US3686886A

US3686886A - Plant for the manufacture of floating concrete structures in a body of open water

Info

Publication number: US3686886A
Application number: US887224A
Authority: US
Inventors: Hans Christer Georgii
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-12-20
Filing date: 1969-12-22
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: SU378028A3; DK140112C; JPS506957B1; NO135700C; DK140112B; NO135700B; DK554275A; GB1287000A

Abstract

A plant for the manufacture of floating concrete structures in open and substantially unsheltered bodies of water, comprising a concrete ring floating in the water with its axis normally substantially vertical and its upper end above the water surface. The wall structure of the concrete ring includes a plurality of circumferentially spaced, pressure-tight, preferably cylindrical cavities extending in the axial direction of the ring. At least some of these cavities are adapted to serve as ballast and trimming tanks which can be filled with water to a variable extent, whereby the buoyancy, the floatation height and the attitude of the concrete ring in the water can be controlled. The total volume of the cavities is such that the total displacement of the concrete ring exceeds substantially the total dead-weight of the ring. The water area enclosed by the concrete ring is efficiently protected against wave motions, currents and winds, wherefore the manufacture of floating concrete structures can take place in this water area substantially without any disturbances from weather forces. The upper ring-shaped end of the floating concrete ring supports all those apparatuses, equipments, devices and facilities that are necessary for the production, such as concrete mixing stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pump stations, control stations for the control of the ballast and trimming tanks of the concrete ring, workshops, crew spaces etc. Some of the large cavities in the wall structure of the floating ring can also be used as store spaces for materials necessary for the production, such as cement, gravel, sand, reinforcement materials etc. The concrete ring is moored through a large number of mooring ropes to an anchor resting upon the bottom of the body of water. The anchor consists preferably of a concrete ring having a wall structure including a plurality of circumferentially spaced, sealed, pressure-tight cavities adapted to serve as ballast tanks which can be filled with water to a variable extent for determining the total weight of the anchor ring and thus the anchoring force thereof. Preferably, the total volume of the ballast tanks in the anchor ring is such that the displacement of the anchor ring in the water exceeds the deadweight of the anchor ring, whereby this can be brought to a floating position in the surface of the water in that the ballast tanks are emptied. In this way the anchor ring can be towed in a floating position to the intended site of use.

Description

United States Patent Georgii [54] PLANT FOR THE MANUFACTURE OF FLOATING CONCRETE STRUCTURES IN A BODY OF OPEN WATER Inventor: Hans Christer Georgii, 42, Rindogatan, Stockholm, Sweden Filed: Dec. 22, 1969 Appl. No.: 887,224

[30] Foreign Application Priority Data Dec. 20, 1968 Sweden ..17706/68 us. or. ..6l/46.5, 61/82, 4/5 F rm, c1. ..E02d 29/06 Field 0fSc8I'ch.....61/46, 46.5, s2, s2; 14/5 1),

References Cited UNITED STATES PATENTS 5/1966 Georgii ..61/46 8/1970 Miller ..61/46.5 11/1970 Georgii ..6l/46 Primary Examiner-J. Karl Bell Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A plant for the manufacture of floating concrete structures in open and substantially unsheltered bodies of 1 water, comprising a concrete ring floating in the water i with its axis normally substantially vertical and its upper end above the water surface. The wall structure of the concrete ring includes a plurality of circum- I ferentially spaced, pressure-tight, preferably cylindri- T cal cavities extending in the axial direction of the ring.

' 14 1 Aug. 29,1971

At least some of these cavities are adapted to serve as ballast and trimming tanks which can be filled with water to a variable extent, whereby the buoyancy, the

floatation height and the attitude of the concrete ring in the water can be controlled. The total volume of the cavities is such that the total displacement of the concrete ring exceeds substantially the total deadweight of the ring. The water area enclosed by the concrete ring is efficiently protected against wave motions, currents and winds, wherefore the manufacture of floating concrete structures can take place in this I water area substantially without any disturbances from weather forces. The upper ring-shaped end of the floating concrete ring supports all those apparatuses,

equipments, devices and facilities that are necessary for the production, such as concrete mixing stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pump stations, control stations for the control of the ballast and trimming tanks of the concrete ring, workshops, crew spaces etc. Some of the large cavities in the wall structure of the floating ring can also be used as store spaces for materials necessary for the production, such as cement, gravel, sand, reinforcement materials etc. The concrete ring is moored through a large number of mooring ropes to an anchor resting upon the bottom of the body of 1 water. The anchor consists preferably of a concrete force thereof. Preferably, the

ring having a wall structure including a plurality of cir cumferentially spaced, sealed, pressure-tight cavities adapted to serve as ballast tanks which can be filled with water to a variable extent for determining the otsLwsis of e mh r s.ansltllustheas ins total volume of the ballast tanks in the anchor ring is such that the displacement of the anchor ring in the water exceeds the deadweight of the anchor ring, whereby this can be brought to a floating position in the surface of the water in that the ballast tanks are emptied. in this way the anchor ring can be towed in a floating position to' the intended site of use.

