Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Perner, Reinhard; Schorn, Roland; Atzl, Georg | New construction of Albula Tunnel II - Experience with steel fibre shotcrete / Neubau Albulatunnel II - Erfahrungen mit Stahlfaserspritzbeton | Geomechanics and Tunnelling | 4/2021 | 377-389 | Topics |
KurzfassungThe new construction of the 5860 m long Albula Tunnel was mainly carried out by blasting from the Preda and Spinas portals. Due to the exposed location in the high mountains, mixing plants were installed on both portal sides for the concrete supply; the concrete aggregate was largely produced from the excavated material, with a gravel plant being built in Preda for this purpose. The planned tunnel lining provides for a single-shell shotcrete construction for the most part. In the course of the excavation work, the excavation support was optimised so that the reinforcement mesh in the main support class in the single-shell area were replaced by steel fibre shotcrete. x | |||||
Proksch-Weilguni, Clemens; Wolfger, Hannes; Kollegger, Johann | Optimized reinforcement in longitudinal joints of segmental tunnel linings | Geomechanics and Tunnelling | 4/2021 | 390-399 | Topics |
KurzfassungWhen building tunnels using segmental lining, the segmental lining takes over the supporting role of the excavated soil. With the workspace in tunnel construction being very constricted the circular, segmental linings are divided into small segments called tubbings which are assembled by a tunnel boring machine. This kind of construction results in numerous longitudinal and circumferential joints. The loading situation for the longitudinal joints is typically dominated by the compressive normal forces combined with relatively small bending moments. The thickness of the tubbings usually depends on the longitudinal joints of the individual segments. The cross-sectional area of the tubbings has to be reduced at the joints in order to avoid spalling of the concrete leading to higher compression in the joints themselves. The Institute of Structural Engineering of TU Wien developed a new reinforcement design for tubbings with strengthened longitudinal joints. With a patent application pending, the newly designed joints were manufactured and tested demonstrating that the TU Wien proposal significantly increases the load-bearing capacity of the tubbings in comparison to conventional tubbing solutions. The very satisfying results, obtained from the large-scale tests of the newly developed joint design, show great potential for the construction of tunnels with thinner tubbings in the near future. x | |||||
Voit, Klaus; Depiné, Manuel; Hofmann, Matthias; Orsi, Georg; Murr, Roland; Zangerl, Christian; Bergmeister, Konrad | Material characteristics and compactability of phyllitic tunnel excavation material / Verdichtungseigenschaften von schiefrig-phyllitischem Tunnelausbruchmaterial - Examination of non-recyclable spoil at the Brenner Base tunnel / Betrachtung von nicht verwertbarem Ausbruch beim Brenner Basistunnel | Geomechanics and Tunnelling | 4/2021 | 400-415 | Topics |
KurzfassungLarge quantities of excavated rocks are generated during tunnel driving. Recycling possibilities and total percentage of recycling are depending on the rock conditions (rock type and rock properties), as well as the applied driving method. If recycling of the excavated rock mass is not possible or reasonable from a technical or economical point of view, the excavated material needs to be deposited in landfills. Thereby, the consumed landfill volume depends on the material volume of non-recyclable rock and its compactability as a function of the loosening of the rock by excavation and landfill installation. Both, material volume and compactability of the excavated material, are difficult to evaluate in advance. Apart from unpredictable lithological changes and variation of the driving parameters (e.g. depth of advance in conventional driving, contact pressure of tunnel boring machine), external influences - like afflux of water or weather conditions during installation of the material - significantly affect the compactability of the excavated aggregates. In this study, the actual example of phyllitic rock material excavated by conventional drilling and blasting from the main tunnel tubes of the Brenner Base Tunnel has been chosen to take a closer look at the research question concerning the compactability of phyllitic rock material. Since excavation material is increasingly used in construction industry, detailed knowledge on this matter is necessary for a successful application. x | |||||
Morocutti, Alex; Lussu, Andrea; Leitner, Edgar; Kaiser, Christian; Ertl, Anton; Grüllich, Sebastian | Innovative TBM transport logistics in construction section H33 of Brenner Base Tunnel / Innovative Transportlogistik zur TBM-Versorgung im Baulos H33 des Brenner Basistunnels | Geomechanics and Tunnelling | 3/2021 | 233-244 | Topics |
