, finally, it shows the construction experience. x | |||||
Panwar, Akshay; Manvani, Jitendra; Muniyappa, Prathap; Krenn, Florian | Design of a NATM crossover at Mumbai metro line 3 | Geomechanics and Tunnelling | 6/2020 | 658-663 | Topics |
KurzfassungThe construction of underground structures in metro rail projects is always challenging as the project works normally affect a large number of adjacent surface structures with stringent settlement criteria and protection requirements. Project implementation becomes even more complex when the overburden is shallow and the area of the cross-section is comparatively large. In the case of design and build metro rail projects, the Client provides a tender stage design to the Contractor's designer; this initial design is often based on limited data and does not consider the construction phase in detail. This is a significant challenge for the Contractor's designer as the new design has to consider all relevant parties and boundary conditions with respect to the compatibility of other parts of the project. This paper describes such a challenge at Mumbai metro line 3, where a crossover structure had to be implemented during the detailed design as a change of scope. The initially proposed crossover cavern was re-arranged during the detailed design. The main emphasis of this paper is to explain the revised crossover arrangement, for optimized construction feasibility, construction staging and geotechnical stability of the excavation. After the options presented by the Contractor's designer met the original objectives, the detailed design of the primary support and modified construction sequence was carried out in accordance with the principles of NATM design. x | |||||
Golser, Johann; Keuschnig, Markus; Weichenberger, Franz Peter | NATM - Review and Outlook / NÖT - Rückblick und Ausblick | Geomechanics and Tunnelling | 5/2020 | 466-474 | Topics |
KurzfassungBased on mining experience and historical conventional construction processes a new type of construction has evolved - the New Austrian Tunnelling Method (NATM). NATM changed the view on the rock mass surrounding the tunnel from the forcing to the load-carrying component. NATM is a proven methodology for conventional tunnelling applied worldwide. New observation- and measurement techniques as well as digital models (e.g. geological model) will be increasingly integrated within the Building Information Modelling (BIM) process. BIM provides a sound basis of vital information for decision support across different project phases. x | |||||
Bauer, Manfred; Rath, Andreas | New Austrian Tunnelling Method (NATM) - Experiences, critical discussion and outlook from an executive perspective / NÖT - Neue Österreichische Tunnelbaumethode - Erfahrungen, kritische Auseinandersetzung und Ausblick aus ausführender Sicht | Geomechanics and Tunnelling | 5/2020 | 476-486 | Topics |
KurzfassungTunnel constructions according to the principles of NATM are representing an essential key competence for construction companies. Likewise, extensive demands are placed on the people involved, and essential rules and requirements must be taken into account in order to be used successfully. The current developments in the cooperation in project management as well as the tendencies in the environment are critically examined and attempts are made to explain the necessary measures to secure this construction method in the future. Successful implementations are presented using two selected project examples. x | |||||
Reichenspurner, Peter; Riedel, Thomas | Rohtang Tunnel - NATM in the Indian Himalayas / Rohtang Tunnel - NÖT im indischen Himalaya | Geomechanics and Tunnelling | 5/2020 | 489-497 | Topics |
KurzfassungThe 8,900 m long Rohtang Tunnel lies in the Indian Himalayas north of the Manali tourist region. It avoids the dangerous route over the Rohtang Pass, which is at an elevation of almost 4,000 m, shortening the Manali-Leh Highway by approx. 50 km and enabling access to the northern regions of the state of Himachal Pradesh and onto Jammu and Kashmir even during the winter. x | |||||
Pilgerstorfer, Thomas; Hölzl, Harald; Moritz, Bernd | Passing a major fault zone three times: NATM helps TBM to succeed / Dreimalige Durchörterung einer Störungszone: NÖT hilft TBM zum Erfolg | Geomechanics and Tunnelling | 5/2020 | 498-508 | Topics |
