Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Richter, Wolfgang; Vereide, Kaspar; Zenz, Gerald | Upgrading of a Norwegian pressurized sand trap combined with an open air surge tank | Geomechanics and Tunnelling | 5/2017 | 620-624 | Topics |
KurzfassungIn 1988 the Tonstad power plant (Norway) was upgraded from 640 to 960 MW. The headrace system to the reservoirs was not upgraded except for an additional pressure shaft, surge tank and an additional sand trap. Even with about 50 % higher discharge in the main tunnel, the sand traps worked adequately after the commissioning. However, in recent years, higher flexibility of demand is challenging the power plant and has resulted in events with flushing of sediments to the turbines. Higher flexibility demands also challenge the current surge tank design. During one event, free surface flow is believed to have occurred in the sand trap since severe damage to two of the turbines was observed. This contribution presents the background of the power system situation at the Tonstad power plant and the current flexibility demands of the power market and its challenges for the hydraulic system, as well as the proposals to solve the sand trap issues and the oscillation demands for the surge tank. The paper discusses the possibility of utilizing a model predictive controller with real-time flow simulations to solve the challenges without structural reconstruction, and possible options should structural reconstruction be necessary. The contribution compares analysed options for improving the efficiency of sand traps. Finally, an outlook is offered to future demands for flexibility in hydropower plants with increasing supply of renewable power sources. x | |||||
Schubert, Wulf; Blümel, Manfred; Staudacher, Robert; Brunnegger, Stefan | Support aspects of tunnels in fault zones / Aspekte des Ausbaus von Tunneln in Störungszonen | Geomechanics and Tunnelling | 4/2017 | 342-352 | Topics |
KurzfassungSpecial considerations are required for the support of tunnels in fault zones. On the one hand, standard support elements are not compatible with the imposed displacements. On the other hand, local shearing can cause damage to the lining already at rather small displacements magnitudes. Cracks in the lining frequently are observed, when the geometry of the tunnel changes, or at the intersection with cross passages. As strengthening of the lining in many cases cannot prevent damage, temporarily leaving an open gap in the primary lining. Implementing yielding elements into the lining is as well feasible, as economical increasingly replaces the traditional method of leaving open gaps. This results in a better utilization of the lining's capacity and a considerable reduction of displacements. As the lining with integrated yielding elements develops considerable thrust, a transfer of the loads via the construction joints is required. Thus, careful construction of those joints is essential. Another problem can be the bond between bolt, grout, and rock mass, as the bolts are installed, when the displacement rate is highest, and the strength of the grout still low. This paper deals only with phenomena caused by discontinuities and large displacements, and does not address other hazards, like flowing ground. x | |||||
Brandtner, Markus; Lenz, Gerold | Checking the system behaviour using a numerical model / Überprüfung des Systemverhaltens anhand eines numerischen Modells | Geomechanics and Tunnelling | 4/2017 | 353-365 | Topics |
KurzfassungThe Semmering Base Tunnel with a total length of approx. 27 km is being driven through a complex system of fault zones. During the investigation period, technically demanding site investigations were carried out to obtain information on geological and hydrological conditions including the determination of the strength and stiffness of the faulted zones. The results formed the basis for the geotechnical design, performed according to the Guideline for the Geotechnical Design of Underground Structures with Conventional Excavation published by the Austrian Society for Geomechanics. According to the regulations, the system behaviour must already be tested against the designed support measures during the design stage. In this case the behaviour was assessed using a complex 3D Finite Element model. The expected and therefore predicted system behaviour represents the baseline for the observational method. x | |||||
Lenz, Gerold; Kluckner, Alexander; Holzer, Robert; Stadlmann, Thomas; Schachinger, Tobias; Gobiet, Gerhard | Prediction of fault zones based on geological and geotechnical observations during tunnel construction / Prognose von Störungszonen auf Basis geologisch-geotechnischer Beobachtungen im Vortrieb | Geomechanics and Tunnelling | 4/2017 | 366-379 | Topics |
