DE19961633A1 - Production of fire-resistant tunnel construction made of concrete, especially spray concrete, comprises applying flexible sliding and water-impermeable sealing layer and inner layer made of concrete mixture - Google Patents

Abstract

Production of a fire-resistant tunnel construction made of concrete, especially spray concrete, comprises applying a flexible sliding and water-impermeable sealing layer and then an inner layer made of a concrete mixture having high carbonate fine components in the binder, carbonate additives and fine pore-forming materials as a multiple layer composite system after a first outer layer made of spray concrete is applied.

Description

The invention relates to a method for producing a fire-resistant Tunnel construction made of concrete, especially of shotcrete.

Over the past few years there have been a number of sensational ones Fires in traffic tunnels result, e.g. B. Eurotunnel, Leinebuschtunnel, Mont Blanc tunnel, Tauern tunnel, St. Gotthar tunnel, which is the problem of Fire safety in traffic tunnels has come to the fore very strongly. The impact of fires in traffic tunnel structures is not just that a hypothetical, but also a highly realistic risk. In addition to the economic problems that arise from the destruction of the construction There are also problems that pose a high risk to people themselves put. In the course of the trunk road connections and railway lines it is indispensable to have secure connection paths. On the other hand, it is undisputed ten that these fires in the past construction some questions posed. A number of proposed solutions are shown to increase the fire safety of tunnels.

In the newer road and rail tunnels there is an expansion (single-shell with shotcrete or reinforced concrete segments as well as double-skin with in-situ concrete shell), the false ceiling when ventilation ducts are arranged above the Traffic space and the carriageway slab above the base vault made of reinforced Concrete. Also for the carriageway for motor vehicles and solid concrete (FF) for rail traffic as well as the edge and escape routes, concrete is ver turns. The same applies to rescue materials and shafts.

In the event of fires in traffic tunnels, temperatures can quickly rise to 1300 ° C stand. If these only work for a short time with the mostly limited fire load, so they mean a shock effect on the concrete. Ver by the heat the water bound in crystal form during hydration evaporates in the concrete. This leads to flaking and cracks in the concrete, which increases the stability is affected. Delicate components are particularly affected small dimensions, such as B. the false ceiling above the traffic area or the segments with single-layer installation. Around this impact of fire to reduce the reinforcement concrete reinforcement (fine mesh reinforcement) or against excessive heating due to fire protects (fire protection plaster: vermiculite or perlite spray plaster in the Elbe tunnel; Fire protection panels, steel fiber concrete, etc.).  

In the event of a fire, the tunnel construction increases due to the extremely high temperature or less punctual. The structural fire protection measures must sen are dimensioned according to the previous considerations so that they the Criteria for the attack are suitable and defined for the particular case Object protection is sufficient. This means that the tunnels are constructed this way must ensure that there is no damage to the load capacity in the event of a fire or endanger the construction of the entire structure. In addition, the Function will not be disturbed. So z. B. may in the long term z. B. no leaking or deformation etc. occur. In Germany, for the Bemes solution of the structural fire protection measures of the tunnels, the so-called RABT curve assumed as a temperature curve. This curve is based on ver various metrological findings that have been collected recently have been. It is assumed that a high temperature, namely of 1200 ° C, is reached, which then subsides after half an hour.

The currently applicable assessment bases "Additional technical contract conditions and guidelines for the construction of road tunnels part 1 ", which in Germany is a contractual component of all tunnel construction designs; shows that to ensure structural fire protection, the inner shell of the Tunnels with a thickness of more than 30 cm and the reinforcement a concrete cover of at least 6 cm. This assumes that the Einhal this construction rule, the temperature at the reinforcement in the event of a fire the inner shell stays below 300 ° C and plastic stretches in the movement largely excluded. In various theoretical sub searches was first calculated purely arithmetically, what temperature distributions occur in an inner tunnel shell. It turns out that after 30 Minutes at a depth of 5 cm approximately 120 ° C, at a depth of approximately 3 cm 500 ° C and 1200 ° C on the surface. Thus the knowledge is off to ensure that very high temperatures only occur in near-surface zones ten.

In DIN V ENV 1982-1-2: Eurocode 2, part 1-2: "Planning of reinforced concrete - and Prestressed concrete structures - general rule - structural design for the Fire, German version ENV 1992-1-2; 1995 "and Hack, Sever and Krampf, German Committee for Reinforced Concrete, No. 352, pages 35-65, 1984, shows that shock-like cooling when the temperature is reached of approx. 300 ° C there is a residual load-bearing behavior of 65-70%.  

