WO2021054836A1

WO2021054836A1 - Floating bridge construction

Info

Publication number: WO2021054836A1
Application number: PCT/NO2020/050225
Authority: WO
Inventors: Geir Lasse Kjersem
Original assignee: Pontemar As
Priority date: 2019-09-16
Filing date: 2020-09-04
Publication date: 2021-03-25
Also published as: NO345826B1; NO20191119A1

Abstract

The present invention disclose a system for joining two or more floating structural box sections in the construction of a floating bridge, comprising a first structural box comprising a pin face with at least two pins extending from the pin face; a second structural box comprising a sleeve face with at least two sleeves recessed into the sleeve face; where the pin face is arranged to contact the sleeve face, wherein each pin aligns with a corresponding sleeve when the pin face is in contact with the sleeve face; wherein the outside diameter of each pin is smaller than the inside diameter of its corresponding sleeve, and the length of each pin is shorter than the depth of its corresponding sleeve; when then pin face is in contact with the sleeve face, a sealed annular space is defined between the inside of the sleeve and the outside of the pin; wherein a grout infusion port for the addition of grout into the annular space is arranged in the bottom portion of the annular space, and a vacuum injection port through which a vacuum can be applied to the annular space is arranged in the top portion of the annular space. A plurality of the floating structural boxes is joined together and bonded by grout, where the pin faces of said structural boxes is in contact with the sleeve faces of the adjoining structural boxes and the pins are arranged inside the corresponding sleeves, and the annular spaces are filled with grout, where the plurality of structural box sections are arranged between two or more abutments to shore, thus forming a floating bridge support structure. The present invention also disclose a method for joining and bonding two or more floating structural box sections characterized by the following steps: 1) obtaining two or more structural boxes; 2) aligning the pin face of a first structural box with the sleeve face of a second structural box such that each pin is aligned with a corresponding sleeve; 3) inserting the pins into sleeves to assemble and seal the joint between the first and second structural boxes; 4) inserting grout into the annular spaces through the grout infusion ports and applying vacuum to the annular space through the vacuum injection ports; 5) allowing the grout to fill the annular chambers while under vacuum; 6) allowing the grout to cure to a desired degree for a desired initial bond strength between the structural boxes. The method may be used for joining two or more floating structural box sections for constructing a floating bridge.

Description

Floating bridge construction

Field of the invention

The present invention relates a system for joining two or more floating structural box sections in the construction of a floating bridge, a floating bridge support structure comprising a plurality of structural box sections, a method for joining and bonding two or more floating structural box sections, and use of the method for joining two or more floating structural box sections for constructing a floating bridge.

The present invention concerns the technical field of construction of a floating bridge.

A flotation bridge in accordance with the present invention may be installed and operated in both calm waters and rough waters with large waves and swells. It may also be combined with the passage of ships. It may cross very broad fjords and sounds, and span distances of up to 10-20 km, making this kind of bridge extremely versatile.

By floating bridge we refer to a construction spanning open water between two or more abutments to shore, that may be arranged with a transport surface, for example a roadway such as a multilane road surface for transport of vehicles and/or people, or tracks for trains etc.

Background of the invention and disclosure of the state of art.

Floating bridges are also known as pontoon bridges. They are made of large water tight concrete or steel pontoons connected rigidly end-to-end, upon which the roadway is built. Although many floating bridges are temporary structures, permanent floating bridges is an economical alternative to suspension bridges from anchored piers. Floating bridges may encompass a section that is elevated, can be raised or moved vertically in order to allow waterborne traffic to pass. The floating bridge must be flexible enough to allow one section to be more heavily loaded than others as traffic pass, and to be able to move with the waters it is placed in, and thus have some natural flexiblity similar to other type bridges, without building up too much strain on the bridge construction.

The pontoons are usually made of concrete, but one can also use steel or other suitable materials. The pontoons are dimensioned and spaced to ensure the necessary buoyancy and stability, and at the same time minimize the impact thereon by the environment (water, waves, wind etc), and to withstand possible impact from ship collisions.

The floating bridge is usually connected to land by abutments, but they can also be connected to another construction. The requirements for the end connection points/abutments are different for a floating bridge than for a suspension bridge. For a suspension bridge, all the force experienced by the bridge rest on these points, while for the floating bridge only a relatively small portion of said forces are transferred to the abutments since the bridge rests upon the waters. On the other hand, a floating bridge is by definition more subject to the forces of waves, swells and currents than a bridge up above the water. Therefore, the structural strain on the floating bridge is a combination of the pontoons movements in response to the forces of the sea, the construction of the bearing elements of the bridge, and the spacing between the pontoons.

The load bearing structure of floating bridges are usually constructed either as a box structure or with trusses. The box structure is also known as a box girder bridge or box section bridge, where the main beams comprise girders in the shape of a hollow box. This gives a light but strong structure suitable to cross smaller distances, such as between pontoons. A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, i.e. a structure of connected elements for instance forming triangular units. This is also light since it is an open framework capable of tolerating forces in different directions, and is also suitable for resting on pontoons since the distances between these are relatively short (compared to the entire bridge length).

