Field of the invention

The present invention relates to an anchoring bolt or plug for suspension of lining, membranes, PE foam, layer of shotcrete, concrete elements, fire protection and/or accompanying equipment, on tunnel or rock walls or ceilings and a method for manufacturing such anchoring bolt or plug.

Background of the invention

In tunnels, on rock walls and similar, there is a need for securing the walls and ceilings in order to prevent loose rocks from falling out and to provide a fixation for lining, membranes, layer of shotcrete, concrete elements, fire protection and accompanying equipment to the wall or ceiling. The purpose for such lining is inter alia to serve as support for shotcrete, to prevent water from entering the tunnel, to prevent formation of ice formation on the tunnel wall and subsequent dropping down, causing a hazard.

Anchoring bolts for use in rock walls, tunnel walls and the like are known. The anchoring bolt is used in order to secure the walls preventing loose rocks from falling out and/or to ensure that linings or membranes, layers of shotcrete or concrete elements are secured to the rock or tunnel walls. The anchoring bolts are rigidly fixed to the surface of the walls and ceilings of the tunnels or the rock and a plurality of anchoring bolts are distributed across the surface of the walls and ceilings.

Working on tunnel or rock walls and ceilings is a heavy and demanding over head work environment. Handling heavy equipment, often with the arms stretched out or up, is a source of wear and tear on the operator. Anchoring bolts used are typically made of steel. Handling heavy steel bolts and specifically handling heavy steel bolts above shoulder height is a challenge in view of ergonomics as it is a source of wear and tear on the operator. Anchoring bolts are typically manually installed, and anchoring bolts are typically installed in the tunnel or rock wall in a grid pattern of e.g. 120 cm x 120 cm. A large number of bolts are thus needed and may reach a number of several hundred thousand in one single tunnel dependent upon length, width and height of the tunnel, following a substantially high number of man-hours needed for installation.

Steel bolts are a constant source of corrosion. In order to protect the bolts from corroding it is important to not expose the bolts or at least reduce the exposure of the bolts to a corroding environment. The concrete covering, either by concrete elements and/or shot concrete, the walls and/or ceilings of tunnels or rocks, are typically further secured by an over-coverage of concrete in order to ensure a non-corroding environment as possible.

Anchoring bolts made of glass fibers addressing the above-mentioned challenges are known, having a low weight and high corrosion resistance. However, glass fibers are having a low melting point of 6-700°C compared to steel bolts of 1500°C. Glass fiber bolts are thus not fire retardant and will melt when exposed to high temperature. It is an HSE requirement that the bolts shall keep the membranes or linings, concrete etc. from falling down as long as possible preferably in order to at least be able to evacuate the site.

Heavy equipment is difficult and expensive to both transport and handling. There is a constant demand in reducing the expenses but also the fuel consumption during transport and handling of equipment.

There is a need to address the above challenges.

Summary of the invention

In the following throughout the specification, the following terms means:

The term “bolt or plug” used throughout this document is used to describe a longitudinal bar, preferably cylindrically with a more or less circular cross section, the bolt or plug may hold different lengths for different applications, typically in the range of 500 mm to 6000 mm long, preferably in the range of 500 mm to 3000 mm long. The term “bundle of fibers” used throughout this document is a plurality of fibers in a parallel, twisted or braided state.

A main object of the present invention is to provide a bolt or plug for anchoring in walls and ceilings of tunnels or rocks walls, for suspension or fixation of membrane, linings, shot concrete and/or concrete elements and other belonging equipment.

Another object of the present invention is to provide a low weighted anchoring bolt or plug maintaining and improving mechanical characteristics.

A further object of the present invention is to provide a bolt or plug improving the HSE aspects and eliminating or at least reducing the weight exposure during repeatedly installation work, in particular but not limited to above the head work during installation.

Moreover, it is an object of the present invention to provide a bolt or plug to reduce labour time and risk of operator through reduced weight and ease handling of bolt or plug to be installed.