12 Claims, 10 Drawing Figures PATENTEDAUBZQ I'm asaases PLANT FOR THE MANUFACTURE OF FLOATING CONCRETE STRUCTURES IN A BODY OF OPEN WATER The invention concerns a plant for manufacturing in open unsheltered waters concrete structures which are floating the water during the major portion of the fabrication process.

The U.S. Pat. No. 3,249,664 describes a method for manufacturing very large concrete structures intended to be used in water. Characteristic for this method is primarily that the concrete structures being manufactured are designed with internal, sealed, pressure-tight cavities having such a volume that the total displacement of the concrete structures exceeds substantial the total dead-weight of the structures, whereby the concrete structures can float independently in the water. Further, at least some of said cavities are designed to be filled with water to avariable extent for the control of the buoyancy, the floatation height and the attitude in the water of the concrete structure. According to the abovementioned method such concrete structures are manufactured in that firstly a comparatively short end section of the concrete structure to be fabricated is manufactured in a more or less conventional manner on land or in a ship's clock. This end section has one closed end and an opposite open end and is after its fabrication launched so as to float in the water with its open end facing upwards, its axis substantially vertical and its upper open end above the surface of the water. From the upper end of this end section the remaining portion of the concrete structure is subsequently cast in vertical direction upwards and simultaneously water is filled into at least some of said cavities in the concrete structure so that the completed portion of the structure sinks vertically downwards in to the water but remains independently floating therein with its upper end, where the casting process is taking place, at a desired level abov'e the water surface. By this method it is possible to manufacture directly in the water very large concrete structures, as for instance pontoons, tube sections, tunnel sections, ship's-hull, concrete rings for storing and/or transporting of oil, floating concrete platforms for oil drilling under water etc. The manufacturing of concrete structures by means of this method requires obviously access to a body of water with a depth at least corresponding to the axial dimension of the concrete structures to be manufactured. Further the manufacturing process must be carried out in a body of water where the wave motions are not too strong and large. In particular, this is important during the initial stage of the manufacturing process, when the completed portion of the concrete structure floating in the water is still comparatively small and thus more easily affected by wave motions in the water. The larger the concrete structure being manufactured becomes the more insensitive it is for any wave motions in the water and at the same time the upper end of the structure, where the casting process is taking place, can be positioned at a substantial height above the water surface. However, there exist very large cost-stretches substantially completely without sheltered water areas with a sufficient depth.

The object of the present invention is therefore to provide a plane permitting the manufacture of concrete structures by the use of the above described manufacturing method in open and substantially unsheltered waters.

The plane according to the invention is primarily characterized in that it comprises a concrete ring disposed floating in the water with its axial direction normally substantially vertical, said concrete ring having a wall structure including a plurality of circumferentially spaced, pressure-tight, preferably cylindrical cavities, which extend in the axial direction of the concrete ring and have closed lower ends and such a total volume that the total displacement of the ring in the water exceeds substantially the total dead-weight of the ring and the ring floats in the water with its upper end above the surface of the water, at least some of the said cavities being designed as ballast and trimming tanks which can be filled with water to avariable extent for the control of the buoyancy, the floatation height and the attitude of the ring in the water, said upper end of the concrete ring supporting means, devices, apparatuses and equipments, such as concrete mixer stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pump stations, workshops, material stores, crew spaces etc., necessary for the manufacture of concrete structures in the water area enclosed by the concrete ring.

The floating concrete ring which constitutes the main portion of the plane according to the invention may preferably be manufactured. by the use of the manufacturing method described in the foregoing. This manufacture can be carried out either in a sheltered body of water or in a previously manufactured plant according to the present invention, whereafter the concrete ring is provided with all those apparatuses, equipments and systems which are necessary for the operation of the plant, as for instance concrete mixer stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pumps and control systems for filling and removing water respectively into and from the ballast and trimming tanks of the concrete ring, workshops, crew spaces etc. Thereafter, the completed plant can be towed to the desired site of use and on this be anchored or moored to the bottom. For the mooring of the floating concrete ring to the bottom it is preferable to use an anchor consisting of a large concrete ring having in its wall structure a plurality of circumferentially spaced, sealed and pressure-tight cavities which can be filled with water to such an extent that the ring rests on bottom with the required anchoring force. Also this ring-shaped anchor may preferably be manufactured by the use of the manufacturing method described in the foregoing and be towed in a floating attitude to the site of use and there be sunk to the bottom in that water is filled into the ballast tanks in the wall structure of the anchor ring.

