CN107542101B - Construction method of offshore four-buoy-buoyancy tank combined foundation structure - Google Patents
Construction method of offshore four-buoy-buoyancy tank combined foundation structure Download PDFInfo
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- CN107542101B CN107542101B CN201710895702.4A CN201710895702A CN107542101B CN 107542101 B CN107542101 B CN 107542101B CN 201710895702 A CN201710895702 A CN 201710895702A CN 107542101 B CN107542101 B CN 107542101B
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Abstract
The invention belongs to the technical field of foundation structures of ocean engineering, and discloses an offshore four-pontoon combined foundation structure and a construction method thereof, wherein the foundation structure comprises four pontoons which are sequentially connected on a horizontal plane according to the center points thereof to form a square, a pontoon is connected between every two pontoons, and the pontoon penetrates through the axes of pontoons at two ends of the pontoon along the central line of the length direction; the upper parts of the pontoon and the buoyancy tank are connected with a transition section tower, and the transition section tower is used for connecting upper wind power equipment; the construction method comprises the steps of prefabricating a structure, preparing for initial adjustment, carrying on water, filling water into a foundation, sinking through under negative pressure, grouting, ballasting, installing an upper structure and recycling. The invention has the characteristics of both gravity type foundation and suction type foundation, has simple and convenient transportation and installation mode while improving bearing capacity, can be recycled and reused, and greatly reduces construction cost.
Description
Technical Field
The invention belongs to the technical field of foundation structures of ocean engineering, and particularly relates to a construction method of a foundation structure applied to offshore wind power and offshore wind measuring facilities, which realizes integrated operations of integral assembly, transportation control, sinking installation and recovery.
Background
The development of the offshore wind power industry has driven the construction of a series of wind farms. As a lead project of an offshore wind power project, an offshore wind tower structure is a high-rise structure building, and a base type adopted at present is a steel pipe pile base. The foundation type construction process is complex, and large-scale machines are required for transportation and hoisting, so that the construction period is long and the construction cost is high; pile sinking positioning, torsion angles and the like of the steel pipe piles are difficult to accurately grasp, and pile sinking efficiency is low. The marine environment in which the upper anemometer tower structure is located generally contains waves, currents and the main wind load. The transmission of upper portion load can form great moment of flexure to the bottom, need design a novel foundation structure type and satisfy the bearing capacity requirement, construction cost can reduce. The traditional foundation type has a gravity foundation, the external load is resisted by the whole self weight of the structure and the weight of the filler and the ballast on the gravity foundation, the structural stability is maintained, the construction principle is simple, the cost of the filler and the ballast materials is low, but the self weight and the geometric dimension of the foundation are large, the foundation occupies a wider range of the seabed, and the construction, the transportation mode and the cost are limited for deep water areas with requirements on the seabed conditions. The novel cylindrical foundation structure is simple in form, applicable seabed conditions are wide, meanwhile, the sliding stability of the cylindrical skirt is high, the construction and installation principle is simple, but the problems of incomplete sinking and difficult leveling control exist in the sinking process, and meanwhile, the problems of buckling and the like of steel structures such as skirtboards exist in the working state, so that the development of the cylindrical foundation is restricted. These problems are also present in offshore wind turbines, and the increase in capacity of the wind turbine unit and the diversity of the geological conditions of the seabed in deep water present new challenges to the basic structural model of the offshore wind power plant.
Disclosure of Invention
In order to comprehensively adopt the characteristics of low cost, strong bearing capacity, convenient transportation of the suction cylinder foundation, wide adaptability and the like, and simultaneously to avoid the burden on the construction process and the construction cost caused by oversized foundation size of a single structural type, the invention provides the construction method of the offshore four-pontoon-floating box combined foundation structure, which has the characteristics of the gravity foundation and the suction cylinder foundation, has the advantages of improving the bearing capacity, realizing convenient transportation and installation mode, recycling and greatly reducing the construction cost.