KurzfassungThis paper discusses the design and construction of a fault zone of the OeBB Koralmtunnel lot KAT3. Due to the experience gained during the advance of the parallel-situated southbound tunnel and the aim to minimize the geotechnical hazard for the subsequent excavation of the northbound TBM bore, an extensive redesign regarding the excavation-concept and -method was performed. Five different alternative solutions have been subject to a risk analysis to optimize the required measures and to minimize the cost-effective risks and hazards to an acceptable level. The set of measures, which was evaluated and juxtaposed, contained solutions for strengthening the rock mass with grouting from the TBM and from aside the bore, conventional tunnelling and backfill with a top heading or full-face excavation. Finally, the fault zone has been excavated with a conventional top heading drive from a nearby-situated cross-passage. Subsequently this tunnel stretch has been excavated by TBM without any construction delay. The paper focuses on highlighting the importance of a consequent application of the observational method and thereof derived measures in the context of a geotechnical safety management plan for controlling the residual risks. x | |||||
Holzer, Robert; Prall, Karoline; Wagner, Oliver Kai; Gobiet, Gerhard | Semmering Base Tunnel - Tunnelling in challenging geotechnical and geological conditions in major fault zones / Semmering-Basistunnel - Geologisch-geotechnische Herausforderungen beim Vortrieb in Störungszonen | Geomechanics and Tunnelling | 5/2020 | 509-518 | Topics |
KurzfassungOne of the major fault zones in the Semmering area runs along the Auebach Valley. In this fault zone a combination of soft fault rocks and water bearing hard rocks led to extremely challenging conditions in the design and execution of the tunnel. In difficult conditions, overlapping exploratory drillings in front of tunnel drive are essential to improve the geological-hydrogeological model and to assess geotechnical risks. However, in the encountered geological-hydrogeological conditions, the well-established exploratory drilling methods reached their limits. Despite the ongoing risk analysis, a very large-scale water and ground inflow with subsequent tunnel face collapse and development of a sinkhole on the surface occurred during the tunnelling. This paper describes the causes of the incident and the development of procedures to cope with the problem. In addition to the geological-geotechnical analyses, the article also discusses the limitations of geotechnical surveillance in complex heterogeneous rock masses. x | |||||
Grunicke, Urs H.; Stefan, Christian; van Linn, Andreas; Weninger-Vycudil, Alfred; Mellert, Lars Derek | Traffic tunnels - Development of a cross-asset, reliability-based life cycle management / Verkehrstunnel - Weiterentwicklung eines gewerkeübergreifenden, zuverlässigkeitsorientierten Lebenszyklusmanagements | Geomechanics and Tunnelling | 5/2020 | 520-530 | Topics |
KurzfassungTunnels within primary road networks are complex systems. The prerequisite of a good level of service is the seamless interaction of the various tunnel components (structural elements and technical equipment). Due to their heterogeneous nature, electrical and structural components are subject to divergent aging processes which require recurring maintenance procedures and rehabilitation measures. Considering the diversity of specifications and requirements among electrical/mechanical and structural components, it is evident that there is a considerable mismatch of maintenance cycles among them. Hence, tunnel asset management faces the challenge to develop strategies to integrate both the necessary functional integrity of the individual components over their respective lifecycle and the requirement of an optimized management for the overall system. Yet, the synchronization of measures towards maximizing system availability must not contradict positive wear-and-tear contingencies of the various tunnel components. Evidence based forecasting and reliability centred decision models are key elements of modern life cycle management. They must include interdependencies between the diversity of components and their manifold maintenance cycles. x | |||||
Condic-Marinovic, Tomislav; Thiessen, Andrea | Further development of condition assessment and structure management of DB Netz AG, by example of tunnels and culverts / Weiterentwicklung der Zustandsbewertung und des KIB-Managements der DB Netz AG am Beispiel Tunnel und Durchlässe | Geomechanics and Tunnelling | 5/2020 | 531-537 | Topics |
KurzfassungThe aim of this project is to achieve a uniform and comparable method for the technical assessment of the state of structures throughout Germany (for bridges, tunnels, culverts; in general, for underground and support structures). By clustering defects, damage and measures according to their relevance to the technical condition of the structures, it is possible to make a more precise analysis and compare the repair and investment requirements for the system. This makes it easier for DB Netz AG to prioritize work and allocate the necessary resources. For the end user, the new process management and the support for damage assessment provided by the newly introduced damage catalogue, including pictures of the damage, is an essential part of uniform comparability and also ensures the transfer of know-how necessary for the actual work to be done. The article provides an insight into the progress with the project to date, the current state of the work and an outlook for the introduction of the new procedures for tunnels and culverts. x | |||||