Concrete rings of the type constituting the major portion of a plant according to the invention can be manufactured with very large dimensions by the use of the manufacturing method described in the foregoing. Due to the very large mass and the hydrodynamic stability of the concrete ring, which. serves as a floating production platform, the ring will be very insensitive to even very large and strong wave motions, currents and wind forces. The water area surrounded by the concrete ring is therefore very effectively protected against wave motions, currents and winds, and if the concrete ring is made sufficiently high and lowered sufficiently deep into the body of water also thevertical movements in the water surrounded by the ring will be completely eliminated. Thus in this water area the production of floating concrete structures, for instance by the manufacturing method described in the foregoing, can be carried out without disturbances and interruptions and substantially independently of wave motions, currents and winds, even if the plant is located in a body of open unsheltered water. The diameter and the axial height of the concrete ring are also dependent on the dimensions of the concrete structures to be manufactured at the plant. If the diameter of the concrete structures being manufactured, several such concrete structures can be manufactured simultaneously in the water area surrounded by the floating concrete ring. Of course, a plane according to the invention can also be used for the manufacture of floating concrete structures in the water area immediately outside the concrete ring, if the prevailing condition permit.

It is also appreciated that a production plane according to the invention can be moved from one site of use to another comparatively easily.

A special problem at a plant according to the invention is the supplying of the plant with raw materials and goods necessary for the production at the plant and the operation of the plant itself, such as cement, gravel, sand, reinforcement material, fuels, etc. As very large quantities of raw materials are required, the supply must obviously be made by sea. However, wave motions, currents and high windforces at the plant may make the unloading of cargo vessels by means of conventional equipments and devices, such as elevators, conveyors and cranes, a very difficult and time-consuming operation, which may also involve large risks for the personel as well as for the transport vessels, the plant itself, and the equipments used for the material handling. During long periods and weather conditions at the plant may be such that no unloading of conventional cargo vessels at the plant is possible. This constitutes a very serious problem, as the operation at the plant is dependent upon an uninterrupted supply of raw materials to the plant. This problem can be solved, however, by the use of a special cargo transport system which permits necessary raw materials being transported to and unloaded at the plant practically independently of the prevailing weather conditions, as wave motions, currents and winds.

In the following the invention will be further described with reference to the accompanying drawing, in which FIG. 1 is a schematic side view of a plant according to the invention shown by way of example;

FIG. 2 is a top view of the same plant;

FIG. 3 is a vertical section through the plant along the line llllll in FIG. 2;

FIG. 4 is a horizontal section through the plant along the line IV-IV in FIG. 1;

FIGS. 5 and 6 illustrate schematically two different operations at the plant illustrated in FIGS. 1-4 for the removal of finished concrete structures from the plant;

FIG. 7 illustrates schematically another possible form of a plant according to the invention;

FIG. 8 illustrates schematically a transport system for supplying a plant according to the invention of the type illustrated in FIGS. 1 to 4 with raw materials and other goods necessary for the operation of the plant;

FIG. 9 is a cross section through a transport cylinder used in the transport system illustrated in FIG. 8; and

FIG. 10 is a section along the line XX through the plant in FIG. 8, showing a terminal cylinder in the plant with a transport cylinder received therein.

The plant according to the invention schematically illustrated in FIGS. 1 to 4 consists primarily of a concrete ring, generally indicated by 1. As most readily seen in FIGS. 3 and 4, the wall or shell structure of this concrete ring 1 includes a large number of circumferentially spaced, pressure-tight, cylindrical cavities or tanks 2 which extend in the axial direction of the ring from the lower and to the upper end thereof and which are closed at the lower end. These cavities have such a total volume that the total displacement of the concrete ring 1 exceeds substantially the total dead-weight of the ring. Consequently, the concrete ring 1 can float on these cavities 2 in the wall structure of the ring and at the same time support a considerable load. As shown in FIGS. 1 and 3, the concrete ring 1 is disposed floating in the surface 3 of the body of water where the plant is to be used with the axis of the ring normally vertical. At least some of the cavities 2 in the wall structure of the concrete ring 1 are designed to serve as ballast and trimming tanks which can be filled with water to a variable extent, whereby the buoyancy, the floatation height and the attitude of the concrete ring 1 in the water can be determined and controlled. The amount of water in the various ballast and trimming tanks can be controlled individually for the different tanks, whereby any ununiform distribution of the load supported by the concrete ring can be compensated and the ring may be moved to a heeling position, as will be described in further detail in the following.

The water area 4 enclosed by the concrete ring I is effectively sheltered by the ring against wave motions, currents and winds, wherefore in this water area floating concrete structures may be manufactured for instance by the use of the manufacturing method described in the foregoing, substantially without any disturbances from wave motions, currents and winds, even if the plant is located in an open unsheltered water. On its upper ring-shaped end the floating concrete ring 1 supports all those devices, apparatuses, equipments etc. that are necessary for the intended production at the plant. Thus, for instance store spaces 5 for for instance reinforcement materials, cables, tools and other materials necessary for the productions are provided as well as buildings 6 for crew spaces, workshops, electric power plants, heating plants, pump stations, control station for the control of the position of the concrete ring 1 in the water, etc. The roofs on these buildings 6 may be adapted to serve as landing platforms 7 for helicopters. Further, two concrete mix-;

ing stations 8 are positioned diametrically upon the upper end of the concrete ring. Cranes, elevators, conveyors and similar system for the transport and handling of material are also provided but not shown in detail in the drawing.

