Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Huymajer, Marco; Operta, Dzan; Mazak-Huemer, Alexandra; Huemer, Christian | The Tunneling Information Management System - A tool for documenting the tunneling process in NATM projects | Geomechanics and Tunnelling | 3/2022 | 259-264 | Topics |
KurzfassungThe documentation of the tunneling process is a crucial task of every tunnel construction project. It provides evidence of the work performed and thus, serves as a basis for invoicing and for several further analyses. Therefore, continuous digitalisation of this documentation is essential. For this purpose, we provide a digital Tunneling Information Management System (TIMS), which is a prototypically implemented software tool for replacing the still common paper-based documentation process of tunneling projects using the New Austrian Tunneling Method (NATM). The data model presented here defines the data structures managed by this tool. Based on this, the software architecture and the implementation of TIMS is shown. x | |||||
Paskaleva, Galina; Niedermoser, Christoph; Vierhauser, Michael; Mazak-Huemer, Alexandra; Hruschka, Sabine; Huemer, Christian | Data Drops for Tunnel Information Modelling | Geomechanics and Tunnelling | 3/2022 | 267-271 | Topics |
KurzfassungIn the Architecture, Engineering and Construction (AEC) industry, as well as in the tunnelling domain, inter-company processes between partners in different roles in large-scale construction projects still exhibit great potential towards digitalisation. Thereby, information should be seamlessly shared between partners according to the Building Information Modelling (BIM) paradigm. Today, different types of artefacts (e.g., models, plans, documents, etc.) are shared at different points in time, which differ in terms of requirements, information content, as well as data formats. In this article, we extend and prototypically implement the concept of Data Drops to provide those artefacts in a digitalised form via a shared Data Drop management platform. For this purpose, we have developed a formal, well-defined indexed data structure on a metadata level. This not only facilitates traceability, but also enables searching for specific meta-information and provides a common view on Data Drops. In addition, a networked view between different drops can be provided. The approach is being evaluated on the use case of a real tunnel construction project. x | |||||
Wenighofer, Robert; Eder, Nina; Speckmoser, Valentin; Villeneuve, Marlene; Winkler, Leopold; Galler, Robert | Adaptive and parameterised 3D BIM model for the tunnel tender and excavation phase | Geomechanics and Tunnelling | 3/2022 | 272-278 | Topics |
KurzfassungBuilding information modelling (BIM) is a frequently discussed topic in tunnelling since it promises less loss of information and reduced lifetime cost of underground infrastructure. There is still some way to go as standardisation in this sector is immature, the implementation of three-dimensional (3D) BIM models is developed for pilot cases of tunnelling only, and data transfer between software tools is a challenge. The long linear structures of tunnels make a specific approach of parameterised and adaptive modelling necessary to meet the requirements of repetitive construction elements and the natural differences of forecast and actual excavation conditions. This approach renders the matching of construction elements in the model and service items feasible for determining quantities for the tender and billing in tunnel projects. In this article, we show that only 57 % of service items can actually be linked to a physical item in traditional two-dimensional (2D) design and highlight the need to consider how to incorporate these items into a BIM model. We also use a case study to propose an approach for parameterised and adaptive modelling of repetitive construction elements and show a way of a continuous data transfer from the forecast tunnelling class distribution via 3D BIM modelling to a billing software without data loss. x | |||||
Winkler, Leopold; Melnyk, Oleksandr; Goger, Gerald | Prerequisites for BIM-based invoicing in NATM projects | Geomechanics and Tunnelling | 3/2022 | 279-283 | Topics |
KurzfassungThe successful management of big tunnelling projects requires the complete documentation of technical and financial data as well as their ongoing evaluation. The current study reviews the possibilities for digital documentation of tunnel construction with the subsequent integration of this data with an invoicing software. It suggests an implementation model, a building information modeling (BIM) project element list and a digital on-site data recording tool for a workflow in New Austrian Tunnelling Method (NATM) projects. This digital resource enables central data management that improves and speeds up automated invoicing processes. x | |||||
Exenberger, Hans; Massimo-Kaiser, Ines Maria; Flora, Matthias | Current developments of digital ground modelling in tunnelling | Geomechanics and Tunnelling | 3/2022 | 284-289 | Topics |