Hellmich, Christian; Pichler, Bernhard; Heissenberger, Roman; Moritz, Bernd | 150 years reliable railway tunnels - Extending the hybrid method for the long-term safety assessment / 150 Jahre zuverlässige Eisenbahntunnel - Erweiterung der hybriden Methode zur langfristigen Sicherheitsbewertung | Geomechanics and Tunnelling | 5/2020 | 538-546 | Topics |
KurzfassungQuantification of the level of loading of shotcrete supports from measured displacements of NATM-driven tunnels is common practice in Austria. At construction sites of the Austrian Federal Railways (OeBB), a hybrid method developed at the TU Wien (Vienna University of Technology) has been successfully applied over the last 15 years. Because OeBB tunnels are designed for a lifetime of 150 years, the long-term reliability of the support structures is of paramount interest. This provides the motivation for the development of hybrid methods applicable during the entire service life of tunnels, including also inner linings and segmental linings. The required extensions are intended to be carried out within a research program. The paper describes the state-of-the-art and projected future developments. x | |||||
Balbi, Gianpiero | Fedro's Tunnel Renovation Method - Renovation of a non-reinforced primary lining using night shifts while keeping all traffic lanes open during peak traffic periods / Astra-Tunnelerneuerungsmethode - Erneuerung einer nicht armierten Innenschale in Nachtarbeit bei Gewährleistung des Betriebs aller Fahrstreifen in Spitzenzeiten | Geomechanics and Tunnelling | 5/2020 | 547-556 | Topics |
KurzfassungTo secure the availability and usability of the motorway network, the Federal Roads Office (Fedro) developed new solutions for the renovation of road tunnels while keeping them open to traffic and initiated a pilot project. The aim is to replace a non-reinforced inner shell at night and ensure the availability of all lanes during the day. The solution involves partially removing the existing inner shell, then installing a drainage and waterproofing system, and finally installing a new inner lining of self-compacting concrete during the night. x | |||||
Vetter, Stefan; Steiner, Peter; Galli, Mario | Refurbishment of the Kuckuckslay tunnel - Current experience in the use of the "Tunnel-im-Tunnel-Methode" / Erneuerung Kuckuckslay Tunnel - Aktuelle Erfahrungen beim Einsatz der Tunnel-im-Tunnel-Methode | Geomechanics and Tunnelling | 5/2020 | 557-565 | Topics |
KurzfassungThe 450-metre long Kuckuckslay Tunnel is a double track railway tunnel dating from 1871. It is located in Germany on the line between Trier and Cologne along the river Kyll. Since its commissioning, the tunnel is a non-electrified line and has undergone only a few refurbishing measures. In 2018, a joint venture was commissioned to refurbish the Kuckuckslay Tunnel. During a 2.5-year construction period, the Kuckuckslay Tunnel will be expanded using conventional tunnelling and provided with a new concrete lining. The so-called 'Tunnel-im-Tunnel-Methode' would be used for the expansion, during which rail traffic could be maintained. In this case, the loading gauge of the railway in the area of the tunnelling work would be protected by a mobile construction rig. The Kuckuckslay Tunnel construction project offered a particular challenge due to the severely limited space inside and outside the tunnel, as well as the environmental conditions within a protected area. This article describes how these challenges were implemented and gives an overview of the state of work, as well as technical solutions and experience from the work completed. x | |||||
Gloimüller, Stefan; Pánová, Petra; Lang, Georg | Analytical and numerical load evaluation from excavation shoring on the powerhouse Kirchbichl / Analytische und numerische Belastungsermittlung aus Baugrubenumschließung auf das Krafthaus Kirchbichl | Geomechanics and Tunnelling | 5/2020 | 566-573 | Topics |
KurzfassungTiroler Wasserkraft AG realized the extension of hydropower plant Kirchbichl located in the Unterinntal built in the 1940s for the first time. The excavation pits were retained by a bored pile wall with jet grouting connections between the piles, supported with up to two bracing horizons. Safety against uplift during construction stage is managed by a deep-set jet grouting plate, which is partially anchored. Due to the dismantling of the bracing during the construction progress a partially load transfer from the bored pile wall on the partly completed concrete construction and the jet grouted plate occurs. This interaction is simulated at the static calculations. The excavation shoring was calculated by using a geotechnical program. The resulting spring supporting forces from geotechnical consideration were used in the finite element model as loads on the new reinforced concrete walls to calculate the necessary reinforcement content during construction sequence. The results from construction sequence were perpetuated at final state of the new powerhouse structure to get the governing reinforcement content. x | |||||