Yet another object of the present invention is to provide a corrosion resistant bolt or plug.

Moreover, it is an object of the present invention to provide an anchoring bolt or plug maintaining functional capacity at temperatures up to 1000 °C and within unavoidable natural variation of that temperature.

Another object of the present invention is to provide a bolt or plug dimensioned and produced/built-up in the same manner so that the system can be used as rebars for reinforcing concrete structures such as concrete floor, bridges, and other suitable concrete structures.

Another object of the present invention is to provide a bolt or plug reducing the fuel consumption of transporting needs and thus reduce the costs related to transport. In a first aspect, the present invention relates to an anchoring bolt or plug for suspension of lining, membranes, PE foam, layer of shotcrete, concrete elements, fire protection and/or accompanying equipment, on tunnel or rock walls or ceilings, the bolt or plug comprises

- a roving, wherein the roving comprises o a core layer comprising a plurality of straight, longitudinally arranged parallel fibers, o at least one circumferential outer layer encircling the core layer, the at least one circumferential layer comprises a plurality of straight, longitudinally arranged parallel fibers, wherein the fibers of the core layer and the at least one circumferential outer layer are made of different materials alternating between glass fibers and basalt fibers,

- a resin applied to the outer surface of the roving, wherein the at least one circumferential outer layer and core layer are permeated by the resin,

- a bundle of fibers is helically arranged around the outermost circumferential outer layer in the longitudinal direction of the anchoring bolt or plug, wherein the bundle of fibers is permeated by the applied resin,

- the outermost circumferential outer layer is made of basalt fibers and the bundle of fibers is a bundle of basalt fibers.

In embodiments, the outermost circumferential outer layer is made of glass fiber.

In embodiments, the roving comprises two or more circumferential outer layers of straight longitudinal arranged parallel fibers encircling the core layer, the fibers of the three or more layers alternating between a layer of glass fibers and a layer of basalt fibers.

In embodiments, the helically arranged bundle of fibers has between 5 and 20 windings per 100 mm bolt or plug. In embodiments, the helically arranged bundle of fibers has between 7 and 14 windings per 100 mm bolt or plug.

In embodiments, the helically arranged bundle of fibers prior to being helically arranged is a plurality of fibers in a parallel, twisted or braided state.

In embodiments, the helically arranged bundle of fibers is pre-tensioned in longitudinal direction prior to being helically arranged.

In embodiments, the resin is an epoxy, polyester, etc.

In embodiments, the resin is an EPIKOT® Resin 828.

In embodiments, the resin comprises a fire retardant.

In embodiments, the fire retardant is an Exolit® OP 550, being a non-halogenated phosphorus polyol, or an Exolit® AP 422, being an ammonium polyphosphate powder.

In embodiments, the resin comprises a hardener.

In embodiments, the hardener is an Ancamine® R215, being an amine hardener.

In embodiments, the roving has a circular cross-section.

In embodiments, the bolt or plug has a further bundle of fibers helically arranged in the opposite direction of the first helically arranged bundle of fibers, around the roving and the first helically arranged bundle of fibers in the longitudinal direction of the anchoring bolt or plug.

In embodiments, the diameter of the bolt or plug is between 12 mm to 30 mm, or more preferably between 16 mm and 25 mm. In embodiments, the diameter of the inner core layer is 20-80% of the total diameter of the bolt or plug, or more preferably 30-70% of the total diameter of the bolt or plug.

In embodiments, the length of the bolt or plug is between 500mm to 6000 mm, or more preferably between 500mm to 3000 mm.

