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High performance tunnel lining systems as a cost effective part of a fire
protection system
Dr.-Ing. Roland Bornemann
Contents
• material introduction
• structural safety in tunnels according to ZTV-regulations and xicompensation measures
• user safety – retrofit of smoke extraction
• quick installation methods
• Colouring of lining systems and effect of colour
Group of companies
Xella International GmbH
Building materials / bricks & elementsDry lining
systems / boardsRaw
materials
Calcium silicateblocks
Aerated concrete
Aerated concrete
Gypsum fibreboards
Fireprotection
boards
Lime &limestone
Mineralinsulation
boards
What we are taking about: cementitious fire protective boards
consisting mainly out of:
• Hydraulic binder• Perlite
• AR-resistent fibres
• Water
Highly resistant against
• Humidity• frost/thaw
• Deicing agents
Fire protection via:
• Low lambda values
• Water evaporation
Protection of tunnel structures -Type I: cast on version
Protection of tunnel structures -Type I: cast on version
Installation of boards and fixation
of backing strips
Placing of steelreinforcement
Placing of concrete
Protection of tunnel structures -Type I:cast on version
Fire protection boards on framework
Bolted version –Type II: for new structures and retrofit
Bolted to concrete of circular tunnels with backing strip es.
Lilla Bommen, GothenburgHerrentunnelLübeck, D
Backing stripes in order to safeguard
protection in joint area
View into a completed structure
Bolted version –Type II: for new structures and retrofit
Why tunnel lining systems?
Montblanc tunnel 24/03/1999
• Truck with 9 tons of margarine and 12 tons of flour caug ht fire
• Other vehicles caught fire
• fire burnt for over 53 hours
• Peak temperatures higher than 1000°C were reached
• 39 people died
• tunnel was closed for over 3 years
Objectives of a protection system
• Structural safety
• Protection of users (self rescue, 15 minutes)
• Third party rescue (fire fighters)
Theses targets are similar worldwide
Measures taken differ according to national regulations
Structural safety
• Keep temperatures at reinforcement steel < e.g. 300°C (ZTV-Ing criteria)
resi
dual
str
engt
h
resi
dual
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engt
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Structural safety
• Avoid spalling of concret
Tensile strength of HPC
Tensile strength of OPC
Vap
our
pres
sure
[N/m
m²]
Temperature [°C]
Vapourpressure
Destruction of concrete due to:
• Limit concrete deterioration
Structural safety
Bornemann, Roland et al.: fire restistance of UHPC. IN: beton, p.418-422 (9/2002)
Measures for structural safety – ZTV-ING
• peak temperature at reinforcement shall not exceed 300°C
• concrete cover of 60mm plus N94 mesh keeps concrete cove r in place when spalling starts
• further measures are not taken – is that sufficient?
With N94 mesh
Check*) of ZTV-criteria
*) Dehn, F.; Nause,P.; Juknat,M.; Orgass, M.; König, A.: Brand- und Abplatzverhalten von Faserbeton in Straßentunneln. IN: Berichte der Bundesanstalt für Straßenwesen Heft 73B
Tubbingconstruction
Open construction
Fly ash
HWRA
water
Aggregates
Fibres
CEM I 32,5R
Fly ash
w/c(eq.)
w/c
Open construction
ZTV-Ing fire curve and effect on open construct.: steel d12/15mm test with N94 mesh
Thermocouples at 60mm
Thermocouples at 3 – 60mm
ZTV-Ing fire curve and effect on open construct.: steel d12/15mm test with 2kg/m³ PP-fibre
Thermocouples at 60mm
Conclusion:
• No spalling possible because of a porous structure >60vol-%
• better insulation properties
• easy to replace
•Concrete is not kept from spalling by using a N94 mesh
• This is an unreliable approach
• PP-fibres enhance performance
• PP is not perfect because the ZTV-Ing- criteria of <300°C at 60mm is notxfulfilled in all parts
• Concrete cover nevertheless is destroyed > repair with sprayed concrete
Improvement
Solution = porous tunnel lining system
• concrete cover can be reduced > savings• Lining boards can be used as formwork > savings
Positive side effects
Complete heat consumption
At 1.200°C = cp + phase change =
For a 30mm board = 11.700Wh
This equals 19Liter/m² of water
Fundamental idea: consumption of energy from fire
Porous structure: No spalling possible > room for vapour expansion
Stark et al.:Durability of conrete
Calcium Silicate phases dehydrate
� 3CaO*SiO2 + 3*H2O
� 24wt.% are chemically bound water
Ca(OH)2 about 25% of cement weight
Example: tunnel ceiling with 20mm board as lost formwork
Boards 20mm
ceiling
Concrete cast on fireprotective board withoutfixations
Test setup:
• temperature and duration according to ZTV-Ing
• Thermocouples at interface and at 50mm
In order to simulate this setup test according to ZTV-Ing on a furnace
150
20
50
1200
Thermocouples 7 and 8: 50mm fromconcrete surface