KurzfassungDuring the construction of the Semmering Base Tunnel, Lot SBT1.1, the drives have already encountered several fault zones in the Greywacke Zone. Because of the high overburden, the exact position of these fault zones is unknown at tunnel level; a common problem for all tunnelling projects in mountainous regions. Simple exploration drilling techniques such as percussion drillings, where only cuttings and not cores are won, do not always provide enough information to precisely specify the position of the fault zones or their nature ahead of the face. This is reason enough to examine other possibilities for the short-term prediction of fault zones with differing characteristics ahead of the face. Usually displacement data evaluation provides the basis for a short-term prediction of the system behaviour. However, experiences from Lot SBT1.1 show that applying this approach solely does not always yield satisfying results. A further systematic analysis of selected geological data can improve the short-term prediction. In particular, changes of discontinuity and rock mass characteristics mapped at the tunnel face are analysed to spot significant trends indicating fault zones ahead of the face. These trends are then related to and verified by the results of displacement data evaluation. This combination of rock mass characteristics mapped at the face and state-of-the-art evaluation of displacement data has helped to improve the reliability of short-term predictions during the tunnel excavation. x | |||||
Schmidt, Markus; Richter, Thomas; Lehmann, Paul | Innovative geophysical technologies for the exploration of faults, karst structures and cavities in tunnelling / Innovative Geophysik-Technologien zur Störungs-, Karst- und Hohlraumerkundung im Tunnelbau | Geomechanics and Tunnelling | 4/2017 | 380-394 | Topics |
KurzfassungIn rock formations prone to karstification, there are no or only limited geological/hydrological principles that enable safe prognosis of the existence and location of karst and fault structures. The application of geophysical methods offers a high efficiency of detection and localisation of faults, cavities and karst structures, and when combined with targeted verification drillings, provides an extensive three-dimensional structural investigation of rock formations. Four examples of geophysical karst and fault investigations in German tunnelling are presented here to demonstrate the innovative technologies and their respective survey results that in all cases contributed to a safe excavation process and later operation of the tunnels. x | |||||
Leitner, Andreas; Herzfeld, Thomas; Nebois, Christian; Schreitl, Bernhard; Wageneder, Johannes | The new line crossing U2/U5 of the Vienna subway / Das neue Linienkreuz U2/U5 der Wiener U-Bahn | Geomechanics and Tunnelling | 4/2017 | 395-405 | Topics |
KurzfassungVienna is not only a growing city but also one with a high quality of life. One reason for this is the availability of good public transport services, the heart of which is the subway system, which has been steadily extended for 40 years. In order to relieve Line U6 and provide better conditions for changing trains, an underground route will be constructed for Line 2 in the next few years through the densely built-up 19th century part of the city starting from Rathaus station and running to Matzleinsdorfer Platz. Most of the running tunnels will be bored with an EPB machine while the station tunnels, crossovers and cross passages will be excavated conventionally using the New Austrian Tunnelling Method. Most of the tunnels pass through Miocene silt. In addition, a section with driverless operation and platform doors is planned for the construction of the U5 in order to gain experience for future extensions. x | |||||
Kister, Bernd; Rubin, Karl-Heinz | Block rotation on impact - A factor to be considered in the design of rockfall protection embankments / Die Blockrotation beim Impakt - Eine zu berücksichtigende Größe bei der Konstruktion von Steinschlagschutzdämmen | Geomechanics and Tunnelling | 4/2017 | 406-420 | Topics |
KurzfassungIn the course of several research projects carried out at the Lucerne University of Applied Sciences and Arts, the effect of block rotation on impact on protection embankments has been investigated. The occasion for these experimental studies was the conflicting statements in the literature about the influence of block rotation on impact and the different and mostly very simple models for the design and sizing of such structures. Considering this, both small-scale quasi-2D tests and half-scale 3D tests were performed and evaluated. The test results show that block rotation, which has until now been neglected in the design and sizing of rockfall protection embankments, is actually of great significance. Three rules for the geometry of such structures could be derived from the test results. x | |||||