Weiner, Thorsten; Thewes, Markus | Dispersion in slurry shield tunnelling / Dispergierung beim Hydroschildvortrieb | Geomechanics and Tunnelling | 4/2020 | 361-371 | Topics |
KurzfassungIn this contribution the relevance of dispersion for tunnel construction will be demonstrated on the basis of project experience and an exemplary economic consideration. The authors recommend application of the recently developed test for the prediction of dispersion as well as more intensive use of the corresponding contractual mechanism. x | |||||
Zizka, Zdenek; Kube, Sebastian; Schößer, Britta; Thewes, Markus | Influence of stagnation gradient for face support calculation in Slurry Shield Tunnelling - Type of slurry pressure transfer mechanism expressed in terms of stagnation gradient f | Geomechanics and Tunnelling | 4/2020 | 372-381 | Topics |
KurzfassungIn slurry shield tunnelling, a reliable face support is presumed if a sufficient support pressure is transferred and the slurry excess pressure provides efficient support pressure on the soil skeleton. The required support pressure is calculated in reference to the groundwater pressure and the earth pressure. In this paper, the sliding wedge mechanism is applied. To ensure face stability, the support pressure transfer needs to be provided within the theoretical sliding wedge at the tunnel face. Therefore, the penetration depth of the bentonite suspension as a support medium has to be kept within limits. Research shows that certain penetration is required. x | |||||
Gilgen, Samuel; Weh, Markus | Eppenberg tunnel: Hydroshield TBM drive in highly permeable soils above the groundwater table - Unexpected problems and their solution / Hydroschildvortrieb über dem Grundwasserspiegel in hoch durchlässigen Schottern am Eppenbergtunnel - Unerwartete Probleme und ihre Lösung | Geomechanics and Tunnelling | 4/2020 | 382-398 | Topics |
KurzfassungAs part of the four-track improvement of the Zurich-Berne line near Aarau, the 3.1 km long Eppenberg Tunnel was bored using a multi-mode TBM. This involved driving more than 700 m in highly permeable soils, mostly above the groundwater table. The hydroshield drive was confronted with considerable problems. The static yield point of the bentonite slurry repeatedly fell below the critical limit of 10 N/m2, despite its frequent replacement. As a result, large quantities of slurry penetrated into the ground and large quantities had to be replaced. In addition, significant additional grout quantities were repeatedly observed for the filling of the annular gap. A systematic and analytical approach in cooperation with all parties involved made it possible to determine the behaviour of the system. Problems started with highly permeable open-framework gravel layers, which permitted the slurry to penetrate far into the ground. This resulted in overbreak in the crown and local underpressure of the slurry with respect to the grout around the shield. Consequently, the annular gap grout flowed past the shield tail seal and destroyed the thixotropic properties of the slurry by adding free Ca cations. The slurry became unusable and had to be replaced. An extensive set of measures finally made it possible to solve the problems and safely bring the excavation to breakthrough. x | |||||
Bäppler, Karin; Strässer, Michael | Forrestfield Airport Link Project - Challenges and TBM solution | Geomechanics and Tunnelling | 4/2020 | 401-405 | Topics |
KurzfassungA large number of successfully completed tunnelling projects in sensitive environments and airport areas show the highest technical and quality standards of mechanized tunnelling technology, mastering project challenges and individual tasks in the interest of customers, clients and the environment. The Forrestfield Airport Link, currently under construction in Perth, Australia, is one of these projects tackling challenges in an airport area sensitive to any kind of settlement and subsurface conditions. The paper highlights the project challenges that require a well-adapted TBM concept and experience with the use of variable density TBM technology from the manufacturer's point of view. x | |||||
Hegemann, Felix; Stascheit, Janosch; Maidl, Ulrich | Digitalisation and IoT in mechanised tunnelling - an integral approach / Digitalisierung und IoT im maschinellen Tunnelbau - Ein integraler Ansatz | Geomechanics and Tunnelling | 4/2020 | 406-420 | Topics |