In order to make a continuous and uninterrupted production at the plant possible large stores of cement and gravel and sand are necessary. As store spaces for these materials some of the large cavities 2 in the wall structure of the concrete ring 1 may preferably be used. From these store spaces the cement and the gravel and sand respectively can be transported to the upper end of the ring by means of elevators or compressed air.

It is appreciated that if the external conditions, as the wind, the wave motion and the currents, permit, the plant can also be used for the manufacture of floating concrete structures in the water area immediately outside the concrete ring 1.

It has already been mentioned that when using the manufacturing method described in the foregoing for the production of floating concrete structures directly in the water the initial end sections of the concrete structures can not be manufactured in the water but must be cast in a more or less conventional manner and subsequently launched. For this purpose the plant according to the invention illustrated in the drawing is provided with a workplatform or deck 9 on a portion of the upper ring-shaped edge of the concrete ring 1, which is located substantially lower than the remaining portion of the upper edge of the concrete ring. Thus, the work-deck 9 is located in a recess or opening 10 in the wall structure of the concrete ring 1. On this workdeck 9 the end sections for the concrete structures to be manufactured can be cast in a conventional manner and subsequently launched in a comparatively simple manner in that the floatation height of the concrete ring 1 is reduced by more water being pumped into the ballast tanks of the ring and possibly also in that the concrete ring is brought to a heeling position by adjustment of the amount of water in the various ballast and trimming tanks so that the work-deck 9 is lowered to a position under the surface of the water.

For the same purpose the plant according to the invention illustrated by way of example in the drawing is also provided with a similar external work-platform or deck 11 located upon and supported by the upper ends of a number of additional vertical concrete cylinders l2, which are attached to the outer side of the concrete ring I and preferably form an integral part of the concrete ring itself. The lower ends of these concrete cylinders R2 are closed and the cylinders serve as ballast tanks or store spaces for cement and gravel or sand in the same way as the cylindrical cavities 2 in the wall structure of the concrete ring 1.

It is obvious that at a plant according to the invention of the type illustrated in FIGS. 1 to 4 the removal of a concrete structure manufactured in the water area 4 surrounded by the concrete ring 1 from this water area constitutes a substantial problem. It should be kept in mind, however, that the manufactured concrete structures include large, pressure-tight cavities, some of which at least are adapted to serve as ballast and trimming tanks which can be filled with water to a variable extent for the control of the buoyancy and the position of the concrete structures in the water. By filling a sufficient amount of water into these ballast tanks of a manufactured concrete structure it is consequently possible to lower the structure so deep into the water that it is entirely below the lower end of the floating concrete ring I and can be towed away from this in a horizontal direction, whereafter it can be returned to the surface of the water in that some of the water in the ballast tanks is withdrawn. In order to control a large concrete structure completely submerged under the surface of the water, however, a very accurate matching of the total weight (concrete water in the ballast tanks) of the structure to the displacement of the structure in the water is required, wherefore the described procedure for removing completed concrete structures from the plant is rather difficult. It is much easier to control the position and the attitude of a manufactured concrete structure if a portion thereof remains above the surface of the water. If the axial height of the manufactured concrete structure is not too large, the abovementioned recess or opening 10 in the wall of the concrete ring 1 at the upper end thereof can be used for the removal of manufactured concrete structures, in that the concrete ring l by adjustment of the amount of water in the ballast and trimming tanks of the ring is lowered in the water and possibly at the same time also heeled in the manner illustrated schematically and somewhat exaggerated in FIG. 6, whereby the water area inside the concrete ring is connected to the surrounding water area 3 through the opening 10 in the wall of the concrete ring I, and in that simultaneously the manufactured concrete structure by the aid of the ballast tanks therein is raised sufficiently high in the water that it can be pulled out through the opening 10.

If the axial height of a manufactured concrete structure is large, it is of course not possible to remove the structure from the ring ll through the opening 10 at the upper end of the ring in the manner described above. Instead, however, it is possible to use a similar recess or opening 13 in the wall of the concrete ring 1 at the lower end of the ring. When using this outlet opening 13 the concrete ring 1 is raised and possibly also simultaneously heeled in the manner illustrated schematically and somewhat exaggerated in FIG. 5 so that the water area 4 enclosed by the ring l is connected to the surrounding water area 3 through the opening 113 in the wall of the concrete ring, and simultaneously the manufactured concrete structure by use of the ballast tanks therein is lowered so deep into the water that it can be towed out through the opening Elli in the wall of the concrete ring ll. It is appreciated that this is possible without the manufactured concrete structure being completely submerged under the surface of the water.

