Buoyant module of the floating bridge and the floating bridge

Abstract

Buoyant module (1) of a floating bridge comprising at least one stand-up pylon, at least one horizontal girder of the span that gives support to sections of a roadbed, at least two floating supports, where each of floating supports comprises a pontoon system that includes a main large pontoon (13) and a smaller pontoon (14), as well as a counterweight (15), situated under the main large pontoon, wherein the buoyant module comprises two pylons (7), where each pylon is realized in the form of a single structure of the floating tower-pylon in conjunction with one of the floating supports, spaced apart at a distance that is equal to the mounting width of the buoyant module and braced in the upper part with use of two horizontal parallel girders (8) of the span, which are rigidly connected with two parallel bearing arched constructions (9) at the upper parts, and, in its middle part, each horizontal girder of the span, acting as the tie-bar of the corresponding arch, is suspended by steel bracing wires (10) from the corresponding arched construction, and each of two floating tower-pylons is realized in its bottom underwater part with widening (12) in the direction perpendicular to an axial plane of the buoyant module, the corresponding main large pontoon, which is horizontally oriented, is realized in the form of a semicylinder situated in parallel with the widening mentioned above, the smaller pontoon is installed inside the floating tower and meant for the placement at the waterline level, while the counterweight, realized in the form of a semicylinder, is rigidly fixed to the main large pontoon at the bottom.

Description

[0001] Buoyant module of the floating bridge and the floating bridge

[0002] The invention relates to the facilities for negotiating the water obstacles as well as for transportation of people and cargo across the water obstacles where the depths or soil conditions, or high-magnitude seismicity, or high cost and the environmental requirements do not make it possible to build the permanent-type pillars fixed on bottom soils.

[0003] This type of bridges, called as the “floating” bridges, is well-known from the ancient times and widely used up to nowadays. The floating bridges are commonly used as temporary crossings; however, there are many bridges that represent fixed and permanent structures, used for decades. The most famous of the permanent floating bridges are: the Lacey V. Murrow Memorial Bridge, USA, 1940 YrBlt, 2018 meters length; the bridge across Lake Washington, USA, 1989 YrBlt, 1771 meters length https: / / seanews.ru / 2020 / 12 / 02 / ru-samvi-dlinnyi-plavuchii-most-v-mire / ; the Hood Canal Bridge, USA, 1961 YrBlt, 1988 meters length; the New Hood Canal Bridge, USA, 1982 YrBlt, 1151 meters length https: / / wiki5.ru / wiki / Hood_Canal_Bridge; the Okanagan Lake Bridge, Canada, 1958 YrBlt, 640 meters length https: / / wiki5.ru / wiki / Okanagan Lake Bridge; the Bergsoysund Bridge, Norway, 1992 YrBlt, 933 meters length https: / / en.wikipedia.org / wiki / Bergs%C3%B8ysund Bridge; the Nordhordland Bridge, Norway, 1994 YrBlt, 1246 meters length https: / / wiki5.ru / wiki / NordhordlandJBridge;

[0004] In addition, there are another currently-in-use constructions of the floating bridges introduced in RU2049846, published 10.12.1995, RU2494189, published 27.09.2013, RU2560738, published 20.08.2015, EA030880, published 31.10.2018.

[0005] Analyzing the structures of the above-mentioned bridges, as well as their in-service experience, one can notice that along with the obvious advantages of this type of bridges, such as the relatively moderate cost of construction, absence of necessity of erection of dead abutments, especially at great depths, moderate periods of construction, and some others, they have drawbacks as well, and some of them were insurmountable up to nowadays. That did not make it possible to employ this type of bridges in those places where, one would think, they could be the only possible solution to the problem, in particular, in the sea straits, with the Strait of Gibraltar as an example.

[0006] The existing problems and drawbacks inherent in structures of the currently known bridges of this type, concerning the Strait of Gibraltar as an example, are described below.