KurzfassungThe article presents a platform approach, in which the almost complete linking of machine data analysis, Building Information Modelling, document management system and digital ground models can be carried out in real time during a mechanised tunnel drive. All processes of mechanised tunnelling are digitalised and further processed in various applications in real time. The subsequent examples should demonstrate that there are now practically no application limits to the digitalisation of tunnel construction sites. Furthermore the potential and limits of artificial intelligence and machine learning are presented. x | |||||
Lühr, Hans-Peter | Geomembranes for tunnel constructions - Applications, properties and release of pollutants | Geomechanics and Tunnelling | 4/2020 | 421-430 | Topics |
KurzfassungThe sealing of tunnel walls involves the use of membranes which, depending on the situation, are constantly exposed to the leaching action of groundwater, or of water emanating from the surrounding rock. In terms of ecological product compatibility, the question arises as to whether pollutants may be released in the process. Various geomembranes are examined in more detail and subjected to an evaluation system. It emerges that in particular geomembranes with especially worrying components such as phthalates should generally be kept away from the environment for precautionary reasons, even though some phthalate plasticisers have not yet been evaluated by the EU. Phthalates are characterised by the fact that they are released from the membranes in considerable quantities. x | |||||
Eichinger, Stefanie; Leis, Albrecht; Boch, Ronny; Seywald, Christian; Dietzel, Martin | Assessment and formation mechanisms of scale deposits in tunnels of the ÖBB-Infrastruktur AG - A subproject of the Task Force Drainage / Bewertung von Sinter und deren Bildungsbedingungen in Tunnelbauwerken der ÖBB-Infrastruktur AG - Ein Teilprojekt der Task Force Drainage | Geomechanics and Tunnelling | 3/2020 | 273-285 | Topics |
KurzfassungScale deposit formation in drainage systems of railway tunnels represents a major challenge for their functionality and maintenance. The removal of these scale deposits causes high costs and restrictions of system availability. Effective measures to reduce scale deposit formation range from specification of the composition and structure of building materials to the application of tailored prevention and cleaning strategies. This requires advanced knowledge of the origin and type of scale deposits. The aim of this study is a systematic compilation, characterization, classification, and evaluation of scale deposits in relation to their formation mechanisms and the influence of variable environmental factors. The scale deposits from the 16 investigated tunnels mainly consist of the minerals calcite, aragonite, brucite as well as iron (hydr)oxides and detrital components. Four major types of scale deposits are distinguished: (i) unconsolidated-particulate, (ii) shard-like, (iii) porous, and (iv) compact scales. Types (ii) to (iv) show clear indications of microbial activity affecting the formation and appearance of individual deposits by various metabolic processes. The determining factors for the formation of scales - in addition to the geogenic composition of the aqueous solutions in the drainage system (groundwater / surface water) - are the variable interaction of these waters with the binding agents of the building materials used and the tunnel atmosphere. Geogenic conditions and technical-operational specifications of a tunnel determine the type and character of scale deposits, which can be actively influenced based on the case-specific reaction mechanisms by individual adaptations of environmental conditions. x | |||||
Steiner, Walter | Sulphate-bearing rocks in tunnels - Lessons from field observations and in-situ swelling pressures / Verhalten von Sulfatgestein im Tunnelbau - Erfahrungen aus Feldbeobachtungen und In-situ-Quelldrücke | Geomechanics and Tunnelling | 3/2020 | 286-301 | Topics |
KurzfassungTunnels and underground works in sulphate bearing rocks are very challenging. For more than a century experience has accumulated in Switzerland and southern Germany with difficult conditions during construction and operation, which show the difficult conditions with extreme, long lasting heave of the invert and extreme swelling pressures. The analyses of published experience over more than a century and recent personal experience led to the compilation of many pieces of a puzzle and to a better understanding of complex processes. The swelling processes in sulphate bearing rocks are triggered by the formation of flow path for water, the dissolution, concentration and precipitation of minerals. In particular Anhydrite is dissolved and the solution becomes saturated, until precipitation and crystallization of Gypsum starts. The applied construction methods play an important influence on the rock mechanics and geochemical processes and finally the magnitude of in-situ swelling pressures. The in-situ swelling pressure are still large, but substantially less than the swelling pressures from laboratory tests. Estimated swelling pressures will be indicated. x |