AU2012313196A1

AU2012313196A1 - Partially floating marine platform for offshore wind-power, bridges and marine buildings, and construction method

Info

Publication number: AU2012313196A1
Application number: AU2012313196A
Authority: AU
Inventors: Liqiang Chen; Carlos Wong
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-04-11
Filing date: 2012-04-11
Publication date: 2014-11-20
Anticipated expiration: 2032-04-11
Also published as: AU2012313196B2; JP2015519489A; JP6105044B2

Abstract

Disclosed are a partially floating marine platform for offshore wind-power, bridges and marine buildings and a construction method. The platform comprises at least one buoyancy tube disposed vertically and with a tapered base, the buoyancy tube being a hollow column; to the base thereof are added small-bore bored piles or small-bore driven piles fixed to the bedrock or the bearing stratum of the seabed and, together with the soil layer of the tapered base of the buoyancy tube, capable of supporting external forces. The buoyancy force of the buoyancy tube can counterbalance the weight of part of the building and transform a tilting load borne by the entire foundation into loads that vertically press down and pull up on a single buoyancy tube foundation, by means of a spatial structure of multiple buoyancy tubes. The platform is able to be cast in-situ or prefabricated onshore, assembled at coastal margins, and then towed to the installation location. The marine platform can be used in marine environments with more than 5 metres of soil layer on the sea bed and with a water depth of approximately 5 to 50 metres.