Bufalini, Maurizio; Dati, Gianluca; Rocca, Manuela; Scevaroli, Riccardo | The Mont Cenis Base Tunnel | Geomechanics and Tunnelling | 3/2017 | 246-255 | Topics |
KurzfassungThe New Lyon-Turin Line (NLTL) is an essential component of the “Mediterranean Corridor”, one of the nine TEN-T network corridors, the future “European metropolitan railway” that will promote the movement of people and goods by rail, an ecological mode of transport. The goal is to reduce road transport, which increases pollution and greenhouse gas emissions. The core element of the new line is the 57.5 km Mont Cenis Base Tunnel. The reference geological model is based on the data obtained during the excavation of the inclined access adits at Saint-Martin-La-Porte, La Praz and Modane, including the La Maddalena exploratory tunnel. With the planned investigations completed, all the collected data will allow a technical and economical optimization of the construction phase and operation and maintenance of the line. The impact on water resources is minimized by using a full-round waterproofing system up to a hydrostatic pressure of 10 bar. The expected residual water flows at the portals will be exploited for both drinking water and heating purposes. With 12 % of the tunnels already excavated, there are currently 800 people working on the NLTL. This unique project, with its extraordinary history and innovative features, has been proposed as the subject of an international case study. x | |||||
Gamba, Francesco; Brino, Lorenzo; Triclot, Jacques; Hugot, Elsa; Barla, Giovanni; Martinotti, Giorgio | A TBM assembly cavern in the French Alps | Geomechanics and Tunnelling | 3/2017 | 256-264 | Topics |
KurzfassungThis paper deals with the cross-border section of the Lyon-Turin Line, i.e. the 57.5 km long Mont Cenis Base Tunnel between Saint Jean de Maurienne in France and the Susa valley in Italy. Works at Saint Martin La Porte started in 2015 including the 9 km TBM excavation along the south tube of the base tunnel between the access adits of Saint Martin La Porte and La Praz. In order to assemble the TBM, a large underground cavern has been excavated at the end of the Saint Martin La Porte access adit. The size of this cavern, with a length of approximately 45 m, a span of 23 m and a height of 22.2 m, and the geological and geomechanical conditions in the Carboniferous Formation at a depth of about 600 m made this work a challenge. The excavation and support methods adopted are described, together with the rock mass conditions and the observed ground behaviour. The monitoring data obtained during excavation are briefly presented, including the works schedule. x | |||||
Parisi, Maria Elena; Brino, Lorenzo; Gilli, Piergiuseppe; Fornari, Enrico; Martinotti, Giorgio; Lo Russo, Stefano | La Maddalena exploratory tunnel | Geomechanics and Tunnelling | 3/2017 | 265-274 | Topics |
KurzfassungThe Lyon-Turin high-speed rail project includes a 57.5 km long twin-tube base tunnel. The design uses data collected from four exploratory tunnels, three in France, completed in 2010, and one in Italy, named “La Maddalena”. Excavation of this 7 km long Italian exploration tunnel was completed in February 2017 using a 6.3 m diameter main beam TBM under exceptionally high overburden of more than 2,000 m under the Ambin mountain slopes, where mild rockbursts were systematically experienced along nearly half of the alignment. The TBM excavated through gneiss and mica schists. Intercepted water inflows were lower than expected in the design phase, with temperature and chemical composition giving useful information. This exploration tunnel is the subject of the present paper. x | |||||
Skuk, Stefan; Schierl, Heimo | Brenner Base Tunnel: First results of the exploratory tunnels from a geological and geomechanical point of view - Case studies of four fault zones | Geomechanics and Tunnelling | 3/2017 | 275-290 | Topics |
KurzfassungThe Brenner Base Tunnel (BBT) is a straight, flat railway tunnel between Austria and Italy. It runs from Innsbruck to Fortezza (55 km), crossing the main Alpine crest with an overburden up to 1.7 km. Including the connection to the line around Innsbruck, which has already been built and which is the endpoint for the BBT, the total length of the tunnel will be about 64 km. Once finished, the BBT will be the longest underground rail link in the world. A peculiar feature of the BBT is the exploratory tunnel running from one end to the other. This tunnel lies between the two main tunnels and about 12 m below them and is noticeably smaller than the main tubes. So far, a total of 60 km of tunnels have already been excavated in Austria and Italy (access tunnels, exploratory tunnel, main tubes and chambers), driven both by blasting and by TBM. Crossing fault zones is a geological and geomechanical challenge, both for TBM and conventional excavation methods. The Periadriatic fault zone, with a total length of 1 km, has already been driven through. This first step of the project provides an interesting look at the comparison of the predicted rock mass conditions with those that were actually encountered, the rock mass behaviour in fault zones and investigation measures ahead of the tunnel face. x | |||||