In order to solve the technical problems, the invention is realized by the following technical scheme:
a construction method of an offshore four-pontoon combined foundation structure comprises four identical pontoons, four identical pontoons and a transition section tower; the four pontoons are sequentially connected on a horizontal plane according to the central points of the pontoons to form a square for arrangement, each two adjacent pontoons are connected by one pontoon, and the center line of the pontoon along the length direction passes through the axes of the pontoons at the two ends of the pontoon; the upper parts of the pontoons and the buoyancy tanks are connected with a transition section tower, and the transition section tower is used for connecting upper wind power equipment;
the pontoon consists of a pontoon top cover, a barrel wall, a barrel skirt, radial rib plates, annular rib plates and a sub-deck; the upper edge of the floating pontoon top cover is provided with the barrel wall, and the lower edge of the floating pontoon top cover is provided with the barrel skirt; the pontoon top cover and the pontoon wall form an upper structure of the pontoon, and the radial rib plates and the circumferential rib plates are arranged in the upper structure of the pontoon; the floating barrel top cover and the barrel skirt form a lower structure of the floating barrel, and an annular inner skirt plate is arranged in the lower structure of the floating barrel; a soil shearing ring is arranged in the range from the middle part of the cylinder skirt to the bottom end of the cylinder skirt; the height of the cylinder wall of the pontoon is one third to one half of the diameter of the pontoon top cover, and the height-diameter ratio of the height of the skirt of the pontoon to the diameter of the pontoon top cover is 0.8-1.5; the diameter of the annular inner skirt plate of the pontoon is one third to two thirds of the diameter of the pontoon top cover, and the height of the annular inner skirt plate is one third to two thirds of the height of the pontoon skirt;
the floating box consists of a floating box top plate, a floating box bottom plate, side plates, rib plates and a sliding-resistant apron plate, wherein the floating box top plate, the floating box bottom plate and the side plates form a box body with a cuboid cavity structure, a plurality of transverse and longitudinal rib plates are arranged in the box body of the floating box, and the box body of the floating box is divided into mutually communicated areas by the plurality of rib plates; air holes are preset at two ends of the top plate of the floating box, water holes are preset at two ends of the bottom plate of the floating box, and water filling and water draining inside the box body of the floating box are realized through gas-liquid replacement by utilizing the air holes and the water holes; the anti-skid skirt board is arranged at the lower edge of the bottom plate of the buoyancy tank; the height of the side plate of the buoyancy tank is consistent with the height of the cylinder wall of the pontoon, and the height of the anti-skid skirt plate of the buoyancy tank is one third to one half of the height of the side plate;
the transition section tower is composed of four same upright posts, a plurality of supporting rods and eight diagonal rods; the bottom ends of the four upright posts are respectively poured into the centers of the pontoon top covers of the four pontoons and welded together, and are inclined to the center of the foundation structure from bottom to top at the same angle; the support rods are connected among the four upright posts to form a truss type steel structure; the inclined rod is connected between the upright post and the adjacent buoyancy tank, the lower end of the inclined rod is led into the buoyancy tank from the center of the top plate of the buoyancy tank, and a gas-liquid pipeline and a grouting pipeline extending below the bottom plate of the buoyancy tank are arranged in the inclined rod; the device comprises a vertical column, a floating box, a gas-liquid pipeline, a grouting pipeline and a liquid level detection device, wherein the gas-liquid pipeline extends from the vertical column to below a floating barrel top cover of the floating barrel, the grouting pipeline extends from the vertical column to the upper structure of the floating barrel and the inside of the box body of the floating box, and the liquid level detection device is used for judging the air pressure state in the floating barrel corresponding to the bottom of the vertical column by observing the liquid level change of liquid sealed inside the vertical column in the towing process;
the construction method comprises the following steps:
(1) Prefabricating and processing all parts in a land factory, and installing the pontoon, the pontoon and the transition section tower into an integrated combined offshore four-pontoon foundation structure;
(2) Hoisting a combined offshore four-buoy buoyancy tank foundation structure to the sea surface, sinking by utilizing the dead weight of the foundation structure, increasing buoyancy by inflating the inside of the skirt of the buoy, adjusting according to the draft required by towing, and finally injecting water into the upright column for liquid sealing;
(3) Carrying out floating and towing on the combined offshore four-buoy buoyancy tank foundation structure;
(4) The combined offshore four-pontoon buoyancy tank foundation structure is carried to a designated position and then is sunk and installed, the lower structure of the pontoon is subjected to exhaust treatment to reduce buoyancy so as to enable the foundation structure to sink, meanwhile, the tank body of the buoyancy tank is filled with water so as to increase the self weight of the foundation structure, and the foundation structure further sinks until the skirt of the pontoon and the anti-skid skirt plate of the buoyancy tank contact the seabed;
(5) After the skirt of the pontoon and the anti-slip skirt plate of the pontoon are inserted into the foundation, pumping water to the lower structure of the pontoon, so that the foundation structure is further submerged until the pontoon top cover and the pontoon bottom plate are completely contacted with the mud surface, continuously pumping water to the lower structure of the pontoon, and carrying out negative pressure reinforcement treatment on the soil body;
(6) After the negative pressure reinforcement is completed, grouting the inside of the box body of the floating box by using a grouting pipeline, and carrying out stone throwing ballast or grouting ballast on the upper structure of the floating barrel;
(7) After the grouting treatment is completed, hoisting upper wind power equipment, performing water installation and completing construction.
Preferably, the soil shearing ring is arranged on the inner rotating surface and/or the outer rotating surface of the cylinder skirt, and the outer profile of the cross section of the soil shearing ring is angular or arc-shaped.
Preferably, the adjusting according to the draft required by towing in the step (2) is performed by adjusting the ballast water amount in the tank body of the buoyancy tank or the lower structural drainage amount of the pontoon.