KurzfassungThe Tulfes-Pfons construction section of the Brenner Base Tunnel includes a 16.6 km long tunnel section excavated with an open gripper TBM. Due to the very difficult logistic conditions (steep access tunnel with 10 % gradient and a 90° bend at the transition to the exploratory tunnel as well as a limited clearance profile with 8 m diameter), the contractor and client decided on an alternative supply of the TBM - the 'multi-service vehicle' (MSV). This laser-controlled train on rubber wheels without rails is able to handle both the steep access and the 90° bend. After 16 km of excavated tunnel with a top performance of 61 m/d and top monthly performance of up to 800 m in hard rock conditions with 1000 m overburden, the decision to use the MSV has proved to be a complete success. In addition to the logistics and safety advantages, a cost reduction has also been achieved compared to the planned conventional system. MSV are a cost-effective and technically proven alternative to conventional track-bound TBM supply equipment. x | |||||
Goliasch, Robert; Gschnitzer, Ernst | Rail-bound logistics in tunnelling - Challenging logistics for a 30 km long TBM drive / Gleislogistik im Tunnelbau - Logistische Herausforderungen bei einem 30 km langen TBM-Vortrieb | Geomechanics and Tunnelling | 3/2021 | 247-257 | Topics |
KurzfassungDuring the early years of the 19th century, narrow-gauge railways found their way into mines and tunnel projects. Due to economic reasons, these rail-bound transport systems were successfully used for the transport of personnel, supplies and muck operations. While the worldwide transport logistics developed and changed continuously over the following century, there was limited demand within the tunnelling industry on innovation and improvement for these robust, durable and simple railways. Moreover, rubber-tired transport systems were introduced to the market and replaced traditional rail equipment on many tunnelling projects. The MTS tunnel Drive 1, originally planned to be 13 km in length and now extended to 30 km, will become the longest single tunnel drive in the world, demonstrating the flexibility of a rail-bound system. Since the start of the project, various suppliers and manufacturers for rail-bound equipment and rail track systems have been involved in the development of innovative drive systems, under-carriages and rail tracks. This article provides an overview of the design, implementation and lessons learned so far. x | |||||
Dankl, Wolfgang; Reith, Marco | Logistics of deep tunnel construction sites without portal access - SBT2.1 Semmering Base Tunnel / Logistik von tiefliegenden Tunnelbaustellen ohne Portalzugang - Baulos SBT2.1 Semmering Basistunnel | Geomechanics and Tunnelling | 3/2021 | 258-269 | Topics |
KurzfassungThe 27.3 km long Semmering Base Tunnel is a major component of the Baltic-Adriatic Corridor trans-European rail link. The SBT2.1 Fröschnitzgraben Tunnel section involves more construction work than any other contract section of the Semmering Base Tunnel project. First, two shafts over 400 m deep had to be sunk down to tunnel level in order to create the emergency station. From here, the tunnels are being driven towards Gloggnitz and Mürzzuschlag. The falling drives towards Gloggnitz, each approx. 8.5 km long, are being excavated with two tunnel boring machines (TBM), while conventional tunnelling methods (drill and blast) are being used to drive the 4.3 km long rising section towards Mürzzuschlag. Another major component of the contract is the creation and management of the Longsgraben landfill site. x | |||||
Entfellner, Manuel; Hauer, Hannes; Bauer, Johann | Logistic challenges at contract SBT 1.1 - Intermediate construction access Göstritz / Logistische Herausforderungen beim Baulos SBT 1.1 - Zwischenangriff Göstritz | Geomechanics and Tunnelling | 3/2021 | 270-285 | Topics |
KurzfassungBase tunnels usually require temporary intermediate construction accesses in order to be able to carry out the tunnelling work in a timely, economical and logistical reasonable scope. Intermediate construction accesses in the form of shafts lead to particular logistical challenges in supplying the tunnel headings. At contract SBT 1.1-Tunnel Gloggnitz as the eastern section of the Semmering Base Tunnel, the shafts of the intermediate construction access Göstritz cannot be sunk from the surface for topographical reasons but are instead developed by an access tunnel. This fact requires the construction of complex underground structures and logistical interfaces to supply the four tunnel headings, beginning from the building site facilities, via the access tunnel, through the shafts to the tunnel face. In addition to the ongoing supply of all kinds of support measures, the excavated material is mucked by means of fully automatic belt and shaft conveyor systems. To ensure the permanent safety of the crew on-site, the highest demands and resilience are placed on the transport systems through the two 250 m deep shafts, the ventilation and the mountain water drainage systems of up to 500 l/s. The article describes the experience and ongoing optimization of the logistics concept as well as innovative new developments that are applied in this special tunnel project. x | |||||
