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An arrangement in a tunnel vault

The present invention relates to an arrangement in a tunnel vault comprising elongated elements - preferably water- tight, fire-proof, heat insulating, and sound absorbing -, which are suspended at each end by the aid of suitable fastening means, as stated in more detail in the preamble of the following independent claim 1.

Upon blasting a desired profile for a road tunnel it is necessary to carry out various subsequent tasks, like safeguarding tasks to prevent rocks from falling down, and to prevent water from dripping down from the ceiling of the blasted tunnel so as to prevent a wet road surface, and formation of icicles and an iced road surface, respectively, depending on the seasons as well as depending on the length of the tunnel .

Lining the blasted tunnel by spraying a concrete cover onto the raw vault is known and used both in order to achieve a smooth surface and to safeguard against falling rocks. Such concrete spraying may also partly prevent penetration of water and dripping from the ceiling of the tunnel. In order to safeguard against falling rocks and dripping and, furthermore, to prevent leaking water from freezing at tunnel openings, it is known to provide a plate vault beneath the raw vault of the tunnel so as to deflect leaking water to the tunnel sides. In order to prevent such water from freezing, it is also known to design the plate vault with heat insulation at least close to the tunnel openings.

It is known to use plates of foamed polyethylene or sandwich-plates for a plate vault, so as to achieve a frost-proof protective screen against leaking water in road tunnels.

A problem with utilization of foamed polyethylene plates is that it is difficult to join them tightly, also the material is inflammable. Sandwich plate vaults commonly eliminate all leaks, but rather high costs limited the use of them.

Said known sandwich plate vaults and other vault structures were built from slightly curved, elongated vault elements, which are mounted in the blasted tunnel to cover the raw vault, and such elements were in part secured by bolts directly to the rock or in a concrete cover.

Such direct securing of the elements to the raw tunnel vault, inter alia, renders any replacement of elements difficult, when elements are damaged, which may happen in connection with road accidents in a tunnel. By using curved profiles for suspending elongated elements, damaged elements may be replaced more readily, as disclosed in NO-883240. When a tunnel vault is erected in raw tunnels with a bend in the longitudinal direction of the tunnel, it is known from the above mentioned publication to adapt the provided/suspended elements of equal length to the tunnel bend by securing the elements to the curved profiles with a longer mutual distance between ends on the outside of the bend, and with a smaller mutual distance between ends at its inside, and to make a corresponding adapation of the distance between the ends of said elements at the ceiling of the tunnel. Openings will, thus, be formed between the ends of elements in tunnel bends, which openings may be covered with cover profiles.

In said known tunnel structure according to NO 883240 the elements have projecting flanges at their ends, which flanges project into grooves in the curved profile and are attached to said profile by the aid of bolts passing through aligned holes in the flanges and the groove walls, with such bolts being mounted from the outside of the vault. A disadvantage of this manner of fastening is that said bolts, which must be axially displaced, are difficult to reach from the inside of the vault to dismantle damaged elements and, especially, for mounting a new element.

It is an object of the present invention to eliminate the above disadvantages in connection with mounting elements in a tunnel vault, and especially in connection with dismantling and replaceing damaged elements in tunnel vaults. This is achieved by the aid of the distinguishing features stated in the characterizing part of the following independent claim 1, and in the characterizing parts of the following dependent claims.

The invention is disclosed in more detail below with reference to the drawing, which shows some embodiments, and in which

Figure 1 is a cross section of a road tunnel with a tunnel vault built inside said tunnel and shown in perspective;

Figure 2 is a cross section of an arch profile, which is secured to rock by the aid of an anchoring bolt, with elements attached to said arch profile;

Figure 3 is a cross section of an arch profile and a longitudinal section of the end portions of adjacent elements which are attached to said arch profile;

Figure 4 shows a cross section of an alternative embodiment of the arch profile with associated securing members;

Figures 5a and b show a wide, and a narrow element, respect- ively, and Figure 6 shows a section through an arch profile and the end portions of the elements which are attached to said profile at inner vault wall in the tunnel bend, at the ceiling, and at the outer wall, respectively by use of elements of equal length.