Preferably, the floating towing in step (3) adopts single-point or two-point towing, and the water ballast is carried out on the interiors of three or two buoys except the buoys where mooring lines are arranged before towing, so that the foundation structure has a backward tilting angle for neutralizing the burial phenomenon.
Preferably, in the towing process in step (3), the change condition of the liquid level in each upright post is observed through the upright post after internal water injection and the liquid level detection equipment in the upright post, and whether the basic structure is kept in a balanced state is primarily judged, and if the basic structure is inclined from the balanced position, leveling is performed.
Preferably, during the negative pressure submerged process of step (5), leveling is performed by increasing the pumping rate at the lower structure of the buoy that is tilted up and/or by inflating or filling the lower structure of the buoy that is tilted down.
Preferably, during recycling, the wind power equipment at the upper part of the floating pontoon is dismounted firstly, then the air-liquid pipeline inside the upright post is used for injecting water or inflating inside the skirt of the floating pontoon to increase the internal pressure, and the air-liquid pipeline inside the inclined rod is used for injecting water or inflating inside the anti-skid skirt board of the floating pontoon to increase the internal pressure, so that the skirt of the floating pontoon and the anti-skid skirt board of the floating pontoon are separated from the foundation, and the whole foundation structure slowly floats to the sea surface and is towed back to the land by a tug boat
The beneficial effects of the invention are as follows:
the invention relates to an offshore four-pontoon combined foundation structure, which is formed by combining four pontoons, four pontoons and a transition section tower; the upper structure of the pontoon is used as a ballast cabin, the lower structure of the pontoon is used as a suction barrel type foundation, the characteristics of the gravity type structure and the suction barrel type foundation are combined, and the diameter of each pontoon is greatly reduced relative to the geometric shape size of the barrel type foundation or the gravity type foundation with the same scale in a four-pontoon combined mode; the floating box is used as a connecting piece to combine four independent floating cylinders into an integrated structure, the upper box body is loaded, the lower anti-slip apron plate increases the anti-slip stability of the structure, and the upper box body is grouted into a base of the integrated structure after sinking is completed; therefore, the buoyancy tank also has the characteristics of a gravity type structure and a suction skirt plate structure; the floating box and the floating box combined structure strengthen interaction between floating boxes, and simultaneously the supporting function of the sliding-resistant skirt plate at the lower part of the floating box improves lateral rigidity of the floating box skirt and prevents buckling phenomenon of the skirt in the sinking process; besides being used as a connecting structure of upper wind power equipment, the transition section tower structure has the main functions that a pipeline system is arranged inside, so that the detection and leveling in the transportation process and grouting consolidation operation after installation are finished can be realized. After the installation of the wind power equipment at the upper part is completed, the supporting point of the transition section tower structure acts to uniformly disperse the load of the upper part structure to the four buoys and the four buoyancy tanks, so that the bearing capacity of each part in the combined foundation structure is fully exerted.
According to the offshore four-pontoon combined foundation structure and the construction method thereof, the water plane area of a single pontoon is smaller, the towing process is easy to accurately control and level, the cooperation between the four pontoons is increased by combining the pontoon structure, the contact area between the foundation bottom surface and the seabed is increased, the bearing capacity of the end part is increased, and moreover, the pontoon is used as a supporting structure of an upper transition section tower, so that the force transmission system of the structure is optimized, and the stress of each part of the foundation is more uniform. The ballast grouting treatment is finally needed on the upper part of the pontoon and the inside of the box body of the buoyancy box, so that the dead weight of the foundation structure is increased, the anti-overturning stability is improved, the overall bearing capacity performance is improved, the heights of the pontoon and the lower apron boards of the buoyancy box can be greatly reduced, the material cost is saved, the foundation sinking depth is reduced, the probability of inclination in the sinking process is reduced, the sinking leveling operation is greatly simplified, and the overall construction measure is optimized.
Drawings
FIG. 1 is a schematic perspective view of a marine four-pontoon combined foundation structure according to the invention;
FIG. 2 is a schematic top view of the marine four pontoon-pontoon combined substructure provided by the invention;
FIG. 3 is a schematic view of a bottom view of an offshore four pontoon-pontoon combined substructure provided by the invention;
FIG. 4 is a schematic illustration of a pontoon structure of an offshore four pontoon-pontoon combined substructure provided by the invention;
FIG. 5 is a schematic view of a buoyancy tank structure of the marine four-pontoon-buoyancy tank combined foundation structure provided by the invention;
FIG. 6 is a schematic diagram of a transition section tower structure of the marine four pontoon-pontoon combined foundation structure provided by the invention.
In the figure: 1. pontoon, 11, pontoon top cover, 12, barrel wall, 13, barrel skirt, 14, radial rib plate, 15, annular rib plate, 16, annular inner skirt plate, 17, soil cutting ring; 2. the floating box comprises a floating box body, a floating box top plate, a floating box bottom plate, side plates, a side plate, a 24, rib plates, a 25 and a slide-resistant apron plate; 3. the transition section tower frame 31, the upright posts 32, the supporting rods 33 and the diagonal rods.
