Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Lehmann, Gabriel; Käsling, Heiko; Praetorius, Steffen; Seng, Frederic; Thuro, Kurosch | Small-diameter tunneling in difficult ground - Analysis of TBM performance in hard rock | Geomechanics and Tunnelling | 1/2023 | 15-21 | Topics |
KurzfassungSmall-diameter tunneling in hard rock is increasingly widespread due to the need for new and longer utility tunnels comprising sewer, stormwater, freshwater, or hydropower as well as cable tunnels and casings for pipelines transporting gas or hydrogen. Utility tunnels have to deal with a wide range of geological settings, like small overburden, weathered rock, rock-soil transitions, as well as fractured or intact hard rock with high strength and abrasivity. A database has been created including 35 hard rock projects with diameters between 1 and 5 m as well as more than 70,000 m of tunnel alignments, with a median drive length of less than 500 m. Challenges in creating it and some early interpretations based on the contents of the database are presented. Details about an exemplary pipe jacking project in basement rocks in Brittany, France, are given. The large variety in this small-diameter range in hard rock includes different TBM types, cutterhead designs, cutter types, and geotechnical conditions. Potential pitfalls in small-diameter TBM data analysis are shown and general drive parameter trends and penetration prediction approaches are presented and set in relation to the geotechnical conditions. Our analysis shows that difficult ground conditions do not only incorporate rocks with very high strength, but also generally weak rocks like schist or limestone could be responsible for low penetration rates and high thrust forces. x | |||||
Bisenberger, Tobias | Innovative contract and compensation model in mechanised tunnelling - Calculation of the deviating construction time based on digital excavation and process data | Geomechanics and Tunnelling | 1/2023 | 22-27 | Topics |
KurzfassungThe handling of a tunnel construction project poses great challenges for all those involved. Variables that cannot be clearly quantified can arise during the entire process of the project. The subsoil in tunnelling is one of these parameters which is difficult to forecast. The geological and hydrogeological conditions must be assessed during the planning phase with the help of exploratory measures and from the experience from projects that have already been built. x | |||||
Hassanpour, Jafar; Goodarzi, Saeed; Yagiz, Saffet; Rostami, Jamal; Sarem, Milad Davari | Soft sedimentary rocks and their boreability characteristics in mechanised tunnelling projects | Geomechanics and Tunnelling | 1/2023 | 28-37 | Topics |
KurzfassungSoft sedimentary rocks are frequently found in many mountainous regions of the world like Zagros Mountains located in the south and west of Iran, where most of Iran's water conveyance projects have been constructed or are under construction. These rocks usually contain considerable amounts of different types of clay minerals. The clay mineral-rich rocks cause many problems in the deep and long mechanised tunnelling projects. In particular, the boreability of these rocks is very different from other rocks, and due to their plastic behaviour and the lack of complete formation of chips during the cutting process by disc cutters, the prediction of cutterhead penetration in these rocks, with existing models, is often inaccurate. In this paper, a new model for estimating the disc cutter penetration in these rocks is introduced, which is based on data obtained from the main tunnelling projects completed in sedimentary rocks of Zagros Mountains. Then, the validity of the developed model is checked using actual data obtained from a tunnel recently constructed in the area. The new model can offer a more accurate estimate of machine performance in similar rocks. x | |||||
Poisel, Alexander; Meier, Alexander; Bach, Dietmar | The application of the guideline for the geotechnical design of underground structures with TBM excavation in Austria | Geomechanics and Tunnelling | 1/2023 | 38-46 | Topics |
KurzfassungIn 2013, the Austrian Society for Geomechanics published the Guideline for the Geotechnical Design of Underground Structures with TBM Excavation. The Guideline contains general procedures for the geotechnical design and construction. In the design phase, the first steps are evaluating different ground conditions by classifying different ground types, different ground behaviours, their categorization into ground behaviour types, and the determination of construction measures derived from the ground behaviour. On this basis the expected system behaviour in each system sector of the tunnel boring machine (TBM) is predicted and described in detail to enable comparison in the construction phase. In the construction phase, geotechnical relevant ground parameters as well as observations regarding the actual system behaviour are recorded and compared with the assumptions of the design. The geotechnical design is updated continuously based on the encountered ground conditions and geotechnical observations. The improved quality of the geotechnical model allows an optimization of the construction while meeting all safety and environmental requirements. In the first part of the article, the general procedures of the guideline are described and parameters to describe the system behaviour in each system sector adequately are listed. In the second part of the article, the implementation of the guideline during design and construction at the Semmering Basetunnel in Austria is described. x | |||||