Fentzloff, Wolfgang; Rothe, Stefanie; Stahn, Christian; Papantonakis, Dimitrios | BIM meets Lean - Logistics study of a long tunnel using BIM and Lean methods / BIM und Lean im Doppelpack - Logistikuntersuchung eines langen Tunnels mit Methoden von BIM und Lean | Geomechanics and Tunnelling | 3/2021 | 285-297 | Topics |
KurzfassungInfrastructure projects in inner-city areas are gaining in importance on the one hand and are subject to increasingly restrictive requirements due to the space available on the other. This affects not only the site installations, but also to a large extent the access to and the material handling on the construction sites. Implenia has been using the digital capabilities of BIM to improve project execution for several years. Visualisations, data management and collaboration create a transparency that is necessary to face the difficult boundary conditions. Lean Construction method of optimizing and stabilizing material flows, which is new to the infrastructure sector, can ideally use BIM digital tools to map its processes. It was obvious to use this symbiosis of the two methods. x | |||||
Phillips, Mina; Fadhel, Haider; Raafat, Ibrahim; El-Kelesh, Adel | Use of artificial ground freezing in construction of cross passages under Suez Canal / Bodenvereisung für den Bau von Querschlägen unter dem Suezkanal | Geomechanics and Tunnelling | 3/2021 | 298-307 | Topics |
KurzfassungThe Artificial Ground Freezing (AGF) has demonstrated its versatility as an effective approach for both temporary ground stabilization and ground water control in almost all types of saturated soils. This paper describes the use of a closed circuit freezing system in the construction of four cross passages. The passages connect 4.8 km long twin road tunnels that have recently been constructed at depths of up to 60 m under Suez Canal in Ismailia, Egypt. The paper starts by describing the ground conditions at the locations of the cross passages and by presenting the results of laboratory tests conducted on unfrozen, frozen and thawed soil specimens. The main design criteria considered in designing the freezing works are discussed and the freezing and cross passages construction works are described. The frozen body was carefully monitored during the freezing process and construction of passages. Records of the adopted monitoring program are presented and discussed. Significant observations that contribute to effective planning of future freezing works are also presented. x | |||||
Dietler, Thomas | Characterisation of rock as foundation for dams and hydropower plants - Experience from a field geologist's perspective / Beschreibung von Fels als Baugrund für Talsperren und Wasserkraftanlagen - Erfahrungen aus Sicht des Feldgeologen | Geomechanics and Tunnelling | 2/2021 | 129-141 | Topics |
KurzfassungThe characterisation of rock as a foundation for hydropower plants in general and dams in particular is highly complex and requires a great deal of experience on the part of the geologists involved. Geology cannot be studied remotely; it requires geological field surveys and investigations. This paper describes the aspects to be considered, the planning of the investigations and the degree of detail needed at the various planning phases from the field geologist's perspective. It also highlights the internationally recognised methods of investigation used for large-scale projects and describes how the results are documented and recorded. It concludes by briefly outlining the soft factors which constitute an integral part of successful geological feasibility studies. Geology is an “inexact” science that requires extensive experience in order to generate the most realistic ground model possible. For this reason, a clear distinction must be made between facts (basic data) and their interpretation (experience). Furthermore, it is important to consider what other conclusions can be drawn from surveying the subsoil. x | |||||
Kogler, Kurt; Hechenbichler, Johann | Exceptional problems for grouting in power station construction in exposed locations / Außergewöhnliche Aufgabenstellungen an die Injektionstechnik im Kraftwerksbau in exponierten Lagen | Geomechanics and Tunnelling | 2/2021 | 142-157 | Topics |