In a second aspect, the present invention relates to a method for manufacturing the anchoring bolt or plug, wherein the method comprises the steps of:

- arranging a core layer of a plurality of straight, longitudinal arranged parallel fibers providing a more or less circular cross section,

- enclosing the core layer with at least one circumferential outer layer of a plurality of straight longitudinal arranged parallel fibers,

- applying a resin to the outermost circumferential outer layer of fibers such that the resin permeates the at least one circumferential outer layer and the core layer providing an even distribution of resin between the fibers, and thus filling the entire cross section with the resin matrix to establish interconnection between the various parallel fibers and providing an even distribution of resin between the fibers,

- arranging a bundle of fibers helically around the outermost circumferential outer layer of fibers, the applied resin permeating the bundle of fibers, providing an even distribution of resin between the fibers of the bundle, and thus providing an even distribution of resin between the fibers of the bundle,

- stretching the fibers in longitudinal direction,

- curing the resin.

In embodiments, the method comprises a step of tensioning the bundle of fibers in longitudinal direction prior to arranging the bundle of fibers helically around the outermost circumferential outer layer of fibers. In embodiments, the method comprises a step of arranging a further bundle of fibers helically around, in opposite direction of and subsequently to the first mentioned bundle of fibers.

In embodiments, the method comprises a step of cutting the bolt or plug in lengths.

The present invention relates to an anchoring bolt or plug for suspension of lining, membranes, PE-foam, layer of shotcrete, concrete elements, fire protection and/or accompanying equipment, the bolt being at one end anchored in a tunnel or rock walls or ceiling, while the opposite end is configured to support for example a lining, membrane or insulation mats.

The anchoring bolt or plug comprises a roving of a plurality of parallelly arranged straight fibers arranged in longitudinal direction of the bolt or plug. The fibers are arranged in layers of glass fibers and basalt fibers, from a core layer and one or more surrounding circumferential outer layers, forming a more or less circular cross section. The bolt or plug further comprises a bundle of fibers helically arranged around the roving in the longitudinal direction of the bolt or plug. The fibers of the roving and the fibers of the helically arranged bundle of fibers are permeated by a resin of epoxy, polyester, etc. The resin is evenly distributed between each fiber. The outermost circumferential outer layer and the helically arranged bundle of fibers is made of basalt fibers. The outermost circumferential outer layer and/or the helically arranged bundle of fibers may also be made of glass fibers.

Compared to steel bolts, the bolts of glass fibers and basalt fibers are corrosion resistant, having a higher chemical resistance, e.g. do not rust and is not electrically conductive. Basalt is a fire resistant material, but is a more expensive and heavier material than glass fiber. Combining glass fibers and basalt fiber in the bolt structure reduces the cost and weight of the bolt and ensures a longer life time of the bolt when exposed to high temperatures. The resin typically evaporates at temperatures of 200-300°C, glass fibers melts at temperatures of 600-700°C and basalt fibers melts above 1000°C. In the case with a fire in a tunnel, when the temperature reaches about 1000°C, the basalt fibers of the circumferential outer layer and helically arranged fiber bundle of the bolt or plug is left to keep the installed linings, membranes etc. in place, at least for specific period of time, and preferably until the tunnel is evacuated.

Having a higher chemical resistant compared to a steel bolt, e.g. being corrosion resistant, reduces the need of measures for corrosion protection, e.g. reduces the need of extra thick layers of shot concrete, etc.

The resin matrix should preferably comprise a flame retardant. The flame retardant is typically chosen between an Exolit® OP 550, being a non-halogenated phosphorus polyol, or an Exolit® AP 422, being an ammonium polyphosphate powder.

The fibers of the inner core layer and the fibers of the circumferential outer layer(s) are in a straight parallel state in the longitudinal direction of the fibers ensuring that the fibers are not damaged or broken during manufacturing.

The bundle of fibers is either parallel, twisted or braided prior to being helically arranged around the outermost circumferential outer layer.

The helically arranged bundle of fibers may function as threads on a bolt, similar to the threads of a threaded metal bolt. Different number of windings of the bundle per length of the bolts correspond to different thread pitches of a threaded bolt.