Bianchi, Gianpino Walter | Analysis of TBM parameters during tunnelling in adverse conditions - The case study of the Frejus Safety Tunnel, Western Alps | Geomechanics and Tunnelling | 1/2023 | 47-52 | Topics |
KurzfassungOne of the main hazards during tunnel boring machine (TBM) excavation in hard rock is related to the occurrence of unforeseen adverse conditions, leading to unfavourable rock mass behaviour during tunnel boring. In this respect, the continuous analyses of TBM excavation parameters may represent an interesting tool for a continuous monitoring of geotechnical conditions at the tunnel face and for early detection of changing ground conditions in the rock mass. This work provides a back-analysis of TBM data recorded during the excavation of the Frejus Safety Tunnel, bored across the French-Italian border in the Western Alps. It is a 13 km-long tunnel excavated by a 9.4 m diameter, single-shield TBM through strongly anisotropic calcareous schist, with cover up to 1800 m. Main problems faced during TBM excavation were related to the local occurrence of buckling-related convergence and consequent asymmetrical loading on the precast segment rings. Correlating TBM performance parameters to the encountered geological and geomechanical conditions provides the possibility to identify which parameters are most affected by geomechanical properties of the rock mass at the tunnel face and by rock mass behaviour. Conversely, the analysis indicates which parameters can be adopted as monitoring tool of ground conditions during TBM advance. In addition, this work highlights how buckling phenomena can be distinguished, in terms of TBM operation and performance, from other adverse conditions as, e.g., blocky ground or squeezing. x | |||||
Wannenmacher, Helmut; Schlicke, Marcel | Analyses of Pre-Excavation Grouting for TBM Tunnelling | Geomechanics and Tunnelling | 1/2023 | 55-59 | Topics |
KurzfassungPre-excavation grouting (PEG) is essential for mitigating groundwater inflow to unlined tunnel structures. Prevention of initial water inflow proved best practice to balance groundwater conditions throughout the utilisation of a tunnel. The grouted rock mass acts as a circumferential sealing barrier instead of a secondary lining to minimise groundwater inflow to an acceptable level over the structure's lifetime. The construction of unlined tunnels relies on existing favourable in-situ rock mass conditions with an overall low hydraulic head, mainly to keep the effort of grouting inferior and avoid an unbalanced proportion of pre-excavation grouting during the tunnel construction works. x | |||||
Allahverdi, Navid; Bakhshi, Mehdi; Partovi, Maziar; Nasri, Verya | 3D-nonlinear finite element analysis of staged shield-driven tunnel excavation with a focus on response of segmental tunnel lining | Geomechanics and Tunnelling | 1/2023 | 60-67 | Topics |
KurzfassungThe complex and dynamic nature of shield-driven tunnel excavation, staged construction, segmental lining installation process, and tail-void grouting necessitate using detailed numerical modeling for predicting ground behavior and response of segmental lining. In this article, results of three-dimensional advanced finite element modeling are presented for one of the major ongoing construction projects in the North America. Different segment joint models, i.e., rigid joints, perfect hinge joints, Janssen joints, and rigid joints with reduced lining thickness, are used in the analysis. Critical responses such as ground deformation, settlement trough, crown deformation, and the internal forces in the linings considering different segment joint modeling are discussed. x | |||||
Steiner, Walter | Lessons from tunnelling through glacial open gravel deposits / Erfahrungen beim Tunnelbau in durchlässigem glazialen Lockergestein: offener Kies | Geomechanics and Tunnelling | 1/2023 | 68-80 | Topics |
KurzfassungGlacial soil deposits are present in Europe on both sides of the Alps, in Scandinavia, Northern Germany, Poland and in North America. There are typical names of the stages of the glaciation, however, the geotechnical characteristics of glacial deposits are similar in all regions; but are very heterogeneous locally. Glacial deposits extend from boulders to invisible silt particle (rock flour) and to clay particles, both of similar grain size. In this paper the focus will be on clean gravel without fines, so-called open gravel and the challenges and solutions for tunnelling. x | |||||