[0007] The first problem: the Strait of Gibraltar is characterized by the heavy traffic of ships of different types: both cargo carriers up to 550 000 tons' displacement and the war vessels, including the largest modem aircraft carriers and submarines both in surface and submerged conditions. Availabe structures of the floating bridges are characterized by the comparatively moderate height of placement of a bridge decking above the water level, making it impossible even for the small ships to pass under it. In response to this problem, there are buoyant terminal elements stipulated, usually, in the available floating bridges that are drawn aside when there is the need of letting the ships pass through the bridge. Due to the heavy traffic (about 200 ships per every twenty-four hours), such decision is not really suitable for these kinds of sea straits and is not suitable for the Strait of Gibraltar, for instance.

[0008] The second problem: the presence of the current in the sea strait, which is characterized by the velocity of 0,65 m / s, and, under some circumstances, reaches 1 ,0 m / s. Such current imposes a huge shearing force on pontoons that support the roadbed above the water level. In response to this problem, pontoons are usually anchored to the bottoms of basins or to the shores. However, the method of retention of the pontoons in fixed, stationary position is unacceptable when it comes, for example, to the Strait of Gibraltar due to its very deep water (around 900 meters) and the huge width, which is around 14,5 km in the narrowest place of the Strait.

[0009] The third problem: there are quite strong winds that take place in the Strait of Gibraltar, especially in its narrowest part. These winds usually blow in the west and east directions, i.e. they are directed along the Strait. These winds might give rise to the churning of water in the Strait. According to the results of long-term observations, the waves in the Strait can reach the height of 3,1 meters. This phenomenon, in combination with the water current, has a substantial impact on pontoons, which are situated on the surface of water and support the roadbead, and might produce their displacement or, even, might destroy the anchor points and the whole bridge. In particular, such risk increases when the long-length pontoon bridges are used.

[0010] The nearest to the claimed floating bridge and the buoyant module Prior Art reference is the technical decision introduced in RU2699198, published 03.09.2019. The known floating bridge is composed of the buoyant modules and the elements of affixment to the bridge abutments and has two buoyant modules in its central part, braced together through detachable joints and meant for drawing apart and letting the ships pass through. Each buoyant module of the known bridge comprises: one stand-up pylon; at least one horizontal girder of a span that gives support to sections of a roadbed; two floating supports, where each of floating supports comprises a pontoon system that includes a main large pontoon and a smaller pontoon, as well as a counterweight, situated under the main large pontoon.

[0011] As to the known floating bridge, assembled from the buoyant modules, its retention in the position that is fixed relative to the shores is realized through the anchoring of the underwater counterweights to the bottom, precluding the possibility of their employment at great depths in combination with presence of a water current in the place of installation of the bridge. In addition, vertical fluctuations of floating supports of the buoyant module under the circumstances of the impact exerted by waves might lead to displacement of the anchors relatively to the bottom and, even, to the breakage of anchor cables.

[0012] The object of the presented invention is creation of the buoyant module and the floating bridge that comprises the mentioned buoyant modules, that provide generation of the range of removable transport works on their basis coping with the task of rapid conveyance of people and cargo through the formerly impregnable water obstacles both within the existing circumstances and under the emerging new conditions of exploration of deep-sea areas, underwater construction, and development of underwater resources without disruption of usual and increased shipping and ecology.

[0013] The issued task in the buoyant module of the floating bridge that comprises: at least one stand-up pylon; at least one horizontal girder of a span, which gives support to sections of the roadbed; at least two floating supports, where each of floating supports comprises a pontoon system that includes the main large pontoon and the smaller pontoon, as well as a counterweight situated under the main large pontoon, is solved by that the buoyant module comprises two pylons, , where each of pylons is realized in the form of the single structure of the floating tower-pylon in conjunction with one of the floating supports spaced apart at a distance that is equal to the mounting width of the buoyant module and braced in the upper part with use of two horizontal parallel girders of the span, which are rigidly connected with two parallel bearing arched constructions at the upper parts, and, in its middle part, each horizontal girder of the span, acting as the tie-bar of the corresponding arch, is suspended by steel bracing wires from the corresponding bearing arched construction, and each of two floating tower-pylons is realized in its bottom underwater part with widening in the direction perpendicular to an axial plane of the buoyant module, the corresponding main large pontoon, which is horizontally oriented, is realized in the form of a semicylinder, situated in parallel with the widening mentioned above, the smaller pontoon is installed inside the floating towerpylon and meant for the placement at the waterline level, while the counterweight, realized in the form of a semicylinder, is rigidly fixed to the main large pontoon at the bottom.