Detailed Description
For further understanding of the invention, the following examples are set forth to illustrate, together with the drawings, the detailed description of which follows:
as shown in fig. 1 to 3, the present embodiment discloses an offshore four-pontoon combined foundation structure, which mainly comprises four identical pontoons 1, four identical pontoons 2, and a transition-section tower 3.
The four pontoons 1 are sequentially connected on the horizontal plane according to the center points thereof and can be arranged in a square shape.
As shown in fig. 4, each pontoon 1 is composed of a pontoon top cover 11, a barrel wall 12, a barrel skirt 13, radial ribs 14, annular ribs 15, an annular inner skirt plate 16 and a soil shearing ring 17. The upper edge of the round pontoon top cover 11 is provided with an annular barrel wall 12, and the lower edge is provided with an annular barrel skirt 13; the height of the cylinder wall 12 is smaller, and is typically one third to one half of the diameter of the pontoon top cover 11; the height of the skirt 13 is approximately the same as the diameter of the pontoon cover 11, and the ratio (height to diameter ratio) is about 0.8-1.5. The upper structure of the pontoon 1 formed by the pontoon top cover 11 and the pontoon wall 12 has the characteristic of a gravity barrel type foundation and can be used as a ballast area after installation. The upper structure of the pontoon 1 is internally provided with radial rib plates 14 and annular rib plates 15 which are uniformly distributed, and mainly aims to prevent the barrel wall 12 from deforming after ballasting. The lower part of the pontoon 1 is internally provided with a ring-shaped inner skirt plate 16 with smaller height, which plays the roles of a sliding resistance piece and a rib plate; the diameter of the annular inner skirt 16 is typically in the range of one third to two thirds of the diameter of the pontoon cover 11, and the height of the annular inner skirt 16 is typically in the range of one third to two thirds of the height of the skirt 13. The lower structure of the pontoon 1 formed by the pontoon top cover 11 and the pontoon skirt 13 has the characteristics of a wide and shallow suction barrel type foundation, and is used for inflating the lower structure of the pontoon 1 in the floating and towing process to form a cavity so as to increase the buoyancy of the foundation structure and realize the control and leveling in the towing process; on the other hand, the lower structure of the pontoon 1 is exhausted and the buoyancy is reduced in the sinking installation process, so that the pontoon is guaranteed to sink normally, the lower barrel skirt 13 and the annular inner skirt plate 16 are finally inserted into the foundation, the foundation can be tightly attached in a negative pressure pumping mode, the foundation can be reinforced, and the horizontal anti-slip stability is exerted while the anti-overturning stability of the structure is guaranteed. The section from the middle part of the cylinder skirt 13 to the bottom end is provided with a soil shearing ring 17 at any height, the soil shearing ring 17 can be arranged on the inner rotating surface or the outer rotating surface of the cylinder skirt 13, or the inner rotating surface and the outer rotating surface are simultaneously arranged, and the section outline of the soil shearing ring can be angular or arc. The main function of the soil shearing ring 17 is to reduce the side friction resistance of the cylinder skirt in the sinking process and ensure that the foundation structure is sunk to the depth required by design.
Four buoyancy tanks 2 connect the four pontoons 1 with each other, and one buoyancy tank 2 is connected between every two adjacent pontoons 1. The buoyancy tanks 2 are welded on the buoyancy tanks 1 at both ends, so that the four buoyancy tanks 2 and the four buoyancy tanks 1 form a whole, and the central line of the buoyancy tanks 2 along the length direction passes through the axes of the buoyancy tanks 1 at both ends, so that the upper structural load can be uniformly transmitted to each buoyancy tank 1 and buoyancy tank 2 of the foundation structure.