Fantini, Paolo; Miranda, Javier Calderon; Dell'Ava, Gabriele; Flor, Alberto | EPB tunnelling in long, highly sensitive sections - The experience of Grand Paris Line 14 underpassing the Orly Airport | Geomechanics and Tunnelling | 1/2023 | 81-87 | Topics |
KurzfassungThe correct definition and application of face confinement pressure is one of the main challenges for urban tunnels, where soil perturbation can affect the surrounding structures with undesirable or even severe consequences. The choice of this parameter needs to comply not only with minimal geotechnical performances, such as volume loss control, water pressure balance, and front stability, but also with optimization criteria (impact on production rate and Tunnel Boring Machine (TBM) components wear). The Grand Paris Line 14 South tunnel has emphasized this concept especially on the 1.5 km section below the Orly International Airport, with two constraints: the limitation of deformations on sensitive airport structures and the tight schedule due to the Olympic Games of 2024. The 8.83 m-diameter Earth Pressure Balance (EPB) TBM 'Koumba' successfully performed the excavation at 20 m depth. The design face pressure profile, varying between 0.8 and 2.6 bar, was studied. A complex monitoring system was also provided to validate design expectations and to update the TBM-soil interaction prediction model. This article focuses on the experience acquired on the EPB face confinement pressure management along this long, highly sensitive section. The first part presents the comparison between reference values and thresholds given by the designer and the real TBM drive oscillation. The second part is dedicated to the observed influence of the face pressure on the geotechnical aspect, machine mechanical parameters, and production rates. x | |||||
Cordes, Tobias; Voit, Klaus | Structural optimization of shotcrete lining - load capacity comparison of optimized and non-optimized excavation sections / Strukturoptimierung von Spritzbetonschalen - Versagensanalysen von Spritzbetonschalen bei Betrachtung von Vortriebsoptimierungen | Geomechanics and Tunnelling | 1/2023 | 88-101 | Topics |
KurzfassungA framework with a robust design of the driving classes is fundamental for the tunnel design. During tunnel advance, the detailed design of the lining is depending on the documented geology and the observed system behaviour. To reduce costs, the excavation profile is optimized with the aim of reducing overbreaks and shotcrete masses. This achieved profile accuracy is beneficial for the load-bearing capacity of the rock and the shotcrete lining. For temporary and permanent tunnel shotcrete linings, the excavation profile accuracy influences the stress distribution, the crack pattern and the expected deformations. In the course of this study, the effect of the excavation geometry on the load-bearing capacity of the primary lining of drill and blast tunnels was examined. For this purpose, shotcrete linings, reinforced by steel meshes and fibre-reinforced linings, were compared in optimized and non-optimized scanned excavation cross-sections. In each case, an ultimate load and failure analysis was carried out to assess shells in the hardened state by means of numerical modelling (ATENA). The aim is to determine the load-bearing capacity of the shell structure in order to obtain a conclusion regarding its structural robustness. The interaction between the rock/soil soil and the structure as well as a time-dependent material behaviour were not considered. It could be shown how an irregular overbreak or an inconsistent shell thickness has a negative effect on the load-bearing capacity of the structure. x | |||||
Zahed, Mohammad Ali; Seidi, Fouad; Salehi, Samira; Pardakhti, Amirarsellon | Simultaneous assessment of health, safety, and environmental risks using William Fine and FMEA methods based on OHSAS 18001: 2007 standard in the Alborz tunnel, Iran | Geomechanics and Tunnelling | 1/2023 | 103-113 | Topics |
KurzfassungIn this study, the critical risks and their effects on each other for the Alborz tunnel construction project, which is known as the longest road tunnel in the Middle East, have been evaluated on a case-by-case basis. In addition to covering all safety hazards in important tunnel drilling operations using the failure modes and effect analysis (FMEA) method, which is one of the risk assessment methods for operations and has been widely used in manufacturing, drilling, and tunneling industries, health hazards that affect employees and can cause a variety of job diseases have been studied and in order to identify, evaluate, and quantify the results, the William Fine method has been implemented. Also, all the risks have been identified and evaluated within the framework of OHSAS 18001 standard which was presented in 1999 due to the lack of an international standard regarding occupational health and safety and its last revision was done in 2007. Based on the research results, according to FMEA method, a total of 46 critical risks, 26 very high risks, 22 high risks, 8 medium risks, 34 low risks, 29 very low risks, and 8 insignificant risks in the field of safety have been identified and evaluated. In the field of job health, 165 high-level risks, 28 medium-level risks, and 57 low-level risks were assessed and finally in the environmental field, 7 high-level risks and 1 risk for each of the intermediate and low level have been inferred. x | |||||