[0014] The floating tower-pylons of the buoyant module are preferably connected together through the underwater space truss, which is characterized by the rectangular cross-section and realized in such a way that it has neutral buoyancy, wherein the underwater space truss is fixed to the main large pontoons at a depth that is lower than the maximum expected level of draft of the largest modern ships.

[0015] Each floating tower-pylon can be a quadrangular spatial trussed structure, which contains at least ten vertical struts connected with each other through horizontal longitudinal bracings as well as through horizontal lateral bracings and diagonal bracings.

[0016] Each main large pontoon can be equipped with a fore ballast tank in the form of a hemisphere as well as with a tail ballast tank in the form of a half-angle cone.

[0017] It is preferably that two main large pontoons are realized with such dimensions that their displacement ensures positive buoyancy of the buoyant module at the level of 2,5% under the circumstances of free ballast tanks and absence of the useful load exerted on the floating bridge, and neutral buoyancy under the condition of partially filled ballast tanks with sea water in order to immerse the buoyant module to a working depth, at which the mentioned smaller pontoons are placed at the waterline level.

[0018] Each of two bearing arched constructions with a tie-bar in the form of the horizontal girder of the span is preferably composed of at least four sectional tubular arches, connected together through horizontal bracings, vertical bracings, and diagonal bracings and equipped with two bearing side frames, situated at the ends of the bearing arched construction and installed on the upper parts of the floating tower-pylons.

[0019] In order to ensure rigidity and provide additional durability, two bearing arched constructions, situated along the edges of the buoyant module, are connected with each other through horizontal cross-connections situated above the roadbed at a height that does not obstruct the traffic on the bridge.

[0020] The issued task in the floating bridge that is composed of buoyant modules, connected together, and elements of affixment to the bridge abutments is solved by that each of the buoyant modules is realized as claimed, and the buoyant modules are connected with each other in such a way that the main large pontoons and counterweights of two adjacent buoyant modules form cylindrical bodies, while end buoyant modules are equipped with top and lower hinges designed for the affixment to the bridge abutments as well as for construction of the go-ashore facilities.

[0021] The floating bridge is preferably realized in the form of a part of a circle with the downstream center.

[0022] Non-limiting exemplary embodiments of the claimed buoyant module and floating bridge are presented with references to the attached figures, in which:

[0023] Fig. 1 is a diagrammatic representation of an exemplary embodiment of the claimed floating bridge;

[0024] Fig. 2 is a diagrammatic representation of an exemplary embodiment of the claimed buoyant module of the claimed floating bridge in the transport position;

[0025] Fig. 3 is a diagrammatic representation of an exemplary embodiment of the claimed buoyant module of the claimed floating bridge in the working position;

[0026] Fig. 4 is a diagrammatic representation of an exemplary embodiment of two buoyant modules that are connected with each other, and beingin the working position;

[0027] Fig. 5 is a sectional diagrammatic representation of an exemplary embodiment of the floating tower-pylon of the claimed buoyant module of the claimed floating bridge;

[0028] Figs. 6-10 show the sequence of the step-by-step assembly of the buoyant module.

[0029] Fig. 11 is a representation of the bridge abutment of the floating bridge and the first floating tower-pylon, affixed to the bridge abutment through a three-level hinged joint of the first floating tower-pylon.

[0030] Fig. 12 is a representation of the sequence of the step-by-step assembly of the floating bridge using the ready-made buoyant modules in the direction from two bridge abutments to the center of the bridge.

[0031] Fig. 13 is a representation of mounting guy wires situated underwater at a depth that does not obstruct shipping and fix the position of the buoyant modules relative to the shores of the sea strait in the course of erection of the floating bridge and in service.

[0032] The principle of buoyancy is laid down as the foundation for the structure of the claimed floating bridge, i.e. when buoyant modules of the bridge (with exception of the end, adjacent to the shore, buoyant modules) are supported above the water surface with use of pontoon facilities.