KurzfassungPower station construction has always posed very complex problems for engineers. The dimensions of such construction works, their geographical location and the effects on people and nature reflect not only the great public interest but also show how extensive and challenging the design and construction of such construction works can be. Grouting technology is a reliable partner for waterproofing, consolidation and prestressing measures in power station construction and in such exposed locations, provides special solutions for the particular local conditions. The following article describes through selected examples grouting solutions for the refurbishment and new construction of hydropower facilities, concentrating on the implementation of specialised civil engineering measures on international power station projects. x | |||||
Marte, Roman; Ausweger, Georg; Schweiger, Helmut F.; Seiwald, Stephan; Kainz, Florian; Breymann, Helfried | Safety aspects of a water reservoir influenced by a creep like landslide / Sicherheitsbetrachtungen für einen durch eine Massenbewegung beeinträchtigten Speicher | Geomechanics and Tunnelling | 2/2021 | 158-172 | Topics |
KurzfassungOn the basis of a case history of a pumping storage which is endangered by a slow moving landslide, the interaction of the reservoir operation and the deformation behaviour of the landslide will be discussed in this paper. Comprehensive measurements as well as theoretical investigations, which had been performed to understand the determining factors for the deformation behaviour of the landslide, will be discussed. Based on these investigation results a warn and alarm plan as part of the safety concept for the storage had been developed. x | |||||
Hautz, Werner; Neuner, Johann | Expansion of Kirchbichl Power Plant in Tyrol - Challenges of foundation engineering / Erweiterung Kraftwerk Kirchbichl in Tirol - Herausforderungen an den Spezialtiefbau | Geomechanics and Tunnelling | 2/2021 | 175-183 | Topics |
KurzfassungTiwag - Tiroler Wasserkraft AG sees itself as a driving force in the energy transition, pursuing the goals of the Tyrolean and Austrian energy strategies with a moderate, environment friendly expansion of hydropower. The projects are essentially aimed at expanding existing power plants so that they can be used more effectively, and additional hydropower potential can be developed. The Kirchbichl Power Plant is a good case in point. From 2017 to 2020, the power plant was made fit for the next decades as part of an extensive refurbishment and expansion project. The main project components are to improve flood security through the construction of an additional weir field, to adapt to enhanced environmental standards through the construction of a fish passage and a power plant for residual flow, and to increase the discharge of the power plant by installing an additional turbine. One of the challenges was the construction pits in the immediate vicinity of the existing system. The pit design with bored pile retaining wall and base seal with a jet grout slab has proven to be very effective. x | |||||
Innerhofer, Guntram; Bickel, Lukas | Rodundwerk I, new headrace system - Concept and realization / Rodundwerk I, neuer Kraftabstieg - Konzeption und Ausführung | Geomechanics and Tunnelling | 2/2021 | 185-195 | Topics |
KurzfassungAs a result of several feasibility studies from which sound economic and technical arguments emerged, the decision was made to construct a new headrace system for the Rodundwerk I consisting of a low pressure tunnel, a shallow pressure shaft parallel to the surface slope and a subsequent high-pressure penstock gallery. The new distribution pipeline was designed as a concrete-encased gravity abutment. Construction started at the beginning of May 2020 and since then excavation work has progressed according to plan. Particular attention had to be addressed to the impact of construction operations on the existing power plant structures. Hence, a detailed monitoring concept was established concerning the vibration transmission in the rock mass. Excavation works are carried out partly by tunnel boring machine, partly by drilling and blasting and, once the critical threshold of vibration has been reached, by alternative methods. By continuously adjusting the blasting parameters (charge amount, ignition timing), it was possible to minimise the detonation-related effects in the vicinity of the existing structures. x | |||||
Smesnik, Mathias; Nowotny, Hans; Nowotny, Hans; Krstic, Sanja; Sever, Özgür | Lower Kaleköy Dam - A tailor made composite dam structure | Geomechanics and Tunnelling | 2/2021 | 197-206 | Topics |