As shown in fig. 5, the buoyancy tank 2 is composed of a buoyancy tank top plate 21, a buoyancy tank bottom plate 22, side plates 23, rib plates 24, and a skid-resistant skirt plate 25. The buoyancy tank top plate 21, the buoyancy tank bottom plate 22 and the side plates 23 form a box body with a cuboid cavity structure, the height of the box body (namely the height of the side plates 23) is consistent with that of the upper structure (namely the height of the cylinder wall 12) of the pontoon 1, namely the upper structure of the pontoon 1 and the bottom surface of the box body of the buoyancy tank 2 are flush, and the foundation and the seabed surface are completely attached after the sinking and penetration are ensured. The inside of the box body of the buoyancy tank 2 is provided with a plurality of transverse rib plates 24 and a plurality of longitudinal rib plates 24, the inside of the buoyancy tank 2 is divided into a plurality of mutually communicated areas by the plurality of rib plates 24, and the rib plates 24 are used for reinforcing the rigidity inside the buoyancy tank 2 and preventing buckling deformation of the side plates 23 of the steel structure after grouting. The two ends of the floating box top plate 21 are pre-provided with air holes controlled by valves for air charging or air discharging during air-water replacement; valve-controlled water holes are pre-arranged at two ends of the buoyancy tank bottom plate 22 and are used for adjusting the water filling amount in the buoyancy tank 2. The air holes and the water holes can be provided with a plurality of spare holes so as to prevent the blocking phenomenon from happening individually. The air holes are connected with an independent pipeline system, and the water holes are not provided with pipelines, so that water filling and water draining in the box body of the buoyancy box 2 can be realized through gas-liquid replacement. The lower edge of the bottom plate 22 of the buoyancy tank is provided with a slide-resistant apron plate 25, and the height of the slide-resistant apron plate 25 is approximately one third to one half of the height of the side plate 23. The box body of the buoyancy box 2 can be filled with water to increase dead weight in the towing process, and the requirements of towing stability are met by adjusting different draft; when sinking and installing, water is completely injected, the sinking rate is ensured, after foundation sinking and penetrating is finished, the box body inside the buoyancy tank 2 is subjected to grouting consolidation through a grouting pipeline of the transition section tower 3, and the self weight of the structure is increased to enable the buoyancy tank to have the characteristic of a gravity type foundation structure. The anti-slip skirt 25 around the lower part of the buoyancy tank 2 mainly provides anti-slip and anti-capsizing bearing capacity, and the buoyancy tank bottom plate 22 has a larger area and can be used as a main foundation base structure.
As shown in fig. 6, the transition piece tower 3 is composed of four identical columns 31, a plurality of support rods 32, and eight diagonal rods 33. The bottom ends of the four upright posts 31 are respectively poured into the centers of the pontoon top covers 11 of the four pontoons 1 and welded together, and the four upright posts 31 are inclined to the center of the foundation structure from bottom to top at the same angle; a plurality of support rods 32 are welded among the four upright posts 31 to form a truss type steel structure. Since the column 31 of the transition section tower 3 is inserted into the pontoon 1, a cross-shaped stiffening rib plate should be arranged in the range of the inserted section of the column 31 to prevent deformation. The transition section tower 3 is mainly used for connecting a combined foundation structure and upper wind power equipment, and the tower height of the transition section tower is correspondingly adjusted according to the actual water depth. The inside of each upright column 31 is respectively provided with a gas-liquid pipeline, a grouting pipeline and a liquid level detection device, wherein the gas-liquid pipeline extends from the upright column 31 to the position below a pontoon top cover 11 of the pontoon 1, so that the lower structure of the pontoon 1 can be filled with water and drained, and the lower structure of the pontoon 1 can be inflated and exhausted, thereby increasing the buoyancy when the buoyancy is insufficient in the towing process, and adjusting the inflation amount or the ballast water amount after the foundation structure is inclined, so that the corresponding pontoon 1 is lifted or sunk, and the balance of the whole foundation structure is adjusted; the joint of the grouting pipeline can be arranged at a certain height on the side wall of the upright post 31, and the grouting pipeline extends from the upright post 31 to the upper structure of the pontoon 1 and the inside of the box body of the pontoon 2. A diagonal rod 33 is connected between each upright column 31 and the adjacent buoyancy tank 2, the lower end of the diagonal rod 33 is led into the buoyancy tank 2 from the center of the buoyancy tank top plate 21, the diagonal rod 33 plays a role in transmitting the load of the upper structure to the buoyancy tank 2, a gas-liquid pipeline and a grouting pipeline are also arranged in the diagonal rod 33, the gas-liquid pipeline can be tightly attached to the rib plates 24 in the middle position in the buoyancy tank 2, and the diagonal rod can extend below the buoyancy tank bottom plate 22 and is used for inflating the interior of the anti-skid skirt plate 25; the grouting pipe extends below the floating box top plate 21 for grouting the inside of the box body of the floating box 2.
After the structural installation is completed, the upper structure of the pontoon 1 is ballasted by the riprap or grouting is carried out through a grouting pipeline, meanwhile, mortar is filled into the box body of the pontoon 2 through the grouting pipeline, grouting is not carried out in the upright column 31, and all pipeline systems are kept smooth. The box body of the whole buoyancy tank 2 can be guaranteed to be filled with mortar because the areas in the box body of the buoyancy tank 2 are communicated, two outlets are arranged on a grouting pipeline of each upright column 31 in general, and two buoyancy tanks 2 connected to the same pontoon 1 are simultaneously grouted respectively, so that the grouting speed from two ends to the middle of the same buoyancy tank 2 is guaranteed, and the construction speed and grouting uniformity are improved. The diagonal rods 33 are connected between each upright column 31 and the adjacent buoyancy tanks 2, so that the grouting extending from the middle of the buoyancy tank 2 to the two ends can be realized, and the grouting mode can be carried out simultaneously or respectively with the grouting through the pontoons 1.