[0033] The claimed floating bridge (fig.°l) across the sea strait (the Strait of Gibraltar was chosen as an example) is consisted of 80 buoyant modules 1 connected together, where each buoyant module 1 is 200 meters long, and the claimed floating bridge is realized in the form of a circle with the downstream center. The width of the sea strait — the airline distance in the place chosen for the example is 15 790 meters. The length of the floating bridge — the arcual distance is 16 239 meters. The radius of an arc that goes along the fore-and-aft axis of the bridge is 20 000 meters. The end buoyant modules 1 are connected to the bridge abutments 2 with use of the three-level hinged joint. Two lower hinges 3 are situated underwater; the third hinge 4 is situated above the water at the level of the roadbed 5 and acts as a transport passage from the floating bridge to the shore. During the process of assembly of the floating bridge, in order to keep the buoyant modules in a prearranged position, takes place application of the special guy wires 6 attached to the shores upstream and situated at a depth that does not obstruct shipping. These guy wires 6 are equipped with the special stabilizers that provide the guy wires 6 with neutral buoyancy and rule out the possibility of their dipping to a depth in the circumstances of their considerable length. Upon the completion of the assembly of the floating bridge, these guy wires 6 can be kept in the pre-tensioned condition in order to impart additional safety stability to the floating bridge (see fig.°13).

[0034] Each claimed buoyant module I (figs. 2, 3) comprises two pylons, where each of pylon is realized in the form of the single structure of the floating tower- pylon 7 in conjunction with one of the floating supports. The floating tower-pylons 7 are spaced apart at a distance that is equal to the mounting width of the buoyant module 1 and connected in the upper part through two horizontal parallel girders 8 of the span, which are rigidly connected with two parallel bearing arched constructions 9 at the upper parts. In its middle part, each horizontal girder 8 of the span that acts as a tie-bar of the corresponding bearing arched construction 9 is suspended by steel bracing wires 10 from the corresponding bearing arched construction 9. In order to ensure rigidity and provide additional durability, two bearing arched constructions 9 situated along the edges of the buoyant module 1 are connected with each other through horizontal truss cross-connections 11 situated above the roadbed at a height that does not obstruct the traffic on the bridge.

[0035] Each of two floating tower- pylons 7 is realized, in its lower underwater part, with the widening 12 in the direction perpendicular to the axial plane of the buoyant module 1. There is the main large pontoon 13 that is fixed on the lower surface of the widening 12 of each floating tower- pylon 7, directed horizontally and realized in the form of the semicylinder that is situated in parallel with the widening 12 mentioned above. The smaller pontoon 14 is installed inside of each floating tower-pylon 7 and meant for placement at the waterline level.

[0036] The counterweight 15 is realized in the form of a semicylinder and rigidly affixed to the main large pontoon 13 from below by the suspension structure 16. Counterweights 15 are made of the watertight armoured concrete and meant for provision of the assured stability of the buoyant module 1 in any circumstances by the way of lowering of the combined center of gravity of the buoyant module 1 below the level of the bearing area, which goes through the horizontal axes of two main large pontoons 13.

[0037] The floating tower- pylons 7 of the module 1 are connected with each other through the underwater space truss 17, which has a rectangular cross-section and realized in such a way that it has neutral buoyancy. The underwater space truss 17 is affixed to the main pontoons 13 at a depth which is lower than the maximum expected level of draft of the largest modem ships. The underwater space truss 17 is a box-sectional welding space truss made of the tubular members 18 of a special form or equipped with the fairings to reduce the coefficient of their hydrodynamic resistance. All tubular members 18 are leakproof and air-filled. The dimensions of the tubular members 18 of the underwater space truss 17, the width of their walls as well as their mass are rated in such a way that the weight of the underwater space truss 17 in the submerged condition is fully balanced by an uplift force of the tubular members 18 that compose the underwater space truss 17. Therefore, the construction of the underwater space truss 17 contains neutral buoyancy that makes it possible to rule out the possibility of its sagging due to the dead load and provides it with high rigidity and durability even under the circumstances of its substantial cross-sectional dimensions.

[0038] Each floating tower-pylon 7 is a quadrangular spatial trussed structure, which contains at least ten vertical struts 19, connected with each other by horizontal longitudinal bracings 20, horizontal lateral bracings 21, and diagonal bracings 22.