Floating bridges are made in sections, which then have to be assembled when installed. This is of course necessary because there are size limitations to how large parts can be transported to the building site. Since the final bridge will only be as strong as its weakest link, the assembly is very important. Traditionally there are two different main known ways of doing this. One assembly method suggested is to bolt the sections together. This have proven very difficult, as an extreme level of precision is needed. Relatively tiny bolts and holes compared to the sizes of the bridge sections they are located on have to be lined up perfectly and fitted together. Adding to the difficulties created by the precision needed, this operation is performed on the water, with movement in all directions, using large and difficult to precisely manoeuvre crane ships and lighters or barges. This have therefore turned out to be an unpractical solution, and even when it can be done, it takes a very long time.

A different approach is to not use bolts, but to weld the sections together. This is the main approach currently used. This is however also problematic due to high cost and extensive time needed to complete the full welding operations. The sections still must be held together with the bracing struts lined up. Welding outdoors at sea is dangerous and difficult, it is time consuming and complex involving a range of different operations to weld together the various, mainly horizontal, structural box modules, and can only be done in calm weather conditions. It typically takes 3-4 weeks just to weld one joint - two floating bridge sections - together. A series of consecutive operations is needed to execute high quality welding operation related to all types of bridges , whereas the result must be documented and certified. For a floating bridge this is especially complex. It involves typically alignment of the steel modules using crane barges and support vessels, re-mobilizing the welding area including covering the welding area with temporary tents for weather protection, sand blasting and cleaning of welding joints, front side welding, backside welding, a repeated sand blasting, non-destructive testing (NDA), documentation and approvals, and applying several layers of paint before demobilizing and moving the welding team for the next welding operation.

As an example, for a two lane bridge with a width of approximately 13-14 meters the full welding team will need in excess of 2000-2500 man-hours, which due to constraints in the available working area will translate into about 3-4 weeks of working time for each welding operation (each bridge section joined). If one is constructing a 2 km long floating bridge made up of 100 m bridge sections, one will then typically have around 20 welding spots/joints between sections. For a four- lane bridge, the welding team will typically need in excess of 3,000 man-hours to weld the larger structural box modules together. During this period, a full marine spread of support vessels and barges must be available with crew. This significantly adds to the total cost of the floating bridge. With expected delays due to weather conditions the assembly will then take over a year. Floating bridges of both box structures or trusses are usually assembled this way.

Further general information can be found in JP S62248703, JP S55145090, JP 2011069064, US 2015/078822, and US 2014/241811.

Objects of the present invention

For the assembly of floating bridges to take as long of a time as they currently do is unfavourable. Not only is it of course desirable to be able to build a bridge fast, the extra time also greatly increases the project costs. Having not just workers, but large constructions such as the barges and cranes on standby for such a long time is very expensive.

Due to these disadvantages of the known art discussed above it is a major aim of the present invention to drastically cut down the time needed for floating bridge assembly. By doing so, the entire bearing construction of a floating bridge can be assembled quickly when the weather and water conditions are optimal, which not only reduce costs drastically but also makes the entire procedure much safer for the workers involved. Then, with the bearing construction in place, the transport surface can be added to the floating bridge not with the aid of barges and ships, but by simply building it from the end(s) of the bridge. Then no ships or barges are necessary, trucks etc. can just drive up on the already finished transport surface and unload building material for more road surface directly onto the bearing construction.

Since the full and complete welding operation is such a time consuming step, the present invention does not require any welding at all to join and complete the structural box of the floating bridge. Instead, structural boxes that will form the bearing structure of the floating bridge are constructed for quick assembly. These structural boxes are not necessary the boxes of a box girder bridge, they could also be parts of a truss bridge, or even a simple straight beam or curved beam bridge, or any other suitable bridge bearing construction that can be assembled from bridge sections. Thus, the term “structural box” herein only refers to a prefabricated load bearing floating bridge section, and not a specific type of floating bridge. The objective of the invention is to significantly reduce the construction time of floating bridges, and thereby reduce cost of manpower and marine support operations significantly. Studies shows that a full hook-up and completion of two structural box modules made in accordance with the present invention can be made in 2-4 days compared to 3-4 weeks for a similar welding operation. Advantages is made from savings in crew, marine spread of vessels, administration, etc as well as giving earlier completion of bridge and reduced weather risk.

After completion of the structural box, independent of selected method, the road structure can be integrated on top of the structural box, using conventional road building methods.

The solution offered by the present invention is twofold. First, a unique post and sleeve system is used to join the structural boxes together. This requires less precision than the known solutions using bolts, and thus is much more feasible and quicker to assemble. Second, after the post and sleeve system is used to position the adjoining structural boxes, in order to permanently join said boxes quickly with a structurally sound joint, grout is applied with a novel vacuum system.

