EP0741231A1

EP0741231A1 - Sealing section for building segments, in particular tunnel segments

Info

Publication number: EP0741231A1
Application number: EP96201230A
Authority: EP
Inventors: Hendrikus Kramer
Original assignee: Trelleborg Bakker BV
Current assignee: Trelleborg Bakker BV
Priority date: 1995-05-04
Filing date: 1996-05-03
Publication date: 1996-11-06
Also published as: NL1000310C2

Abstract

The invention relates to a sealing section (1) for use in tunnel segments and like building elements, manufactured from rubber, rubbery or plastic material, comprising a top surface (2), a bottom surface (3) and two flanks (4) joining the top surface and the bottom surface, with a number of channel-shaped recesses (5) extending under the top surface in the longitudinal direction of the sealing section, wherein the top surface is substantially convexly curved in a direction transverse to the longitudinal direction of the section. The invention also relates to a tunnel segment or like building element comprising a sealing section according to the invention.

Description

This invention relates to a sealing section according to the preamble of claim 1. Such a sealing section is known from European patent specification 0,255,600.
The known sealing section is a section made of rubber or rubbery material, comprising a body of great length compared with its width and height. The body has a top surface, a base surface located on the opposite side of the body, and two flanks joining the top surface and the base surface. Provided in the base surface are a number of grooves, which are open towards the lower end and extend in the longitudinal direction of the section. Further, a series of channels of circular cross section are provided between the grooves and the top surface.
The channels in the base surface define leg-shaped parts on which the section can be supported in a groove in a tunnel segment, while the flanks can be in contact with the sidewalls of the groove. Upon loading of the top surface by, for instance, a section of an adjacent tunnel segment, the legs and the parts between the channels are elastically deformed, whereby the channels and grooves are partly or wholly filled up. The top surface is pressed under tension against the top surface of the adjacent sealing section and thereby provides a sealing of the joint between the two tunnel segments. Moreover, the section is pressed via the legs thereof against the bottom of the groove, so that a second sealing is obtained, which prevents passage of water between the sealing section and the bottom of the groove.
The known sealing section has the disadvantage that in particular the sealing between the sidewalls of the groove and the flanks of the sealing section is not optimal, in particular not when the tunnel segments are not accurately positioned. As a result, the sealing action of the known sealing section is limited, in particular at relatively high pressures, for instance when used at relatively great depth. A further disadvantage of the known sealing section is that shifting of the tunnel segments relative to each other involves the risk of sealing problems arising in that one or each of the sealing section deforms and/or moves as a result of high frictional forces.
It is noted that comparable sealing sections are known from European patent specifications EP 0,210,326, EP 0,222,968, EP 0,306,796, EP 0,340,659 and Dutch laid-open application 8600057.
The object of the invention is to provide a sealing section of the above-described type, whereby the disadvantages mentioned are avoided while the advantages thereof are maintained. To that end, the sealing section according to the invention is characterized by the features according to the characterizing portion of claim 1.
The curved, convex top surface of the sealing section according to the invention provides the advantage that upon loading thereof in a direction approximately perpendicular to the longitudinal direction of the section, which is the usual loading direction during use, the flanks of the section are pressed away laterally, more tightly against the walls of a groove in which the section is at least partly received during use, or against another surface of the building segment to be sealed. In the convex upper part of the sealing section, the pressure forces are transmitted laterally as pressure forces parallel to the surface. This means that according as the load on the section is higher, the sealing between the flanks of the section and the or each surface of the building segment against which the flanks abut increases and hence improves.
The known sealing section has a substantially flat top surface which upon loading gives rise to a uniform distribution of the pressure force over the top surface, with the result that the top surface as a whole is pressed away approximately transversely to the surface of the building segment. In other words, the top surface is pressed away approximately straight in the direction of the pressure force, with the deformation of the sealing section being accommodated mainly by the grooves filling up at the underside and possibly in the middle of the section. As a result, the sealing of the flanks against the sides of the groove is not optimally increased as with a sealing section according to the invention. Given a point load in a central portion of the top surface, the known section even entails the danger of the flanks being pulled away from the sides of the grooves towards the centre, so that the leak seal is lost at that point. With a sealing section according to the invention, this danger is prevented, since in the case of such loading too, the flanks are pressed against the sides.