Results
∆ 220°C
Conclusion 1:
• ZTV-Ing (car) criteria of 300°C over 90 minutes can be m atched with a reduced concrete cover (e.g. cmin 40mm exposition class XD > EC2-1-1/ZTV-5)
• Spalling is avoided by highly porous material
• Fire protective board can easily be replaced (anchored version)
Conclusion 2:
• In order to take advantage of a reduced concrete cover, the material mustsufficiently resistant against frost and thaw
• If not it will deteriorate and no longer offer a sufficient fire protection
Water spray, splash water and leaks > sources of water
Passive fire protection boards should withstand frost
According to ZTV-Ing Part 3 tunnel members should comply with the exposition classes:
� Ceilings exposed to spray = XF2/XD2 (modestly water saturated + deicing agent/Clorides)
� Ramps and portals (spray and splash water) = XF2/XD2
Cementious boards underneath a leakybutt joint Water sprag at portals
Test method: EN 12467 „fibre reinforced boards“
�100 Cycles (class X for all usages, exposed to weather) �Frost (-20°C) / deicing in water bath (20°C) � Comparision of bending strength of frosted/unfrosted samples
(ratio of bending strength >0,75)
Problem: X-class can´t be matched with XF2
Deicing in water Frosting
Surface resistance to thaw and deicing agents
Test method: Slab test (Ö-Norm B3003), 56 cycles
• Guideline „Protective coatings for enhanced fire protection in undergroundtransport systems of the austrian association of concrete and engineering
Number of CyclesScaling
Exposition class Scaling [cm³/m²]
XF4 = for road tunnels without protective coating for portals
XF2 = for road tunnels without protective coating in frosted areas
XF2 = XF 3 = for road tunnels with protective coatings
Surface resistance to thaw and deicing agents
Uncoated specimen > Test method: Slab test > extrapolation of 25 years of use
Before cycling
After 56 cycles
Exposition classes XF1 / 2 / 3
• Guideline „Protective coatings for enhanced fire protection in undergroundtransport systems of the austrian association of concrete and engineering
Surface resistance to thaw and deicing agents
After 56 frost and deicing cycles
• Epoxy coated surfaces
Exposition classes XF1 / 2 / 3 / 4
Other fire curves are more challenging in terms of temperature and duration –what can we do?
Higher requirements than ZTV-Ing:
Femern-belt-Tunnel
RWS 180 minutes
Comparison of ZTV-Ing.-curve versus RWS-curve with regard to temperatureof steel behind 60mm concrete cover*)
*)Dehn, F.; Hauswaldt, S.; Juknat, M.: Grundsätzliche Überlegungen zur Brandprüfung von Tunnelbauteilen. IN: Beton- und Stahlbetonbau 104 (2009), Heft 12
ZTV-ING curve 140 minutes
Exposure to RWS-curve over120Minutes and defined coolingafterwards
Concrete with 2 kg/m³ PP-fibre addition (mix 1)
Concrete with 2 kg/m³ PP-fibre addition (mix 2)∆ 300°C
Elevation:
RWS 120 with 40mm and anchored boards
Temperatures on concrete surface
Elapsed time [min.]
tem
pera
ture
[°C]
Thermal analysis of fire protective board lined walls• finite element analysis
• unidirectional
• parameters: λ(temp), α and enthalpy > dE/dtemp
Layer temperatures 20mm boards with equilibrium moisture and firecurves according to ZTV-Ing and EBA
�Good match between measurement and calculation
� substitute for real fire test
Inner surface
Outersurface
Objectives of a protection system
• Structural safety �
• Protection of users (self rescue, 15 minutes)
• Third party rescue (fire fighters)
EC guideline 2004/54/EG to improve safety in tunnels
Emergency exits accord. to RABT every 300m > retrofit sometimes difficult
Alternatively smoke extraction system > installation at night shifts
Idea: retrofit of existing tunnels with prefabricated smoke extraction ceilings
Example: Elbtunnel Hamburg, tube 4 (Kaefer Construction)
• 3100m long – transverse smoke removal
• smoke extraction every 60m by four extraction flaps
• 1700 prefabricated elements with Aestuver 2x50mm boards
• Installation speed 10 – 12m per night (8h shift, closin g of tunnel)
� Quick and effective installation overnight� Design according to ZTV-Ing 5
> Stainless steel substructure class II (ZTV-4 betriebstech. Ausstatt.)> matches 300°C criteria for steel substructure> average surface temperatures < ∆140K> leakage <10Vol.-%
� Complies with RABT-requirements> tunnel longer >1200m > smoke extraction via electric driven flaps> adjustable flaps at a distance of 60m> Air extraction approx. 240m³/s
Idea: retrofit of existing tunnels with prefabricated smoke extraction ceilings
Film
Other ways to make installation easier
Wesertunnel
Experience of safety –
or what people prefer
What should be changed?
Which are the prefered colours?
Andreas Mühlberger, university of würzburg:behaviour of humans in tunnel. IN: Solid² conference 2012 in Berlin
Epoxy coated surfaces
Light blue Patterns Orange
Gloss