Summary of the invention

The system according to the present invention is characterized by a first structural box comprising a pin face with at least two pins extending from the pin face; a second structural box comprising a sleeve face with at least two sleeves recessed into the sleeve face; where the pin face is arranged to contact the sleeve face, wherein each pin aligns with a corresponding sleeve when the pin face is in contact with the sleeve face; wherein the outside diameter of each pin is smaller than the inside diameter of its corresponding sleeve, and the length of each pin is shorter than the depth of its corresponding sleeve; when then pin face is in contact with the sleeve face, a sealed annular space is defined between the inside of the sleeve and the outside of the pin; wherein a grout infusion port for the addition of grout into the annular space is arranged in the bottom portion of the annular space, and a vacuum injection port through which a vacuum can be applied to the annular space is arranged in the top portion of the annular space.

In accordance with a preferred embodiment of the system of the present invention, three or more spacers are arranged on the inside of the sleeve and/or outside of the pin, ensuring that when then pin face is in contact with the sleeve face the pin does not touch the sleeve in the annular space.

In accordance with another preferred embodiment of the system of the present invention, a plurality of protrusions are arranged on the inside of the sleeve and outside of the pin.

In accordance with another preferred embodiment of the system of the present invention one pin of the at least two pins is a guide pin, where said guide pin is longer than the other pins, and preferably one pin of the at least two pins is a secondary guide pin shorter than the guide pin but longer than the other pins, and more preferably the other pins are of an equal length.

In accordance with another preferred embodiment of the system of the present invention the structural boxes comprising both a sleeve face and a pin face are arranged on opposite sides of the structural boxes.

In accordance with another preferred embodiment of the system of the present invention a sealer is arranged on the surface of the pen face where the ends of the sleeve will make contact when the pin face is in contact with the sleeve face, where the sealer preferably is a gasket.

In accordance with another preferred embodiment of the system of the present invention it also comprises two vacuum ports, a guide pin, a secondary guide pin and two other pins of equal length.

The floating bridge support structure according to the present invention is characterized by comprising a plurality of structural box sections in accordance with the present invention joined together and bonded by grout, where the pin faces of said structural boxes is in contact with the sleeve faces of the adjoining structural boxes and the pins are arranged inside the corresponding sleeves, and the annular spaces are filled with grout, where the plurality of structural box sections are arranged between two or more abutments to shore.

In accordance with a preferred embodiment of the floating bridge support structure of the present invention it further comprises a transport surface being arranged on top of the structure.

The method according to the present invention is characterized by the following steps:

1) obtaining two or more structural boxes according to the present invention

2) aligning the pin face of a first structural box with the sleeve face of a second structural box such that each pin is aligned with a corresponding sleeve;

3) inserting the pins into sleeves to assemble and seal the joint between the first and second structural boxes;

4) inserting grout into the annular spaces through the grout infusion ports and applying vacuum to the annular space through the vacuum injection ports;

5) allowing the grout to fill the annular chambers while under vacuum;

6) allowing the grout to cure to a desired degree for a desired initial bond strength between the structural boxes.

In accordance with a preferred embodiment of method of the present invention, in step 4) vacuum is fully established in the annular spaces before grout is inserted through the grout infusion ports.

In accordance with another preferred embodiment of method of the present invention it further comprises: step 7) adding another structural box to one of the previously joined structural boxes; step 8) repeating steps 1 -7 for each additional structural box.

In accordance with another preferred embodiment of method of the present invention it comprises a step 0) joining the first or second structural box to an abutment.

In accordance with another preferred embodiment of method of the present invention steps 1) to 3) are repeated for each additional structural box to be joined. In accordance with another preferred embodiment of method of the present invention, in step 6) the desired initial bond strength between the structural boxes is between 50 % and 100 %, preferably between 65 % and 90%, and most preferred about 80 % of the final bond strength when the curing is complete.

The use of the method according to the present invention is for joining two or more floating structural box sections for constructing a floating bridge.

Description of the diagrams

Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein:

Figure 1 shows a cross sectional view of the structural box in accordance with the present invention.

Figure 2A shows a cross sectional view of a pin and sleeve according to the present invention, where the pin is lined up to enter the sleeve.

Figure 2B shows a transverse cross section view of the pin and sleeve of Figure 2A. Figure 3A shows a cross sectional view of a pin and sleeve according to the present invention, where the pin is entering the sleeve.

Figure 4A shows a cross sectional view of a pin and sleeve according to the present invention, where the pin is fully within the sleeve.

Figure 5A shows a cross sectional view of a pin and sleeve according to the present invention, with spacers on the sleeve.

Figure 5B shows a transverse cross section view of the pin and sleeve of Figure 5A. Figure 6A shows a cross sectional view of a pin and sleeve according to the present invention, where the vacuum infusion of grout has started.

Figure 6B shows a transverse cross section view of the pin and sleeve of Figure 6A. Figure 7A shows a cross sectional view of a pin and sleeve according to the present invention, where the vacuum infusion of grout has ended.

Figure 7B shows a transverse cross section view of the pin and sleeve of Figure 7A with closed ports. Figure 8A shows a cross sectional view of a pin and sleeve according to the present invention, where measures for increasing friction and avoiding pin and sleeve contact are disclosed.

