Project: TUNFEC - Structural and aerodynamic design of TUNnels under Fire Emergency Conditions

Casualties from tunnel fires can be counted in hundreds and the economic damages have been enormous. At the early stages of a tunnel fire life safety and minimization of casualties is the major concern. Later, structural damage minimization becomes important. Most tunnels exposed to fires have been heavily damaged or collapsed. For these reasons, the EU has funded in the past several projects and studies related to fire safety in tunnels. The already developed models are based on simplified (1-D) laws and (2-D or 3-D) Computational Fluid Dynamics (CFD) models for the solution of the flow and temperature fields, and FEM solvers for the solution of the structural problem of the tunnel lining. They may be used to a) analyze the risk, b) improve the tunnel design c) improve the safety regulations and evacuation plans, and d) improve the ventilation dimensioning/design. The limitations of the existing procedures and software tools are:_x000D_1. The CFD and FEM analyses are performed in a decoupled manner by software tools provided usually by different vendors often with compatibility problems. Different engineering teams usually perform these two studies with minimum interaction._x000D_2. The augmented thermal load for tunnel lining dimensioning is based on temperature time curves, proposed by national/international standards, which differ considerably to each other and represent an envelop of possible fires for an unventilated tunnel, while being insensitive to tunnel’s size, resulting in a possible danger of under-dimensioning._x000D_3. The existence of different computational tools, provided by different vendors makes the data exchange problematic, especially when interaction is needed between different design teams. The highly complicated procedure makes the run of multiple scenarios almost impossible. However these runs are crucial in the risk analysis procedure. Consequently, only a small elite of engineers is capable of performing such computations, with high cost in time and money._x000D_The goal of this proposal is to develop a unified software platform for the coupled, multi-physics, automated simulation of fire events inside tunnels and the consequent effects on the tunnel lining, by utilizing already existing specialized and wide-spread software tools, and developing new ones, aiming at simplifying and accelerating the complete procedure and enabling the coupled computations of the relevant physical phenomena. The final product will enable the tunnel engineers to accurately evaluate different design solutions and fire scenarios, and greatly assist the risk assessment procedure. _x000D_The Project Ps form a close group, work in the same business area and complement to each other. FIDES DV-P is a specialist for numerical computations and software marketing with one focal point in Geotechnical, FEM, CFD and multi-physics applications. Laabmayr Consulting is a prominent engineering firm for infrastructure works and tunneling. ELXIS is working on a variety of large and complex projects for the calculation and installations of tunnel's ventilation systems, while TST can carry out real-scale tests for fire simulation and ventilation. _x000D_FIDES has developed a FEM software for steady, unsteady and transient solutions. Tunnel geometrical modeling tools, specialized meshing tools and pre/post-processing software have been also developed. FIDES has also developed a general purpose 3D, compressible/incompressible CFD solver, and a heat transfer solver for the computation of heat conduction inside solids. Using the resulting temperature field, a separate coupled thermal-structural analysis can be performed to predict the induced structural damage._x000D_The aim of the proposal is to completely couple the above sequential analysis procedures, i.e. CFD analysis / thermal analysis / structural analysis to a more accurate holistic approach of fire events. By reaching this aim, the final goal will be to obtain a generic computational platform with the capability of numerically simulating, testing and assessing the effects and damages of any possible fire event during the design or rehabilitation stage of already damaged constructions. The following distinct components will be developed tested and demonstrated during the project:_x000D_- Modification of existing geometric modeling, mesh generation and pre/post-processing tools_x000D_- Development of radiation, combustion, buoyancy and smoke propagation models_x000D_- CFD models including ventilation fans_x000D_- Examination of the effects of different fire suppression systems_x000D_- Parallel processing for multi-core computers_x000D_- Coupling of CFD/thermal/structural analysis tools by using new global convergence criteria, equilibrium states, interfaces and boundary conditions_x000D_- Implementation of lining spalling criteria_x000D_- Fire Risk Models incorporating the project's results _x000D_- Integration of the various software tools into a unique application_x000D_The CFD code will be verified by carrying out real-scale experiments by TST._x000D_