KurzfassungThis article analyses and discusses the current state of the art in the development of digital ground models in tunnelling. Following a review and discussion of the literature research combined with interview responses, a deficit analysis was performed. It shows why current projects mainly work with models and software that function as isolated solutions. A lack of software developments and limited collaborative work mean that the effects of current findings cannot immediately be implemented in models. Accordingly, the enormous potential of full coaction can only be imagined. A further problem is the lack of loss-free data exchange across varying project phases and participants. Science is already moving in the right direction with the goal of harmonising the basic systematics. Finally, requirements for a digital ground model are formulated, and in combination with collaborative working and improved communication, these result in a large number of advanced possible applications. x | |||||
Paar, Gerhard; Mett, Michael; Ortner, Thomas; Kup, Daniel; Kontrus, Heiner | High-resolution real-time multipurpose tunnel surface 3D rendering | Geomechanics and Tunnelling | 3/2022 | 290-297 | Topics |
KurzfassungTunnel surveys making use of photogrammetric three-dimensional (3D) tunnel reconstruction reach resolutions in the millimeter range. Classical big data visualization approaches display point clouds only, neglecting this considerable resolution difference between structure and texture. The article suggests a data structure that separates structural and textural resolution by a regular grid on the unwrapped design surface for 3D, combined with a UV mapping technique as regularly used in computer graphics. For real-time rendering of huge multiscale data sets, the result of photogrammetric commercial-off-the-shelf reconstructions is transformed into a proprietary hierarchical data structure. It facilitates to only load currently relevant parts of the tunnel surface from the hard drive, and only upload and render currently adequate levels-of-detail onto the graphics card for seamless exploration of high-resolution geometric and image 3D tunnel data of arbitrary length. The solution allows for smooth interactive analysis and annotation such as crack identification and mapping, inventory, deformation assessment, and dimensional measurements. Aspects of data generation are addressed and information is given about the data structure, showing examples from entire tunnel 3D representations to demonstrate the smooth behaviour of the real-time rendering of huge data volumes in various scales on standard graphics hardware. x | |||||
Rabensteiner, Stefan; Weichenberger, Franz Peter; Chmelina, Klaus | Automation and digitalisation of the geological documentation in tunnelling | Geomechanics and Tunnelling | 3/2022 | 298-304 | Topics |
KurzfassungIn tunnelling, the geological documentation comprises the daily recording and processing of various data for continuously assessing the geological-geotechnical conditions on-site. One of the core tasks is the documentation of the tunnel face area. With Geodata's Tunnel Mapper, a new measuring system is presented enabling a highly automated data acquisition and the processing of a geo-referenced three-dimensional (3D) tunnel face model. Versions of the measuring system for both conventional and mechanised tunnelling have been developed. From the 3D model, high-quality digital products as well as geometric and geological parameters can be derived, which serve as a basis for decisions on-site. The data can then be integrated into the geological information system TUGIS.NET of Geoconsult, merged there with other data and further (geologically) evaluated, analysed and visualised. A spatial model that has been interpreted and quantified by the geologist can be established and used for target/actual comparisons and forecasts. The model can be transferred into building information modeling (BIM)-compatible data structures for integration into an overall BIM model of the project. The further automation and digitalisation of the geological documentation and the full documentation (geometry and geology) of the face area are achieved in the interaction of the systems mentioned. x | |||||
Hofer, Peter; Eder, Julian; Hager, Lukas; Strauß Bakk, Clemens; Jacobs, Sebastian | RApid Data Integration and Visualization (RADIV) in Subsurface Operations | Geomechanics and Tunnelling | 3/2022 | 305-310 | Topics |
KurzfassungComplex subsurface operations are characterized by a life-threatening environment, a skilled and initiative opponent, and the absence of predictability of the events due to a high level of interdependencies. The reduction of complexity by provision of essential information is crucial for decision-making and rapid integration and visualization of heterogeneous data is essential for successful mission accomplishment. Currently, only standalone applications are available for the underground operational environment, and collaborative planning and working spaces in command and control are missing. The RApid Data Integration and Visualization (RADIV) process addresses exactly this challenge and ensures the lateral continuity of visualization systems across the entire reality-virtuality continuum (2D ó 3D ó mixed reality). It provides a comprehensive command and control system for subterranean operations by processing and visualizing data in different views for different purposes. Integration of these data within the Subsurface Operations Mission Tool (SOMT) will increase the decision quality by improved perception and collaboration. Close cooperation and information exchange between operators and action forces is a prerequisite for success by displaying the relevant information within the truly comprehensive common operational picture, thereby enabling more accurate and precise action reducing own losses and collateral damage. x | |||||