It is also possible to design the floating concrete ring, which serves as a platform for the production plant, as an open ring having a break or interruption in its wall structure, as schematically illustrated in FIG. 7. At a plant according to the invention designed in this manner there exist obviously no difficulties in towing the manufactured concrete structures 16 through the interruption or opening 14- in the wall of the concrete ring 15 serving as a floating production platform. In such an embodiment of the invention the water area enclosed by the floating concrete ring 15, in which water area the manufacturing process takes place, is of course not sheltered to the same extent as in the embodiment of the invention illustrated in FIGS. l to 4, where the floating concrete ring is circumferentially unbroken. Therefore, an embodiment of the invention according to FIG. 7 cannot be used in a completely unsheltered body of water. However, it may be particularly advantageous when manufacturing very large concrete structures which consist of a series of vertical, mutually parallel and mutually interconnected concrete cylinders, in which case the manufactured concrete structure can be fed out from the production plant (from the concrete ring at the rate it is manufactured, as schematically illustrated in FIG. 7. Concrete structures of this type can for instance be used for dams and dikes for separating one water area from another water area and similar purposes and may therefore be very large. Due to this it may be advantageous when manufacturing such concrete structures to move the production plant (the concrete ring 15) at the rate of the manufacturing process instead of moving the manufactured concrete units. In this case it is particular advantageous that the plant according to the invention is easily movable.

At the plant according to the invention illustrated by way of example in FIGS. 1 to 4 the floating concrete ring 1 serving as a production platform for the manufacturing process is moored by means of a large number of mooring cables or ropes 17 to an anchor 19 resting on the bottom 18 of the body of water. This anchor 19 consists of a concrete ring which has substantially the same diameter as the floating ring 1 and which, exactly as the floating concrete ring, has a wall structure including a plurality of circumferentially spaced, sealed, pressure-tight cavities serving as ballast tanks which can be filled with water to a variable extent for determining the effective weight of the anchor ring 19 in the water and thus the anchor force of the anchor. By pumping water out of the ballast tanks in the anchor ring this can be brought to a floating position at the surface of the water, wherefore also the anchor ring can easily be towed to the intended site for the plant.

The mooring ropes or cables 17 consist preferably of elastic ropes of synthetic plastic, which are prestretched by adjustment of the amount of water in the ballast tanks of the concrete ring 1 floating at the surface of the water. Due to this prestretching of the elastic mooring ropes a uniform distribution of the mooring force on all mooring ropes is obtained even if the total mooring force varies. Further a more stable mooring of the concrete ring 1 is achieved. If the concrete ring should be affected by a horizontal force tending to displace the ring in a horizontal direction, the mooring ropes 1 will be resiliently stretched, whereby a horizontal force is created which strives to return the concrete ring 1 to a position straight above the anchor ring 19.

The mooring ropes 17 can also be arranged to assist the guiding of a manufactured concrete structure when this is removed from the plant through the lower outlet opening 13.

As an example only serving the purpose of illustration various data for a plant according to the invention of the type illustrated in FIGS. 1 to 4 will be given in the following:

The floating production unit Total 225,000 in Draft Empty 25 in With normal cargo 30 in With ballast tanks filled m Anchor Diameter, outer m Diameter, inner 50 m Axial height 20 m Number of mooring ropes, 6" plastic ropes about 300 Total volume 90,000 m Total weight 50,000 tons Volume of ballast tanks 70,000 m Anchor force 30,000 tons Buoyancy with empty ballast tanks 40,000 tons Capacity Concrete mixing stations; 2 Gravel store; normally 20,000 tons, max 40,000 tons Mixers per station, 4 rotating mixers of 5m each Production capacity per station:

normally l,000 m /day, max 10,000 m lday Casting speed; normally about 4 m/day Casting area; normally 250 m (dependent on the cross section of the structure being cast) Casting capacity; I000 mlday Effective working days; 200 per year Annual capacity; 200,000 In concrete When estimating the casting capacity of the plant due consideration must be taken to the design of the concrete structures being manufactured. The crosssection as well as the size of the concrete structures to be manufactured will have an influence upon the casting speed as well as the total casting capacity. In estimating the data given above a comparatively low degree of efficiency has been assumed in order to allow for ample margins.

As already mentioned in the foregoing, the operation of a plant according to the invention requires an uninterrupted supply of large quantities of raw materials and other goods, such as cement, gravel, sand, reinforcement material, fuel, etc.