The anchoring bolt or plug is to be installed in predrilled holes in the tunnel or rock wall or ceiling. The bolt or plug is anchored in the hole by means of known technics such as mechanically anchoring, anchored by grouting, etc. The anchoring bolt or plug is at one end anchored in a pre-drilled hole in the tunnel or rock wall or ceiling, by threading the bolt or plug into the pre-drilled hole and subsequently filling the open space between the bolt or plug and the pre-drilled hole with fresh concrete. The bolt or plug is in the other end projecting out of the tunnel or rock wall or ceiling and suspends the lining, membrane or PE-foam together with a layer of shotcrete etc. Between the tunnel or rock wall or ceiling and the suspended lining etc. there is an interval or open space of between 1/2m to 1 m. In the case of a fire and the temperature rises, the part of the bolt or plug in the pre-drilled hole and that surrounded by shotcrete etc. will not experience such rapid temperature rise as the interval or open space and the open space of the tunnel itself as it is protected by e.g. the concrete, and the bolt will more or less or at least for a longer period of time keep its capacities. The glass fibers and resin material of the bolt in the interval or open space will, as described above, melt or evaporate. The basalt fibers of this area of the bolt will hang more or less as a rope, keeping the lining and shotcrete connected to the tunnel or rock wall or ceiling, at least for a specific period of time, and preferably until the tunnels are evacuated.

The bolts or plugs of the invention is typically manufactured in a pultrusion process.

The anchoring bolt or plug is manufactured by the steps of:

- arranging a plurality of longitudinal parallel straight fibers in a core layer of a more or less circular cross section,

- arranging a plurality of longitudinal parallel fibers in at least one circumferential outer layer enclosing the core layer,

- applying a resin to the outermost circumferential outer layer of fibers such that the resin permeates the at least one circumferential outer layer and the core layer, providing an even distribution of resin between each fiber,

- arranging a bundle of fibers helically around the outermost circumferential outer layer of fibers, the applied resin permeating the bundle of fibers, providing an even distribution of resin between each fiber of the bundle,

- stretching the fibers in longitudinal direction, ensuring that the fibers of the core layer and outer circumferential outer layer(s) are kept in a longitudinal parallel state,

- curing the resin.

Each fiber is typically fed by pulling the fiber from a spool or bobbin through a means for guiding the fibers. The means for guiding the fibers ensures that each fiber finds their intended location in their allocated layer, ensuring that each layer is a uniform layer of glass fibers and basalt fibers respectively. The fibers are calibrated with a high tension ensuring that the fibers are kept in their final and intended location. The fibers are then guided through a zone for applying resin matrix, e.g. an injection box for injecting a resin matrix by means of injecting points or nozzles, providing a better and more efficient distribution and penetration of resin between the fibers compared to guiding the fibers into a resin bath. The injection box provides a closed chamber for a controllable manufacturing of the bolt or plug and provides a cleaner production with no odor or harmful, toxic gasses. The fibers are thereafter guided into a winder, for winding a bundle of fibers onto the surface of the outermost circumferential outer layer of fibers ensuring a helical arrangement of the fiber bundle. The resin was applied in an amount ensuring that all fibers of the core layer, circumferential outer layer(s) and the helically arranged fibers are permeated by the resin. For curing the resin, the fibers are pulled through a heating zone and a subsequently cooling zone. The fibers are constantly, from the spools or bobbins, being pulled by means of a caterpillar or the like in order to keep the fibers stretched during manufacturing and also to pull the fibers through all the steps of the manufacturing. The finished product is then cut into required lengths before transport.

Description of the figures

Specific embodiments of the present invention will now be described, by way of example only, with reference to the following figures, wherein:

Figure 1 shows schematically and in perspective an illustration of prior art bolt.

Figure 2 shows schematically a cross section of an installation of bolts or plugs in a tunnel.

Figure 3 shows schematically and in perspective a view of a bolt or plug according to the present invention having a helically arranged bundle of fibers, the helical having a low pitch height. Figure 4 shows schematically and in perspective a view of a bolt or plug according to the present invention having a helically arranged bundle of fibers, the helical having a high pitch height.