Dorninger, Peter; Studnicka, Nikolaus | Efficient digitization of the Zentrum am Berg research tunnel - From laser scan to triangulated surface model within one day | Geomechanics and Tunnelling | 3/2022 | 311-316 | Topics |
KurzfassungUnthinkable just a few years ago, the precise laser-scanning survey of a kilometer-long tunnel in one day by one operator has become possible. This article describes how 261 scans were taken with a RIEGL VZ-400i laser scanner to digitize the Zentrum am Berg (ZaB) research tunnel with millimeter resolution. The data has been automatically registered during the acquisition process within the instrument. After applying multistation adjustment, a block adjustment postprocess step, the high accuracy of the point cloud with respect to a network of 35 retroreflective bireflex targets has been approved. For further applications such as analysis, simulation, or visualization, a homogeneous 3D-meshed surface model has been created automatically from the point cloud representing an as-built 3D documentation of the tunnel. x | |||||
Konstantis, Spyridon; Prountzopoulos, George; Spyridis, Panagiotis | Ensuring face support and control in soft ground urban tunnels: FEM validation | Geomechanics and Tunnelling | 3/2022 | 317-326 | Topics |
KurzfassungWhen designing and constructing a tunnel in an urban setting with the use of a closed face Tunnel Boring Machine (TBM), the objective is to ensure both the tunnel face stability and the control of induced ground deformations within predefined, acceptable limits. Unless the exerted active face pressure will match the in situ ground stresses, there will be ground deformations taking place in the advance core, i.e., face extrusion and pre-convergence, resulting in settlements or heave for active pressure lower or higher than the in situ stresses, respectively. This article presents the validation through finite element method (FEM) of an analytical methodology that can be applied on soft ground urban tunnels to assess the level of active face support to be considered in numerical analysis, to ensure elastic relaxation in the advance core and thus effective ground deformation control. The methodology combines the classic Anagnostou and Kovari method with the Convergence-Confinement method for face support proposed by Aristaghes and Autuori. In the current article, the methodology is described in detail and subsequently validated through three-dimensional FEM analyses. The article concludes with a discussion on the results and the applicability range of the methodology. x | |||||
Vollmann, Goetz; Stepien, Marcel; Riepe, Werner; König, Markus; Lehan, Anne; Thewes, Markus; Wahl, Hendrik | Use of BIM for the optimized operation of road tunnels: Modelling approach, information requirements, and exemplary implementation | Geomechanics and Tunnelling | 2/2022 | 167-174 | Topics |
KurzfassungIn the operating phase of a road tunnel, not only maintaining or increasing the availability in the network but the economic optimization regarding the life cycle costs of the structure are also important priorities. A consistent application of the Building Information Modelling (BIM) methodology can theoretically make a useful and targeted contribution, as it provides a complete digital model of the structure with all installed elements and the information required for the operator tasks. In the research project FE https://doi.org/15.0623/2016/RRB “Building Information Modeling (BIM) in Tunneling, ” the Institute of Tunneling and Construction Management and the Institute of Computing in Engineering (both Ruhr University Bochum) in cooperation with BUNG Ingenieure AG developed the basics for a BIM-based operating model of road tunnels with funding from the Federal Highway Research Institute commissioned by the Federal Ministry of Transport and Digital Infrastructure. In the article, the results of the research are presented on the basis of specific use cases of a BIM-based operation and maintenance management. x | |||||
Jeon, KiSeok; Dalton, Edward; Bakhshi, Mehdi; Nasri, Verya | Use of BIM technology for optimization and virtual build of TBM tunnels | Geomechanics and Tunnelling | 2/2022 | 175-181 | Topics |
KurzfassungThe practical application of accurate design and coordination in Building Information Modeling (BIM) environment for precast rings in Tunnel Boring Machine (TBM)-bored tunnels is becoming more achievable. These rings, made up of individual segments, are subject to many constraints which include: 1) deviations from theoretical alignment, as modeling the straight centerline of a ring into a curved alignment naturally produces minor deviations in line and grade, 2) avoiding crucifix joints when the joints between segments align in the longitudinal direction, reducing sealing performance, 3) and TBM shield design by minimizing the diameter of the TBM to reduce overcut and required backfill. This article describes the automated procedures for developing our design intent in the BIM environment with consideration for ring length optimization in tunnel curves, geometrical analyses of the staggered pattern of joints, and the minimum diameter and overcut envelope of the TBM shield. This procedure is demonstrated in multiple light-rail transit lines in Montréal including the Réseau Express Métropolitain (REM) airport link tunnel and the expansion of the Montreal Blue Line Metro. Virtual build of these segmentally lined tunnels negotiating all straight and curved drives of the alignment with BIM modeling is realized and summarized in this article. x | |||||