Kaspar, Achim; Kunsch, Andreas | Energy transition - Insights and trends / Energiewende - Einblicke und Ausblicke | Geomechanics and Tunnelling | 6/2022 | 703-710 | Topics |
KurzfassungThe success of the energy transition in relation to achieving a low carbon fossil-free energy of the future largely depends on the extent to which collective efforts are geared towards specific goals, as the actual transformation of the energy sector is shaped by many challenges and uncertainties. Pandemics, uninterrupted supply chains and ongoing conflicts add to the complexity of the situation. The International Energy Agency has published its “World Energy Outlook” since 1998 and demonstrates ways of achieving a decarbonised energy of the future based on different scenarios. Taking three energy scenarios as the starting point, possible routes and corresponding effects by 2050 are outlined. x | |||||
Seywald, Christian; Rettenbacher, Martin | The new railway line between Köstendorf and Salzburg - Looking back to the past and forward to the future / Die Neubaustrecke Köstendorf-Salzburg - Ein Blick von der Vergangenheit in die Zukunft | Geomechanics and Tunnelling | 6/2022 | 711-719 | Topics |
KurzfassungTo increase capacity and reduce travel time for long-distance traffic, the Austrian Federal Railways (ÖBB-Infrastruktur AG) are planning a new railway line between Köstendorf and Salzburg. The centrepiece of the project is the Flachgau Tunnel - an approx. 16 km long, twin-tube single-track tunnel system. The selected tunnel alignment ''K5 optimiert'' was developed in a multi-year route selection procedure. Further optimisation within the current design stage - the detailed submission - achieved a 200 m shortening in tunnel length. The chosen standard cross-section was substantiated with life-cycle-cost and carbon-footprint investigations which also coincided with experiences from the construction and operation of existing tunnel structures with varying cross-sections and travel speeds. Both studies show the advantages of the larger 54 m2 cross-section compared to a smaller 44 m2 cross-section. Complex hydrogeological conditions require a water pressure-tight tunnel design capable of withstanding a maximum pressure of approx. 11 bar. These conditions are especially challenging for conventional tunnelling methods and require a waterproofing concept with two independent sealing layers. At present, the construction of the project is scheduled to take place from 2027 until 2040. x | |||||
Sempelmann, Franz; Edlmair, Gerald | A26 Linz motorway - Past and future challenges / A26 Linzer Autobahn - Herausforderungen im Rückblick und Ausblick | Geomechanics and Tunnelling | 6/2022 | 720-727 | Topics |
KurzfassungAfter a long design and approval process, the construction works for the first phase of the A26 started in 2019. The A26 not only relieves the central part of the road network of the city of Linz but also allows the river Danube to be crossed by means of a bridge: a 300 m long bridge, anchored in the rock slopes forming the banks of the Danube. The elements of the first phase are the Danube bridge and the two underground motorway junctions, Danube North and South, with excavation cross-sections of up to 400 m2 and the tight radii of the motorway on-ramps. Besides these conditions, urban planning requirements such as the protection of residents against immissions caused by noise and vibration, and the increased negative impacts resulting from the traffic during construction have an effect on the construction works. The excavated material from the tunnel is transported off site by ship. The existing rock mass requires excavation by means of the drill-and-blast method. The project-specific boundary conditions such as the high number of portals, the noise-reflecting effect of the “Danube gorge” and the low overburden require substantial measures to limit and monitor the immissions. x | |||||
Stephan, Sara; Renz, Florian; Hoffmann, Björn | Västlänken - The West Link Project, Korsvägen construction section in Gothenburg, Sweden / Projekt Västlänken, Bauabschnitt Korsvägen in Göteborg, Schweden | Geomechanics and Tunnelling | 6/2022 | 728-734 | Topics |