Gobiet, Gerhard; Nipitsch, Gernot; Wagner, Oliver K. | The Semmering Base Tunnel - Special challenges in construction / Der Semmering Basistunnel - Besondere Herausforderungen beim Bau | Geomechanics and Tunnelling | 3/2017 | 291-297 | Topics |
KurzfassungThe Semmering Base Tunnel (SBT) is about 27.3 km long and is being driven from the portal at Gloggnitz and from three intermediate construction accesses in Göstritz, Fröschnitzgraben and Grautschenhof. The main components of the tunnel system are the two single-track running tunnels, cross passages at a maximum spacing of 500 m and an emergency station in the middle tunnel section, with two shafts about 400 m deep for ventilation and extraction in case of an incident. For organisational, scheduling and topographical reasons, the tunnel is divided into three construction contracts. The eastern contract section SBT1.1 “Tunnel Gloggnitz” has been under construction since mid 2015. Construction started on contract section SBT2.1 “Tunnel Fröschnitzgraben” at the start of 2014. The western contract section SBT3.1 “Tunnel Grautschenhof” has been under construction since May 2016. x | |||||
Amvrazis, Seraphim; Voit, Klaus; Cordes, Tobias; Bergmeister, Konrad | Drill and blast excavation forecasting using 3D laser scanning / Ausbruchprognose beim Sprengvortrieb mittels 3D-Laserscanning | Geomechanics and Tunnelling | 3/2017 | 298-316 | Topics |
KurzfassungThe application of 3D laser scanning technology in tunnelling has gained increasing significance in recent years. Laser scanning is an innovative holistic approach for data acquisition in tunnelling regarding the geometrical parameters. It is a distance-based imaging technique for three-dimensional and high-resolution illustration (3D point cloud) of the surrounding rock that can be applied at various times to provide a variety of visualization and analysis possibilities. A new approach deals with excavation forecasting by linking the acquisition of the 3D geometry of previously excavated rounds with the geological documentation of the tunnel face. This approach enables the gathering of information about the expected overbreak or underprofile of subsequent excavation in similar rock conditions. Using this information, an optimization of the borehole positions (especially of the peripheral boreholes) can achieve the best possible excavation profile. This approach offers an improvement of excavation performance and saving potential with regard to excavation quantity and shotcrete consumption. The uniform excavation shape and consistent shotcrete thickness improve tunnel stability and finally increases the service life the tunnel structure. x | |||||
Schubert, Peter; Joham, Kurt; Bauer, Manfred | Optimisation of the TBM drive at the Boßler Tunnel using the observation method and an incremental design and contract development process / Optimierung der TVM-Fahrt am Boßlertunnel durch Anwendung der Beobachtungsmethode und eines inkrementellen Planungs- und Vertragsentwicklungsprozesses | Geomechanics and Tunnelling | 2/2017 | 123-134 | Topics |
KurzfassungThe 8.8 km long Boßler Tunnel was tendered in 2012 as a NATM tunnel, although a variant with a tunnel boring machine (TBM) was permitted for the first 2,800 m of the tunnel from the north side. The joint venture Tunnel Albaufstieg ATA won the contract in a negotiation process with the variant TBM for the first 2,800 m. Out of the conviction that a large part of the Boßler Tunnel should be feasible for a TBM, the ATA made an optimisation proposal, according to which extensive additional investigation should be undertaken in the preceding NATM tunnel and to demonstrate the feasibility of extended TBM operation. This concept was successively implemented, with a 55 m deep investigation shaft being sunk and a 20 m long investigation tunnel excavated. The investigations brought the hoped-for improved estimation of the rock mass behaviour and finally convinced all those responsible for the project (client and the contractor) that a TBM drive along the entire length of the tunnel was feasible. This procedure demanded extreme flexibility from all parties involved since the design work mostly had to be undertaken at the last minute. x | |||||
Voringer, Jürgen; Zenz, Reinhard; Meyer, Anna-Maria; Strauss, Armin; Hofmann, Arno | Experience with the TBM drive through clay rocks with low strength in the Boßler Tunnel / Erfahrungen mit der TVM-Fahrt durch Tongesteine mit geringen Festigkeiten im Boßlertunnel | Geomechanics and Tunnelling | 2/2017 | 135-144 | Topics |