FIGS. 8 to 10 illustrate an advantageous transport system which can be used for the transport of large amounts of cargo to the plant. In this transport system the cargo is transported in large, closed, pressure-tight transport cylinders 20 of concrete. As shown in FIG. 9, the interior of such a transport cylinder 20 is divided into a plurality of cylindrical cavities extending parallel to the longitudinal axis of the transport cylinder. Between these cylindrical cavities or cells there are also smaller, substantially triangular cavities or cells extending in the longitudinal direction of the transport cylinder. Each such cavity or cell is provided with axially partition walls extending perpendicularly to the longitudinal axis of the cylinder. Some of the cylindrical cavities, as for instance the cavities 21, are adapted to serveas ballast and trimming tanks which can be filled with water to a variable extent, whereby the buoyancy and the attitude of the transport cylinder 20 in the water can be controlled. The remaining cylindrical cavities are designed as cargo spaces for the cargo to be transported. In the illustrated embodiment for instance the central cylindrical cavity 22 may be used for gravel or sand, the cavity 23 for reinforcement material, the cavity 24 for cement, the cavity 25 for cables and the cavity 26 for various materials and goods. The smaller cavities with triangular cross section can also be used as ballast and trimming tanks. The total volume of the ballast and trimming tanks is such that the total displacement of the transport cylinder 20 exceeds the sum of the dead-weight of the cylinder as such and the maximum weight of the cargo. One end of the transport cylinder 20 can be opened in some suitable manner not illustrated in detail in the drawing so that the cargo spaces in the cylinder can be loaded and unloaded respectively through this end of the cylinder. A concrete transport cylinder of this type may preferably be manufactured by the manufacturing method described in the foregoing.

By variation of the amount of water in the various ballast and trimming tanks in the transport cylinder it is possible to determine and control very accurately the buoyancy and the attitude of the cylinder in the water. During the actual transport the cylinder 20 is preferably moving in a surface position. It may either be towed or provided with its own propulsion machinery.

For the docking of the transport cylinder 20 at the floating concrete ring 1 during the unloading of the cargo in the transport cylinder, at least one of the cylindrical cavities 2 in the wall structure of the concrete ring 1 has an open lower end, whereby this cavity forms an open, vertical cylindrical tube which extends down into the water and is filled with water to the same level as the surrounding water surface 3. This cylindrical concrete tube 27 has an inner diameter which is somewhat larger than the outer diameter of the transport cylinder 20 and forms a docking or terminal cylinder for this.

When a loaded transport cylinder 20 has arrived at the floating concrete ring 1 but still is at such a distance from this that no risk for collision between the transport cylinder and the concrete ring exists, even if the weather conditions should be very bad, water is filled into the ballast and trimming tanks in the transport cylinder in such a manner that the transport cylinder is completely submerged and brought to assume a substantially vertical attitude in the water with the end of the cylinder pointing upwards that can be opened for the loading and unloading of the cylinder. During this operation the transport cylinder 20 may be guided for instance by a guide line or cable 28 extending between the upper end of the concrete ring 1 and the anchor 19, as schematically illustrated in the drawing. The transport cylinder 20 is guided to a position straight underneath the lower end of the terminal or docking cylinder 27 in the wall structure of the concrete 1. When the transport cylinder 20 has been brought to this position, water is pumped out from the ballast and trimming tanks in the transport cylinder, whereby this rises upwards into the terminal cylinder 27, until the upper end of the transport cylinder extends above the water surface within the terminal cylinder 27. In this position the transport cylinder 20 is thus floating in the water inside the terminal cylinder 27 in the wall structure of the concrete ring 1 and is consequently completely protected against wave motions, currents and winds. At this stage the upper end of the transport cylinder can be opened and the cargo in the transport cylinder unloaded without any disturbances from the external conditions. The unloading of the transport cylinder can be carried out by means of cranes, elevators, compressed air conduits and other conventional means for material handling.

During the unloading of the transport cylinder 20 this will of course move upwards in the terminal cylinder 27 as the cargo in the transport cylinder is reduced. Such a mutual movement between the terminal cylinder 27 and the transport cylinder 20 can be permitted to the extent that it is not prevented by the apparatuses and equipments used for the unloading of the cargo. However, the vertical position of the transport cylinder in the terminal cylinder 27 can also be maintained substantially constant during the unloading in that more water is pumped into the ballast and trimming tanks of the transport cylinder and possibly also into some of the emptied cargo spaces.

When the transport cylinder 20 has been completely unloaded, it is closed once more and lowered out from the terminal cylinder 27 in that water is pumped into the ballast and trimming tanks of the transport cylinder. When the transport cylinder has been lowered in this way to position completely below the concrete ring 1, water can once more be pumped out from the ballast and trimming tanks in the transport cylinder so that this is brought up to the water surface to a position with its longitudinal axis horizontal, this operation being guided by means of the guide line 28.

The loading of the transport cylinder can of course be carried out in a manner exactly similar to the unloading operation described above. It is also appreciated that a transport system of this type may preferably be used for the transport of materials to or from any type of plant located in an open unsheltered water.

By means of the transport system described above it is obviously possible to transport materials to the plant substantially independently of external conditions, as

high waves, strong currents and hard winds.

What is claimed is:

1. A plant for the manufacture of floating concrete structures in a body of water, comprising a generally ring-shaped concrete body with open opposite axial ends floating in the body of water with its axis of symmetry normally substantially vertical, said concrete body having a wall structure including a plurality of circumferentially spaced, preferably cylindrical cavities,

which extend in the axial direction of the concrete body, said cavities having their lowermost axial ends water-tightly closed and having such a total volume that the total displacement of said concrete body in the water exceeds substantially the total dead-weight of the concrete body, and the concrete body thus floating in the body of water with its lower axial end submerged in the water and its upper axial end above the surface of the water, at least some of said cavities being adapted to serve as ballast and trimming tanks which can be filled with water to a variable extent for variation and control of the buoyancy, and the position of the floating concrete body in the water; and apparatuses and equipments, comprising concrete mixing stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pump stations, workshops, material stores, crew spaces etc., as required for the manufacture of concrete structures in the water area enclosed by said generally ring-shaped floating concrete body being supported by said concrete body on its upper generally ring-shaped end.