Accordingly, when a sealing section according to the invention is used, during use a seal on four sides is obtained, viz. between the top surface and an adjoining top surface of an adjacent section, on opposite sides between the flanks of the section and surfaces of the building segment, in particular sidewalls of a groove fabricated therein, and between the bottom surface of the sealing section and a surface of the tunnel segment against which the sealing section is positioned, in particular the bottom of a groove provided in the tunnel segment. As a result, the sealing action of a sealing section according to the invention is more complete than that of the known sealing section, which chiefly provides a seal on two sides only.
A further advantage of the convex curvature of a sealing section according to the invention is that if two sealing sections of adjacent building segments or a sealing section and another adjacent surface are brought into contact with each other, it is still possible to displace them relative to each other in a simple manner, without giving rise to undesired displacements or deformations of the or each section, because the contact surface initially is relatively small. In the known sealing sections this movement is counteracted, often by ribs in the contacting surfaces, so that upon transverse displacement the or each section may be pressed out of the groove or at least be deformed.
When use is made of a sealing section according to the invention which has the convex top surface thereof pressed against an abutment surface, for instance a further sealing section, while the or each sealing section is at least partly compressed, then, upon loading by water pressure from the outside, the top surface is further compressed on the side proximal to the water. This results in an increased pressure of the flanks against the abutment surfaces in question, so that the sealing action is increased even further upon increase of the water pressure. With the known sealing section, by contrast, at least the flank located on the side proximal to the water is pulled away from the abutment surface in question, which increases the risk of leakage.
In an advantageous embodiment, a sealing section according to the invention is characterized by the features according to claim 2.
The arcuate top part provides in a highly convenient manner for the transmission of pressure forces exerted on the top surface to the flanks. The legs extending at a mutual inclination, which support the top part, constitute resilient parts which provide a favorable spring characteristic. Upon compression of the top part, pressure forces are exerted in each leg. Initially, the leg is slightly compressed, for which purpose a great deal of energy is absorbed. Thereafter, each leg bends outwards in a direction transverse to the direction of compression, so that deformation of the leg requires relatively little force. Eventually, when a maximum bend has been achieved, further deformation of the leg will arise by compression of material, which in turn requires relatively much energy. Accordingly, in a deformation diagram of a sealing section according to the invention, a curve with a relatively flat central portion is obtained. The resilient parts have a relatively flat spring characteristic over a relatively long range, which is favorable for the sealing action of the sealing section.
The invention further relates to a tunnel segment or like building element, comprising a sealing section according to the invention. Such a tunnel segment is characterized according to the invention by the features according to claim 5.
In such a tunnel segment, the convex top surface of the sealing section always extends above the surface of the tunnel segment in which or on which it is arranged. This provides the advantage that both a relatively large and a relatively small compression of the or each sealing section result in a seal being obtained. When two such tunnel segments are placed next to each other, with the or each sealing section interposed between them, the tops of the convex top surfaces will touch first. Upon further approximation of the tunnel segments, the contact surface becomes larger and larger, until the tunnel segments have been brought into the desired position, for instance in that they touch. Since the convex top surface always extends outside the relevant surface of the or each tunnel segment, the transmission of the pressure forces to the flanks is always maintained, so that the sealing action thereof is always optimal.
Further advantageous embodiments of a sealing section and tunnel segment according to the invention are characterized by the features according to the subclaims.
To clarify the invention, exemplary embodiments of a sealing section will be described with reference to the drawings, wherein:

Fig. 1 is a perspective view of a first exemplary embodiment of a sealing section according to the invention;
Fig. 2 is a cross-sectional elevation of two adjacent tunnel segments, each provided with a sealing section according to Fig. 1;
Fig. 3 is a perspective view of a second exemplary embodiment of a sealing section according to the invention; and
Fig. 4 is a graphic representation of the correlation between the extent of compression of a sealing section and the leakage pressures occurring.