Figure 8B shows a close up of area P in Figure 8A disclosing two embodiments of the protrusions.

Figure 9A shows a cross sectional side view of two different structural boxes before being joined together.

Figure 9B shows a cross sectional top view of the two different structural boxes of Figure 9A before being joined together

Figure 9C shows a perspective view of the two different structural boxes before of Figure 9A being joined together.

Figure 10A shows a cross sectional side view of two different structural boxes when the first pin has entered the sleeve.

Figure 10B shows a cross sectional top view of the two different structural boxes of Figure 10A when the first pin has entered the sleeve.

Figure 10C shows a perspective view of the two different structural boxes before of Figure 10A when the first pin has entered the sleeve

Figure 11 A shows a cross sectional side view of two different structural boxes when the joint is ready for grouting.

Figure 11 B shows a cross sectional top view of the two different structural boxes of

Figure 11 A when the joint is ready for grouting.

Figure 11 C shows a perspective view of the two different structural boxes before of Figure 11 A when the joint is ready for grouting.

Figure 12 shows a top view of three structural boxes, showing pontoons, being joined together.

Figure 13A perspective view of the process of assembling a floating bridge according to the present invention as assembly is started.

Figure 13B perspective view of the process of assembling a floating bridge according to the present invention as the first two structural boxes have been joined with an abutment.

Figure 13C perspective view of the process of assembling a floating bridge according to the present invention at five structural boxes have been joined. Figure 13D perspective view of the process of assembling a floating bridge according to the present invention as assembly is complete.

Detailed description of preferred embodiments of the invention

In order for two neighboring structural boxes 2, also referred to as bridge sections herein, to be joined and locked in place in respect to each other, a minimum of two connection points must be present. Usually it is preferable to have more for added strength. Figure 1 shows a typical section view of a bridge section with four connection points 1. The bridge body is typically either a steel plated or a truss construction with a transport surface 3. The connection points 1 is comprised of a pin end arranged on one of the two adjoining structural boxes, and a matching sleeve end on the other structural box. A section view of one such pin 4 and matching sleeve 5 is shown in figure 2A.

In figure 2A the pin 4 and matching sleeve 5 is lined up, and the pin is starting to be inserted into the sleeve. As can be seen in the figure, there is a lot of play between the pin and sleeve, providing a lot of play for the operator to be able to match the pin and sleeve. Such play is not possible to achieve with bolts. Figure 3A shows the same pin and sleeve, but here the pin is entering the sleeve, and in figure 4B the pin and sleeve is fully joined. Figure 2B shows a cross section of the section between the arrows 6 and 7 in figures 2A. This same cross section is seen in figures 5A, 5B, 6A, 6B, 7A and 7B. Even though the pin is located in the center of the sleeve in the figures, it does not have to be perfectly centered. In figure 3 it is clear that the space between the inside of the sleeve and outside of the pin 12 is relatively large in relation to the size of the pin and sleeve, allowing for a lot of play. This space 12 is also referred to as a void or annular volume herein. Thus, this makes the positioning of the pin and sleeve relative to each other easier.

Preferably one of the two or more pin and sleeve pairs has a longer pin and sleeve than the other pin and sleeve pairs joining two structural boxes. This extra-long pin will then serve as a guide, making pairing up of the boxes easier. First the extra-long pin is then positioned partially inside its corresponding sleeve. The operator maneuvering the structural boxes into place then only have to concentrate on hitting this one point correctly. This requires much less precision in all planes than joining multiple pins and sleeves simultaneously. Once this first longest pair has been successfully partially joined, this will act as a guide, holding the two structural boxes partially in place with respect to each other. Then the operator can concentrate on joining the shorter pins and sleeves together.

According to an even more preferred embodiment, there can be even more pin and sleeve pairs of different lengths, further taking advantage of the same principle of the operator only having to concentrate on positioning one pin and sleeve pair at the time. Thus, the second pin and sleeve to be joined can be shorter than the first pair, but longer than the remaining pairs. Once this second pair has been successfully partially joined, with the pin at least partially inside its sleeve, the adjoining structural boxes will be matched in two dimensions. Then any remaining pin and sleeve pairs, which should all be shorter than the first two pairs, and preferably have the same length, can be easily joined as the two structural boxes are moved towards each other and all the sleeve and pin pairs are fully joined.

When the two adjoining structural boxes have been successfully joined and thus positioned correctly, the joint must be permanently sealed. This is done with grout after near vacuum has been established in the void/annular space 12. There is a wide range of commercial grouts commercially available with different properties and curing time, depending on requirements. Curing time is important and curing profile may be designed to obtain satisfactory strength shortly after injection of grout. Many of the most widely used grouts obtain 80% of their final strength within 24 hours, and then more slowly 100% of the strength capacity after e.g. 3 - 14 days. For assembly purposes 80% after 24 hours is satisfactory when constructing of floating bridges, as this is well within the safety factors for floating bridge in full operation.

Most of the grouts are two components and are mixed just prior to commencing the grouting operation. It can be e.g. cement based (where water is added), it can be epoxy based (e.g. Araldite), or a combination thereof. Thus, the grout can be a cement slurry or any other bonding agent which can be added in liquid form and will harden to provide the necessary strength to the joints.