It is known to use a shotcrete mix for tunnel constructions made of steel and combine plastic fibers with special plastic dispersions that aiming for a better adhesive bond of these fibers in the concrete (DE-OS 22 21 373). Effective temperature protection for tunnel constructions however, you cannot achieve this.

DE 33 43 212 describes a method for lining construction spaces, in particular known from shafts, lines, tunnels and the like, in which a two layer system is used. The first layer is a sealing layer made of fast-reacting two-component plastic in two-component Spray applied. After that, a conventional shotcrete layer opened up. Even this lining cannot be an effective temp Ensure protection of the construction in the event of fire. In addition, the Kos factor of the two-component plastic in large tunnel constructions considerably and the processing complicated to accomplish.

The invention is based, in the event of a tunnel fire the task hand to keep the temperature influence of about 1200 ° C low and a maxi Male penetration depth of the high temperatures damaging the concrete matrix to reach a few centimeters and on the other hand a scaling of size avoid concrete parts.

Surprisingly, a large number of experiments were carried out that the solution of this task only by a system of several components can be brought about.

This is achieved according to the invention in that as a multi-layer Composite system after a first outer layer of shotcrete a flexible Slidable and waterproof layer and then an inner layer made of a concrete mixture with high carbonate fractions in the bandage medium and carbonate additives as well as fine pore forming sub punching is applied.

The outer shotcrete layer as well as the sliding and sealing layer can one operation, but applied one after the other to the overburden be, the outer shotcrete layer a thickness of max. 40 cm and the sliding and sealing layer has a thickness of 0.3-0.8 cm.  

It is also possible to apply the sliding and sealing layer in a separate operation to apply to the outer shotcrete layer.

The anti-slip and sealing layer is made of a cement-bound plastic-modified mortar with a plastic content of max. 12% by mass the plastic part made of polystyrene balls, shredded PVC and / or polyethylene and / or polypropylene and / or polybutene, e.g. B. Micro hollow spheres, or the like.

The inner shell can either be applied as shotcrete or via formwork as in-situ concrete. Portland cement with a content of at least 20% by weight of finely ground limestone is used as a binder. At least a further proportion of 60 kg of limestone filler is added to the binder per m ^{3 of} concrete.

As fine pore-forming substances, the mixture for the inner layer contains inorganic, finest additives with a melting point below 1100 ° C in proportions of max. 5% by mass and / or organic additives in parts of max. 2 kg / m ^{3 of} concrete with grain sizes of 200-250 µm on average. When using fibers, a length of <1 mm has proven itself.

The additives burn out when exposed to heat and form the finest pores achieve better insulation behavior at high temperatures and Reduce the penetration depth of the heat so that there is no deep matrix damage arise.

The special composite layer structure prevents the inside from being broken up shell, which in conventional constructions due to thermal expansion occurs.

According to the invention, the inner shell slides over gliding and heat Sealing layer on the outer shell without flaking off.

To the in the interface area between aggregate and binder matrix Avoid formation of microcracks due to the damming of water steam would be present in the event of a fire from the hydrate water, plastic balls and / or fibers (steel fibers also possible) become beige inserts to avoid flaking effects.  

Because of the risk of fire in tunnels and the damage described, he was According to the invention, a concrete is developed from these findings that has sufficient strength and tightness, but on the other hand is so ductile that no or only slight flaking and cracks occur when exposed to fire, the destruction of components (false ceilings, etc.) can be avoided.

Own complex investigations have shown the following picture. Will the conventional aggregate completely replaced by carbonite aggregates, the chipping effect decreases by about 50%. That is, with a defi temperature effect (1200 ° C, 30 min. on the surface) there are significantly fewer signs of flaking than when stressed with silicate surcharge. In the present case, these are stored on a B 55 without art fabric fibers at about 50 mm. Are higher Ge from the binder side if used, there is little spalling under similar conditions. An increase in the proportion of binder improved in our own experiments the spalling phenomena very clearly. Almost no flaking This occurs when carbonate supplements with an increased fineness portion (replacement or supplement of the fine portion) can be used. Like in Example 1 shown goes with this choice in connection with fillers creates a fine pore fraction, strongly back. This As shown by our own experiments, very fine pores can be added by adding conventional process technologies, such as fine air through additives become. However, additionally added organic fractions or inorganic additives, such as hollow microspheres (polysterol) plastic fibers, ge ground vermiculite or perilte, ground in the finest form good results. An increase in mobility through simultaneous sliding and sealing prevents the path between the outer and inner shell, as calculations have shown ben, the decoupling in the end of the block joints.