A sealing section 1 as shown in the drawing is manufactured from rubber, plastic or a material comparable with rubber, for instance by extrusion. The suitable material can be simply determined by any skilled artisan on the basis of the desired sealing action and other conditions of use. The sealing section 1 has a top surface 2, a bottom surface 3, two flanks 4 joining the top surface 2 to the bottom surface 3 and three channel-shaped recesses 5 extending in the longitudinal direction of the section 1. In the exemplary embodiment shown, the bottom surface 3 is flat, the flanks 4 extend from the bottom surface 3 and slant outwardly. The top surface 2 is convexly curved in a direction transverse to the longitudinal direction of the section 1 and joins the flanks 4 on the side remote from the bottom surface.
The top surface 2 is formed by the top side of an arcuate top part 6 which extends at the top along the recesses 5 between the flanks 4. The top part 6 is supported on opposite sides by a flank part 7 forming the corresponding flank 4 and centrally by two legs 8 extending at an inclination relative to each other and the bottom surface 3. The flank parts are slightly thicker than the top part 6. In the direction away from the bottom surface 3 the legs 8 slant inwards and meet approximately at the underside of the top part 6. The legs have a slightly hourglass-shaped cross section with an average thickness approximately corresponding with the thickness of the flank parts 7 and extend over the entire length of the section 1. At the lower end, the legs 8 and the flanks 4 are connected through a relatively thin bottom part 9. The central recess 5' accordingly has an approximately triangular cross section with the vertex at the top; the two recesses on opposite sides thereof have a slightly drop-shaped cross section. Owing to the bottom part 9, the recesses are closed off on all sides when the ends of the sealing section have been closed against each other.
By way of illustration, a number of dimensions are given of a possible embodiment of a sealing section according to the invention, which dimensions should not in any way be construed as limiting. The convex top surface has, for instance, a bending radius of approximately 55 mm, with the cross-section of the sealing section having a maximum width of approximately 55 mm and a maximum height H of 16 mm. The flank parts have a thickness of approximately 6 mm, the average thickness of the legs is also approximately 6 mm. The bottom part is approximately 2 mm in thickness. The top part has a thickness of approximately 4 mm, the legs include an angle of approximately 60° with the bottom part, the flanks an angle of approximately 70°.
As appears, for instance, from Fig. 3, a different (greater or smaller) number of recesses can be chosen, depending on the desired properties of the sealing section or, in principle, the channel-shaped recesses can be omitted.
Referring in particular to Fig. 2, a sealing section according to the invention can be used as follows.
Two building elements, in particular tunnel segments, are provided with a continuous groove 11 in the side surfaces 10 forming the longitudinal edges. Such tunnel segments are used in particular in drilled tunnels, have in a first direction a bending radius corresponding with half of the diameter of the tunnel to be formed (a radius of a few meters, for instance 3 m) and are substantially straight in a direction perpendicular to the first direction, that is, have in that second direction an infinite bending radius. The groove 11 is trough-shaped, its cross section substantially corresponding with the shape of the bottom surface 3 and the adjoining flanks 4 of the sealing section 1. The convex top surface 2 extends entirely above the relevant side surface 10 and has a bending radius R which is less than a bending radius, if any, of the relevant side surface 10. In the exemplary embodiment shown, the side surface 10 has an infinite bending radius.