In relation to the grouting procedure, it should be understood that the expressions “grout” and “grouting” are used herein as general expressions. “Grout” is reefing to any bonding agent suitable for assembling structural boxes in accordance with the present invention, where said “grout” is applied in a liquid or partially liquid state, and eventually hardens into cured (not liquid) grout. Likewise, “grouting” refers broadly to the application of said bonding agent in order to join structural boxes in accordance with the present invention. This can also be called “mating”, but since this expression can be confused with the lining up and joining of the pins and sleeves of the structural boxes rather than the following step where the grout is applied, we are using the expression “grouting” herein.

Even though the pin does not have to be perfectly centered in the sleeve, there needs to be some minimum space between the inside of the sleeve and the pin surface. This is necessary because if the two adjacent surfaces were completely flush in an area, this would leave no space for grout, and there would be a lack of proper bonding in this area. Thus, to avoid this, in accordance with a preferred embodiment of the present invention pacers 27 are added. Such spacers 27 can be added to both the inside of the sleeve and the outside of the pin, or on just one or the other.

The function of such spacers 27 is to ensure that in the event that the sleeve and pen is not perfectly aligned as in the figures, but rather misaligned so much that the pin will be touching the sleeve at some point, the spacers will then not allow the pin and sleeve be so misaligned as to fully touch. Only the spacer will form a touch point between the sleeve and pin. This touch point will have a small enough surface that missing grout at this point will not be of any consequence. Thus when the grout is added, there will not be weak points where there is no grout and therefore no seal between pin and sleeve, as there will always be some room left between pin and sleeve where the grout may enter.

The spacers 27 thus function as insert guides. They can be added anywhere on the inside of the sleeve or on the pin surface. In order to perform their intended function, a minimal of 3 spacers is needed, arranged around the annular volume, as shown in figures 5A and 5B. With a minimum of 3 spacers per pin and sleeve pair one can ensure that the proper space is achieved in all directions. More spacers can of course be used. Four or five spacers is a preferred embodiment.

The spacers are relatively small structural distance pieces which may be welded onto the surface either on outside of the pin or on the inside of the sleeve, or otherwise fastened. The height of the spacers are defined herein as how far they reach into the void, from either the sleeve towards the pin or the opposite. It is preferred that the pacers are located in the sleeve rather than on the pin, but both are possible. The height of the spacers is of course dependent on what the minimal thickness of grout is for the specific type of grout used in order to achieve prober bond strength. A typical minimal height could be 2-3 cm. Although it is of course possible to use a longer spacer than what the grout requires, too high spacers should preferably be avoided. The reason for this is that if the spacers are too high, they may start obstructing the insertion of the pin in the sleeve, effectively limiting the amount of play between pin and sleeve. For the same reason, it is better that the spacers are not located right at the end of the sleeve where the pin is first inserted, as it is at this critical point it is most important to have as much play as possible to make the insertion easier on the operator. If the spacers are located a bit deeper inside the sleeve, this will not be a problem but they may still serve their function in guaranteeing an ample minimum distance between the pin and sleeve for grout to fully encapsulate the pin.

The spacers shown in figure 5A are not very long. Length is defined as the distance of the spacer along the surface it is mounted on. But, it is possible for the spacers to be of considerable length. In accordance with a preferred embodiment of the present invention, three or more spacers are located on the inside of the sleeve as shown in figure 5B, but they have a very long extension in the axial direction of the sleeve.

This will aid in guiding the pin into the sleeve as well as ensuring proper space for complete bonding of the grout. As an example, for sleeves of 3-4 m, there could be arranged 3 pacers evenly around the circumference, with a height of 2-3 cm, but with a length of 1-2 m, where the spacers would start a little ways into the sleeve. This would offer good strength during the penetration phase.

Please note that figures 2A-8A are shown with what would be the top side of the joints on the top of the figures, and the bottom sides of the joints at the bottom of the figures, i.e. gravity will pull downwards as the figures are shown. Thus, the grout infusion port 9 shown at the bottom towards the end of the sleeve really is positioned on the bottom of the chamber 4 to be filled with grout. In figures 6A and 7A a grout fill line is shown hooked up to the grout infusion port 9. Thus, the grout is filled in from below. It is possible to fill grout from the side or top of the sleeve, but it is preferable to fill from below, i.e. the bottom side of the sleeve, to avoid air pockets as much as possible. An important feature of the present invention is to minimize air pressure or preferably eliminate air inside the void 12 prior to commencing grouting. In the traditional method, the grout is poured from the top and then vibrated in order to remove the air pockets. Unfortunately, this often does not remove all of the air bubbles. These air bubbles reduce the strength of the bond. Also, arranging for vibration would cause operational problems so is not very feasible. In addition, the absence of air bubbles cannot easily be documented and hence certification of the bonding strength after curing cannot be given, which makes this procedure obsolete.