KurzfassungThe Tunnel Albaufstieg consortium won the contract with an alternative proposal to drive a section about 2.8 km long of the 8.8 km long Boßler Tunnel with a tunnel boring machine (TBM). The next section, where squeezing conditions were forecast, was to be tunnelled by the shotcrete method according to the tender documents. Manifold and extensive additional investigations delivered the basis for the extension of the TBM drive along the entire length of the Boßler Tunnels. The driving of the section through the Aalenian 1 geology was problem free due to the low strengths and good cuttability of the rock mass combined with its impermeability. The next section in the intercalation of claystone and sandstone of the Aalenian 2 was much more differentiated but managable. The breakthrough of the east bore of the Boßler Tunnel confirms to the responsible people for the client and contractor that the decision to follow the aim of consistent mechanised tunnelling had been correct. x | |||||
Goldberger, Harald; Esslinger, Christoph; Lützerath, Thomas; Müller, Jörg Rainer; Galli, Mario | Why were 800 m of the Boßler Tunnel built twice? - TBM passing a shotcrete section / Warum wurde der Boßlertunnel auf 800 m zweimal gebaut? - Durchfahrt einer TVM durch eine Spritzbetonstrecke | Geomechanics and Tunnelling | 2/2017 | 145-159 | Topics |
KurzfassungImpermeable tunnels are usually built conventionally with drill and blast or excavators followed by an inner lining or by mechanized tunnelling method with a segment lining. A combination of both methods on certain sections is commonly used for large tunnels due to geological and geotechnical considerations. The construction of the same section with both methods is not common and seems bizarre. x | |||||
Atzl, Georg; Soranzo, Enrico; Mihaylov, Vladislav; Hochgatterer, Bernhard | Special segments at the cross passages in the Filder Tunnel - Interpretation of the data from monitoring segments / Sondertübbinge im Bereich der Verbindungsbauwerke im Fildertunnel - Interpretation der Messergebnisse der Messtübbinge | Geomechanics and Tunnelling | 2/2017 | 160-176 | Topics |
KurzfassungThe 9, 468 m long twin-bored Fildertunnel is the longest railway tunnel of the Stuttgart 21 project. The maximum overburden is approximately 220 m, the tunnel tubes lie up to 60 m below the water table and the distance between the cross-passages is approximately 500 m. The precast concrete segments for the mechanised excavation of the Fildertunnel are equipped with measuring devices in proximity of the cross-passages to assess the lining strains prior to the construction of the cross-passages and to serve as a basis for the further design. The lining stresses are derived by applying an appropriate calculation method, which transforms the measured strains into material stresses, hence achieving the active load configuration. The strains measured on the outside and inside of the lining with embedded vibrating wire strain gauges are converted into stresses and internal forces, enabling a direct assessment of the internal forces along the entire circumference of the segmental lining. In this article the measurement results in the area of the cross passages 6a and 7a of the Fildertunnel are described and interpreted. The significant internal forces in the segments after their installation and their time development are described, their dependence on influence factors such as self-weight, thrust forces, grout pressure, rock mass and water pressure is discussed and the results are compared to the design calculation. x | |||||
Zimmerer, Martin; Wenger, Philipp; Lienhart, Christoph; Heer, Sebastian | Design and construction of the new railway bridge over the River Neckar - Challenges of the foundations / Planung und Bau der neuen Eisenbahnbrücke über den Neckar - Herausforderungen bei der Gründung | Geomechanics and Tunnelling | 2/2017 | 177-192 | Topics |
KurzfassungAs part of the Stuttgart 21 infrastructure project, German Railways is building a four-line railway bridge across the River Neckar in Stuttgart, work started in 2016. x | |||||
Vardijan, Tomas; Pradel, Michael | The technical solution for working beneath the protected DB directorate building on the major Stuttgart 21 project / Darstellung der technischen Lösung zur Unterfahrung der denkmalgeschützten DB Direktion im Großprojekt Stuttgart 21 | Geomechanics and Tunnelling | 2/2017 | 194-203 | Topics |
KurzfassungBuilt in 1914, the listed Reichsbahn directorate building was formerly used as an administrative building by Deutsche Bahn AG in Stuttgart. The Stuttgart 21 Project requires new tracks from the Feuerbach and Bad Cannstatt Tunnels to be built, which branch off from 4 to 8 tracks in the area beneath the DB directorate. Complete demolition of the directorate building was not possible due to the objection of the listed monument authorities, the city administration, the municipal council of architects and the former building owner Vivico. In view of this the preservation of the main building was specified in the planning decision of 28/01/2005. x | |||||