Chiu, Jessica Ka Yi; Hansen, Tom F.; Wetlesen, Thorvald | Norwegian tunnel excavation: Increasing digitalisation in all operations | Geomechanics and Tunnelling | 2/2022 | 182-189 | Topics |
KurzfassungIn the past decades, Norwegian tunnelling has undertaken a major digital development in all operations from planning to the excavation phase. The breakthrough is driven by digital contract requirements from forward-leaning clients and innovative industrial stakeholders, aiming for ever more efficient, quality-oriented and risk-reducing operations. A formal milestone documenting this development was the publication of Digitalisation in Norwegian Tunnelling in 2019. From 2019, most contracts of new infrastructure tunnels must deliver a level 3 Building Information Modeling (BIM) model. Control systems for drilling jumbos are fully digitalised. All drilling must be monitored and documented with Measurement While Drilling techniques. Via cloud servers, the drilling information is interpreted and delivered live to face engineers for decision support. Sensors are used to monitor rock grouting flow and pressure in each drill hole. Digital electronic detonators with exact delay time are used for blasting. Geotechnical mapping is carried out on field tablets. High-resolution scans with RGB imaging must be carried out on the exposed rock surface and after rock support/linings. The next step is to utilise all the collected data to a higher degree by advanced analysis with machine learning (ML) and similar techniques for automation and optimisation. This study reviews and exemplifies the digital focus and achievements in core operations in Norwegian tunnel excavation. x | |||||
Großauer, Karl; Huis, Melanija; Jedlitschka, Gernot; Matt, Robert; Mulitzer, Günther; Zwittnig, Gerald | New built and refurbished railway tunnels: Data delivery from BIM Models to OEBB's asset management | Geomechanics and Tunnelling | 2/2022 | 190-200 | Topics |
KurzfassungDigitalisation in the construction industry has been progressing continuously and bringing major changes for everyone involved in virtually all areas. Austrian Federal Railways ÖBB has been pushing BIM (Building Information Modelling) for the construction and rehabilitation of their infrastructure. By means of various pilot projects, the basics and the processes required for design and construction are developed and applied with a strong focus on system operation. For Granitztal tunnel and a total length of ≈6.1 km, the as-built design of the civil structures is done with an element-based, open BIM model. As part of the handover to the maintenance and operation division, the data of civil structures relevant for operation are derived from the BIM model, validated by means of automatic methods and transferred to the facility management system (AVS, Anlagen-Verzeichnis-System). In the absence of an IFC (Industry Foundation Class) structure tunnel, a semantic and spatial data structure is developed. Furthermore, the model will be enriched with components of railway equipment. On the other hand, there is the over-100-year-old Karawanks tunnel as part of the railway section between Villach and Jesenice. The line has been in operation since 1906 and includes the ≈8 km-long, single-tube Karawanks tunnel. The current situation of the tunnel including the superstructure and technical equipment no longer meets performance, safety and durability requirements and is being rehabilitated within an international cooperation project between Austria and Slovenia. The focus in this BIM project is set on the as-built design and merging data of the existing historic tunnel structure with information of new components implemented during refurbishment. A core task is the structured transfer of data contained in the BIM model to the facility/asset management system of ÖBB (AVS) and the Slovenian infrastructure operator. The case histories of Granitztal tunnel and Karawanks tunnel are used to describe the implementation of BIM, including the development of required data structures, validation mechanisms and data delivery to the asset management. x | |||||
Magursi, Leonardo; Zurlo, Raffaele; Sorbello, Rosario | Dynamic evaluation of the top-down construction of the Belfiore high-speed railway station | Geomechanics and Tunnelling | 2/2022 | 201-206 | Topics |
KurzfassungThe construction phase of underground railway stations executed with top-down method is often susceptible to a considerable number of interferences. The interference between the excavation of the Florence high-speed station and tunnels' execution is a critical element of the Florence underpass project, which foresees the simultaneous construction of the two infrastructures. The project's complexities and the interference between the various construction phases have been studied and resolved by developing the entire project in a Building Information Modeling (BIM) environment. In particular, the implemented four-dimensional (4D) BIM model managed to simulate the possible macrophases and identify an optimal construction solution or, at least, the crucial actions to be taken to ensure the simultaneous construction of the station and tunnels. The 4D BIM model allowed an accurate simulation of the specific critical construction phases by identifying spatial interferences between completed works, temporary structures, and overlapping interventions. Consequently, it was possible to adopt appropriate technical solutions and develop a reliable work plan. In addition, it was possible to verify the potential scenarios of the TBM passage through the excavated station, which allowed to foresee some specific interventions needed to ensure works' continuity. The BIM methodology also allowed to find optimal solutions in a reasonable time, preventing a significant use of resources. x | |||||