By utilizing the liquid level detection device, the four upright posts 31 of the transition section tower 3 can also be used as a leveling observation system, and the main principle is that liquid seal gas is filled in the upright posts 31, so that on one hand, the bottom of the pontoon 1 is inflated and not leaked, and on the other hand, the air pressure in the pontoon 1 corresponding to the bottom of the upright posts 31 and whether air leakage occurs can be judged by observing the liquid level change condition of liquid after liquid seal in the upright posts 31 in the towing process, thereby controlling the air pressure balance in the four pontoons 1 and ensuring that the whole foundation structure is in an upright state.
When the whole structure is recovered, the gas-liquid pipeline inside the upright post 31 is used for injecting or inflating the inside of the skirt 13 of the pontoon 1, the gas-liquid pipeline inside the inclined rod 33 is used for injecting or inflating the inside of the anti-skid skirt plate 25 of the pontoon 2, so that the air pressure inside the skirt 13 of the pontoon 1 and the anti-skid skirt plate 25 of the pontoon 2 is enhanced, the total pressure difference is reduced to gradually jack up the foundation structure, the foundation slowly floats after the skirt 13 and the anti-skid skirt plate 25 are separated from the seabed, and finally the pontoon is hauled to the shore.
The four pontoons 1 and the four pontoons 2 are sequentially welded together and are independent of each other, measures such as inflation, drainage, grouting and the like among the parts can be independently and simultaneously carried out, mutual interference is avoided, and the construction period is shortened.
The construction method of the combined offshore four-buoy buoyancy tank foundation structure comprises the following steps:
(1) Prefabricating a structure: all parts are prefabricated and processed in a land factory, and the pontoon 1, the pontoon 2 and the transition section tower 3 are assembled into an integrated combined offshore four-pontoon foundation structure.
(2) Initial tone preparation: the combined offshore four-pontoon buoyancy tank foundation structure is hoisted to the sea surface, the foundation structure is submerged to a certain depth by self weight, buoyancy is increased by inflating the inside of the skirt 13 of the pontoon 1, the buoyancy is adjusted according to the draft required by towing, the inside of the buoyancy tank 2 is filled with water for ballasting when the draft is insufficient, and the lower structure of the pontoon 1 is inflated to increase the drainage amount or the buoyancy tank 2 is inflated to discharge a certain amount of ballast water when the draft is excessive, so that the self weight is reduced.
Then the column 31 is filled with water for sealing, so as to prepare for the subsequent water delivery.
(3) Carrying on water: the combined marine four-buoy buoyancy tank foundation structure is towed by a towing rope through a towing ship device, and a mooring rope point is arranged on one or two buoys 1 and is generally flush with the water surface, so that the towing speed is not too high.
Before towing, the other three or two buoys 1 need to be filled with water and ballasted, so that the structure has a certain back inclination angle, and the buoys 1 at the mooring points can generate a relatively obvious buried head phenomenon in the whole towing process, so that the initial back inclination angle can neutralize the forward inclination phenomenon formed by the buried heads, thereby ensuring the stability requirement in the towing process and reducing the power response.
In the shipping process, through the upright posts 31 after internal water injection and liquid level detection equipment in the upright posts 31, the change condition of the liquid level in each upright post 31 is observed, whether the foundation structure is in a balanced state is primarily judged, and if the foundation structure is inclined from the balanced position, leveling is performed.
(4) And (3) adding water into a foundation: and the floating pontoon is carried to a designated position and then is sunk and installed, the lower part of the floating pontoon 1 is subjected to exhaust treatment to reduce buoyancy, the foundation structure is sunk, meanwhile, the box body of the floating pontoon 2 is filled with water, the self weight of the foundation structure is increased, the foundation structure is further sunk, and the floating pontoon 1 is further sunk until the skirt 13 of the floating pontoon 1 and the anti-skid skirt plate 25 of the floating pontoon 2 are contacted with the seabed.
(5) Negative pressure penetration: after the skirt 13 of the pontoon 1 and the anti-slip apron plate 25 of the pontoon 2 are inserted into the foundation for a certain depth, pumping water to the lower structure of the pontoon 1, and further sinking the foundation structure until the pontoon top cover 11 and the pontoon bottom plate 22 are completely contacted with the mud surface, continuously pumping water to the lower structure of the pontoon 1 for a period of time, and carrying out negative pressure reinforcement treatment on the soil body.
In the process of negative pressure penetration, when the soil quality is uneven or the water pumping rate of the lower structure of the pontoon 1 is inconsistent, the sinking depth of each pontoon 1 is different, so that the foundation structure is inclined, and therefore, the leveling operation is needed, and the leveling operation is carried out by increasing the water pumping rate of the upper inclined lower structure of the pontoon 1 and/or inflating or filling water in the lower inclined lower structure of the pontoon 1.
(6) Grouting and ballasting: after the negative pressure reinforcement is completed, grouting treatment is performed on the inside of the tank body of the buoyancy tank 2 through grouting pipelines of the upright posts 31 and the diagonal rods 33, and the upper structure of the pontoon 1 can be ballasted by riprap or ballasted by grouting.