Description

PARTIALLY FLOATING MARINE PLATFORM FOR OFFSHORE WIND-POWER, BRIDGES AND MARINE BUILDINGS, AND CONSTRUCTION METHOD 5 FIELD OF THE PATENT APPLICATION The present patent application generally relates to offshore platform technology of fixed foundation, especially for prestressed concrete platforms with or without piles for the 10 support of wind turbines, bridges and buildings, using large diameter hollow cylindrical columns as the floaters and a unique cone matching technique to fast fix the columns of the platform onto the seafloor, piling using small diameter piles could then be installed inside the floater if needed. BACKGROUND 15 Foundation types for offshore platforms can be classified in three groups: the gravity, pile supported and the floating type covering water depths from shallow, medium to the deep respectively. For wind turbine and bridge structures, the horizontal forces of wind, wave, surge and earthquake are likely to be the controlling load cases, since the structural dead weight is small. However, this may not be the case for building structures 20 as the gravity load is relatively large. In the case of horizontal forces controlling the design, the use of tension piles is more effective than with ballast for the increase of dead weight of the foundation except that the bearing stratum for the foundation is strong, i.e. bedrock, so that the bearing stratum can sustain the weight of the ballasted structures. On the other hand in the case of vertical forces controlling the design, the use of gravity type 25 foundation is effective if the founding layer is close to the surface of the seafloor, such that excavation of the soft material will not be in huge quantity. The gravity type will be advantageous. To reduce the strength demand for the founding layer, either to increase the contact area or reduce the loads. In the case of piled foundation, the challenges are piling operation at sea and the construction of pile cap in the water. 30 The present patent application is to address these challenges by inventing a cone matching technique with hollow cylindrical floater to compensate part of the gravity load at temporary and/or at permanent state, and piling inside the floater to accomplish the tasks without the needs of expensive piling vessel at sea. The key innovative techniques in the present invention include: turning the usual 1 vertical pier or column into a hollow cylinder-called floater which provides buoyancy allowing the floater alone or the floater-platform unit to float in a body of water; the buoyancy provided by the floaters reduces the bearing pressure on the founding stratum in temporary or in permanent state; and with the unique cone matching technique, the floater 5 can easily be fixed to the seafloor, and with the large space inside the floater, piled foundation can be realized by installing small diameter piles inside the floater and construct the pile cap, furthermore, all in a dry working environment. SUMMARY The present patent application is directed to a partially floating supported offshore 10 platform for offshore wind turbines, bridges and buildings, and the construction methods. The partially floating supported offshore platform for offshore wind turbines, bridges and buildings comprises a plurality of beams and hollow cylindrical columns referred to as floater to form a platform. The said floater is hollow section capped at the two ends by slabs. The bottom slab is configured to a single or multiple cone objects with 15 the apex of the cone pointing downward. The floater provides buoyancy capable to allow the floater itself to float, and compensates part or total of the dead weight of the platform when the platform is deposit in a body of water. The said floaters and beams to form the platform structure are constructed by match casting segmental construction method, which includes the casting of floaters, 20 beams, and deck (if any) in a number of matching segments in a factory or casting yard; the segments are then joined together in a harbor or dock side into a platform that can float in a body of water. In a special aspect where the number of floater is a singular the said platform comprises a vertically aligned hollow cylinder capped at both ends by slabs wherein the 25 bottom slab is configured to a single or multiple cone objects with the apex pointing downward. In another aspect, the floater can be tapered out at the base so that the bearing pressure on the founding stratum can be minimized to a small value for gravity type floaters. The same tapered out floater can accommodate raking piles to be installed easily 30 in a piled floater A cone matching method, which is unique to this patent application, is used to fix the said platform in the seabed wherein: 2 at the corresponding location of the floater bottom cone vertically down on the seafloor a mirrored indented cone object of the floater bottom cone referred to as reversed cone is made into a concrete bed, which is mass concrete deposit in a pothole left by removing the soft material on the seafloor, exposing the founding layer; further, the 5 preferred procedures of making the reversed cone in the concrete bed include but not limited to: at the corresponding location of the floater bottom cone in the seafloor, soft material is being excavated, dredged or sucked away to expose a firm stratum of material that can withstand the expected load of the platform; 10 float in the platform and at the same time concrete bed is prepared by filling the potholes left by the excavation in the seafloor with concrete from construction vessels using a pipe down to the seafloor according to established underwater concreting technology; The quantity of the concrete for the concrete bed should be when the platform level 15 attains the design level; the cone of the bottom slab is completely inside the body of the concrete bed; prior to the concrete setting in the concrete bed, lower the platform by adjusting its buoyancy with water in-take until its bottom cones of the floaters are completely inside the said concrete bed; 20 maintain the platform's level and orientation until the said concrete starts to set, i.e. start to harden, use high pressure water to flush separate the two faces of the floater bottom slabs and the concrete bed, then raise the platform, a reversed cone is made; when the said concrete has reached its design strength, lower the platform again onto the reversed cones which will guide the platform move to the matching position 25 previously created; maintain platform level and orientation, any gap between the surfaces of these two said cones is grouted via grout pipes pre-installed in the body of the floater and that complete the installation of the platform; In another aspect, a pressure piping system is installed in the floater to deliver high 30 pressure water jet, cement grout through the openings at the bottom part of the floater. Pumping machinery may be located inside the floater, or form outside in the construction vessels. 