Wittke, Walter; Wittke, Martin; Erichsen, Claus; Wittke-Schmitt, Bettina; Wittke-Gattermann, Patricia; Schmitt, Dieter | AJRM as basis for design and construction of more than 70 km of tunnels of the Railway Project Stuttgart-Ulm | Geomechanics and Tunnelling | 2/2017 | 204-211 | Topics |
KurzfassungThe tunnels of the railway project Stuttgart-Ulm are located in sedimentary rock of the Keuper Formation, the Black Jurassic, the Brown Jurassic and the White Jurassic formation. The two longest tunnels are excavated by tunnel boring machine over most of their length. The remaining tunnels, which the authors are involved in, are excavated by conventional tunnelling. All tunnels are designed on the basis of the AJRM-method. This method is based on an anisotropic, elasto-viscoplastic model for jointed rock and corresponding FE-software, which has been extended to seepage and swelling. The method has been applied to practical projects for the last 40 years. By means of rock mechanical test programs and back-analyses of projects in a variety of rocks, the reliability of the predictions is quite high and the application leads to safe and economic solutions. x | |||||
Sellmeier, Bettina; Thuro, Kurosch | Comparison of two 3D rockfall codes on behalf of a case study in the Bavarian Alps | Geomechanics and Tunnelling | 1/2017 | 15-23 | Topics |
KurzfassungRockfall events along main traffic routes in alpine regions emphasize the necessity of enhancing hazard assessment, especially in terms of rockfalls. In the field of regional rockfall modelling it becomes more and more important to work with 3D rockfall codes to account for morphological structures. Due to the general scale of regional rockfall modelling it is in most cases not possible to collect quantitative field data. Thus the input parameters are determined according to disposition models like in the Bavarian hazard map. The current paper deals with a detailed rockfall study which was accomplished during rockslope scaling works in the Bavarian Alps. The rock slope consisting of the Hauptdolomite-Formation extends along the federal road B 305 north of the village of Schneitzlreuth in Bavaria. Due to attending rockslope scaling works in cooperation with the State Agency for Construction in Traunstein, a quantification of block dimensions according to real rockfall field tests was possible. After having determined the three main block axes for over 300 rocks, rockfall modelling were accomplished applying the 3D rockfall codes Rockyfor3D and RAMMS::Rockfall. One part of the parameter studies covers the main proportion of the detected block sizes using Rockyfor3D. The second part of the study presents a comparison of the Rockyfor3D and RAMMS::Rockfall outcomes, taking the same block class for both codes into account. This paper demonstrates the limits and possibilities of using different 3D rockfall codes taking detailed field data into account. x | |||||
Mölk, Michael; Rieder, Benedikt | Rockfall hazard zones in Austria. Experience, problems and solutions in the development of a standardised procedure / Steinschlag-Gefahrenzonen in Österreich. Erfahrungen, Probleme und Lösungsansätze bei der Entwicklung einer standardisierten Vorgangsweise | Geomechanics and Tunnelling | 1/2017 | 24-33 | Topics |
KurzfassungThe Österreichische Raumordnungskonferenz (ÖROK) set up a partnership in 2011 to deal with “Risk management for gravitational natural hazards in landuse planning”. As gravitational natural hazards have a decisive influence on development in the Alpine Region, standard procedures were developed for the assessment of the relevance of these processes for landuse planning. This paper describes the recommended procedure for the assessment of hazards affecting permanent settlements from rockfall in a top-down approach. The first step to define potential conflicts between the maximum run-out of rockfall processes and the presence of settlements is a conservative empirical assessment based on rock outcrops serving as potential detachment zones and the maximum reach of such rockfalls, leading to a hazard indication map. This approach is only based on existing cartographic information, field investigations are not necessarily involved at this stage. To ensure conservative results, the use of a high-resolution 1 m ground model to identify rock outcrops is recommended. The next step includes a thorough examination of those areas in the hazard indication map with conflicts between the maximum reach/run-out of falling blocks and settlements. This stage includes field investigations with mapping of maximum reach blocks, block size distributions, underground conditions of the transit zone and the condition of rock outcrops that act as potential detachment zones. All this information is subsequently integrated into a 3D rockfall simulation. As a result the modelling enables a delineation of areas out of reach (no rockfall hazard), areas with potential impact energies ≤ 100 kJ (low intensity) and areas with potential impact energies > 100 kJ (high intensity). x | |||||