[0039] Each main large pontoon 13 is realized in the form of a steel semicylinder and equipped with the fore ballast tank 23 in the form of a hemisphere and the tail ballast tank 24 in the form of a half-angle cone. Displacement (uplift force) of two main large pontoons 13 provides positive buoyancy of the buoyant module 1 at the level of 2,5% in the circumstances of free ballast tanks 23, 24 and without the useful load exerted on the floating bridge (see fig. 2) and neutral buoyancy under the condition of partially filled ballast tanks 23, 24 with sea water in order to immerse the buoyant module 1 to a working depth (see figs. 3, 4), at which the mentioned smaller pontoons 14 are situated at the waterline level.

[0040] Each of two bearing arched constructions 9 of the buoyant module 1 (fig. 2) is consisted of four sectional tubular arches 25 connected together through horizontal bracings 26, vertical bracings 27, and diagonal bracings 28 and equipped with two bearing side frames 29 situated at the ends of the bearing arched construction and installed on the upper parts of the floating tower-pylons 7. The tie-bars for the each of two bearing arched constructions 9 are the corresponding girders 8 of the span oriented horizontally, along the longitudinal axis of the buoyant module 1 , and rigidly connected with the bearing arched constructions 9 and bearing side frames 29. Girders 8 act as the bearings for the sections of the roadbed 5 decking system, which is characterized by a trapezoid cross-sectional shape. Sections of the roadbed 5 decking system are fastened together and with girders 8 though bolt joints (have not shown in figures) and, in combination with horizontal inter-arched cross-connections 11 , ensure durability and high stiffness of the whole overwater part of the buoyant module 1.

[0041] The bearing arched constructions 9, in combination with the girders 8 of the span, after the assemblage of all buoyant modules 1 in the single bridge crossing, form the upper horizontal arch, which connects shores over the water and is situated at a great height relative to the lower horizontal arch, which connects shores underwater and is formed by the underwater space truss 17. The stand-up floating tower-pylons 7 of all buoyant modules 1, from which the floating bridge is composed of, will act as linking members connecting together horizontal overwater and horizontal underwater arches, imparting high durability and stiffness to the floating bridge.

[0042] According to calculations of height of the position of the center of gravity of the claimed buoyant module 1 of the floating bridge, carried out with taking the overall dimensions of the bridge across the Strait of Gibraltar as an example, which are presented on page 5, the center of gravity of the buoyant module 1 (without consideration of the useful load exerted on the floating bridge) is situated 5,275 meters lower than the bearing area that goes through the horizontal axes of two main large pontoons 13.

[0043] Installation of each single buoyant module 1 is implemented in the following order.

[0044] All individual elements, such as tubular members 18 of the underwater space truss 17, horizontal longitudinal bracings 20, horizontal lateral bracings 21, diagonal bracings 22 and vertical struts 19 of the floating tower-pylon 7, horizontal bracings 26, vertical bracings 27, and diagonal bracings 28 of sectional tubular arches 25, as well as girders 8 of the span are manufactured in advance according to a previously drawn-up specification. The semi- cylindrical bodies of main large pontoons 13, box-type bodies of smaller pontoons 14, as well as the trapezoid cross-sectional decking system of the roadbed 5 are fabricated beforehand as well.

[0045] Each floating tower-pylon 7, underwater space truss 17, as well as each sectional tubular arch 25 of the bearing arched construction 9 are assembled from ready elements by fastening them together in a proper order by bolt or welded joints.

[0046] The upper part of each buoyant module 1 is assembled beforehand (on a shore); the upper part is composed of:

[0047] - two bearing side frames 29;

[0048] - two horizontal longitudinal girders 8 of the span;

[0049] - two bearing arched constructions 9, connected together by horizontal cross-connections 11 and connected with the girders 8 of the span with use of bracing wires 10;

[0050] - and sections of the roadbed 5, connected together and with girders 8.

[0051] Further, as it is shown in figs. 6 to 10, each buoyant module shall be installed bottom-up and in succession.

[0052] Two fixing footplates 30 are installed at the bottom of the dock at a distance that is equal to the length of the constructed buoyant module 1 , in which the semicylindrical counterweights 15 (figs. 6a, 6b, 6c), fabricated beforehand, are freely placed.

[0053] The assembled underwater space truss 17 with the suspension structures 16 affixed on it is fastened between a pair of main large pontoons 13 (figs. 7a to 7e).