Figure 1 shows a cross section of a tunnel vault 1 comprising elongated elements 2, which are suspended at each end by the aid of suitable fastening means, on arch profiles 3 in order to cover the raw vault 5, or if desired, a concrete cover 6 of the blasted tunnel 4. The arch profiles 3 extend across the longitudinal direction of tunnel vault 1 at an equal mutual center distance in straight tunnels and at a mutually equal center distance of the bend tops of tunnel 4. The arch profiles are secured to the raw vault 5 or concrete cover 6 of the vault by the aid of anchoring bolts 7, the free ends of which are releasably connected with arch profiles 3 by the aid of fastening means 8 (see Figures 2, 3, 4).

The elongated elements 2 are of equal length L and are suspended side by side from a pair of successive arch profiles 3 by the aid of fastening means 9. Fastening portions 3c of arch profiles 3 which face the elements 2 have a width B permitting attachment by the aid of fastening means 9, which in the drawing are shown to be self-drilling and self-tapping screws 9a.

As will appear from Figure 1 elements 2 are provided side-by-side on said arch profiles 3 and are aligned with corresponding elements 2 on one of the already mentioned arch profiles 3 and a further arch profile 3. The fastening portions 3c of arch profiles 3 facing elements 2 have a total width B which permits fastening by the aid of fastening means 9 of elements 2 which are aligned in their longitudinal direction at a mutual distance A of approximately zero and upwards (see Figure 6a, b, c), in order to correct any deviation from the normal center distance between arch profiles 3 along corresponding portions of them, e. g. in bends of tunnels.

When tunnel vaults 1 are to be erected in bends of tunnels, elements 2 of equal length L may, thus, still be used.

Elements 2 are placed in an adjoining manner, i.e. at a mutual distance A of substantially zero at the tunnel vault 1 wall which is innermost in a bend and at a large distance A3 at the outer tunnel vault wall of the bend in order to correct for the greater length of the outer bend wall relative to the inner bend wall.

Said distances A between the ends of elements 2 which face each other will, thus, vary from substantially zero between elements 2 of the inner bend wall to maximum distance A3 of the outer bend wall, via an intermediate distance A2 at the ceiling of tunnel vault 1. This distance between elements 2 increasing from the inner to the outer bend wall may be covered by a cover profile (not shown) which has a width corresponding to width B of the arch profiles 3 and which may be fastened to elements 2 or fastening profiles 3 by suitable means (not shown).

By the aid of a suitable choice of lengths L of as well as widths C of element 2, adaptable longitudinal and transversal profiles may be achieved on the finished tunnel vault 1.

In case of a sharp bend arch profiles 3 may be arranged at a lower center distance than in straight tunnels for use with elements 2 of corresponding shorter length L in order to achieve said adaptable profile. In this manner arch profiles 3 of the same width B may be used both in case of sharp and less sharp bends. In sharp bends the distance A between the ends of elements 2 adjacent arch profiles 3 will increase more towards the outer vault wall of the bend than in a gentle bend. In order to avoid that said distance A is made substantially equal to or larger than the distance between fastening means 9, i.e. screws 9a in Figures 2, 3, and 4, shorter elements 2 with correspondingly smaller distance between arch profiles 3 in the tunnel bend may be used.

Arch profiles 3 may have various cross sections, since the cross section must only have a sufficiently wide fastening portion 3c for fastening elements 2, and a portion facing in the opposite direction to secure the fastening means 8 of anchoring bolt 7.

A suitable cross sectional shape of the arch profiles 3 is shown in the drawing, Figures 2, 3, and 4, in which arch profile has a substantially U-shaped cross section with a web 3b, and legs 3a having transversal flanges at their ends constituting the fastening portions 3c for elements 2. As shown in the drawing, said transversal flanges project outwards from legs 3a. They might project both outwards and inwards or, if desired, only inwards, towards each other. In that case the U-shape must be correspondingly wide. With the shown U-shape of the arch profile in Figures 2 and 3, the web 3b constitutes the fastening portion for fastening means 8 of anchoring bolt 7. The end of anchoring bolt 7 is threaded in this case and extends through holes 3d in web 3b of arch profile 3, and it is secured to the latter by the aid of nuts 8a, one on each side of web 3b. The distance of arch profile 3b from raw vault 5 of tunnel 4 may, if desired, be slightly adjusted by the aid of nuts 8a. In Figure 2, however, an adjusting sleeve 7a is shown on anchoring bolt 7, which may have two threaded portions with opposite pitch directions for cooperation with anchoring bolt 7 and a projection of the same with opposite pitch which, in turn cooperates with nuts 8a and arch profile 3. In this manner adjustment of a distance corresponding to the length of adjusting sleeve 7a may be achieved.