3 According to a further embodiment, piling is added to the foundation in cases where the concrete founding stratum for the floater coned end cannot resist further loads imposed on the founding stratum, piles are then used with a preferred embodiment includes: 5 a plurality of small diameter piles installed inside the space of the floater; install raking piles if necessary; pile cap cast at the bottom end of the floater According to the preferred but not limited to the procedures for installing small diameter piles as follows: 10 Recess holes without steel bars are cast in the bottom slab at the piling locations; Install the pile by either of boring/drilling/driving using established piling technology with the small piling plant sitting on the floater top or at the bottom of the floater when the ingress of water can be dealt with; the pile penetrates the recess hole, the concrete bed, and the soil/sand strata finally socketed into rock; 15 Dewater the floater by pumping or concrete to the bottom of the floater to make a concrete plug to stop water seeping out the water to turn to a dry working environment; Cut the piles to the required level and make good the pile head to be ready for a pile cap casting according to established procedures; Connect and fix the pile cap reinforcement bars to the embedded bar connectors in 20 the floater wall; Cast the pile cap to complete the installation. In a further aspect, a stiffened ring slab is optionally joined to the floater bottom slab to increase the bearing area in order to reduce the bearing stress in the soil stratum. In another aspect, circular bottomless steel is dropped to the excavated pothole 25 with diameter larger than the outer most diameter of the floater or the stiffened ring slab, reinforcement bars may be welded to inner face over the lower part of the concrete bed for the confinement of the concrete and reinforcing the concrete bed. In another aspect, the said bottomless steel can being replaced by dumping stone and gravel at the perimeter of the pot hole to confine the concrete. 30 In yet another aspect, the floater bottom slab and the underneath concrete bed can be joined together by post-drilling holes through the two with grouted steel rods to provide sheer key function. 4 In another aspect, includes a plurality of platforms can be joined to form a large platform. In another embodiment of the said platform, includes the preferred procedures for the assembly of the platform for the partially floating supported offshore platform but not 5 limited to: segmental match cast the floaters and beams in factory; transport the floater segments to the assembly harbor and tow to the assembly location; at least 3 guided piles are needed to be driven into the seabed at the location of the 10 floater, and are capable of supporting an overhead frame for lifting the segment; place the segment in the location of the floater, and ensure the 1st segment or the aggregate of the segments can float on the water, using the guided piles to adjust the position; for the segment that is connected with beams, an overhead frame/truss is used to 15 hang the section of the floater so that the connection can be performed above water level, but if the section of the floater has adequate buoyancy then overhead frame/truss is not needed; float in or bring in by barge those beams to be connected and by using temporary support in the guided piles, the beams to be connected is lifted and temporarily fixed onto 20 position. The gap between the floater and the beam is then fixed and lapped with steel bar from both ends, erect the shutter formwork and cast the joint with concrete; the completed platform is designed to be able to float on its own, remove the guided piles and free the platform, which is now free to be towed away. The advantages of the partially floating supported offshore platform for offshore 25 wind turbines, bridges and building structures are the adaptability for different water depths and different seabed conditions, wherein: for shallow water or the bedrock or the founding stratum close to the seabed level, a single gravity type floater can be used by using the matching cone and reverse cone technology as described in the above to fix the platform on the seabed; 30 for medium depth water, single or multiple floater platforms can be used with small diameter drill-in piles or drilled in steel H-piles. The small piling machine is sitting on the platform to perform the piling work above the sea level in dry condition, therefore, 5 no need for large and expensive offshore piling vessels. Furthermore, the risk associated with manual working under water is eliminated. In another embodiment, the installation of the platform is self completed in preferred but not limited to procedures: 5 Float in the platform and adjust its co-ordinates and orientation and maintain its position and sink to the bottom of the seabed by taking in water. When it is sitting firmly on the seabed, use high pressure jet from the nozzles in the bottom slab to clear the soft material, until bedrock surface or the designed founding layer is revealed, using the build-in tremie concrete down pipe provided in the floaters to pour the wet concrete into 10 the water jet cleared pot holes and at the same time to adjust the platform position and level and maintain in this position to allow the concrete pour bury the floater's coned slab, and level with the stiffened ring slab(if any). After the concrete becomes hardened, raise the platform by reducing its water ballast, so that the concrete bed can be cured without the influence of wave and current that being transferred by the platform on the concrete 15 bed if it stays in the concrete bed. Thereafter, the remaining procedures are similar to those described in the above and are not repeated. ATTACHED DRAWINGS Fig.1 A tri-floater piled platform for a wind turbine in the present patent application 20 Fig.2 The internal piping concept of the present patent application Fig.2B The preformed recess concept for the bottom slab of the floater in the present patent application Fig.2C The preformed recess concept for the top slab of the floater in the present patent application 25 Fig.3 Plan view of the tri-floater platform in the present patent application Fig.4 Side view of the tri-floater platform in the present