It is of course possible to add more grout lines if desirable. In addition, there are one or more vacuum ports 8 arranged at the top side of the sleeve 5 to further aid in the grout infusion, thus the operation is termed vacuum injection of grout. Figures 6A, 6B and 7A shows vacuum lines 14 attached to the vacuum ports 8. Before the void in the annular volume 12 is filled with grout, it is therefore necessary to seal it and make the seal air tight, i.e. leak proof for air, in order to obtain a vacuum inside the void prior to commencing vacuum injection of grout. This is important in order to get as strong bonding as possible, air pockets in the grout must be avoided, and in order to do so a vacuum as strong as practically possible needs to be established before the vacuum grouting commences. Thus, the absence of air bubbles in the set grout can be documented.

Figures 6 and 7 shows how the grout is added to the space between the outside of the pin and inside of the sleeve 12, thus permanently joining the pin and sleeve. In figure 6A, the vacuum infusion of the grout is just started. Grout is added from below, while the vacuum lines establish a vacuum or under-pressure in the space 12. Thus, the grout is effectively sucked up into the space 12, without any air present, so no air pockets are formed. This provides for a very strong bond. Figure 6B shows a cross- sectional view of figure 6A. In figures 7A and 7B the entire volume of the space 12 has been filled with grout, which will then attempt to fill the vacuum lines. The grout line ports and vacuum line ports are then sealed, as can be seen in figure 7B. If there are multiple vacuum ports 8, as in these figures (there are two shown in this embodiment), this has the advantage that they can be shut at different times, allowing for an as even and full grout filling as possible. This may be an issue for example if the grout is a thick slurry, so that it flows in a bit uneven, and reaches the closest vacuum port first (in this case the vacuum port closest to the end of the sleeve). It is an advantage to design the liquid grout with favorable viscous properties. An important parameter of the grout will therefore be viscosity to ensure a laminar and even flow of grout inside the annular space (void) 12 during the critical grouting operation. In order to seal the void in the annular volume 12 and enable the vacuum infusion of grout, it is important to have a tight seal between the end of the sleeve 5 and the surface 10 of the structural box the pin is attached to. This can be achieved with very flush surfaces, but it is more preferred to have a sealer 11 added to the surface 10, such as a gasket. It is also possible to obtain a seal by temporary welding the border area between the pin and the sleeve. In these manners or others providing a seal, a better vacuum seal can be provided, ensuring complete and prober vacuum-infusion of grout.

Figures 8A and 8B shows the same pin and sleeve pair as the earlier figures, here with seals in place on the vacuum and grout ports. The figures also shows, as tiny dots on the inner surfaces of the sleeve and outer surface of the pin, small protrusions 15. These are measures for increasing friction. Figure 8B shows close ups of two varieties of such protrusions, one as beads and one as squares. These are only examples of protrusions, they may have any feasible shape. Beads have been chosen here because they can be welded on when the sleeve or pin is made. Likewise, squares could be irons added on during construction. The protrusions could also be made by leaving small filler rods when the pin and sleeve is constructed by welding, or by abrasion. According to a preferred embodiment of the present invention, such protrusions are added to both the inside of the sleeve and the outside of the pin. The purpose of the protrusions is to increase friction. If the surfaces bound by the grout, i.e. the surfaces in the annular volume: the inside surfaces of the sleeve and the outer surfaces of the pin, are too smooth, the grout will not bond properly thereto. This will make the set cement more likely to shear off, i.e. when the seal is under stress the cured grout can loosen from the inside of the sleeve and/or outside of the pin and “pop off”. Increasing friction will prevent this from happening by increasing the bond strength.

Figures 9-11 shows the bridge sections/structural boxes joining. Flere there are 4 connection points, as shown in the embodiment of figure 1 , but shown as a cross section of a side view in 9A, 10A and 11 A, a top view in 9B, 10B and 11 B, and as perspective view in figures 9C, 10C and 11C. Flere the preferred embodiment with one long lead pin 13 (and matching sleeve), one secondary lead pin 14 and two short pins 15,16 is shown. Pins 13-16 is matched to sleeves 17-20, respectively.

Pins 15-16 are of equal short length, while pin 13 is the longest, and pin 14 is of an intermediate length. The pin and sleeve arrangement of figures 9-11 allows for an optimal pairing of the joints. Figure 9 shows the two adjacent structural boxes with their adjoining ends being lined up but not touching. They are ready for joining. In figure 10, the longest lead pin 13 has barely entered its sleeve 17, while the shorter pins 14, 15, 16 have not made contact with their sleeves 18, 19, 20. In figure 10, all four pins are in their sleeves, and the joint is assembled and ready for grouting.