Acronym	TUNFEC (Reference Number: 5292)
Duration	01/10/2010 - 28/02/2014
Project Topic	The project TUNFEC aims at the development of a unified computational platform for the holistic simulation of tunnel fire effects, including fire and air flow, ventilation, smoke propagation, radiation, heat transfer, lining response and concrete spalling; experiments will support the development.
Project Results (after finalisation)	All the scientific objectives of the project have been achieved with great success. The aim of the project for the development of a unified software platform for the coupled, multi-physics, automated simulation of fire events inside tunnels and the prediction of the consequent effects on the tunnel lining, has been completely fulfilled. This unified platform with the capability of numerically simulating, testing and assessing the effects and damages of any possible fire event can be used during the design or rehabilitation stage of already damaged constructions. The final product will enable the tunnel engineers to accurately evaluate different design solutions and fire scenarios, and greatly assist the risk assessment procedure._x000D_The software developed comprises CFD analysis / thermal analysis / structural analysis and their coupled or complementary use to a more accurate holistic approach of fire events. It can be also used for the estimation of ventilation velocities for preventing the backlayering effect and the assessment of the effectiveness of various fire suppression or fire protection systems/arrangements._x000D_This software application consists of the following components (each one of them can stand as a separate scientific result of the project), most of which have been developed in the context of TUNFEC:_x000D_• Three dimensional CFD software enhanced with models for the numerical solution of the energy or heat transfer equation for the simulation of fire evolution in tunnels. The following components have been developed as new capabilities of the CFD code for the prediction of the transient flow and temperature fields and smoke propagation under fire emergency conditions in tunnels:_x000D_- Heat, smoke contaminant and volatile products sources as a function of time (transient problem)_x000D_- Radiative heat transfer model and its insertion into the CFD thermal code. _x000D_- Addition of a momentum source (nodal or surface) to model thrust of jet fans_x000D_- Amendment of Turbulence model with buoyancy production terms (k-omega SST, LES)_x000D_- Smoke/soot propagation model _x000D_- Fire suppression models_x000D_- Integration of the above components to a stable, accurate, parallel CFD tool for the evaluation of 3D flow behaviour in complex tunnel caverns. The new software has been integrated into the WinTUBE environment (FiDES’s software for modeling tunnels and dimensioning tunnel lining). _x000D_• Algorithm and interfaces for the coupling of fire spread evolution in the tunnel cavern and the heat transfer problem through tunnel lining in order to calculate the coupled temperature distribution in tunnel lining and air temperature and the concentration of gases under fire emergency conditions. The coupling procedure and relevant convergence criteria were defined, developed and tested in the context of TUNFEC. Experimental data and theoretical models for the modification of the properties of lining materials with temperature, were also incorporated into the material properties library of the relevant application of FiDES (namely WinTUBE). _x000D_High temperatures may cause explosive ‘spalling’ of the tunnel lining. The spalling effect within this Project has been treated as a thermo-mechanical process. _x000D__x000D_Two real-scale experiments of LAAB and TST were carried in order to observe the fire induced phenomena, such as back-layering phenomenon, time evolution of smoke propagation, control of ventilation velocity in order to diminish buck-layering phenomenon and reduce smoke concentration downstream the fire pool and to measure airflow quantities in order to compare experimental measurements with TUNFEC’s software results.
Network	Eurostars
Call	Eurostars Cut-Off 3

Project partner

Number	Name	Role	Country
4	ELXIS Engineering Consultants S.A.	Partner	Greece
4	FIDES DV-P Beratungs- und Vertriebs-GmbH	Coordinator	Germany
4	IL - Ingenieurbüro Laabmayr & P ZT GmbH	Partner	Austria
4	Tunnel Safety Testing, S.A.	Partner	Spain