KurzfassungWest Link (Swedish: Västlänken) is one of the biggest infrastructure projects in Sweden building an in total 8 km double-track railway tunnel in Gothenburg, which is currently under construction. “E05 Korsvägen” is a construction lot which is part of the West Link project with the Swedish transport authority Trafikverket as the client. The works were awarded to the Joint Venture (JV) West Link Contractors consisting of Wayss & Freytag Ingenieurbau AG and NCC. A special contract model with a design and build part combined with a regular bill of quantities comprises building an underground double-track railway tunnel with a length of 3.2 km and the new Korsvägen station. This sub-project includes three drill and blast sections and three open excavation sections. All three construction pits will be executed in challenging soft ground conditions. The JV is confronted with high environmental demands and special requirements for the blasting works in the urban area of Gothenburg. x | |||||
Gallego, Francisco; Matt, Kajetan; Helgason, Einar | Tunnel Drammen (Norway) - Solution for excavating a tunnel in loose soil with the presence of groundwater / Tunnel Drammen (Norwegen) - Tunnelvortrieb im Lockermaterial und anstehendem Grundwasser | Geomechanics and Tunnelling | 6/2022 | 737-744 | Topics |
KurzfassungThe soil tunnel in Drammen (Norway), part of Bane NOR's 'New Double Track Drammen-Kobbervikdalen' project, has a length of 290 m; however, the different unfavourable boundary conditions combined with a large excavation cross section (156 m2) make this section the most technically challenging part of the project. The soil tunnel is driven mostly in saturated glaciofluvial sediments, which consist primarily of sand and gravel with a low content of fines, resulting in a low cohesion to cohesionless soil. The groundwater level, always within or above the tunnel section, cannot be lowered during the construction due to project requirements. These geological/hydrogeological conditions together with the large cross section present a high-risk scenario for any tunnelling project and, in the case of Norway, an unprecedented challenge. Moreover, the tunnel is located in an urban area and has a low overburden of just 8 to 9 m during the first 80 m. For the client it was critical that the design solution was safe, robust, and able to respond to the existing level of uncertainty and potential unexpected occurrences. ILF's design is able to answer these technical challenges while removing many of the typical risks associated to saturated soil tunnelling with a solution that relies mainly on extensive pre-excavation ground improvement works in the form of jet grouting executed from the surface. x | |||||
Ganster, Mark | Contribution of modern blasting technology to achieve accurate contour profiles in tunneling / Beitrag der modernen Sprengtechnik zur Erreichung der Profilgenauigkeit im Tunnelbau | Geomechanics and Tunnelling | 6/2022 | 745-755 | Topics |
KurzfassungThe profile accuracy during tunnel excavation will be influenced by several factors. Basically the design of the blasting pattern, the confinement conditions, the peak particle velocity generated, the escape of the gas volume and the geology are shown here, which are decisive criteria for successfully avoiding damage induced by blasting operations. Smooth blasting methods have been used successfully for years to minimize rock damage. By using electronic initiation systems in combination with software programs for modeling the energy conditions and the peak particle velocities generated, subsidence damage caused by blasting can be largely avoided. x | |||||
Schönlechner, Christian; Längle, Thomas; Müller, Christoph; Weber, Wolfgang | Safety gallery Kerenzerberg (CH) - Practical experiences with an innovative and emission-free logistics concept / Einsatz eines innovativen und emissionsfreien Logistikkonzepts beim Bau des Sicherheitsstollen Kerenzerberg (CH) | Geomechanics and Tunnelling | 6/2022 | 756-766 | Topics |
KurzfassungThe main lot of the Kerenzerberg safety gallery, a project of the Swiss Federal Roads Office (ASTRA), is currently under construction. In addition to the main works, the construction of a 5.2 km long safety gallery with a tunnel boring machine, the contract includes the excavation of 20 cross-passages and 52 ventilation galleries. The Joint Venture KER450 that was awarded the contact chose to excavate these cross headings simultaneously to the main drive. To implement the logistics concept, which needs to be highly capable and flexible at the same time, the contractor decided on an innovative and emission-free supply system known as Automated Service Vehicles (ASV). These fully electric, wheel-bound vehicles allow an almost automatic operation and were recently developed and supplied by the company VirtuRail. The first experiences after approximately one year of operation are very positive and have proven to be a main factor in the successful realisation of a challenging logistics concept. x | |||||