Sabanovic, Nedzad; Wannenmacher, Helmut; Stauch, Felix; Fentzloff, Wolfgang | Demands on digital data capturing of TBM and conventional tunnel drives | Geomechanics and Tunnelling | 2/2022 | 207-214 | Topics |
KurzfassungTunnels are significant in shaping our future infrastructure. Increasing limitations of the available ground require underground solutions for future infrastructure projects. Due to various reasons, boundary conditions for project realization are becoming more and more substantial, and the parties involved have to tackle a wide range of stakeholders' interests. Digitization may be able to handle some of these challenges and is one of the most relevant topics in the near future of the construction industry. First approaches of digital data capturing in different activity fields of project execution, such as geological and geotechnical conditions, survey, and reporting, are launched within Implenia's initiative. This article discusses essential aspects of data capturing, particularly in the light of the vast data volumes generated throughout tunnel construction in Europe and gives an insight into the various activities of Implenia on how to tackle these problems. The various TBM and drill-and-blast excavated tunnel projects illustrate the variability of data management and implemented solutions to work with the tremendous amount of data. In each case, one can clearly state that construction teams involved in digital data management highly appreciated the merits for their daily business: saving time, gaining transparent information, controlling processes, and more. The beneficial capability of appropriate data management in project execution is evident and will be carried out within Implenia's projects. x | |||||
Erharter, Georg H.; Weil, Jonas; Tschuchnigg, Franz; Marcher, Thomas | Potential applications of machine learning for BIM in tunnelling | Geomechanics and Tunnelling | 2/2022 | 216-221 | Topics |
KurzfassungMachine Learning (ML) and Building Information Modelling (BIM) are two topics that are part of a revolutionizing transformation in the construction industry - commonly referred to as digitalization. Being part of the research for artificial intelligence (AI), most of today's ML applications deal with computational processes that try to make sense of data. Automatic rockmass behaviour classification based on tunnel boring machine (TBM) data or tunnel construction site surveillance via closed-circuit television (CCTV) analysis is an example for applications of ML in tunnelling. BIM describes a new type of planning, including model-based collaboration and information exchange, which requires well-organized storage and handling of data - a precondition and valuable source for any automated analysis method like ML. While other sectors of the construction industry have implemented BIM systems successfully, the development in underground engineering is currently at its beginning with multiple actors working towards common standards for semantics, data exchange formats, etc. This article seeks to combine the two fields by giving an overview of the two topics and then points out four potential fields of applications: semantic enrichment and labelling, automation of technical processes, knowledge derivation and online data analysis. x | |||||
Hansen, Tom F.; Erharter, Georg H.; Marcher, Thomas; Liu, Zhongqiang; Tørresen, Jim | Improving face decisions in tunnelling by machine learning-based MWD analysis | Geomechanics and Tunnelling | 2/2022 | 222-231 | Topics |
KurzfassungIn Norwegian drill and blast tunnelling, contracts stipulate collecting Measurement While Drilling (MWD) data from all drillholes. The MWD approach is an objective way of collecting, processing and visualising advance drilling data that have been successfully used in making face decisions for many years in Norwegian tunnelling. MWD data collection consists of equipping drill rigs with sensors recording different drilling parameters, with subsequent near real-time data processing for access by on-site personnel and face engineers in decision-making process. A deficiency in the MWD approach is still the subjective data interpretation necessary to translate visualised data into actual face decisions. Digital scepticism and a lack of digital knowledge are other obstacles in automating the process from data interpretation to decisions. Thus, MWD data are sometimes only used for nice visualisations and as-built documentation. This study proposes machine learning (ML)-based methods to characterise the rock mass from sensor data using data from five twin-tube tunnels in a Norwegian highway project. Results show that the deep learning-based method - convolutional neural network - is capable of translating complex patterns in MWD data to functional rock mass characterisation, thereby aiding face engineers with data analysis. The study is, to our knowledge, the first known attempt to use deep learning-based computer vision techniques to interpret MWD data framed as images. x | |||||
Dolsak, Wolfgang; Reich, Christian | Virtual reality simulator for pipe umbrella installation works | Geomechanics and Tunnelling | 2/2022 | 233-238 | Topics |