(7) Mounting the upper structure: and after the grouting treatment is finished, hoisting upper wind power equipment, and performing water installation.
(8) Recycling: firstly, the wind power equipment at the upper part of the floating pontoon is dismounted and assembled, secondly, the inside of the skirt 13 of the floating pontoon 1 is filled with water or inflated through a gas-liquid pipeline in the upright post 31 to increase the internal pressure, and the inside of the anti-skid skirt plate 25 of the floating pontoon 2 is filled with water or inflated through a gas-liquid pipeline in the inclined rod 33 to increase the internal pressure, so that the skirt 13 of the floating pontoon 1 and the anti-skid skirt plate 25 of the floating pontoon 2 are separated from a foundation, the buoyancy is further increased, the whole foundation structure slowly floats upwards, and the floating pontoon can be towed back to the land through a tug after floating on the sea.
Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative, not restrictive, and many changes may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the appended claims, which are to be construed as falling within the scope of the present invention.
Claims (7)
1. The construction method of the offshore four-pontoon combined foundation structure is characterized in that the offshore four-pontoon combined foundation structure comprises four identical pontoons, four identical pontoons and a transition section tower; the four pontoons are sequentially connected on a horizontal plane according to the central points of the pontoons to form a square for arrangement, each two adjacent pontoons are connected by one pontoon, and the center line of the pontoon along the length direction passes through the axes of the pontoons at the two ends of the pontoon; the upper parts of the pontoons and the buoyancy tanks are connected with a transition section tower, and the transition section tower is used for connecting upper wind power equipment;
the pontoon consists of a pontoon top cover, a barrel wall, a barrel skirt, radial rib plates, annular rib plates and a sub-deck; the upper edge of the floating pontoon top cover is provided with the barrel wall, and the lower edge of the floating pontoon top cover is provided with the barrel skirt; the pontoon top cover and the pontoon wall form an upper structure of the pontoon, and the radial rib plates and the circumferential rib plates are arranged in the upper structure of the pontoon; the floating barrel top cover and the barrel skirt form a lower structure of the floating barrel, and an annular inner skirt plate is arranged in the lower structure of the floating barrel; a soil shearing ring is arranged in the range from the middle part of the cylinder skirt to the bottom end of the cylinder skirt; the height of the cylinder wall of the pontoon is one third to one half of the diameter of the pontoon top cover, and the height-diameter ratio of the height of the skirt of the pontoon to the diameter of the pontoon top cover is 0.8-1.5; the diameter of the annular inner skirt plate of the pontoon is one third to two thirds of the diameter of the pontoon top cover, and the height of the annular inner skirt plate is one third to two thirds of the height of the pontoon skirt;
the floating box consists of a floating box top plate, a floating box bottom plate, side plates, rib plates and a sliding-resistant apron plate, wherein the floating box top plate, the floating box bottom plate and the side plates form a box body with a cuboid cavity structure, a plurality of transverse and longitudinal rib plates are arranged in the box body of the floating box, and the box body of the floating box is divided into mutually communicated areas by the plurality of rib plates; air holes are preset at two ends of the top plate of the floating box, water holes are preset at two ends of the bottom plate of the floating box, and water filling and water draining inside the box body of the floating box are realized through gas-liquid replacement by utilizing the air holes and the water holes; the anti-skid skirt board is arranged at the lower edge of the bottom plate of the buoyancy tank; the height of the side plate of the buoyancy tank is consistent with the height of the cylinder wall of the pontoon, and the height of the anti-skid skirt plate of the buoyancy tank is one third to one half of the height of the side plate;
the transition section tower is composed of four same upright posts, a plurality of supporting rods and eight diagonal rods; the bottom ends of the four upright posts are respectively poured into the centers of the pontoon top covers of the four pontoons and welded together, and are inclined to the center of the foundation structure from bottom to top at the same angle; the support rods are connected among the four upright posts to form a truss type steel structure; the inclined rod is connected between the upright post and the adjacent buoyancy tank, the lower end of the inclined rod is led into the buoyancy tank from the center of the top plate of the buoyancy tank, and a gas-liquid pipeline and a grouting pipeline extending below the bottom plate of the buoyancy tank are arranged in the inclined rod; the device comprises a vertical column, a floating box, a gas-liquid pipeline, a grouting pipeline and a liquid level detection device, wherein the gas-liquid pipeline extends from the vertical column to below a floating barrel top cover of the floating barrel, the grouting pipeline extends from the vertical column to the upper structure of the floating barrel and the inside of the box body of the floating box, and the liquid level detection device is used for judging the air pressure state in the floating barrel corresponding to the bottom of the vertical column by observing the liquid level change of liquid sealed inside the vertical column in the towing process;
the construction method comprises the following steps:
