Tension leg platform suction pile anchoring foundation

Abstract

The utility model discloses a suction pile anchoring foundation of a tension leg platform, which relates to the technical field of ocean engineering and comprises a base structure and a mud-entering steel structure. The base structure is fixed to the top of the mud entering steel structure. The base structure is of a double-wall cylindrical structure, a ballast tank is arranged in the base structure, and a ballast system is arranged in the ballast tank; a drainage pipeline is further arranged in the base structure and communicates with the interior of the mud inlet steel structure and the water suction pump. A lug plate structure is arranged on the side wall of the base structure; the mud entering steel structure is of a single-layer wall cylindrical structure, and the cylindrical opening direction of the mud entering steel structure is opposite to the cylindrical opening direction of the base structure; and a to-be-mounted counterweight is placed in the upper opening structure of the base structure. The technical problem that the axial pulling resistance capacity of a traditional suction pile anchoring foundation is limited by a suction barrel structure type, an installation mode and soil conditions, and the traditional suction pile anchoring foundation is not suitable for a tension leg type floating platform including a floating wind power platform is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of ocean engineering, and specifically relates to a tension leg platform suction pile anchoring foundation. BACKGROUND

[0002] Suction pile type anchoring foundations are widely used in ocean engineering and provide anchoring foundations for positioning of ocean engineering structures. The structure is a steel cylinder type structure with a closed upper end and an open lower end. The barrel wall penetrates into the seabed soil under the self-weight of the anchoring foundation to form a closed space. Then, the liquid in the closed space is pumped out by a pump to form a pressure difference between the closed space and the outside, so that the external pressure further penetrates the barrel wall into the seabed soil.

[0003] The design features of the general suction pile anchoring foundation are as follows: 1) the self-weight of the anchoring foundation structure penetrates the barrel wall into the seabed soil to a certain depth to form a closed space; and 2) the closed space can form a large enough internal and external pressure difference to overcome the friction between the barrel wall and the soil to press the suction barrel to the designed depth. The above two points make the depth at which the traditional suction barrel anchoring foundation can penetrate into the soil under a given suction barrel diameter depend on the soil conditions, and further determine the axial uplift capacity of the traditional anchoring foundation. In order to ensure the stability of the tension leg type wind power platform, the mooring cable (chain) of the tension leg type wind power platform needs to be kept in a tensioned state at all times, and thus the anchoring foundation of the tension leg type wind power platform needs to have a large axial uplift capacity. For example, the anchoring foundation of a 15-megawatt tension leg type floating wind power platform needs to have an axial uplift capacity of several thousand tons or more.

[0004] Generally speaking, the traditional suction pile anchoring foundation has good horizontal load resistance and is more suitable for application in cohesive soil, but is not conducive to application in sandy soil. Therefore, the suction pile type foundation designed according to the traditional scheme and having a high axial uplift capacity can only be applied in a few areas with particularly good soil conditions, which limits the application area of the suction pile type foundation with a high axial uplift capacity, and thus the traditional suction pile anchoring foundation is generally not suitable for tension leg type floating platforms (including floating wind power platforms). SUMMARY

[0005] The purpose of the utility model is to provide a tension leg platform suction pile anchoring foundation to solve at least one of the above technical problems.

[0006] The utility model discloses an embodiment provides a kind of tension leg platform suction pile anchoring foundation, comprising: pedestal structure and mud entering steel structure;The pedestal structure is fixed on the top of the mud entering steel structure;The pedestal structure is double-wall cylinder structure, ballast cabin is arranged in the pedestal structure, and ballast system is arranged in the ballast cabin;Drain line is also arranged in the pedestal structure, one end of the drain line passes through the bottom of the pedestal structure and is communicated with the inside of the mud entering steel structure, and the other end of the drain line passes through the top of the pedestal structure and is connected with water suction pump;Ear plate structure is arranged on the sidewall of the pedestal structure;The mud entering steel structure is single-wall cylinder structure, and the cylinder opening direction of the mud entering steel structure is opposite to the cylinder opening direction of the pedestal structure;The upper opening structure of the pedestal structure is placed with the weight to be installed inside.