patent application Fig.7A Concept of construction method in the present patent application Fig.7B Concept of construction method in the present patent application Fig. 8A Concept of construction method in the present patent application 30 Fig. 8B Concept of construction method in the present patent application Fig.9A Concept of construction method in the present patent application Fig.9B Concept of construction method in the present patent application 6 Fig. 10A Concept of construction method in the present patent application Fig. 10B Concept of construction method in the present patent application Fig. 11 Concept of construction method in the present patent application Fig. 12 Concept of Bridge pier installation in the present patent application 5 Fig. 13 Concept of Ocean building structural form in the present patent application Fig. 14 Concept of multi-platform scheme in the present patent application Drawing Notes 1. Floater 2. Bottom coned slab 10 3. Regulating tower section 4. Stiffened ring slab 5. Wind turbine tower 6. Seabed/seafloor 7. Rubble wall/mount 15 8. Sea surface 9. Concrete bed 10. Partially floating supported offshore platform 11. Reversed cone 12. Cement grout or simply grout 20 13. Soil/sand strata 14. Founding stratum 15. pothole 17. Pile cap 21. Small diameter pile 25 22. Dredging arm 23. Dredger 24. Boring plant 25. Casing 26. Operation vessel 30 27. Small diameter piles 28. Piling plant 31. Tremie concrete pipe 7 37. Pressure pipe 38. Value 39. Recess hole 40. Bedrock 5 DETAILS DESCRIPTION Reference will now be made in detail to a preferred embodiment of the partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings disclosed in the present patent application, examples of which are also provided in the following description. Exemplary embodiments of the partially floating supported offshore 10 platform 10 for offshore wind turbines, bridges and buildings disclosed in the present patent application are described in detail, although it will be apparent to those skilled in the relevant art that some features that are not particularly important to an understanding of the partially floating supported offshore platform 10 may not be shown for the sake of clarity. 15 Furthermore, it should be understood that the partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings disclosed in the present patent application is not limited to the precise embodiments described below and that various changes and modifications thereof may be effected by one skilled in the art without departing from the spirit or scope of the protection. For example, elements and/or 20 features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure. In order to explain clearly the intension of the present patent application, detailed description is now given as follow: 25 Work example 1 The intention is to install a platform 10 as described in the present patent application in an open sea of 25m deep for the support of a 3MW horizontal axis wind turbine 5. The platform 10 constructed in accordance with the present patent application has 30 the benefits of the floater 1 that floatation can offset up to 1/2 of its dead weight. The ballast of water inside the floater 1 can change the base frequency of the structure so as to avoid the max wind energy spectrum earthquake energy. 8 Fig. 1 shows a platform 10 of the present patent application, includes 3 vertically aligned floaters 1, which are supported by partially buoyancy force. Small diameter piles 27 are installed at the bottom of the floaters 1. The piles are anchored to the bedrock 40 or to the founding stratum 14. The bottom 5 slab of the floater 1 is cast with a cone pointing downward 2. In Fig 1-4, the inner face of bottom slab of the floater 1 has circular recess holes 39. Piles 27 are guided into the recess holes and penetrate into the concrete bed 9 and the soil/sand strata 13 in the seafloor 6 and finally socketed into the bedrock 40 or to the founding stratum 14. Fig.3 shows the three floaters 1 are inter-connected to form a 10 platform 10 with one of the floaters 1 to be installed with a horizontal axis wind turbine 5. It is also possible to use one single floater 1 to form a platform 10, as given in Fig.9B. A single floater 1 platform comprises a vertically aligned floater 1 and the stiffened ring slab 4 at the bottom of the floater 1/or with small diameter piles 27. In multi-floater platform, a spatial structure is formed by connecting the vertically placed floaters 1 with beams and 15 with or without small diameter piles 27 in group fixed to the bottom of the floaters 1. Fig.1 shows a said platform 10 with a triangular shape in plan. One must not be conceived that the said platform applies only to triangular shape, but by the same principle, the said platform can be of other shapes, such as square, rectangle, pentagon etc. The section of the floater 1 can also be polygon other than circle. 20 In the work example, the dimension and member sizes can be taken as: height of floater 1 30m; floater 1 wall thickness 0.35m; top slab thickness 0.35m to 0.5m; bottom coned slab 2 thickness 0.35m to 0.6m. In Fig.2, the said platform 10 consists of hollow cylindrical floater 1. However, the floater 1 can be of tapered shape with its bottom greater than the top to increase stability 25 and reduce the bearing pressure on the bearing stratum. Furthermore, a stiffened ring slab 4 can be added to the bottom of the floater 1 to increase the area further, in order to reduce further the bearing pressure. As shown in Fig.1, the said platform further includes a regulating tower section 3 over the top of the floater 1 that support the wind turbine. The level of the regulating tower 30 section 3 should be above the max designed wave height. In the implementation work example, e.g. Fig.2A, 2B, 2C, the internal of the floater 1 is pre-installed with pressure pipes 37 for pumping high pressure water and 9 cement grout to the bottom water side of the said floaters 1 by coupling the inlet with water pump or concrete/cement grouting plant. The outlets of the pressure pipes are at the water side of the bottom slab. The water pipes are used for flushing the seabed and for flush open the gap between the floater 1 bottom coned slab 2 and the concrete bed 9. 5 Optional, the floater 1 can be filled with water or sand to increase the self weight in order to stabilize the floater 1. For a 3MW horizontal axis wind turbine, the steel tower 5 will have a height of 65m; the nacelle is placed on top of towers and is weight 400t. In the work example 1, the design of the said platform 10 for wind turbine support, 10 the key issue is to resist the uplifting force in the floater 1 induced by huge overturning moment. In the calculation, the small diameter piles 27 are 0.3m, embedded length into rock 3m, reinforcement bar 3x50 mm, high pressure grouted mini-pile. Horizontal load is resist by the stiffened bottom coned slab 2 which translates the force to the concrete bed 9 which in turn translates the force into the bearing stratum 13. 