Figs. 5A-C schematically show embodiments of the bolt or plug 100 of the present invention where Fig. 5A mainly corresponds to Fig. 3, and Fig. 5B and 5C show embodiments where the helical has variable pitch.

Figs. 6A-C schematically show embodiments of the bolt or plug 100 of the present invention corresponding to the embodiments shown in Fig. 5A-C.

Figure 7 schematically shows an embodiment of the bolt or plug 100 of the present invention with more than one bundle of fibers.

Figure 8 shows schematically an example of a flow chart of a proposed manufacturing line illustrating the steps of manufacturing the bolt or plug.

Description of preferred embodiments of the invention

The following description of the exemplary embodiments refers to the accompanying drawings. The drawings illustrate exemplary embodiments of the invention configured to be installed in rock walls or ceilings and walls of tunnels. The exemplary embodiments disclosed in the drawings should not be understood as a limitation to the scope of protection of the invention, merely to illustrate certain aspects of the invention.

The same reference numbers in the different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.

Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further particular features, structures or characteristics may be combined in any suitable manner or in one or more embodiments.

Figure 1 shows schematically and in perspective an illustration of a prior art rock bolt made of glass fibers. The bolt comprises a plurality of longitudinally arranged parallel glass fibers in an inner roving wherein a helical wrapping of a roving comprising a plurality of glass fibers helically arranged around the inner roving. The rovings are permeated with a resin.

Figure 2 shows schematically a cross section of an installation of bolts or plugs 100 in a tunnel, indicating a plurality of anchoring bolts or plugs 100 installed in the tunnel wall and ceiling 200, suspending a lining or membrane 300, pairs of sealing disks 400 on opposite sides of the lining, and a layer of shotcrete or concrete elements 500. The lining 300 may e.g. be flexible and bendable sheets or a layer of PE foam. The bolt or plugs 100 are typically installed in a grid pattern (not shown) at distances of for example 120 cm x 120 cm. The anchoring bolts or plugs 100 are installed in predrilled holes in the tunnel or rock wall or ceiling 200. The bolt or plug is 100, in one end, anchored in the predrilled hole by means of known technics such as mechanically anchoring, anchored by grouting, anchored by means of an adhesive, an adhesive sleeve or casing etc. The bolt or plug 100 is in the other end, being the end projecting out of the wall or ceiling of the tunnel 200, suspending one or more of lining, membrane, PE foam 300, sealing disks 400, layer of shotcrete, concrete elements 500 etc.

Figure 3 shows schematically in perspective a view of one embodiment of the anchoring bolt or plug 100 of the present invention. The illustration to the left of figure 2 shows part of the core layer 111 , the outermost circumferential outer layer 112 and the helically arranged bundle of fibers 120 cut away. The figure 3 shows a roving 110 comprising a core layer 111 comprising a plurality of straight fibers arranged in the longitudinal direction of the bolt or plug 100, and a circumferential outer layer 112 surrounding the core layer 111. The circumferential outer layer 112 comprising a plurality of straight fibers arranged in the longitudinal direction of the bolt or plug 100. In embodiments, the roving 110 may further comprise one or more circumferential outer layers 112 (not shown) surrounding the core layer 111. The roving 110 or the outermost circumferential outer layer 112, in figure 3 being the one and only layer, is surrounded by a bundle of fibers 120 being helically arranged around the outermost circumferential outer layer 112. A resin (not shown) is permeating the roving 110, from the core layer 111 , the one or more circumferential outer layers 112 and the helically arranged surrounding bundle of fibers 120. Figure 3 shows a bolt or plug 100 with a core layer 111 and one circumferential outer layer 112. It is not limited to only one circumferential outer layer 112, there may be two or more circumferential outer layers 112. The core layer 111 and the neighboring circumferential outer layers 112 are made of different materials, alternating between glass fiber and basalt. In one embodiment the core layer 111 may be made of glass fiber, the circumferential outer layer 112 closest to the core layer 111 is then made of basalt, the next circumferential outer layer 112 of glass fiber and so on. In another embodiment the core layer 111 may be made of basalt, the circumferential outer layer 112 closest to the core layer 111 is then made of glass fiber, the next circumferential outer layer 112 of basalt and so on. The outermost circumferential outer layer 112 and the helically arranged bundle of fibers 120 are made of basalt.