Zumbrunnen, Thomas; Thuro, Kurosch; König, Sebald | Dealing with natural hazards along federal and state roads in Bavaria / Umgang mit gravitativen Naturgefahren entlang von Bundes- und Staatstraßen in Bayern | Geomechanics and Tunnelling | 1/2017 | 34-46 | Topics |
KurzfassungRoads in the municipal Berchtesgaden are among the traffic infrastructure in Germany most highly endangered by natural hazards. Landslide, avalanche, rockfall and debris flow events led to repeated accidents and road closures. In order to improve the safety of main roads, a three-stage approach has been introduced by the responsible road authority, especially in the light of finding the most suitable and sustainable solutions quickly. The first stage was a systematic spatial detection and delineation of all risk areas, as well as assessment of the level of risk and the resulting urgency. Based on this assessment, a more detailed investigation was conducted, leading to the development of tailored protection concepts. The main criteria for the entire design phase of any measure have always been the necessary level of protection, reasonable costs and environmental compatibility. Matching all these requirements is critical for rapid construction and therefore a reasonable use of resources. A good example of this approach is the integral protection concept for the B 21 main road with its central structure of a multifunctional protection gallery near Baumgarten. This has been completed recently, and several other projects are currently under construction. x | |||||
Nickmann, Marion; Schweigl, Theresa; Thuro, Kurosch | Engineering geological and geotechnical analysis of a rock slide in the quarry Frauenmühle near Metten (Lower Bavaria) / Ingenieurgeologisch-geotechnische Analyse einer Felsrutschung im Steinbruch rauenmühle bei Metten (Niederbayern) | Geomechanics and Tunnelling | 1/2017 | 47-58 | Topics |
KurzfassungIn spring 2008 a rock slide detached from one of the walls in the quarry “Frauenmühle” locally used as climbing park, mobilizing a volume of 50 m3. The binary granite is relative fresh on the bottom of the walls, but the weathering increases significantly to the natural surface. The bedrock shows an orthogonal joint system enabling the so-called “Wollsackverwitterung”. Mapping of the joints followed by a kinematic analysis of the quarry wall by DIPS (Rocscience) indicates the slope failure to be of a planar sliding type on a medium-steep dipping plane. As the contributing factor for the slide, weathering along the plane has to be considered. Thereby the destruction of rock bridges downgrades the overall shear strength. A stability analysis based on the reconstructed block geometry and the determined shear parameters verifies the instability of the block. For today's situation, the kinematic analysis detects some critical intersections of joints being able to generate slide wedges. x | |||||
Hofmann, Robert; Sausgruber, Johann Thomas | Creep behaviour and remediation concept for a deep-seated landslide, Navistal, Tyrol, Austria / Kriechverhalten und Sanierungskonzept einer Großhangbewegung, Navistal, Tirol, Österreich | Geomechanics and Tunnelling | 1/2017 | 59-73 | Topics |
KurzfassungIn the valley of Navis, the village of Kerschbaum with 84 houses stands on a slowly downhill moving, relatively corase grained, aqua bearing earth-flow/-slide about 40 m thick. This secondary movement overlies a deep-seated rock slide. The rates of movement at the surface of the earth-flow/-slide were between 1 und 3 cm/a before the implementation of remedial works. Starting from the geotechnical and geomechanical model of the slope, measures were developed, which were intended to reduce the movement. A monitoring system was installed to provide information about the movement and slope water conditions of the earth-flow/-slide and the sliding rock mass. In order to estimate the creep behaviour of the earth-flow/-slide, the ductility index ILZR was determined from shear tests. A simple flow law was assumed for the estimation of the change of creep rate. Measurements over a period of about 18 months after the first phase of remedial works show rates between 0.5 and 1.2 cm/a. The reduction of the rate of movement is compared with the creep model applied and the viscosity index ILZR to check the validity. x |