15 Work example 2 Fig.12 shows a bridge pier 35, 36 supported on a platform 10 which in turn is supported by 2 floaters 1 and the small diameter pile 27 system. Floater 1 diameter 8m, height 30m, wall thickness 0.4m for water depth 30m, soil/sand layer 25m, small diameter 20 pile 27 socketed into bedrock 40. Work example 3 Fig. 13 shows the said platform 10 in grid formation with floaters 1 located at the nodes. The main structure frame is formed by connecting the floaters 1 with main beams 25 32 on the top level and optional main beams 34 at the lower level. Secondary beams 33 branch out to suit the building layout. The basic module for offshore building platform has 4 cylindrical floaters 1 supporting a grid of beam 30mx3Om overall. The sizes of the platform can be increased by combining a number of the basic modules. In this work example, the dimension and sizes 30 of the structural members are in the following: Water depth 30m; soil/sand layer 20m; floater 1 diameter 8m, height 30m, wall thickness 0.4-0.5m, top and bottom slabs 0.4-0.6m 10 Work example 4 Fig.5-11 show the installation of a tapered single floater platform fixed to the seafloor. 5 Fig. 1 shows a dredger vessel 23 is used to excavate the seabed 6 to expose the founding stratum 14 in the excavated pothole 15 in the seabed 6. Fig.6 shows the operation vessel 24 uses a tremie concrete pipe 31 to pour concrete in the pothole 15 to form a concrete bed 9 confined by the rubble mount 7, and at the same time platform 10 being floated in. 10 Fig.7A, prior to the concrete set, lower the platform 10 to the concrete bed 9 in the seabed 6. Fig.7B, the platform 10 is at the design level, with its bottom coned slab completely inside the still wet concrete bed 9. Fig.8A shows the platform 10 is raised after the concrete in the concrete bed is set 15 (hardened) leaving a mirrored indented reversed cone 11 in the concrete bed 9. Fig.8B shows the platform 10 is lowered again sitting on the concrete bed 9 with the bottom coned slab fitting in well with the reversed cone 11 in the concrete bed 9. The gap between the two faces is then grouted 12. Fig.9A shows a small diameter pile 21 is installed with the small boring plant 24 20 situated on the bottom of the floater 1 through the bottom coned slab 2, the concrete bed 9, and the soil/sand strata 13 and finally socketed in to bedrock 40. Fig.9B shows the piles 21 are cut to level and pile cap 17 is cast into the bottom of the floater 1. Fig.10A shows a boring plant 24 executes boring pile using a casing 25 from the 25 top end of the platform 10. Fig. 1OB shows a piling plant drives pile 27 from the top of the platform 10. Fig. 11 shows a group of small diameter pile 27 has been installed with short length of pile casing bring grouted 12 left in the pile cap 17. 30 Work example 5 The casting of concrete bed 9 on the seafloor 6 optionally can be formed without the needs of excavation vessels as indicated in the above, provided that the seafloor 6 11 geological condition is favorable. The platform 10 for this application is equipped with high pressure water jet and concrete pipe which open to the water side in the bottom slab. For shallow bedrock 40 in the seabed with a layer of relatively thin soft material, the seabed concrete bed 9 can be 5 made by the platform itself. Float in the platform and adjust its co-ordinates and orientation and maintain its position and sink to the bottom of the seabed by taking in water. When it is sitting firmly in the seabed, use high pressure jet from the nozzles in the bottom slab to clear the soft material, until bedrock 40 surfaced or the designed founding layer is revealed, use the 10 build-in tremie concrete down pipe provided in the floaters 1 to pour the wet concrete into the water jet cleared potholes 15 and at the same time to adjust the position and level and maintain in this position to allow the concrete pour to bury the floater l's coned slab, and level with the stiffened ring slab 4(if any). After the concrete hardened, raise the platform by reducing its water ballast, so that the concrete bed 9 can undergo curing without the 15 influence of wave and current that the platform would have endured otherwise, if it stays in the concrete bed 9. After the concrete bed 9(with a mirrored indentation of the coned slab) has reach the design strength, sink the platform and sit on the concrete bed 9 with the floater 1's bottom cone slides in the reversed cone in the concrete bed 9, and then using the 20 pre-installed pressure pipe to inject cement grout, filling the gap 12 between the floater 1 and the concrete bed 9, that fix the floater 1 onto the seafloor 6. The assembly of the partially floating supported offshore platform 10 may be executed but not restricted to the following manners: segmental matching casting of the segment for floater 1 in the factory or casting 25 yard; segmental matching casting of the segments for the connecting members in the factory or casting yard; at the harbor, install at least 3 guiding piles for each floater 1 at the floater 1 location for the use of confining the segment of floater 1 into position and supporting the 30 weight of the segment of the floater 1 by an overhand frame/truss; transport the floater 1 segment to the harbor site; by the use of floating crane or other means, lift the bottom segment into position 12 guided by the guiding piles, which should be floatable under the weight of itself and the immediate segment above it; lift the next segment onto the completed section and use prestressing to join this next segment; and repeat the process until the last segment; 5 when the completed floater 1 length contains a joint for connecting a beam; the said length is hung from the overhead frame/truss and restrained by the guiding piles transport the segment of the beam to site and joined together to form the beam; lift the beam and place on temporary support on the guiding pile or by the overhead frame/truss; 10 fix steel bars and lap the steel bars from the floater 1 and the beam; cast the joint with insitu concrete; when all the segments are fixed; remove all the confinement mechanism to allow the platform to float by its own; remove the overhead frame/truss, and the guiding piles; float out the platform; 15 platform assembly complete; optional to install the wind turbine; 13