KurzfassungWorldwide various type of dams are used to create reservoirs for multiple purposes. Particularly in usual cases, a single dam type is used to form a watertight barrier. Keeping safety and finance in mind, less challenging dam locations, that concerns with aspects like foundation conditions, seismicity at the dam sites, availability of construction materials, etc. are preferred. Ironically, where there is a demand for a reservoir, a suitable dam location is not always available. In those cases, these circumstances make advanced design of dam structures indispensable. An example of such a dam design is the Lower Kaleköy composite dam structure. The same consists of a roller compacted concrete gravity dam at the right bank, which is linked with one of the world's highest deformation joint to the very first asphalt core embankment dam in Turkey, situated on the left bank. The Lower Kaleköy Hydroelectric Power Plant (HEPP) constructed and operated by Kalehan Genç Enerji Üretim A.. with an installed capacity of 500 MW, as part of the Beyhan Kaleköy HEPP cascade is located on the Murat River, a tributary to the Euphrat River in Eastern Turkey. This paper summarizes the design methodology developed by the design consortium (AFRY/Temelsu), headed by AFRY, for the tailored composite dam. x | |||||
Grunicke, Urs H.; Lienhart, Werner; Vorwagner, Alois | Long-term monitoring of visually not inspectable tunnel linings using fibre optic sensing / Langzeitmonitoring von nicht visuell inspizierbaren Tunnelinnenschalen mittels Faseroptik | Geomechanics and Tunnelling | 1/2021 | 19-32 | Topics |
KurzfassungRegular structural assessments of tunnel linings are commonly performed by visual inspection. Crack phenomena and their development over time are essential indicators of changes of the stress regimen. These are the most prominent input data for the structural assessment of linings. Cladding for fire protection or noise control inhibit visual inspection and call for alternative methods of crack detection and monitoring. This paper presents the application of an alternative method which employs distributed fibre optic sensing (DFOS) which is installed on already existing linings. The objective is to obtain monitoring results with best reliability in comparison to conventional inspection. While the application of DFOS with fibres embedded in new linings has already been tested extensively, later installation on existing linings poses various challenges. Based on findings obtained from laboratory and field tests in an operational highway tunnel, we found that by means of later installed fibres with lengths of up to 70 m, strain measurements can achieve accuracies of about 1 &mgr;m/m over 10 mm. This allows the detection of both current and historical crack widths at 0.01 mm precision, conspicuous strain patterns and temperature abnormalities. The system can be mounted onto the inner lining surface which is covered by later claddings and are hence inaccessible to visual inspection. The structural performance can eventually be inferred from interpreted crack patterns. x | |||||
Moritz, Bernd; Heissenberger, Roman; Schachinger, Tobias; Lienhart, Werner | Long-term monitoring of railway tunnels / Langzeitüberwachung von Eisenbahntunneln | Geomechanics and Tunnelling | 1/2021 | 35-46 | Topics |
KurzfassungAt the large infrastructure projects of the Austrian Federal Railways in the Alpine region geotechnical structures with different characteristics are encountered. Especially heterogeneity and composition of fault zones associated with different stress conditions are a great challenge during tunnelling. Although the system behaviour resulting from ground-support interaction is measured by monitoring methods, after completion of tunnel works with installation of the inner lining usually the tunnel is no further monitored. The goal of ÖBB-Infrastructure AG is to apply robust, reliable and durable monitoring systems for the observation of geotechnical relevant structures during a service life of the tunnels of 150 years. Thereby unfavourable tendencies of system behaviour shall be detected early and measures in terms of predictive maintenance planned in due time to ensure high availability of the tunnels during operation. The paper presents the implementation of long-term monitoring at the projects Koralm Tunnel and Granitztal Tunnel and gives an outlook at the Semmering Base Tunnel. x | |||||
Keuschnig, Markus; Schober, Andreas; Delleske, Robert; Brandner, Katharina; Höfer-Öllinger, Giorgio | Scale-oriented landslide monitoring and early warning system for uranium legacy complexes in Mailuu Suu, Kyrgyzstan | Geomechanics and Tunnelling | 1/2021 | 47-53 | Topics |