Bischoff, Jean-Luc; Eberli, Martin | Grand Paris Express Lot 16 - Sustainable infrastructure development in Paris / Grand Paris Express Los 16 - Nachhaltiger Infrastrukturausbau in Paris | Geomechanics and Tunnelling | 6/2022 | 767-773 | Topics |
KurzfassungThe Grand Paris Express is an urban infrastructure project in the Paris agglomeration. The outer districts, which will be enlarged with 70,cp te000 new flats per year, are to be connected to the public transport network of the core city. At the same time, various economic centres are planned around the city, similar to the La Défense banking centre. The metro lines connect the suburban railways, three airports and various TGV stations as a large ring and with direct connections to other transport hubs. The 19.3 km Grand Paris Express Line 16.1 connects the suburbs north and east of Paris in the Seine-Saint-Denis department. The cramped construction sites require modern construction processes that are sustainable and can be implemented quickly. For the fully automatic and completely underground line the client, Société du Grand Paris (SGP), is using segmental linings made of steel fibre concrete. The designer Egis, the contractor Eiffage Génie Civil and the segment manufacturer Bonna Sabla optimised the original solution of the 9.5 m ring in terms of productivity and quality in order to complete the construction site within SGP's desired schedule. For the MC2010 performance class, the segments use C50/60 concrete reinforced with 40 kg/m3 of Dramix high performance steel fibres. The 0.75 mm thin fibres, with a tensile strength of more than 1800 N/mm2, form a massive network of 11.6 km fibres/m3 concrete. The entire project also saves over 10,000 t of CO2 due to less steel consumption. x | |||||
Hauzinger, Elisabeth; Galler, Robert; Schneider, Daniel; Benedikt, Michael; Ulrici, Luisa; Gutleber, Johannes; Charitos, Panagiotis | CERN Future Circular Collider - The Mining the Future competition / CERN-FCC Future Circular Collider - Der Wettbewerb Mining the Future | Geomechanics and Tunnelling | 6/2022 | 774-782 | Topics |
KurzfassungCERN (Conseil Européen pour la Recherche Nucléaire) is the world's largest research centre for high-energy and particle physics. The research infrastructure contributed to the greatest successes in the field of experimental physics. A new, approximatively 91 km long subsurface infrastructure connected to the existing particle accelerator complex is being conceived in the frame of the Future Circular Collider. It would serve a global community of researchers with two subsequently operated particle colliders until the end of the 21st century. Even at an early stage of such a project, comprehensive investigations have to be carried out into the nature of the subsoil in order to find an optimal utilisation strategy for the excavated material in accordance with the national and international regulations in order to promote the recycling of excavated tunnel material in terms of resource conservation and the improvement of the sustainability of underground construction projects. x | |||||
Starke, Roland | Tunnel excavation material and circular economy in Austria - General requirements, current situation and further developments from the waste management perspective / Tunnelausbruchmaterial und Kreislaufwirtschaft in Österreich - Rahmenbedingungen, Ist-Stand und weitere Entwicklungen aus Sicht der Abfallwirtschaft | Geomechanics and Tunnelling | 6/2022 | 783-791 | Topics |
KurzfassungExcavation material from tunnel constructions, which is generally regarded as waste, has to be disposed of properly, but is good input material for producing recycling aggregates or for on-site reclaiming or recycling action. Due to the large mass and potential contaminations from rock formations and/or tunnelling process, reclaiming or recycling has to be monitored. The waste law provides standardized examination methods and parameters, limit values, quality classes and requirements. In the course of the revision of the Austrian landfill ordinance and the Austrian circular economy strategy by the Federal Ministry Republic of Austria Climate action, environment, energy, mobility, innovation anf technology (BMK), adaptions regarding the promotion of circular economy for this material should be developed. This study provides a description of the technical and legal requirements, actual challenges and an outlook to possible changes of the requirements. x | |||||
Golser, Johann; Friess, Jakob; Luniaczek, Thomas | CO2 reduction in tunnelling from the point of view of construction design and implementation / CO2-Reduktion im Tunnelbau aus der Sicht der Planung und Umsetzung beim Bau | Geomechanics and Tunnelling | 6/2022 | 792-798 | Topics |