Figure 12 shows three bridge segments being joined. Each section 22 is supported by a pontoon 21 , and joined by joints 23. Bridge sections 22A and 22B on pontoons 21 A and 21 B respectively has already been joined in joint 23A. Bridge section 22C on pontoon 21 C is being maneuvered by vessel 24 into place for joining the sleeve ends 23B at the end of bridge section 22B to the pin ends 23C of bridge section 22C. Thus the bridge sections/structural boxes can be quickly joined, one after another, and then sealed in place. This is also shown in figure 13. This shows roads 25A, 25B on each side of a waterway 26 to be crossed by the floating bridge. In figure 13A, bridge sections 22 on pontoons 21 are all floating freely separately, ready to be joined. In figure 13B the first two bridge sections are connected to the road on one side 25B, while in figure 13C 5 sections have been connected, and in figure 13D all 6 sections are connected and the structural framework of the floating bridge is set in place

It is of course possible to join all the bridge sections/structural boxes before commencing with grouting. Then the structural boxes would have to be held together by different means until the grout was sufficiently cured. Flowever, it is a preferred embodiment of the present invention to start the grouting as soon as possible after each joint is connected and vacuum established by methods well known in the field. Thus, one would preferably join two structural boxes and immediately start the grouting process, either before the next structural box is added, or as it is added, to the said two structural boxes. It is most preferred to first join two structural boxes, then add the grout to the joint in-between said boxes, wait until the grout is at least partially cured, and then proceed with adding the next structural box.

Thus, according to a preferred embodiment of the preset invention, the grout should be at least partially cured to an initial bond strength between the structural boxes of between 50 % and 100 %, preferably between 65 % and 90%, and most preferred about 80 % of the final bond strength when the curing is complete. The type of grout and its curing profile may be selected tailor made for each individual bridge project based on size of the bridge and the local environmental conditions. As the grout will preferably be injected into the voids during benign weather conditions, the environmental forces expected during the curing process will be far less than the maximum forces the bridge is designed for and is possible in full operation, e.g. an extreme 100 year storm. At 50 % strength, this will usually be enough to hold the grouted structural box sections together while more sections are added. At 65 % strength this is enough even in sub-optimal weather conditions. At 80% strength, since bridges are dimensioned to withstand much higher force than will normally be applied, it would be completely safe to continue adding sections. The advantage of not waiting for 100% is to save time.

As an example, if a grout that is 80 % cured after 24 hours is used, one could use 1 day per joint, and the assembly process would take as long as the number of structural boxes making up the entire floating bridge. This is of course dependent on the type of cement (grout) used. In this example one may want to wait for about a week for the grout in the last joint grouted (and thus the bearing structure of the floating bridge is assembled) to reach 100% strength before starting to build the transport surface on top of the fully assembled and cured floating bridge framework.

The size of the pin and sleeve pairs will be dependent on the size of the structural boxes and bridge. One may for instance use a sleeve of 1 m internal diameter with a pin of 60-80 cm diameter, leaving a 20-40 cm play room. The inner diameter of the sleeve 5 should preferably be 5%-120% larger than the diameter of the pin 12, preferably between 15%-80%, most preferably 30%-50%. One skilled in the art will be able to find an ideal range for specific use. One factor in determining this is the environmental conditions during installation. Rough water can require a larger sleeve 5 size than calm waters during installation. The size of the sleeve 5 can also vary depending upon the amount of bonding agent/grout (e.g. cement) needed to affix the pin 12 inside of the sleeve 5. Some types of bonding agent will not affix if there is not enough space between the pin 12 and the sleeve 5. On the other hand, too much bonding agent can produce a weaker bond. There are a number of other factors in this decision that will not be discussed.

The longest lead/guide pin 13 could be 5%-100% longer than the length of the shorter pins 14, 15, 16, preferably between 15%-80%, most preferably 30%-50%. The exact size of the longest lead pin 13 can be determined by one skilled in the art. Factors that can include needing a longer lead pin 13 include environments with rougher weathers, and if the size of the pins compared to the size of the structural box is very small. Also a longer lead pin 13 and it’s corresponding sleeve can be useful when requiring more support at that portion of the bridge segment.

Although pins with a circular cross section is shown in the figures and a preferred embodiment, the pins may be elliptical, square, or have another cross sectional shape. This could be for increased bond strength, or if using different materials. A shape with straight edges may be easier to fabricate for some materials. Each pin is preferably of an even thickness along its length, as this is easiest to produce, but it can be narrower at the end that first enters the sleeve. This can make it easier to fit the pin into the sleeve as the end of the pin can act as a guide. The end of the pin would then be a lot smaller than the end of the sleeve where it first enters, allowing for more play. Additionally, this narrower end can help correct the angle if the two bridge sections are not matched. It is preferable that the pin is straight, but it can be curved. This shape would be useful for attaching the structural boxes at an angle, rather than straight. The pin doesn’t have to be aligned along the same longitudinal axis as the bridge section and could be at an angle. The pins could be hollow (like a pipe) where grout would enter inside of it. This would have the advantage that it would provide more surface area for the grout to bond to, and thus a stronger bond. The disadvantage of this embodiment is that it would be more fragile during the insertion phase so the operator would have to be more careful in order to avoid any damage if the pin were to collide with anything.