In an alternative embodiment of arch profile 3, the latter has projections, if desired, grooves 10 at each end of web 3b for cooperation, preferably, with a resilient gripping hoop 8b with gripping ends 8c facing each other. At its central portion gripping hoop 8b is secured to anchoring bolt 7 by the aid of means known per se, as mentioned above.

E clamping bolt 11 with a nut 12 passing through holes 13 1 each hoop leg, is provided to ensure the hold of gripping hoop on/in projections, if desired grooves 10, of arch profile cf. Figure 4.
For mounting elements 2 on arch profiles 3 in tunnel 4 holes 2e may be drilled in elements 2 and holes 9b in fastening portions 3c of arch profile 3, while the elements are held in place, whereupon self-tapping screws 9a are inserted into said holes 2e and 9b and are tightened.

It is also possible to use selv-drilling and self-tapping screws 9a, in which case said holes 2e and 9b are provided at the same time as screws 9a are screwed in.

In order to adapt elements 2 to various tunnel cross sections, with arch profiles 3, e.g. showing relatively straight lower portions forming the walls of the tunnel vault, and a relatively acute arched ceiling, wide elements 2 may be used for the straight walls, whereas narrow elements 2 are used for the more acutely curved ceiling. In this manner it is possible to achieve rapid attachment of w de elements lowermost and a more adaptable profile uppermost with correspondingly more fastening operations for the narrower elements 2.

It may also be considered to use one or two lower elements of suitable width in order to provide for more ready replacement of said lower elements in connection with bumping.

Also, it may be considered to provide shock-absorbing elements between said elements 2 at a desired level above the roadway, which may absorb any impact motions from the lower elements 2 in connection with any bumping. Such bumping which results in damage may be caused by a large vehicle with a box-shaped truck body. In this case the damage would occur high up on the wall of the tunnel vault.

In order to achieve a water-tight tunnel vault 1 the rear faces of the elements may be provided with water-tight films overlapping the edges of adjacent elements 2, which must be placed in such a manner relative to each other that water from elements higher up flows down past the upper edge of a lower element 2 and on to the basis of tunnel vault 1 and to a drainage ditch. At the fastening points of elements 2 on arch profiles 3 rubber packings or the like may be used between the rear faces of elements 2 and the fastening portions 3c of the arch profiles. Additionally, the arch profiles 3 must then be watertight, and the fastening means 8 must be fastened to arch profile 3 in a water-tight manner as known per se.

In order to achieve a water-tight, fire-proof, heat insulating, and sound-dampening tunnel vault 1 elements 2 may be designed to be cassettes comprising a front surface of perforated steel plate 2a which faces the tunnel 4 space, as shown in Figure 3, and is filled with a filler material 2b of mineral wool or another suitable materiale. The rear side of the element consists of a water-proof and mechanically strong plastic film 2c which covers the filler material 2b and is fastened to and extends beyond the rear edge portions 2d of the cassette, with said edge portions, e.g. being provided by bending the edge portions of steel plate 2a.

Plastic film 2c may be provided in such a manner that it extends outside and beyond the upper edge and the plastic film of a lower element. In this case water may flow down and onto the basis of the tunnel vault. The plastic films may, if desired, be connected in a water-tight manner by the aid of glueing or welding. At the fastening points of elements 2 to arch profiles 3 packing strips should preferably be placed between the fastening portion 3c of the arch profiles and the plastic film 2c in order to provide a water-tight connection during mounting of elements 2 onto arch profiles 3 by the aid of fastening screws 9a.