Claims

1. A partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings adapted for water depth greater than 5m comprising: 5 a plurality of floaters 1 inter-connected with beams to form a platform fixed support on concrete beds 9 that cast on the seafloor 6 to support wind turbines, bridges and buildings;

2. The partially floating supported offshore platform 10 of claim 1 further comprising: 10 a plurality of small diameter piles 27 installed inside the floater 1 through the recess holes 39 pre-formed in the top face of bottom slab of the floater 1 where the bored piles or the driven piles penetrate the recess holes 39 and the underlain concrete bed 9, soil strata 13 and finally socketed into bedrock 40 or founding layer; the socketed piles provide counter uplifting force. 15

3. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of claim 1 is further comprising a coned bottom slab 2 for the floater 1 with the apex of the cone pointing downward. 20

4. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of the claim 1 further includes at least a tri-floater platform with one of the floaters supports a wind turbine.

5. The partially floating supported offshore platform 10 for offshore wind turbines, bridges 25 and buildings of claim 3 further includes a stiffened ring slab 4 extended outside from the floater 1 bottom slab.

6. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of claim 1 further includes a section of regulation tower 3 extended from the 30 floater 1 that support the wind turbine.

7. The partially floating supported offshore platform 10 for offshore wind turbines, bridges 14 and buildings of claim 6 wherein the floater 1 and/or the said regulation tower 3 being fabricated from steel or prestressed concrete/lightweight concrete/fiber reinforced concrete or steel-concrete composite material. 5

8. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of claim 1 includes a pressure pipe system 37 installed in the body of the floater 1 with value 38 at the top floaters 1; for pumping high water jet to clean the soft material in the seabed or to flush open the gap between the floater 1 cone face and the concrete bed 9 face; also used to pressure grout the gap 12 around the floater 1 bottom slab 10 face.

9. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of claim 1 wherein the floater 1 being filled with sand and/or water to increase the platform self weight in order to counter the uplifting force induced by wind 15 loads.