2. A plant as claimed in claim 1, wherein some of said cavities (2) in'the wall structure of said concrete body (1) are adapted to serve as store spaces for materials, such as cement, gravel, sand, reinforcement materials etc., necessary for said manufacture.

3. A plant as claimed in claim 1, wherein said upper ring-shaped end of said concrete body (1) is on a portion of its circumference provided with a work-platform (9) for the casting of such portions of the concrete structures to be manufactured which must be cast at a dry place above the surface of the water, said portion of the upper end of the concrete body provided with said work-platform being located lower and thus closer to the surface of the water (3) than the remaining portion of the upper end of the concrete body, whereby structures cast on said work-platform can be launched in that the floatation height of the concrete body in the water is reduced and possibly simultaneously the concrete body is heeled.

4. A plant as claimed in claim 1, wherein said floating concrete body (1) is connected through a plurality of anchor lines (17) to an anchor (19) resting upon the bottom of said body of water, said anchor consisting of a concrete ring having a wall structure including a plurality of circumferentially spaced, sealed, water-tight cavities having a total volume such that the total displacement of said anchor ring exceeds the total deadweight thereof, said cavities being adapted to serve as ballast tanks which can be filled with water to a variable extent for determining the effective weight of said anchor ring.

5. A plant as claimed in claim 4, wherein said anchor lines (17) are arranged to assist in the guiding of a floating concrete structure being manufactured in the water area (4) enclosed by said floating concrete body (1) when said concrete structure has reached such a size that it extends below the lower axial end of the floating concrete body.

6. A plant as claimed in claim 4, wherein said anchor lines (17) consists of ropes of elastic plastic material prestretched by the buoyancy of said floating concrete body l 7. A plant as claimed in claim 1, wherein said generally ring-shaped floating concrete body is provided with an interruption (14) in its circumferential wall structure through which interruption the water enclosed by the concrete body communicates directly with the water area outside the body and through which concrete structures manufactured in the water area enclosed by the concrete body can be removed therefrom.

8. A plant as claimed in claim 1 provided with a transport system for the transport of materials to and/or from the floating concrete body (1), said transport system including at least one closed, water-tight, transport cylinder (20) movable in the water, the interior of said transport cylinder being divided into a plurality of preferably cylindrical cavities extending parallel to the longitudinal axis of the cylinder, some (21) of said cavities being ballast and trimming tanks which have such a total volume that the total displacement of the transport cylinder exceeds the sum of the dead-weight of the cylinder itself and the maximum cargo to be transported in the cylinder and which can b f'lled with water to a variabl xtent fo the control of the buoyancy and the positi on of t e transport cylinder in the water, and others (22-26) of said cavities being cargo spaces for the cargo to be transported in the cylinder, said cargo spaces being accessible for loading and unloading at one end of the transport cylinder, the wall structure of said floating concrete body (1) including at least one substantially vertical terminal cylinder (27) which has an inner diameter somewhat larger than the outer diameter of said transport cylinder and a lower open end located at a substantial depth under the water surface (3), whereby a transport cylinder arriving at the floating concrete body can be moved into said terminal cylinder in that water is pumped into the ballast and trimming tanks of the transport cylinder so that this is lowered completely under the water surface to a position directly un demeath the open lower axial end of the terminal cylinder with the longitudinal axis of the transport cylinder pointing upwards and subsequently water is pumped out from the ballast and trimming tanks of the transport cylinder so that this is raised into the terminal cylinder until the upper end of the transport cylinder extends above the water surface.

9. A plant as claimed in claim 7, wherein said transport cylinder (20) consists of concrete.

10. A plant as claimed in claim 1, comprising a plurality of vertical, water-tight concrete cylinders (12) connected to the outer side of said generally ringshaped concrete body (1), said concrete cylinders having water-tightly closed lower axial ends submerged in the water and upper axial ends located above the surface of the water (3) when said concrete body is in its normal position in the water and a work-platform (11) supported on the upper axial ends of said concrete cylinders for the casting of concrete structures to be manufactured or portions thereof at a dry-place above the surface of the water, said work-platform (l 1) being located lower and thus closer to the surface of the water than the upper generally ring-shaped end of said concrete body, whereby concrete structures cast on said work-platform can be launched in that the floatation height of the concrete body is reduced and possibly simultaneously the concrete body is heeled.

