Concrete repair of tubbings

Abstract

A lining (2) for an inside surface of a tunnel, preferably the inside surface of tubbings, wherein it is provided in accordance with the invention that it comprises at least two layers of different tensile strength and extensibility.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Austrian Application No. GM 285/2008 filed May 19, 2008. Applicant also claims priority and this application is a continuation under 35 U.S.C. §120 of International Application No. PCT/EP2009/056000 filed May 18, 2009, which claims priority under 35 U.S.C. §119 of Austrian Application No. GM 285/2008 filed May 19, 2008. The international application under PCT article 21(2) was not published in English.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a lining for an inside surface of tunnels, especially the inside surface of tubbings, according to the preamble of claim 1.

2. Description of the Related Art

In tunneling, excavation is performed either by blasting or with special tunnel boring machines. So-called tubbings are frequently used in mechanical tunnel construction with tunnel boring machines. These concerns prefabricated concrete parts which are used as lining elements for the inside shell of a tunnel. As a result of the different loads that act upon the inside shell of a tunnel such as the loads from rock pressure, water pressure, filling pressures, or the dead weight, tubbings with a thickness of 20 to 40 cm are required. These tubbings are compiled in the course of tunnel advance by means of suitable machines into a first outside inner shell of the tunnel. The handling of the heavy tubbings occurs with the help of recesses in the tubbings, the so-called erector cones, in which the respective mandrels of special working machines engage. The tubbings are screwed together, which occurs with the help of further recesses in the tubbings, the so-called screw pockets, in which the screws are accommodated in an obliquely lying fashion. These recesses can have diameters of up to 20 cm. Butt joints are further obtained between the respective adjacently disposed tubbings which also represent irregularities in the surface.

A lining is then fastened to the inside surface of the tubbings such as plastic seal sheeting (KDB) made of a flexible plastic material in order to form a water-impermeable layer. The extensibility of the lining is especially important for the reason that future movements and deformations of the inside shell of the tunnel will not lead to any tearing of the lining and for the compensation of irregular surface profiles such as those caused by elevations or depressions in the surface of the tubbings. The fastening of this water-impermeable layer to the tubbings occurs increasingly by gluing. Although mechanical fixing would be possible, it is rarely used in practice due to high costs.

Finally, a concrete shell is provided for reasons of fire protection which seals the inside shell of the tunnel towards the interior of the tunnel. This fire-protection shell made of concrete is usually arranged with light reinforcement. This leads to the problem in practice that as a result of the pressure exerted on the lining the lining is pressed into the recesses of the surface of the tubbings such as the erector cones and the screw pockets, which might lead to damage to the lining and thus to an impairment in the impermeability of the same. Although the recesses can be filled, mortared or plugged, such a measure is very work-intensive because an inside surface of a tunnel made of tubbings usually comprises several thousand such recesses.

SUMMARY OF THE INVENTION

It is therefore the goal of the invention to avoid this problem by suitable measures, especially damage to the lining and impairment of the watertightness by the surface irregularities in the inside surface of the tunnel, preferably the inside surface of tubbings.

This goal is achieved by the features of claim 1. Claim 1 relates to an inside shell of a tunnel comprising a lining for an inside surface of the tunnel, preferably the inside surface of tubbings, with the lining comprising at least two layers of different tensile strength and extensibility, wherein it is provided in accordance with the invention that the lining comprises two layers with a first layer consisting of an elastic plastic material with higher extensibility than the second layer, and the second layer consists of a tear-proof fabric, and the first layer is connected to the second layer at least in sections. The lining can thus be optimized to meet two different requirements. On the one hand, the previously desired properties are given by the layer with higher extensibility but lower tensile strength, and on the other hand the second layer with lower extensibility but higher tensile strength prevents bulging of the lining into the recesses of the inside surface of the tunnel such as the erector cones and the screw pockets of the tubbings. The choice of tensile strength and extensibility of the layer with lower extensibility will be adjusted to the respective requirement. If it is necessary to cover comparatively large recesses and prevent any considerable bulging of the lining, higher tensile strengths or very low extensibilities are necessary. If it is only necessary to cover the butt joints between adjacent tubbings, a comparatively low tensile strength and a higher extensibility can be chosen. The respective choice of tensile strength and extensibility will easily be made by the person skilled in the art with the knowledge of the surface to be coated, especially the occurring irregularities of the surface.

In accordance with a preferred embodiment, the second layer can especially concern a polyester, polyethylene, carbon or glass-fiber grid fabric.