KurzfassungRadioactive waste and the legacies of uranium mining combined with massive landslides pose tremendous risks to vast areas of Kyrgyzstan and their inhabitants. These risks comprise the potential destruction of radioactive legacies and thus, the mobilisation of radioactive material through streams and rivers into intensively cultivated agricultural areas. To tackle these challenges, a scale-oriented landslide monitoring and early warning system (LMEWS) was developed to increase the safety of Kyrgyz uranium legacy complexes in the Mailuu Suu region, southern Kyrgyzstan. The LMEWS utilizes cutting-edge technologies like satellite- and ground-based InSAR as well as Unmanned Aerial Systems (UAS) to ensure flexibility, transferability, and maximum protection against vandalism. x | |||||
Radon i , Nedim; Sattlegger, Elisabeth; Lacourse-Dontigny, Xavier; Mitsch, Thomas | Designing a state-of-the-art monitoring system in challenging operating conditions | Geomechanics and Tunnelling | 1/2021 | 54-62 | Topics |
KurzfassungThe construction joint venture NouvLR is constructing the new light rail network in Montreal. One of the major challenges is the advance below the existing runways and taxiways of the Montreal-Trudeau International airport and the construction of the subway station below the airport. The airport must remain under operation during the construction, and very tight requirements have been imposed regarding the tolerable surface settlements and availability of the monitoring data. The regulations regarding operations of the airport and possible presence of foreign objects in vicinity of its runways and taxiways represent an additional challenge, requiring usage of less straightforward monitoring concepts. The works for the installation of the monitoring equipment must be closely coordinated with airport operations and require a reliable schedule. x | |||||
Golser, Johann; Steiner, Walter | International and European standards for geotechnical monitoring and instrumentation / Internationale und europäische Normen für geotechnische Überwachung und Instrumentierung | Geomechanics and Tunnelling | 1/2021 | 63-77 | Topics |
KurzfassungGeotechnical monitoring and instrumentation are indispensable parts of the Observational Approach. in tunnel design and construction. They are an essential requirement for a proper risk management. Since 2013 several standards, valid both in Europe under CEN and international under ISO, were developed dealing with geotechnical monitoring. Five standards have been published by 2020, covering general rules, extensometer, inclinometer, piezometer and pressure cells. Further standards on settlement measurements, strain monitoring and load cells are in progress and will be published in the next few years. x | |||||
Wilfing, Lisa; Michael, Joachim; Schütz, Dirk | Risk assessment of route options for the Hanau-Würzburg/Fulda railway project / Risikoabschätzung von Varianten im Bahnprojekt Hanau-Würzburg/Fulda - Optimised exploratory concept and application of BIM in early project phases / Optimiertes Erkundungskonzept und Anwendung von BIM in frühen Projektphasen | Geomechanics and Tunnelling | 1/2021 | 78-88 | Topics |
KurzfassungIn the course of the preliminary planning of the new Gelnhausen-Fulda railway line which is part of the railway project Hanau-Würzburg/Fulda, two route options with tunnels, bridges, cuts and embankments are to be investigated and assessed as efficiently as possible with regard to potential geotechnical risk areas. Due to the geological and hydrogeological conditions within the north-eastern Hessian Buntsandsteingebirge, several groundwater levels, landslides in tunnel portal areas and karstification structures are to be expected on the two route options, each of which is approx. 45 km long. In order to obtain detailed and, above all, large-scale knowledge of geotechnical hazards of each route = in the preliminary stage of the exploration programme, geophysical surface investigations are a cost- and time-optimized exploration method in addition to standard drilling. These findings as well as existing subsurface information are combined by means of BIM, so that risk areas can be identified at an early stage of the project and taken into account when selecting the most affordable route. x | |||||
Lutz, Robert; Zizka, Zdenek; Röchter, Lars; Thewes, Markus | Surface settlements caused by mechanised tunnelling in hard rock with heterogeneous tunnel face conditions - Empirical and numerical calculations using the example of Boßler Tunnel / Oberflächensetzungen bei maschinellen Tunnelvortrieben im Festgestein bei heterogener Ortsbrust - Empirische und numerische Berechnungen am Beispiel des Boßlertunnels | Geomechanics and Tunnelling | 1/2021 | 89-104 | Topics |