KurzfassungTunnel construction is not immune to the climate crisis - here too there is an urgent need to improve the carbon footprint. The production of concrete and consumption of cement cause climate-damaging CO2 emissions. A tunnel with a 10 m diameter, for example, generates around 10 t of CO2 per linear metre. The main priority is thus to reduce the amount of concrete and steel reinforcement used and to select low-carbon cements and binders, as well as employing single-shell construction methods suited to the requirements of the construction project. We need to consider practical approaches to reducing concrete volumes which go beyond structural requirements. CO2 reduction in tunnelling starts with the design and approval process, so financial incentives must be built into award criteria and construction contracts. This article aims to highlight ideas which in future will play an increasingly important role in the design of underground construction works than is currently the case. Although many well-established work practices and design details in underground construction are based on decades of experience and are bound by normative and contractual framework conditions, it is now time to re-examine the facts and consider new ideas that reflect the need to reduce CO2 in concrete construction. x | |||||
Aldrian, Wolfgang; Bantle, Annika; Juhart, Joachim | CO2 reduction in tunnel construction from a material technology point of view / CO2-Reduktion im Tunnelbau aus materialtechnologischer Sicht | Geomechanics and Tunnelling | 6/2022 | 799-810 | Topics |
KurzfassungTunnelling and underground construction is a material-intensive undertaking that involves the use of large quantities of concrete. Analyses of the life-cycle assessment of a new tunnel show that the carbon footprint is largely determined by cement and concrete consumption. Optimising the quantity used, composition and properties of this construction material is thus crucial to reducing ''grey'' emissions - CO2 emissions arising from the construction phase. While strength and durability requirements along with exposure classes are clearly set out in directives and tender specifications, CO2 emissions per cubic metre of concrete are not currently considered a relevant criterion when it comes to project design, award and implementation. And this, despite the fact that the current state of knowledge and research shows that substantially lower-carbon concretes could be used than is generally the case today. A paradigm shift is required to achieve the goal of carbon neutrality in the construction industry. x | |||||
Heissenberger, Roman; Grunicke, Urs H.; Raschendorfer, Jürgen; Holzer, Clemens | Sustainable Tunnelling - An infrastructure operator's, planner's, contractor's and scientist's perspective / Nachhaltigkeit im Tunnelbau - aus Sicht des Betreibers, des Planers, der Bauindustrie und der Wissenschaft | Geomechanics and Tunnelling | 6/2022 | 811-820 | Topics |
KurzfassungSustainability is a guiding principle for political, economic and ecological action, which in companies, societies and countries all over the world, is based on the following three pillars: ecology, economy and social aspects. With the associated worldwide efforts to reduce emissions, this topic has also arrived in the construction industry in general and thus in tunnel construction in particular. In addition to the actual planning, construction, use and maintenance of mined structures, tunnel builders certainly have a special role to play, since the creation of underground structures relieves overground structures and can also change living space for the better. However, the influences and impact must always be considered in the overall context of all three pillars of sustainability - and in our fast-paced times, this requires a considerable change in mindset as well as a clear change and expansion of the assessment standards. The following article draws a current picture of “sustainable tunnelling” on the basis of four sub-sections that describe selected tasks and approaches from the perspective of operators, planners, the construction industry and science as a basis for discussion. x | |||||
Innerhofer sen. ?, Guntram; Greiner, Richard; Innerhofer jun., Guntram; Innerhofer, Gerhard | Pressure shafts of hydro power plants - Bridging a single fissure in the rock mass / Druckschachtpanzerungen - Überbrückung eines Einzelrisses im Felsmantel | Geomechanics and Tunnelling | 6/2022 | 821-841 | Topics |
KurzfassungIn a former paper of the authors a concept for dimensioning pressure shafts, considering the passive resistance of rock-mass, has been developed. The assumption made there was that many cracks are distributed evenly over the circumference. The width of a single fissure was estimated by a reduction factor on the cumulated width of cracks. This question was now investigated analytically on basis of common mechanical principles and was confirmed by FE calculations. On hand of examples a dimensioning concept for bridging a single fissure by the steel lining has been developed. In the annex questions frequently arising over the planning process are discussed. It is intended to facilitate an overall judgement of the individual system by better knowledge of the complex relations. x |