After a tunnel opening has been drilled, a suitable number of tunnel segments 12 are arranged by the side surfaces 10 thereof in the tunnel opening, so as to form a circular tunnel element. Such a tunnel element can for instance be made up of some eight tunnel segments each including an angle of 45°, having a length of about 1.20 m and a thickness of, for instance, 12 cm. The tunnel segments are prefabricated from, for instance, concrete. Each tunnel segment 12 comprises a circumferential sealing section 1 or is at least provided with such a section on all side surfaces. Between the tunnel segments 12, pairs of sealing sections 1 are placed against each other through their respective convex top surfaces 2, with the tops thereof preferably in abutment. Then the tunnel segments are pulled against each other using connecting bolts 13 or like tensioning means. The curved top part 6 of each sealing section 1 is thereby pressed in the direction of the bottom of the groove 11, with the legs 8 and possibly the flank parts 7 providing a counterpressure. A part of the pressure force exerted by the abutting sealing section 1 on the top part 6 is transmitted directly in a direction approximately parallel to the top surface 2, so that the flank parts 7 are pressed away outwardly, that is, in the direction of the sidewalls of the groove 11. As a result, an optimum seal against the sidewalls of the groove 11 is obtained.
When the sealing section 1 is compressed, a part of the pressure force is transferred to the legs 8 jointly behaving as a compression spring. Initially, the legs 8 are slightly compressed in the longitudinal direction. When a given force, which is dependent inter alia on the dimensions and the material, is exceeded, each leg 8 buckles to some extent, so that two bending points arise. Further deformation of the legs 8 thereafter occurs through outward bending of the legs 8. That requires a relatively small, substantially constant additional deformation force. Only when the legs have been bent outwards to the extent where at least one of the sides of the legs touches another part of the section, the required deformation force increases again relatively strongly. The legs thereby provide, in particular in the central region, for a relatively long deformation path with a relatively flat deformation characteristic, so that the sealing action of the sealing section increases proportionally to the deformation of the sealing section over a long path.
The legs 8 are supported via the bottom part 9 by the bottom of the groove 11. As a result, at the location of the legs 8 a pressure peak is obtained, so that a doubled optimum sealing action of the underside 3 of the sealing section against the bottom of the groove 11 is obtained. As a result, leakage is prevented. In an embodiment with several legs 8, as shown in Fig. 3, a greater number of barriers are obtained, so that the protection against leakage is increased. Simultaneously, a pressure peak is obtained adjacent the top of the legs 8 in the top part 6, so that a maximum seal is obtained there. This pressure peak will also arise if the two sealing sections 1 have not been placed against each other with the tops of the convex parts 2 in exact alignment, for instance as a result of a slight misalignment of the tunnel segments, so that in the case of such an arrangement too, an optimum seal is obtained. Moreover, tunnel segments can move slightly relative to each other when the sealing sections 1 are pressed against each other, without the sealing sections thereby being undesirably deformed as a result of friction arising or moved within the groove 11. Adjustment of the tunnel segments accordingly remains an option for a long time.
When two tunnel segments 12 with interposed sealing sections 1 have been brought in the desired position and secured, an optimum sealing is obtained on four sides of each sealing section 1. Moreover, when the two sealing sections 1 pressed against each other are loaded by water or a like pressure medium from one side (in particular the outside of the tunnel), the sealing sections are compressed slightly further on the loaded side. As a result, the sealing section has its flanks 4 pressed even more firmly against the sidewalls of the groove 11, so that the sealing action of the sealing section, upon increasing pressure, increases too, while the other seals remain optimal.
Fig. 3 shows an embodiment of a sealing section according to the invention in which two pairs of legs 8 are included between the bottom part 9 and the top part 6. This number of pairs can naturally be greater or be shaped differently, depending upon the desired spring characteristic. The recesses in the sealing section preferably have such dimensions that when two adjacent tunnel segments have been pressed against each other completely, the sealing sections are received entirely within the grooves 11 and the recesses are fully closed under the pressure. In this way, optimum use is made of the material of the sealing section.
To clarify the sealing action of a sealing section according to the invention, an example of a sealing section under test conditions will be described with reference to Fig. 2.

