Federal Highway Research Institute

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Tunnel and foundation engineering, tunnel operation, civil security

Tunnel Block Backfill and GInjection Methods for Sealing Secondary Tunnel Liners (15.0674)
The planned block backfilling of mined tunnel structures with a hydrostatic membrane barrier is intended to serve as a post-compacting injection measure in the area between the sheet waterproofing membrane (KDB) and the secondary tunnel concrete lining (bulkhead field) to increase the tightness of double-shell tunnel constructions. In Austria and Switzerland, the measure is anchored in the valid guidelines and recommendations. The current German regulations (ZTV-ING), on the other hand, provide for full-surface injection via the injection nozzles of the integrated injection system as a fallback measure (subsequent injection if required) in the event of leaks caused by defects in the sheet waterproofing membrane. The basic prerequisite for fulfilling the sealing purpose of post-injections is the feasibility of a complete backfilling of the bulkhead field of the leaking tunnel block. At present, there is no clear knowledge about the optimal geometrical arrangement in combination with different injection materials as well as different diameters and materials of the injection hoses of the so called “test and injection system (according to ZTV-ING)”. The aim of the research project is to investigate, by means of large-scale laboratory tests, the effects of different boundary conditions on the injection and sealing success in the tunnel block backfilling of secondary tunnel liners.

Testing of geothermal mountain water utilisation at the Füssen border tunnel (15.0656)
Within the scope of the project "Technical preparation of geothermal pilot applications for foundation and tunnel constructions", 3 tunnel portals on German motorways were examined for their suitability for the construction of a geothermal pilot plant for keeping road surfaces free of snow and ice. The aim of this project was to plan a direct, passive geothermal surface heating system using the previously unused tunnel drainage water. With the help of this system it is possible to use the water without the addition of coolants and without the use of a heat pump. It can therefore be fed into the receiving water after the heat has been extracted. The direct use of mountain water represents a sustainable and energy-efficient use of resources. The aim of the present project is to provide an implementation aid for operators and users (federal government, road construction authorities) for the use of direct, passive open space heating systems to keep road surfaces free of snow and ice. Special focus is to be placed on the consideration of user-specific requirements and on the most efficient and trouble-free operation of the systems.

Review of assumptions and parameters for risk analyses for road tunnels (15.0663)
Several Regulations define minimum requirements for the equipment and operation of road tunnels. These requirements must always be observed. In justified exceptions, however, deviations from the specifications may be made. In the event of a structural or technical deviation of a tunnel or in the case of a special characteristic, risk analyses are necessary to show that a comparably high level of safety can be guaranteed by the use of alternative measures. With regard to a desired broadening but also standardisation of the approaches, there is a need for investigation both with regard to the updating of input parameters used and the risk influence of input parameters that have not yet been taken into account, such as the influence of speed on accident frequency and accident severity. The aim of the study is to further complete the parameters affecting the overall level of tunnel safety as well as individual equipment features, to determine their influence on risk, and to review and, if necessary, adjust parameters already known and used. The results should demonstrate the possibility of a future intensified risk-analytical dimensioning of safety-relevant equipment elements of road tunnels in connection with enhanced cost-benefit considerations.

Investigations into the ventilation of road tunnels using a generic model (15.0643)
The investigation is intended to extend the informative value of the BASt model tunnel on a scale of 1:18 as an experimental model and the numerical model developed in parallel to investigations on the model tunnel, and to enable the model-based processing of specific questions on the ventilation of road tunnels. A main focus of the investigation is the execution of real scale measurements in a tunnel to complete the validation of the experimental and the numerical model. For a closer integration of the two models as a generic model the question is addressed to what extent fluid mechanical investigations can be carried out in a spatially delimited manner, but still be related to the entire tunnel with sufficient transferability. This is expected to simplify the handling of complex situations as well as to extend the decision basis for planning issues, based on parameter studies using the numerical model.

Building Information Modeling (BIM) in tunnel construction (15.0623)
BIM applications for the digital project management of infrastructure projects differ depending on the project and work phase. In order to promote the use of the digital planning method, the BMVI supports BIM pilot projects on rail, road and waterway until 2020, divided into two pilot phases. The main subject of the pilot projects is the planning and construction phase. BIM application cases, which involve the use of BIM in the context of structural maintenance (maintenance and ongoing operation) of tunnels, play no or only a subordinate role in previous considerations. The aim of this project is to point out the effects, requirements and potentials of the application of BIM for an optimized maintenance planning of tunnels as well as to develop a target-oriented, practice-oriented BIM concept for the maintenance of tunnels including recommendations. The developed concept will be demonstrated at a representative tunnel.

Execution of large-scale fire tests to ensure the structural fire protection of tunnel liners (15.0649)
In the construction of new road tunnels, the use of PP fibre concrete as structural fire protection is part of the standard construction method according to ZTV-ING. In the course of implementation, several research projects and field trials were carried out (BASt Report B 73). Current research projects and tunnel construction measures have shown that it is necessary to investigate supplementary experimental boundary conditions. These include other fibre geometries with larger fibre diameters, other concrete formulations as well as the influence of the tunnel construction method or its test piece geometry and the illustration of realistic load situations. The aim of the project is to increase the knowledge of the influence of micro PP fibres, the concrete formulation and the geometry of the test specimens on the spalling behaviour of concrete specimens in large fire tests. Also, the processability of fresh concrete formulations in combination with different PP fibre geometries that conform to regulations and are currently used in tunnel construction will be investigated and discussed with regard to their suitability for practical use. The knowledge gained from the tests serves to review and further develop the rules and regulations for structural fire protection in tunnel construction.