[0054] Further, in the surface condition, the main large pontoons 13, assembled at the previous stage together with the underwater space .truss 17, are drawn to counterweights 15 (fig. 8a), and, by partially filling the main volume of the main large pontoons 13 with water, lowered to the counterweights 15 situated in fixing footplates 30. After that, counterweights 15 are fastened together with the suspension structures 16 of the underwater space truss 17 (fig. 8b).

[0055] By emptying the main volume of the main large pontoons 13 from water and by unfastening the counterweights 15 from the fixing footplates 30, the assembled part of the floating towerpylon 7 is brought to the surface condition (fig. 8c, 8d), and, after that, the floating towerpylon 7, assembled beforehand, is fastened to each main large pontoon 13. The floating tower-pylon 7 is already provided with the smaller pontoon 14 installed before, during the assembly process (fig. 9a, 9b).

[0056] The upper part of the buoyant module 1 , assembled beforehand, is lowered, with use of the hoisting crane, on floating tower-pylons 7, situated in the surface condition, and fastened together with floating tower- pylons 7 (fig. 10a, 10b).

[0057] Upon completion of this operation, the buoyant module 1 is considered as entirely assembled and being in a transport position (fig. 2), i.e. the buoyant module 1 is ready to be transferred to the place of installation by the way of towing afloat.

[0058] Fig. 12 is a diagrammatic representation of the process of installation of the claimed floating bridge, taking the Strait of the Gibraltar as an example. The shore of Africa, which is shown schematically, is labeled by the “A” letter, and the shore of Europe, which is shown schematically too, is labeled by the “E” letter.

[0059] Mounting of the floating bridge begins simultaneously both from the side of Africa and from the side of Europe by installation of the first floating tower-pylon 7 (fig.12a and 12f), which is affixed to the bridge abutment 2 with use of two underwater delta hinges 3 and one abovewater delta hinge 4 (fig. 11).

[0060] Further, the preassembled buoyant module 1 is drawn in the transport position (see fig. 2) to the first floating tower-pylon 7 that is affixed to a shore and, after that, filling the ballast tanks 23 and 24 with water, the buoyant module 1 is brought into the working position as it is shown in fig. 3and fig. 10c, and after the buoyant module 1 is immersed to a working depth, it is connected to the first floating tower-pylon 7 (figs. 12b and 12g). After that, with use of the mounting guy wire 6, situated at a depth that does not obstruct shipping, the assembled buoyant module 1 is affixed to the shore station 31 , which is situated on the corresponding shore, upstream (fig. 13, fig. 12c to 12e and fig. 12h to 12k).

[0061] The above-mentioned operation (figs. 12a, to 12e and 12f to 12k) are repeated many times until the joining of two assembled halves of the floating bridge takes place in the middle of the water obstacle (see fig. 1).

[0062] The first problem, described above, in the claimed construction of the buoyant module and the whole floating bridge is solved due to the fact that there will be no obstacles under the bridge obstructing journey of any ships that are available nowadays since the width of the area occupied by the buoyant module, available for journey of ships, taking the bridge across the Strait of Gibraltar as an example, will be at least 171,4 meters, the height from the water surface to the lowest point of the roadbed will be at least 70 meters, the depth, availabe for journey of ships, will be at least 31 meters.

[0063] Currently, the draught of the largest ships in the world (https: / / en.wikipedia.org / wiki / Symphony_of_the_Seas) is not more than 25 meters, the width is not more than 68 meters, and the height from the water line is not more than 64 meters. The claimed construction will provide the possibility for the submarines, if it will be needed, to cross the Strait not only up-top, but in the submerged condition at a depth of 60 meters and deeper.

[0064] The whole floating bridge, in this particular example, is composed of 80 buoyant modules 1 , connected together, with the 200 meters length of each, and the pass width under each of them is at least 171,4 meters.

[0065] Therefore, the given construction will not obstruct the shipping in, for example, the Strait of Gibraltar in no way since there are 80 bridge spans (modules) that are all simultaneously available for the journey of ships with the usable width of each - at least 171,4 meters.