(1) Prefabricating and processing all parts in a land factory, and installing the pontoon, the pontoon and the transition section tower into an integrated combined offshore four-pontoon foundation structure;
(2) Hoisting a combined offshore four-buoy buoyancy tank foundation structure to the sea surface, sinking by utilizing the dead weight of the foundation structure, increasing buoyancy by inflating the inside of the skirt of the buoy, adjusting according to the draft required by towing, and finally injecting water into the upright column for liquid sealing;
(3) Carrying out floating and towing on the combined offshore four-buoy buoyancy tank foundation structure;
(4) The combined offshore four-pontoon buoyancy tank foundation structure is carried to a designated position and then is sunk and installed, the lower structure of the pontoon is subjected to exhaust treatment to reduce buoyancy so as to enable the foundation structure to sink, meanwhile, the tank body of the buoyancy tank is filled with water so as to increase the self weight of the foundation structure, and the foundation structure further sinks until the skirt of the pontoon and the anti-skid skirt plate of the buoyancy tank contact the seabed;
(5) After the skirt of the pontoon and the anti-slip skirt plate of the pontoon are inserted into the foundation, pumping water to the lower structure of the pontoon, so that the foundation structure is further submerged until the pontoon top cover and the pontoon bottom plate are completely contacted with the mud surface, continuously pumping water to the lower structure of the pontoon, and carrying out negative pressure reinforcement treatment on the soil body;
(6) After the negative pressure reinforcement is completed, grouting the inside of the box body of the floating box by using a grouting pipeline, and carrying out stone throwing ballast or grouting ballast on the upper structure of the floating barrel;
(7) After the grouting treatment is completed, hoisting upper wind power equipment, performing water installation and completing construction.
2. The construction method of the marine four-pontoon combined foundation structure according to claim 1, wherein the soil-cutting ring is arranged on the inner rotation surface and/or the outer rotation surface of the skirt, and the outer contour of the cross section of the soil-cutting ring is in an angle shape or an arc shape.
3. The method of claim 1, wherein the adjusting in step (2) is performed according to the draft required by towing, in particular, by adjusting the ballast water amount in the tank of the pontoon or the water displacement of the lower structure of the pontoon.
4. The method of claim 1, wherein the floating towing in step (3) is carried out by single-point or two-point towing, and the three or two other buoys except the buoys at the mooring line are filled with water before towing, so that the foundation structure has a backward tilting angle for neutralizing the burial phenomenon.
5. The method for constructing a four-pontoon combined foundation structure at sea according to claim 1, wherein in step (3), in the towing process, the change of the liquid level in each column is observed through the column filled with water and the liquid level detection device in the column, and whether the foundation structure is kept in a balanced state is preliminarily determined, and if the foundation structure is inclined from the balanced position, the foundation structure is leveled.
6. The method according to claim 1, wherein the leveling operation is performed by increasing the pumping rate of the lower structure of the buoy which is tilted upward and/or by inflating or filling the lower structure of the buoy which is tilted downward during the negative pressure penetration in step (5).
7. The construction method of the offshore four-pontoon combined foundation structure according to claim 1, wherein the suspended upper wind power equipment is firstly removed during recycling, then the inner pressure is increased by injecting water or inflating the inner part of the skirt of the pontoon through the gas-liquid pipeline in the upright post, and the inner pressure is increased by injecting water or inflating the inner part of the anti-skid skirt plate of the pontoon through the gas-liquid pipeline in the diagonal rod, so that the skirt of the pontoon and the anti-skid skirt plate of the pontoon are separated from the foundation, and the whole foundation structure slowly floats to the sea surface and is towed back to the land through a tug.
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| GB2570911B (en) * | 2018-02-09 | 2022-02-02 | Frederic Armour Joseph | Modular marine vessel |
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| CN110607799B (en) * | 2018-06-15 | 2024-03-22 | 深圳市移动海工技术有限公司 | Multifunctional caisson foundation structure and burial depth control method thereof |
| CN109653229A (en) * | 2018-11-19 | 2019-04-19 | 中交上海三航科学研究院有限公司 | The more negative well bore pressure cylinder anemometer tower composite foundations of jacket automate negative pressure method for sinking |
| CN109736343B (en) * | 2019-03-01 | 2023-03-21 | 江苏金风科技有限公司 | Offshore wind power foundation, installation method thereof and wind generating set |
| CN110172992B (en) * | 2019-05-07 | 2021-06-04 | 天津大学 | Four-barrel fan foundation recycling construction method |
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| CN110453712A (en) * | 2019-06-28 | 2019-11-15 | 天津大学 | A kind of combined cylinder buoyancy tank foundation structure and its construction method |
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| CN110949615B (en) * | 2019-11-15 | 2020-12-29 | 中国电建集团华东勘测设计研究院有限公司 | Floating pile-stabilizing platform device based on anchoring positioning control and pile sinking method |
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| CN112556260B (en) * | 2020-12-22 | 2024-01-05 | 天津大学 | Floating ice type wind power foundation recovery equipment and operation method |
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