KurzfassungAn empirical and a numerical calculation model were developed to predict the surface settlements due to EPB tunnelling in hard rock with heterogeneous face conditions. For this purpose, surface settlement and TBM driving data from Boßler Tunnel were considered. The TBM launching area characterised by a low overburden (z/D < 2) and a nature conservation area at surface was examined. The developed models were calibrated against the measured surface settlements of the first eastbound tube and were used to predict the surface settlements of the subsequent westbound tube. The prediction was then compared to the actual measured settlements during the excavation of the westbound tube. From this, findings for future settlement predictions in similar ground conditions were derived. It could be shown that both models are suitable for the application in the investigated subsoil conditions and can be used successfully in practice in different phases of the project development. x | |||||
Leinauer, Johannes; Jacobs, Benjamin; Krautblatter, Michael | Anticipating an imminent large rock slope failure at the Hochvogel (Allgäu Alps) | Geomechanics and Tunnelling | 6/2020 | 597-603 | Topics |
KurzfassungCosts for installation and maintenance of protective structures are increasing while alpine hazards progressively threaten alpine communities, infrastructure and economics. Thus, reliable process-based anticipation and early warning strategies offer a cost-effective and smart solution for alpine societies in the near future. However, only few comprehensive pre-failure observations of alpine rock slopes have been reported so far. This paper demonstrates pre-failure observations of a rapidly deforming rock mass (potentially 260,000 m3) at the Hochvogel (Allgäu Alps, 2,592 m a.s.l.) and a geotechnical monitoring and warning concept. This is implemented in the complementary multi-method approach of the AlpSenseBench project and the basis for an effective and reliable early warning system. Since 2014, overall displacement rates in the range of 2 to 10 mm/month in the main decametre deep fracture are observed. It is expected that predictive acceleration patterns will appear in the final pre-failure stage. A detailed knowledge of multiple anticipative signals in correlation with accelerating rock slope deformations will contribute to an advance in accuracy and reliability of rock slide early warning. x | |||||
Illeditsch, Mariella; Preh, Alexander | The concept of design block size - A critical review of ONR 24810 "Technical Protection against Rockfall" | Geomechanics and Tunnelling | 6/2020 | 604-611 | Topics |
KurzfassungIn Austria, the Guideline for “Technical Protection against Rockfall”, named ONR 24810 provides guidance to assess rockfall hazard (at object scale) by determining a so-called design block size. The aim of this article is to critically review the concept of design block size and to suggest alternatives. The design block size is derived from a block size distribution and event frequency, both of which may be very uncertain. Modelling a single “constant” design block may result in trajectories far away from reality. The design approaches of ONR 24810 and Eurocode 7 are compared. A case study is presented and discussed. Reducing input parameters at the beginning of the design approach results in apparent characteristic energy levels and bounce heights, which are not characteristic, as defined by EC7. By disregarding all small and the biggest blocks, valuable information of maximum energy levels and bounce heights is lost. The entire block size distribution should be used for rockfall simulations, rather than a single block size. Fragmentation should be considered, if applicable. x | |||||
Schneider-Muntau, Barbara | Modelling of the interaction between structures and creeping slopes / Die Modellierung der Interaktion von Bauwerken und Kriechhängen | Geomechanics and Tunnelling | 6/2020 | 612-619 | Topics |
KurzfassungTo quantify the interaction between structures and creeping slopes, 3D calculations under consideration of a time-dependent material behaviour are necessary. In this paper 3D finite element calculations are performed on a hypothetical creeping slope. The time-dependent material parameters are determined by back calculation on a slope without any structures. Subsequently, the influence of a retaining wall and of a tunnel structure built in the creeping slope are investigated. The results of the modelling show that the structures locally decrease the creeping velocity of the slope. The influence of the tunnel structure is more pronounced due to its spatial extension. At the same time the stresses on the structures increase over time. Linear time-dependent material models do not consider the hydrostatic pressure in their formulation. Non-linear time-dependent material models, which are based on soil mechanical principles and which take the hydrostatic pressure into account, are therefore better suited to represent the time-dependent soil-structure interaction. x |