[0066] The second problem, described above, is solved due to the fact that for the stable positioning of the floating bridge and in order to overcome the impact of the Atlantic surface current exerted on the floating bridge, instead of anchoring of the floating bridge to the bottom of the Strait or to the shores, the structure of the floating bridge provides free supporting of the floating bridge by the bridge abutments 2 at the extreme points of the floating bridge. In fact, taking into consideration the bridge crossing as a whole, it will represent the single-span arched construction resting upon two shores and placed in a horizontal plane instead of a vertical plane, which sustains the uniformly distributed load of the water flow that moves though the Strait from the side of the Atlantic Ocean towards the Mediterranean Sea instead of the gravity-type load.

[0067] Taking into account the fact that the vertical distance between the upper (above-water) and lower (underwater) horizontal arches in the chosen example, i.e. the bridge across the Strait of Gibraltar, will be more than 100 meters, the given construction will be exceptionally resistant to all underwater (tides, flows, waves) and above-water (winds) impacts on it.

[0068] In order to solve the third problem, i.e. in order to protect the floating bridge from the impact of waves, there is the construction with use of pontoons situated at the two levels vertically, which is applied in the structure of the floating bridge. The pontoons of the first (lower level) — main large pontoons 13, in their in-service (working) position, will be situated at a depth unreachable for sea waves. The structure of each of two main large pontoons 13 provides the presence of two ballast tanks 23 and 24, where one of them — the fore ballast tank 23 is situated in the fore (spherical) part of the main large pontoon 13, and the second one — the tail ballast tank 24 is situated in the tail (cone-shaped) part of the main large pontoon 13.

[0069] Displacement of ballast tanks is designed in such a way that in the circumstances of empty ballast tanks (not filled with water) the main large pontoons 13 will provide the whole structure of the bridge (as well as the single buoyant module 1) with positive buoyancy at the level of 2,5% that makes it possible for the construction to be afloat on the water surface during its tugging to the mounting location. When all four ballast tanks of the buoyant module 1 are filled with sea water, its buoyancy becomes equal to zero and the buoyant module 1 starts submerging. This submergence will continue until the buoyant module 1 reaches the depth at which the upper pontoons (smaller pontoons 14), located inside the floating towerpylons 7 and meant for accommodation of the useful load, contact with the water surface, and the submersion will stop.

[0070] Taking into account the bridge across the Strait of Gibraltar as an example, total displacement of two main large pontoons 13 of each buoyant module 1 will be 40046,77 tons and meant exclusively for taking up the weight of the whole construction of the bridge module, which, taking into account the weight of water that fills the ballast tanks of the main large pontoon 13, is 40046,77 tons as well. This weight does not include the weight of the useful load exerted on the floating bridge (the weight of transport, asphalt coating, processing facilities, and others).

[0071] Total displacement of two smaller (upper) pontoons 14 of each buoyant module 1 is 3 678 tons. It is rated on the basis of the amount of the extreme useful load exerted on each buoyant module — 1 800 tons and the excess unexpected load — 1 878 tons.

[0072] By the extreme load, in this particular example, is meant the situation, in which all eight driving lanes of the carriage-way of the floating bridge are occupied by stopped, for some reason, motor transport with the interval between the vehicles — 1,5 m.

[0073] Such a construction where the main large pontoons 13, which carry 97,6% of the overall weight of the buoyant module 1 , are situated at a depth, at which there is no churning of water evoked by the surface waves, and the smaller pontoons 14, exposed to the water load but characterized by the comparatively small overall dimensions, take up only 2,4% of the overall weight of the buoyant module 1 , ensures the stable position of the buoyant module 1 and the floating bridge even in the situation where the height of the waves is 3,1 meters, which take place in the Strait of Gibraltar sometimes.

[0074] In addition, under the water, at a level below the main large pontoons 13, there are two ballast counterweights 15 with total mass of 23 161 tons, rigidly mounted to the main large pontoons 13 through the special suspension structures 16, which impart rigidity and stability to the buoyant module 1 and, therefore, to the whole structure of the floating bridge.

[0075] The circumstance that the center of gravity of each buoyant module is always situated lower than the bearing area that goes through the axes of the main large pontoons 13 utterly guarantees the whole floating bridge and each buoyant module 1 in particular against overturning under the condition of exertion of any external stresses on them.

[0076] That is to say, each buoyant module 1, even if it is taken into account separately, can be considered as an independent floating craft that contains guaranteed floatability and stability and, in consequence, as the completely safe one, even in the environment of the open sea.