EXAMPLE

Two steel plates are provided with a groove in which a sealing section according to the invention is received in the position shown in Fig. 2. The dimensions of the sealing sections are as follows:
The convex top surface has a bending radius of approximately 55 mm, with the cross section of the sealing section having a maximum width of 55 mm and a maximum height H of 16 mm. The flank parts have a thickness of 6 mm, the average thickness of the legs is also approximately 6 mm. The bottom part is 2 mm thick. The top part has a thickness of 4 mm, the legs include an angle of 60° with the bottom part, the flanks an angle of 70°. The sections are partly glued in the grooves. The groove depth is 8 mm, so that each sealing section extends 8 mm at a maximum above the top surface of the respective steel plate.
The distance Y between the side surfaces of the steel plates is adjustable, so that the depth of compression of the sealing section can be varied between 0 mm (Y=16 mm) and 8 mm (Y=0 mm). The steel plates are moreover displaceable in the direction transverse to the longitudinal direction of the sections, indicated in Fig. 2 by the arrow X. When the steel plates are positioned in a central position, such that the tops of the convex surfaces are disposed directly opposite each other, dX is 0 mm; otherwise, dX is the distance between the tops in mm.
The sealing sections were loaded by water pressure from one side of the steel plates and it was measured when leakage arose. For combinations of Y (mm) and dX (mm) the pressure P (bar) was measured at which leakage of water along one of the sides of at least one of the sealing sections occurred.
Fig. 4 is a graphic representation of the leakage pressures P depending on the compression of each of the sections, for dX is 0 mm and for dX is 12 mm. As appears clearly from Fig. 4, a sealing section according to the invention already has an excellent sealing action upon relatively slight compression, which sealing action increases proportionally to the extent of compression and is dependent only to a slight extent on the relative position of the sealing sections.
The invention is not in any way limited to the exemplary embodiments represented in the drawing and the description. Different modifications thereof are possible. For instance, the sealing section can have a differently shaped bottom surface and/or differently shaped flanks, for instance stepped or ribbed, and the channel-shaped recesses can be differently shaped or even be omitted, with the spring action being obtained entirely by material properties. Further, a tunnel segment can be fitted with, for instance, two sealing sections arranged side by side, which may or may not be coupled to each other. Further, the channels can be filled up partly or wholly with a filler with properties different from the rubber, rubbery or plastic material, and the bottom part 9 can be omitted wholly or partly. Prior to the coupling of the tunnel segments, the section can have its sides proximal to the groove 11 secured in the groove, for instance by gluing, so that the sealing section is not released from the groove. This glued joint need not be very strong since displacements of the sealing section are already adequately prevented by the shape of the top surface in particular. These and many similar modifications are understood to fall within the scope of the invention.

Claims

A sealing section for use in tunnel segments and like building elements, manufactured from rubber, rubbery or plastic material, comprising a top surface, a bottom surface and two flanks joining the top surface and the bottom surface, with a number of channel-shaped recesses extending under the top surface in the longitudinal direction of the sealing section, characterized in that the top surface is substantially convexly curved in a direction transverse to the longitudinal direction of the section.
A sealing section according to claim 1, characterized in that the top surface is formed by the top side of a top part of the sealing section, which top part is of arcuate design and is supported by at least one pair of legs extending at a slant relative to each other.
A sealing section according to claim 2, characterized in that the legs, at the side remote from the top part, are interconnected by a cross piece.
A sealing section according to claim 2 or 3,
characterized in that in a central portion of the section, viewed in cross section, an even number of legs extend pairwise at a mutual inclination, while the distance between the legs of the or each pair increases in the direction away from the top part.
A tunnel segment or like preformed building element, comprising a sealing section according to any one of the preceding claims in or on a edge surface, characterized in that the bending radius of the edge surface of the tunnel segment in a direction approximately equal to the direction of the convex top surface of the sealing section is greater, at least at the location of the sealing section, than the bending radius of the convex part of the sealing section in unloaded condition, such that the convex part always extends outside the relevant edge surface of the tunnel segment.
A tunnel segment according to claim 5, wherein the sealing section at least in unloaded condition is partly received in a groove, with the side of the sealing section remote from the curved portion snugly abutting against the bottom and sides of the groove, and the convex top surface extending substantially above the surface of the building segment.
A tunnel segment according to claim 6, characterized in that the sealing section is wholly receivable in the groove by compression, such that the top surface of the sealing section is substantially flush with a top surface of the tunnel segment, with the or each recess in the sealing section being closed.