In accordance with a further preferred embodiment, the first layer can be laminated or glued onto the second layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained below by reference to an embodiment shown in the enclosed drawings, wherein:

FIG. 1 shows a schematic view of a tunnel profile with a multi-layer inside shell of a tunnel, comprising a first shell made of tubbings, a water-impermeable lining, and a reinforced or non-reinforced concrete shell;

FIG. 2 shows a schematic illustration of an embodiment of the lining in accordance with the invention with a tubbing, and

FIG. 3 shows a schematic view of a tubbing.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is made at first to FIG. 1, which shows a schematic view of a tunnel profile, as was obtained by excavation by blasting or by special boring machines which drill a tunnel tube through the rock. The tunnel tube is then either provided with a layer of spray concrete or lined with tubbings 4. These concern prefabricated concrete parts which are lifted by special working machines to the tunnel tube and are screwed together. Erector cones 6 are provided for this purpose on the one hand, in which the mandrels of the working machines engage in order to enable handling with the heavy tubbings 4, and on the other hand trapezoid screw pockets 5 which are used for accommodating the connecting screws (also see FIG. 3). The tubbings 4 which are screwed together form a first shell 1, on which a water-impermeable lining 2 is subsequently fastened, mostly by means of gluing. The lining 2 concerns a flexible plastic material such as PVC, a flexible polyolefin, a softly set polyethylene such as VLDPE (Very Low Density Propylene), or polypropylene. A concrete shell 3 is provided next to the lining 2, which concrete shell is usually provided for reasons of fire protection. The fire-protection concrete shell is usually provided with a light reinforcement with a weight of approx. 1.0-2.0 kg/m². It is also possible to provide reinforced or non-reinforced concrete shells.

As a result of the pressure exerted on the lining 2, the lining 2 will be pressed into the recesses of the tubbing surface without the measures in accordance with the invention, e.g. into the erector cones 6 and the screw pockets 5, which might lead to damage to the lining 2 and thus an impairment in the impermeability of the lining. That is why it is provided in accordance with the invention that the lining 2 comprises at least two layers 2a, 2b with different tensile strength and extensibility. The first layer 2a with higher extensibility provides the previously desired properties, and the second layer 2b with the higher tensile strength and lower extensibility prevents the bulging of the lining 2 into the recesses on the inside surface of the tunnel, e.g. the erector cones 6 and the screw pockets 5 of the tubbings 4. The choice of tensile strength and extensibility of the second layer 2b with lower extensibility will be adjusted to the respective requirements. If comparatively large recesses need to be covered without providing any considerable bulging of the lining 2, very low extensibility in combination with high tensile strength is required for the second layer 2b. If it is only necessary to cover butt joints between adjacent tubbings 4, a comparatively higher extensibility with lower tensile strength can be chosen, which can be compared with differently thick steel cables for taking up different loads.

The first layer 2a can consist of an elastic plastic for example and the second layer 2b of a tear-proof fabric. In particular, the second layer 2b can concern a polyester, polyethylene, carbon or glass-fiber grid fabric. In accordance with a preferred embodiment, the first layer 2a can be connected at least in sections with the second layer 2b, preferably laminated or glued onto the same.

On the one hand, in the course of mounting the lining 2 in accordance with the invention, the fastening of the second layer 2b with higher tensile strength can be made to the tubbings 4 of the first shell 1 in a first method step, and the fastening of the first layer 2a with the higher extensibility to the second layer 2b in a second method step. On the other hand, the fastening of the lining 2 with the first layer 2a and the second layer 2b which were connected with each other at least in sections in a preceding method step to the tubbings 4 can also be made in a method step. This procedure is recommended when a prefabricated lining 2 with the two layers 2a, 2b for the lining of the inside walls of tunnels is already available.

The coating 2 in accordance with the invention can thus be used to prevent damage to the coating 2 and impairments in the watertightness by irregularities in the inside surface of the tunnel, preferably the inside surface of tubbings 4. The measures in accordance with the invention represent a comparatively inexpensive solution and ensure in particular that the time-consuming and expensive repair of concrete and plugging of the various depressions and openings such as joints, cones, pockets, flaked parts, holes of suspensions, tubings, etc. can be avoided.

Claims

1. An inside shell of a tunnel, comprising a lining (2) for an inside surface of a tunnel, preferably the inside surface of tubbings, with the lining (2) comprising at least two layers of different tensile strength and extensibility, wherein the lining (2) comprises two layers with a first layer (2a) consisting of an elastic plastic material with higher extensibility than the second layer (2b), and the second layer (2b) consists of a tear-proof fabric, and the first layer (2a) is connected to the second layer (2b) at least in sections.

2. An inside shell of a tunnel comprising a lining (2) according to claim 1, wherein the second layer concerns a polyester, polyethylene, carbon or glass-fiber grid fabric.

3. An inside shell of a tunnel comprising a lining (2) according to claim 1, wherein the first layer (2a) is laminated or glued onto the second layer (2b).