In the following, the invention is intended to be based on several exemplary embodiments are explained in more detail:  

example 1 construction Tunnel lining

• - Shotcrete 25 cm
  B 35 with 60 kg / m ³ steel fibers
• - cement-bound, plastic-coated sliding layer with sealing properties (resistant 5-8 mm against 100 bar overpressure; no detachment of the sliding and Sealing layers when train is applied)
• - Inner shells, thickness 22 cm B 45
  Concrete composition m ³
  1850 kg carbonate aggregate
  420 kg cement PKZ (CEM II / A - L 42.5 R)
  80 kg of stone flour
  0.8 kg plastic fibers
  60 kg steel fibers
  4 kg hollow micro spheres (fine air)
  W / Z = 0.42
  Spread with superplasticizer to 70 cm

Such a tunnel lining has the following advantages:

• - In the event of fire from e.g. B. 1200 ° C peak and 60 min. The duration of action does occur in the case of aggregates or fillers of CaCO ₃ → CaO, but the inner shell of the tunnel is able to remain in place for at least 24 hours without significant spalling.
• - There is no detachment of the inner shell.

Example 2

• - Shotcrete 32 cm, B 40, without fibers
• - Sliding and sealing layer 3-5 mm cement-bound
• - Inner shell 18 cm B 55
  1820 kg 400 kg PKZ (CEM II / A - L 42.5 R)
  100 kg stone powder
  0.6 kg plastic
  5.2 milled perlite
  20 kg fly ash
  W / F = 0.62
  (Water / solids)
  Spread 58 cm

This tunnel lining has the following advantages:

• - In the event of fire from e.g. B. 1200 ° C peak and 60 min. The duration of action does occur in the case of aggregates or fillers of CaCO ₃ → CaO, but the inner shell of the tunnel is able to remain in place for at least 24 hours without significant spalling.
• - There is no detachment of the inner shell.
• - However, the construction has a much longer load-bearing behavior.

Example 3

Concrete for the false ceiling, such as concrete inner shell, e.g. B. Example 1.

Claims (11)

1. A method for producing a fire-resistant tunnel construction made of concrete, in particular shotcrete, which is applied to the overburden, characterized in that as a multilayer composite system after a first outer layer made of shotcrete, a flexible sliding and water-impermeable sealing layer and then an inner layer is applied from a concrete mixture with a high carbonate content in the binder and carbonate aggregates as well as substances with fine pores. 2. The method according to claim 1, characterized in that the outer spray concrete layer as well as the sliding and sealing layer in one step can be applied to the overburden one after the other. 3. The method according to claim 1 and 2, characterized in that the sliding and sealing layer in a separate operation on the outer shotcrete layer is applied. 4. The method according to claim 1 to 3, characterized in that the outer Shotcrete layer with a thickness of max. 40 cm - over profile not included - is applied. 5. The method according to claim 1 to 4, characterized in that the sliding and sealing layer is applied in a thickness of 0.3-0.8 cm. 6. The method according to claim 1 to 5, characterized in that the sliding and sealing layer made of cement-bonded plastic-modified mortar a plastic content of max. 12 M% is produced. 7. The method according to claim 6, characterized in that as Kunststoffan some polystyrene balls, shredded fibrous PVC and polyethylene and / or Polypropylene and / or polybutene residues, e.g. B. hollow microspheres, and the like. be used.   8. The method according to claim 1, characterized in that the inner shell is applied as shotcrete or as in-situ concrete. 9. The method according to claim 1 and 8, characterized in that as a bandage medium a Portland cement with at least 20 M% finely ground limestone is used. 10. The method according to claim 1, 8 and 9, characterized in that the binder at least 60 kg / m ³ concrete limestone filler is added as a carbonate fine fraction. 11. The method according to claim 1, 8, 9, 10, 11, characterized in that inorganic fine additives with a melting point below 1100 ° C in proportions of max. 5% by mass and / or organic additives in proportions of max. 2 kg / m ^{3 of} concrete with grain sizes of on average 200-250 µm are added.