10. A construction method for the partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings includes the preferred but not limited to procedures: 20 to excavate the soft materials in the seafloor 6 at the location of erecting the floater 1 by dredging, sucking or flushing methods; pour the tremie concrete by gravity method or by pumping concrete method into the potholes; lower the platform until the bottom coned slab 2 is completely inside the tremie concrete bed 9 prior to the initial setting of the wet concrete of the concrete bed 9; 25 maintain the level and position of the platform until the tremie concrete in the concrete bed 9 is at the initial set, i.e. the wet concrete starts hardening, use the high pressure water jet to flush separate the two said cone faces and raise the platform; lower the platform with the cone in the bottom slab of the floater 1 pointing to the reversed cone in the concrete bed 9 at the seafloor 6; 30 after the cone of the bottom slab of the floater 1 and the reversed cone of the concrete bed 9 joined together, pressure grout to the gap between the surfaces of the cone in the bottom face of the floater 1 and the reversed cone face of the concrete bed 9 in the 15 seafloor 6; the platform is fixed to the concrete bed 9 which is in turn fixed to the seabed firm stratum. optional piling support includes: install the piles 27 by either of boring/drilling/driving using established 5 piling technology with the small piling plant sitting on the floater 1 top or at the bottom of the floater 1 when the ingress of water can be dealt with; the pile 27 penetrates the recess hole, the concrete bed 9, and the soil/sand strata 13 finally socketed into rock; dewater the floater 1 by pumping or concrete to the bottom of the floater 1 10 to make a concrete plug to stop water seeping in before dewatering for a dry working environment; cut the piles 27 to the required level and make good the pile 27 head to be ready for a pile cap 17 casting according to established procedures; connect and fix the pile cap 17 reinforcement bars to the embedded bar 15 connectors in the floater 1 wall; cast the pile cap 17 to complete the installation.

11. A construction method for the installation of the partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings includes: 20 float in the platform into position; hover the floater 1 above the soft material in the seafloor 6, then using the high pressure water jets from the pipes to flush the soft material away until a founding layer is reached; lower the platform aiming the floater 1 at the seafloor 6 of the excavated potholes, pour the tremie concrete by gravity method or by pumping concrete method into the potholes; one special aspect is to deliver the tremie 25 concrete via the pipes installed in the body of the floater 1; lower the platform until the bottom coned slab 2 is completely inside the tremie concrete bed 9 prior to the initial setting of the wet concrete of the concrete bed 9; maintain the level and position of the platform until the tremie concrete in the concrete bed 9 is at the initial set, i.e. the wet concrete starts hardening, use the high 30 pressure water jet to flush separate the two said cone faces and raise the platform; lower the platform with the cone in the bottom slab of the floater 1 pointing to the reversed cone in the concrete bed 9 at the seafloor 6; 16 after the cone of the bottom slab of the floater 1 and the reversed cone of the concrete bed 9 joined together, pressure grout to the gap between the surfaces of the cone in the bottom face of the floater 1 and the reversed cone face of the concrete bed 9 in the seafloor 6; the platform is fixed to the concrete bed 9 which is in turn fixed to the seabed 5 firm stratum. optional piling support includes: install the pile 27 by either of boring/drilling/driving using established piling technology with the small piling plant sitting on the floater 1 top or at the bottom of the floater 1 when the ingress of water can be dealt with; the pile 27 10 penetrates the recess hole, the concrete bed 9, and the soil/sand strata 13 finally socketed into rock; dewater the floater 1 by pumping or concrete to the bottom of the floater 1 to make a concrete plug to stop water seeping in before dewatering for a dry working environment; 15 cut the piles 27 to the required level and make good the pile 27 head to be ready for a pile cap 17 casting according to established procedures; connect and fix the pile cap 17 reinforcement bars to the embedded bar connectors in the floater 1 wall; cast the pile cap 17 to complete the installation. 20