The pin face can have both pins and sleeves. This would cost more to produce, but could be plausible. There could be more sleeves than pins on a face. This can be useful if a manufacturer desires to create a universal sleeve face, with different kinds of pin faces on the bridge structures depending on local building codes, loads, or environments, etc. While it is preferable for each structural box to have a pin face and a sleeve face on opposite faces of said box, this is not required. Boxes with two pin faces on opposite sides could connect with boxes with two sleeve faces on opposite sides, so that there would be an arrangement of every second boxes having pins or sleeves only. The boxes could also have more than two pin and/or sleeve faces, enabling branching of the floating bridge.

Although only two pairs of pin and sleeves are needed to join two structural box sections, it is preferred to use more pairs. Two pairs are the minimum in order to lock the sections together in two dimensions. More pin-sleeve pairs would add more stability and more contact spots for bonding and thus extra strength. With more pairs one could therefore have smaller pins and sleeve and have the same strength. But too small pins would be more difficult to join with their sleeves. A preferred embodiment is having one pin in each corner of the pin faces, securing said corners. This is the embodiment shown in the figures.

Claims

1. A system for joining two or more floating structural box sections in the construction of a floating bridge, a first structural box comprising a pin face with at least two pins (4) extending from the pin face; a second structural box comprising a sleeve face with at least two sleeves (5) recessed into the sleeve face; where the pin face is arranged to contact the sleeve face, wherein each pin (4) aligns with a corresponding sleeve (5) when the pin face is in contact with the sleeve face; characterized by wherein the outside diameter of each pin is smaller than the inside diameter of its corresponding sleeve, and the length of each pin is shorter than the depth of its corresponding sleeve; when then pin face is in contact with the sleeve face, a sealed annular space (12) is defined between the inside of the sleeve and the outside of the pin; wherein a grout infusion port (9) for the addition of grout into the annular space (12) is arranged in the bottom portion of the annular space, and a vacuum injection port (8) through which a vacuum can be applied to the annular space is arranged in the top portion of the annular space.

2. System in accordance with claim 1 , characterized by three or more spacers (27) arranged on the inside of the sleeve (5) and/or outside of the pin (4), ensuring that when then pin face is in contact with the sleeve face the pin does not touch the sleeve in the annular space (12).

3. System in accordance with claims 1 -2, characterized by a plurality of protrusions (15) being arranged on the inside of the sleeve (5) and outside of the pin (4).

4. System in accordance with claims 1 -3, characterized by one pin (13) of the at least two pins being a guide pin, where said guide pin is longer than the other pins (14, 15, 16), and preferably one pin (14) of the at least two pins is a secondary guide pin shorter than the guide pin (13) but longer than the other pins (15, 16), and more preferably the other pins (15, 16) are of an equal length.

5. System in accordance with claims 1 -4, characterized by the structural boxes comprising both a sleeve face and a pin face arranged on opposite sides of the structural boxes.

6. System in accordance with claim 1 -5, characterized in that a sealer (11 ) is arranged on the surface (10) of the pen face where the ends of the sleeve (5) will make contact when the pin face is in contact with the sleeve face, where the sealer preferably is a gasket.

7. System in accordance with all of claims 1 -6, further characterized by comprising two vacuum ports (8), a guide pin (13), a secondary guide pin (14) and two other pins (15, 16) of equal length.

8. A floating bridge support structure characterized by comprising a plurality of structural box sections according to any of claims 1 -7 joined together and bonded by grout, where the pin faces of said structural boxes is in contact with the sleeve faces of the adjoining structural boxes and the pins are arranged inside the corresponding sleeves, and the annular spaces are filled with grout, where the plurality of structural box sections are arranged between two or more abutments (25A, 25B) to shore.

9. Structure in accordance with claim 8, characterized by further comprising a transport surface (3) being arranged on top of the structure.

10. A method for joining and bonding two or more floating structural box sections (22A, 22B, 22C) characterized by the following steps:

1 ) obtaining two or more structural boxes according to any of claims 1 -7

2) aligning the pin face of a first structural box with the sleeve face of a second structural box such that each pin (4) is aligned with a corresponding sleeve (5);

3) inserting the pins (4) into sleeves (5) to assemble and seal the joint (23) between the first and second structural boxes;

4) inserting grout into the annular spaces (12) through the grout infusion ports (8) and applying vacuum to the annular space through the vacuum injection ports (9);

5) allowing the grout to fill the annular chambers while under vacuum;

11. Method according to claim 10, wherein step 4) vacuum is fully established in the annular spaces (12) before grout is inserted through the grout infusion ports (9).

12. Method according to claim 10 or 11 , further comprising: step 7) adding another structural box (22C) to one of the previously joined structural boxes (22A, 22B); step 8) repeating steps 1 -7 for each additional structural box.

13. Method according to any of claims 10-12, further comprising: step 0) joining the first or second structural box to an abutment.

14. Method according to claim 10, wherein steps 1 ) to 3) are repeated for each additional structural box to be joined.

15. Method according to claim 10, wherein step 6) the desired initial bond strength between the structural boxes is between 50 % and 100 %, preferably between 65 % and 90%, and most preferred about 80 % of the final bond strength when the curing is complete.

16. Use of the method according to any of claims 10-15, for joining two or more floating structural box sections for constructing a floating bridge.