Figure 4 shows schematically in perspective a view of another embodiment of the bolt or plug 100 of the present invention, in principal the same as figure 3, but the helically surrounding bundle of fibers 120 has a different pitch height than the bolt or plug 100 of figure 3.

Figs. 5A-C schematically show embodiments of the bolt or plug 100 of the present invention. The embodiment in Fig. 5A mainly corresponds to the embodiment in Fig. 3. Fig. 5B shows an embodiment where the pitch of the helical bundle of fibers 120 varies along the length of the bolt or plug 100. The pitch can be mainly constant in segments of the length of the bolt or plug 100 but vary from at least one segment to another e.g. as illustrated in Fig. 5B. Fig. 5C shows an embodiment with two bundles of fibers 120 helically arranged around the outermost circumferential layer 112 illustrating that there can be more than one bundle of fibers 120 and one way of arranging these. In the illustrated embodiment the two bundles of fibers 120a, 120b are mainly congruent and arranged mainly in parallel.

Figs. 6A-C schematically show embodiments of the bolt or plug 100 of the present invention corresponding to the embodiments shown in Fig. 5A-C.

Figure 7 schematically shows an embodiment of the bolt or plug 100 of the present invention partly corresponding to Fig. 5C, but where the number of bundles of fibers 120 varies between at least two segments along the length of the bolt or plug 100. In the illustrated embodiment two bundles of fibers 120 two bundles of fibers 120a, 120b are helically arranged in one segment of the bolt or plug 100 but only one in other segments.

The disclosed helical arrangements of bundles of fibers 120 can be combined in different ways like e.g. related to the number of bundles of fibers 120 and pitch of the helical arrangement along the length of the bolt or plug 100. This also relates to possibly arranging at least one further bundle of fibers 120 helically in opposite direction.

Figure 8 shows schematically an example of a flow chart illustrating the manufacturing line 600 indicating the steps of manufacturing the bolt or plug 100. The fibers forming the bolt or plug 100 being pulled through the production line by a means for pulling 680 e.g. caterpillar, located at the end the production line. The means for pulling 680 ensures a constant production velocity and keeps the fibers forming the bolt or plug 100 stretched at a predetermined tension through the manufacturing. A plurality of fibers is in a first step pulled from a rack of spools or bobbins 610 comprising glass fibers and basalt fibers respectively. The fibers are guided through a means for guiding the fibers 620. The mean for guiding the fibers 620 ensures that the fibers are distributed in layers of different materials, with a core layer 111 and one or more circumferential layers 112, typically alternating layers of glass fibers and basalt fibers respectively. The fibers are further pulled and consolidated 630 into a more or less cylindrical shape forming a layered roving 110 of a plurality of parallel straight fibers arranged in longitudinal direction. The roving 110 is in a next step pulled into an area or chamber for injecting a resin matrix 640 onto the outer surface of the roving 110, such that the fibers, from the outermost circumferential outer layer 112 to the core layer 111 forming the roving 110, are permeated, and thus providing an even distribution of resin between the fibers. After applying the resin matrix, the resin permeated roving 110 is pulled through a winder 650, for arranging a bundle of fibers 120 helically around the roving 110. The resin matrix injected in chamber 640 also permeates the helically arranged bundle of fibers 120, and thus also providing an even distribution of resin between the fibers of the bundle. The resin permeated roving 110 and helically arranged bundle of fibers 120 is then cured in a heating zone 660 and subsequently a cooling zone 670. The means for pulling 680 is pulling the bolt or plug 100 into a cutting zone 690 where the bolt or plug 100 is cut into lengths before storage, transport and handling.

Table 1