KurzfassungThe installation of pipe umbrella systems is a complex process that requires well-trained machine operators and installation crews. Due to project and time constraints, adequate operator training in a safe environment without risk of personnel accidents or machine damage often falls victim to cost cuts. Previously, this shortcoming has been compensated by the deployment of selected expert personnel to respective tunnel projects for a certain period. This practice is, however, limited to availability of expert personnel and associated with high travel costs and significant waiting time on-site. Virtual reality (VR) simulator-based trainings have become state-of-the-art in underground construction. They provide enhanced occupational safety by conducting virtual training before commencing works in the tunnel, increased operator performance, and improved installation cycle times. In addition to basic training, the VR simulator can be used for assembly and commissioning, maintenance, as well as refresher trainings and ongoing just-in-time support. Around mid-2019, DSI Underground initiated the development of a realistic and authentic scenario-based VR simulator for the AT - Pipe Umbrella System. This training tool also includes extensive theory background supported by a series of video modules illustrating best underground work practices. This article illustrates the background and development plan of the VR simulator and the implementation based on use cases. x | |||||
Zosseder, Kai; Pfrang, Daniela; Schölderle, Felix; Bohnsack, Daniel; Konrad, Florian | Characterisation of the Upper Jurassic geothermal reservoir in the South German Molasse Basin as basis for a potential assessment to foster the geothermal installation development - Results from the joint research project Geothermal Alliance Bavaria | Geomechanics and Tunnelling | 1/2022 | 17-24 | Topics |
KurzfassungGeothermal energy applications are seen as one key element for a successful heat transition in Bavaria. But there are still some barriers for a further development. To minimize these barriers the joint research project Geothermal Alliance Bavaria (GAB) is established. One important issue to foster the implementations of geothermal projects is the assessment of geothermal load prediction in the South German Molasse Basin (SGMB). This includes, aside from a reservoir temperature prognosis, an accurate description of the hydraulic properties of the Upper Jurassic Malm reservoir. Hydraulic test analyses are conducted in the framework of the GAB to obtain specific information about the hydraulic productivity of the reservoir. Results from these analyses show a decrease of rock permeability in southern direction within the reservoir. Because the spatial distribution of hydraulic test data is limited, the porosity of the reservoir is assessed by borehole core tests and logs interpretation. A trend of matrix porosity decrease with depth is recognised and correlates with the hydraulic test results. Based on these findings and combined with further information the Upper Jurassic reservoir could be classified in separated zones of similar production rates, which can now be used for a thermal output prognosis for the Bavarian part of the SGMB. To spatially expand these prognoses more data must be investigated in the next research phase of the GAB. x | |||||
Potten, Martin; Bohnsack, Daniel; Käsling, Heiko; Thuro, Kurosch | Geomechanical reservoir characterisation in Bavaria within the framework of the Geothermal-Alliance Bavaria / Geomechanische Reservoircharakterisierung in Bayern im Rahmen der Geothermie-Allianz Bayern | Geomechanics and Tunnelling | 1/2022 | 27-36 | Topics |
KurzfassungTo increase the use of geothermal energy in Bavaria, the subsurface, which serves as a reservoir, must be explored as precisely as possible. In the projects of the Geothermal-Alliance Bavaria, the most promising areas for geothermal exploration in Bavaria were characterised based on an extensive geomechanical laboratory testing program which was carried out on both drill cores and analogue samples from quarries. In the North Alpine Foreland Basin (SE Germany), the geomechanical test results on Upper Jurassic carbonate rocks show a high heterogeneity. On the contrary, in the Franconian Basin (NE Bavaria) the geomechanical properties of granite analogues are rather homogenous. For the numerical simulation of the borehole stability, the determined parameters from ultrasonic- and compression tests serve as input parameters for different scenarios. For both locations, the determination of the failure depth around the borehole and the stress distribution in the near-field of the borehole were accomplished. In the North Alpine Foreland Basin, the borehole stability decreases with increasing depth. For all scenarios in NE Bavaria, the borehole stability is very low. In the future, the determined parameter ranges will allow to validate already existing models and to develop new ones. This will enable a better knowledge of the sedimentary and crystalline reservoirs and a more effective use of geothermal energy in Bavaria. x | |||||
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 |
KurzfassungIn 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 |
KurzfassungBased 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 |
KurzfassungAs 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 |
KurzfassungThe 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 |