RITUN (2318014)
Tunnel structures are important elements of the German trunk road network. The aim of the RITUN project is to increase the resilience of road tunnels to external influences and to quickly put them back into operation after disruptive events. In this joint research project, BASt is contributing to the development of solutions which, for example, allow the partial use of the second tunnel tube in oncoming traffic operation when one tunnel tube is closed in directional traffic. Such solutions should lead to a higher availability of the tunnels and at the same time to a veritable reduction of the overall economic costs after an extreme event. The result will be a practical handbook for owners and operators including a user tool. The aim is to achieve a high level of acceptance among end users, which will also be achieved by the demonstration of the research results on a real tunnel led by BASt.

Life cycle assessments of technical equipment in road tunnels (15.0601)
When planning tunnel structures, a theoretical service life of 20 years is currently applied during economic considerations of the technical equipment in line with the German transfer value calculation ordinance (Ablösungsbeträge-Berechnungsverordnung). Some components of the equipment have a considerably longer service life, but on average are unable to make up for the growing share of switchgear and control units that tend not to achieve this theoretical service life. The objective of the project is to determine and provide precise input data for the life cycle assessments of tunnel structures. A differentiated determination of the costs and service lives of the operating and safety-related equipment will enable better planning for future applications. The results of the research project are to be used for the improved planning and assessment of tunnel structures from an economic point of view, and will therefore ultimately contribute to reliable cost and maintenance planning for road tunnels.

Waterproofing and waterproofing transitions for single-shell tunnels (2316005)
With suitable geology and mountain water which is not under pressure, use is frequently made of single-shell shotcrete methods in the construction of cross passages in road tunnels. This structure offers a financial advantage compared with two-shell methods of construction. By bonding the shotcrete layers, the outer shell can also be made to be permanently load bearing so that smaller overall layer thicknesses are required. In the research project entitled "Waterproof shotcrete structures in road tunnel construction” requirements for a permanent and watertight shotcrete were created using extensive experimental tests. A federal state survey showed that leaks were ascertained nevertheless in a larger number of rescue tunnels which had been constructed using the single-shell method. However, in order to avoid leaks in these structures in future, regulations are to be formulated in this research project on how joints and transitions are to be ideally executed in the double-shell method. The results are to be incorporated in the rules and regulations (ZTV-ING, reference drawings).

Network of experts: forecasts and vulnerability analyses (2316002)
Currently there are no uniform approaches for evaluating and forecasting both the safety and the availability of traffic infrastructure in the case of unplanned and undesirable events. Concepts and approaches for quantifying / measuring the availability and safety of road infrastructure elements are to be developed within the course of this project.

Cyber-Safe (2315001)
The objective of the Cyber-Safe project is to increase security to protect traffic, tunnel and public transport control centres from cyber-attacks. Operators should be able to recognise potential risks more effectively than has been the case up to now, and take appropriate safeguarding measures. To this end, the effectiveness of existing security concepts will be tested initially. Improvements will then be devised for any deficits, and their efficacy tested.

An Assessment of the Previous Approach to the Theoretical Operating Life of the Operational and Security Equipment in Road Tunnels within the Scope of a Life Cycle Cost Analysis (2315006)
An analysis of life cycle costs means taking a holistic approach to the costs associated with a structure across its entire operational life. In the past, decisions regarding various design configurations have largely been based on the production costs. This project aims to develop an approach which takes into account different life cycle aspects related to the various operational components of a road tunnel, arriving at a nuanced evaluation of their operating life and the degree to which they influence life cycle costs. To achieve this, it is not only necessary to research the operating life and actual replacement cycles of individual components, but also to develop comprehensive tests from which suitable forecasting models can be derived. This process will also include tests and experience drawn from other countries.

Quality Assurance and Maintenance Concepts for the Use of PP-Fibre Concrete in Improving the Fire and Spalling Properties of Road Tunnel Linings (15.0594)
Two pilot projects have already documented the practical suitability of PP-fibre concrete in the construction of road tunnels. As a result of the experience gained in these projects, the use of PP-fibre concrete has been adopted into the ZTV-ING guidelines as the standard construction method for lining road tunnels on the federal trunk road network in Germany. However, prior to these regulations being included in the updated version of the ZTV-ING, other outstanding issues regarding the use of PP-fibre concrete need to be clarified. These include the degree to which the various constituent parts of PP-fibre concrete react to the characteristics of both fresh and hardened concrete. In addition, the project seeks to develop criteria for the carrying out and evaluation of fire tests which can guarantee the satisfactory effectiveness of each specific type of PP-fibre concrete.

Safety evaluation of road traffic tunnels based on tunnels equipped according to the directives (03.0433)
The development and application of methods for standardised assessment of the safety of road tunnels have become necessary due to the incorporation of European regulations into national law. Road tunnel systems are fairly complex and it is becoming apparent that transparent representation is best achieved with quantitative methods. Risk analysis methods facilitate a traceable evaluation. A quantitative risk analysis method has been developed for this purpose. The purpose of the current project is to create an evaluation framework for comparing the safety level of a road tunnel equipped according to the "Directives for equipping and operating road tunnels (RABT)" with that of a tunnel that deviates from the directive. A range of safety values is to be provided as an evaluation framework. This evaluation framework is to facilitate the evaluation of the total tunnel safety level as well as the effect of individual measures on the safety level. This is to aid in the selection of measures for real tunnels, also for tunnels with strong deviations that may result in a particular characteristic according to RABT. The results will be used for the development of appropriate specifications in national regulations for planning the operational equipment in tunnels.