11. A plant as claimed in claim 1, wherein said generally ring-shaped floating concrete body (1) is unbroken in the circumferential direction and has a recess (10) in its wall structure at its upper axial end, through which recess the water area enclosed by the concrete body can selectively be connected with the water area outside the body by variation of the position in the water of the concrete body.

12. A plant as claimed in claim 1, wherein said generally ring-shaped floating concrete body is unbroken in the circumferential direction and is provided with a recess (13) in its wall structure at its lower axial end, through which recess the water surface enclosed by the concrete body can selectively be connected with the water surface outside the body by variation of the position in the water of the concrete body.

Claims

1. A plant for the manufacture of floating concrete structures in a body of water, comprising a generally ring-shaped concrete body with open opposite axial ends floating in the body of water with its axis of symmetry normally substantially vertical, said concrete body having a wall structure including a plurality of circumFerentially spaced, preferably cylindrical cavities, which extend in the axial direction of the concrete body, said cavities having their lowermost axial ends water-tightly closed and having such a total volume that the total displacement of said concrete body in the water exceeds substantially the total dead-weight of the concrete body, and the concrete body thus floating in the body of water with its lower axial end submerged in the water and its upper axial end above the surface of the water, at least some of said cavities being adapted to serve as ballast and trimming tanks which can be filled with water to a variable extent for variation and control of the buoyancy, and the position of the floating concrete body in the water; and apparatuses and equipments, comprising concrete mixing stations, cranes, elevators, conveyors, electric power plants, compressed air plants, pump stations, workshops, material stores, crew spaces etc., as required for the manufacture of concrete structures in the water area enclosed by said generally ring-shaped floating concrete body being supported by said concrete body on its upper generally ring-shaped end.

2. A plant as claimed in claim 1, wherein some of said cavities (2) in the wall structure of said concrete body (1) are adapted to serve as store spaces for materials, such as cement, gravel, sand, reinforcement materials etc., necessary for said manufacture.

4. A plant as claimed in claim 1, wherein said floating concrete body (1) is connected through a plurality of anchor lines (17) to an anchor (19) resting upon the bottom of said body of water, said anchor consisting of a concrete ring having a wall structure including a plurality of circumferentially spaced, sealed, water-tight cavities having a total volume such that the total displacement of said anchor ring exceeds the total dead-weight thereof, said cavities being adapted to serve as ballast tanks which can be filled with water to a variable extent for determining the effective weight of said anchor ring.

6. A plant as claimed in claim 4, wherein said anchor lines (17) consists of ropes of elastic plastic material prestretched by the buoyancy of said floating concrete body (1).

7. A plant as claimed in claim 1, wherein said generally ring-shaped floating concrete body (15) is provided with an interruption (14) in its circumferential wall structure through which interruption the water enclosed by the concrete body communicates directly with the water area outside the body and through which concrete structures manufactured in the water area enclosed by the concrete body can be removed therefrom.

8. A plant as claimed in claim 1 provided with a transport system for the transport of materials to and/or from the floating concrete body (1), said transport system including at least one closed, water-tight, transport cylinder (20) movable in the water, the interior of said transport cylinder being divided into a plurAlity of preferably cylindrical cavities extending parallel to the longitudinal axis of the cylinder, some (21) of said cavities being ballast and trimming tanks which have such a total volume that the total displacement of the transport cylinder exceeds the sum of the dead-weight of the cylinder itself and the maximum cargo to be transported in the cylinder and which can be filled with water to a variable extent for the control of the buoyancy and the position of the transport cylinder in the water, and others (22-26) of said cavities being cargo spaces for the cargo to be transported in the cylinder, said cargo spaces being accessible for loading and unloading at one end of the transport cylinder, the wall structure of said floating concrete body (1) including at least one substantially vertical terminal cylinder (27) which has an inner diameter somewhat larger than the outer diameter of said transport cylinder and a lower open end located at a substantial depth under the water surface (3), whereby a transport cylinder arriving at the floating concrete body can be moved into said terminal cylinder in that water is pumped into the ballast and trimming tanks of the transport cylinder so that this is lowered completely under the water surface to a position directly underneath the open lower axial end of the terminal cylinder with the longitudinal axis of the transport cylinder pointing upwards and subsequently water is pumped out from the ballast and trimming tanks of the transport cylinder so that this is raised into the terminal cylinder until the upper end of the transport cylinder extends above the water surface.

10. A plant as claimed in claim 1, comprising a plurality of vertical, water-tight concrete cylinders (12) connected to the outer side of said generally ring-shaped concrete body (1), said concrete cylinders having water-tightly closed lower axial ends submerged in the water and upper axial ends located above the surface of the water (3) when said concrete body is in its normal position in the water and a work-platform (11) supported on the upper axial ends of said concrete cylinders for the casting of concrete structures to be manufactured or portions thereof at a dry place above the surface of the water, said work-platform (11) being located lower and thus closer to the surface of the water than the upper generally ring-shaped end of said concrete body, whereby concrete structures cast on said work-platform can be launched in that the floatation height of the concrete body is reduced and possibly simultaneously the concrete body is heeled.