12. A construction method for the installation of the partially floating supported offshore platform 10 for bridges and buildings includes the preferred but not limited to the procedures: to excavate the soft materials in the seafloor 6 at the location of erecting the floater 25 1 by dredging, sucking or flushing methods; using the internal tremie down pipe to pour the concrete from the bottom slab down pipe opening equipped with remote controlled sliding door to the excavated pothole; slide shut the opening door; lower the platform until the bottom coned slab 2 is completely inside the tremie concrete bed 9 prior to the initial setting of the wet concrete of the concrete bed 9; 30 maintain the level and position of the platform until the tremie concrete in the concrete bed 9 is at the initial set, i.e. the wet concrete starts hardening, use the high pressure water jet to flush separate the two said cone faces and raise the platform; 17 lower the platform with the cone in the bottom slab of the floater 1 pointing to the reversed cone in the concrete bed 9 at the seafloor 6; after the cone of the bottom slab of the floater 1 and the reversed cone of the concrete bed 9 joined together, pressure grout to the gap between the surfaces of the cone 5 in the bottom face of the floater 1 and the reversed cone face of the concrete bed 9 in the seafloor 6; the platform is fixed to the concrete bed 9 which is in turn fixed to the seabed firm stratum. optional piling support includes: install the pile 27 by either of boring/drilling/driving using established piling 10 technology with the small piling plant sitting on the floater 1 top or at the bottom of the floater 1 when the ingress of water can be dealt with; the pile 27 penetrates the recess hole, the concrete bed 9, and the soil/sand strata 13 finally socketed into rock; dewater the floater 1 by pumping or concrete to the bottom of the floater 1 to make a concrete plug to stop water seeping in before dewatering for a dry working environment; 15 cut the piles 27 to the required level and make good the pile 27 head to be ready for a pile cap 17 casting according to established procedures; connect and fix the pile cap 17 reinforcement bars to the embedded bar connectors in the floater 1 wall; cast the pile cap 17 to complete the installation. 20

13. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of any one of the claim 10-12, the said floater 1 after fixed to the seabed, being ballasted by filling the void in the floater 1 with water or sand. 25

14. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of any one of the claim 10-12, a circular bottomless steel can is dropped to the excavated pothole with diameter larger than the outer most diameter of the floater 1 or the stiffened ring slab 4, reinforcement bars may be welded to inner face over the lower part of the concrete bed 9 for the confinement of the concrete and reinforcing the 30 concrete bed 9.

15. The partially floating supported offshore platform 10 for offshore wind turbines, 18 bridges and buildings of any one of the claim 10-12, wherein a rubble mount/wall being formed by dumping stones around the excavated pothole to contain the tremie concrete.

16. The partially floating supported offshore platform 10 for offshore wind turbines, 5 bridges and buildings of any one of the claim 10-12, wherein the construction method further includes segmental match casting of floaters 1 and beams in factory or casting yard using prestressed concrete or prestressed lightweight concrete or fiber reinforced concrete; and the floater 1 and beam segments being transported to the harbor or to the implementation venue for installation. 10

17. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of any one of the claim 10-12, wherein the construction method further includes the construction methods for assemble the platform in a harbor; wherein segmental matching casting of the segment for floater 1 in the factory or casting 15 yard; segmental matching casting of the segments for the connecting members in the factory or casting yard; at the harbor, install at least 3 guiding piles for each floater 1 at the floater 1 location for the use of confining the segment of floater 1 into position and supporting the 20 weight of the segment of the floater 1 by an overhand frame/truss; transport the floater 1 segment to the harbor site; by the use of floating crane or other means, lift the bottom segment into position guided by the guiding piles, which being floatable under the weight of itself and the immediate segment above it; 25 lift the next segment onto the completed section and use prestressing to join this next segment; and repeat the process until the last segment; when the completed floater 1 length contains a joint for the connection of a beam; the said length is hung from the overhead frame/truss and being restrained by the guiding piles 30 transport the segment of the beam to site and joined together to form the beam; lift the beam and place on temporary support on the guiding pile or by the overhead frame/truss; 19 fix steel bars and lap the steel bars from the floater 1 and the beam; cast the joint with insitu concrete; when all the segments are fixed; remove all the confinement mechanism to allow the platform to float by its own; 5 remove the overhead frame/truss, and the guiding piles; float out the platform; platform assembly complete; optional to install the wind turbine;

18. The partially floating supported offshore platform 10 for offshore wind turbines, 10 bridges and buildings of any one of the claim 10-12, wherein the bottom coned slab 2 is installed with post-drilled steel rods extended down to the concrete bed 9 with the holes backfilled by cement grout to form shear keys between the bottom coned slab 2 and the concrete bed 9. 15

19. The partially floating supported offshore platform 10 for offshore wind turbines, bridges and buildings of any one of the claim 10-12, wherein a plurality of the platforms being joined together to form a great platform. 20