[0077] Examples of combination of technical features, represented in this disclosure, are not limited to the combinations provided by the claims or embodiments of this disclosure, all technical features provided in this disclosure can be combined by any means unless inconsistence exists.

[0078] It should also be noted that the embodiments mentioned above are only specific embodiments of the invention. Surely, this invention is not limited to the embodiments mentioned above; any subsequent changes or modifications implemented on the basis of this disclosure, which can be directly derived from or easily associated with the disclosure of this invention by those skilled in the art, should be considered to be within the scope of protection of the invention.

Claims

Claims1. The buoyant module of the floating bridge comprising at least one stand-up pylon, at least one horizontal girder of the span that gives support to sections of a roadbed, at least two floating supports, where each of floating supports comprises a pontoon system that includes the main large pontoon and the smaller pontoon, as well as a counterweight, situated under the main large pontoon, characterizing in that the buoyant module comprises two pylons, where each of pylons is realized in the form of the single structure of the floating tower-pylon in conjunction with one of the floating supports, spaced apart at a distance that is equal to the mounting width of the buoyant module and braced in the upper part with use of two horizontal parallel girders of the span, which are rigidly connected with two parallel bearing arched constructions at the upper parts, and, in its middle part, each horizontal girder of the span, acting as the tie-bar of the corresponding arch, is suspended by steel bracing wires from the corresponding arched construction, and each of two floating tower-pylons is realized in its bottom underwater part with widening in the direction perpendicular to an axial plane of the buoyant module, the corresponding main large pontoon, which is horizontally oriented, is realized in the form of a semicylinder situated in parallel with the widening mentioned above, the smaller pontoon is installed inside the floating tower and meant for the placement at the waterline level, while the counterweight, realized in the form of a semicylinder, is rigidly fixed to the main large pontoon at the bottom.

2. The buoyant module, according to the claim 1, characterizing in that the floating towerpylons of the buoyant module are connected together through the underwater space truss, which is characterized by the rectangular cross-section and realized in such a way that it has neutral buoyancy, wherein the underwater space truss is fixed to the main large pontoons at a depth that is lower than the maximum expected level of draft of the largest modem ships.

3. The buoyant module, according to the claim 1, characterizing in that each floating towerpylon is a quadrangular spatial trussed structure, which contains at least ten vertical struts connected with each other through horizontal longitudinal bracings as well as through horizontal lateral bracings and diagonal bracings.

4. The buoyant module, according to the claim 1, characterizing in that each main large pontoon is equipped with the fore ballast tank in the form of a hemisphere as well as with the tail ballast tank in the form of a half-angle cone.

5. The buoyant module, according to the claim 4, characterizing in that two main large pontoons are realized to ensure positive buoyancy of the buoyant module at the level of 2,5% under the circumstances of free ballast tanks and absence of the useful load exerted on the floating bridge, and neutral buoyancy under the condition of partially filled ballast tanks with sea water in order to immerse the buoyant module to a working depth, at which the mentioned smaller pontoons are placed at the waterline level.

6. The buoyant module, according to the claim 1 , characterizing in that each of two bearing arched constructions with a tie-bar in the form of the horizontal girder of the span is composed of at least four sectional tubular arches, connected together through horizontal bracings, verticalbracings, and diagonal bracings and equipped with two bearing side frames, situated at the ends of the bearing arched construction and installed on the upper parts of the floating tower-pylons.

7. The buoyant module, according to the claim 6, characterizing in that two bearing arched constructions, situated along the edges of the buoyant module, are connected with each other through horizontal cross-connections situated above the roadbed at a height that does not obstruct the traffic on the bridge.

8. The floating bridge, composed of buoyant modules, connected together, and elements of affixment to the bridge abutments, characterizing in that each of the buoyant modules is realized according to claims 1-6, and the buoyant modules are connected with each other in such a way that the main large pontoons and counterweights of two adjacent buoyant modules form cylindrical bodies, while the end buoyant modules are equipped with top and lower hinges designed for the affixment to the bridge abutments as well as for construction of the go-ashore facilities.

9. The floating bridge, according to the claim 8, characterizing in that the floating bridge is realized in the form of a part of a circle with the downstream center.

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