[0007] Further, the pedestal structure is a steel plate shell structure, the inner side wall of the pedestal structure is provided with a structure matched with different weights to be installed for fixing the weights to be installed and transmitting the weight of the weights to be installed to the pedestal structure.

[0008] Further, the port of the top end of the drain line connected with the pedestal structure is provided with a flange, and the top port of the drain line is connected with the external pipeline connected with the water suction pump through the flange.

[0009] Further, the ear plate structure includes a horizontal eye plate arranged on the outer sidewall of the pedestal structure and a vertical eye plate arranged on the top edge of the pedestal structure.

[0010] Further, the ballast system includes a first pipeline and a first sea valve, wherein the first sea valve is arranged on the outer sidewall of the pedestal structure, and the first pipeline is connected with the first sea valve.

[0011] Further, the ballast system further includes an air pipe, one end of the air pipe extends into the ballast cabin, and the other end of the air pipe communicates with the outside of the ballast cabin through the top of the pedestal structure.

[0012] Further, the weight to be installed includes iron ore sand or cement.

[0013] Further, the pedestal structure further includes a buoyancy cabin, and the buoyancy cabin is arranged on the top of the ballast cabin.

[0014] This invention provides a suction pile anchor foundation for a tension leg platform. The penetration depth of the suction pile anchor foundation into the seabed soil is increased by the counterweight to be installed, and further increased by drainage pipelines and water pumps. This solves the problem of poor axial pull-out resistance of suction pile anchor foundations, expands their application range, and allows them to be used on tension leg platforms. Compared to driven piles, this invention facilitates offshore installation while solving the problem of relatively weak axial bearing capacity of suction pile anchor foundations, making them unsuitable for tension leg platforms. Meanwhile, the form of the counterweight to be installed makes the base structure itself relatively lightweight, and the inclusion of ballast tanks and buoyancy tanks enables the base structure to float on its own. It can be used by tugboats for wet towing and offshore installation operations, and has the advantage of not needing to use large equipment such as floating cranes. This makes the surface transportation of the base structure more convenient, reduces the equipment requirements and costs for offshore operations, and has an economic advantage. It also alleviates the technical problem that the axial pull-out resistance of traditional suction pile anchor foundations is limited by the suction tank structure type, installation method and soil conditions, making them unsuitable for tension leg floating platforms, including floating wind power platforms. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 A side view of a tension leg platform suction pile anchorage foundation provided for an embodiment of this utility model;

[0017] Figure 2 A side view of a base structure provided in an embodiment of this utility model;

[0018] Figure 3 A top view of the distribution of a first pipeline inside a ballast tank, provided for an embodiment of the utility model;

[0019] Figure 4 A top view of a base structure provided in an embodiment of this utility model;

[0020] Figure 5 This is a partially enlarged view of the side wall portion of a base structure provided in an embodiment of the present utility model.

[0021] In the diagram: 1. Base structure, 2. Mud-entry steel structure, 3. Ballast tank, 4. First pipeline, 5. First sea valve, 6. Vent pipe, 7. Drainage pipeline, 8. Water pump, 9. Horizontal eye plate, 10. Vertical eye plate, 11. Tugboat, 12. External pipeline, 13. Buoyancy tank, 14. Second sea valve, 15. Second pipeline, 16. Upper opening structure. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Figure 1 This is a side view of a tension leg platform suction pile anchorage foundation provided according to an embodiment of the present utility model. Figure 1 As shown, it includes: a base structure 1 and a mud-inserting steel structure 2; the base structure 1 is fixed to the top of the mud-inserting steel structure 2.

[0024] Specifically, the base structure 1 is a double-walled cylindrical structure, including an upper open structure 16, the bottom of which is closed.

[0025] Optionally, the base structure 1 includes any polygonal cylindrical structure (e.g., a square cylindrical structure), a circular cylindrical structure, or an irregular cylindrical structure.

[0026] Preferably, the base structure 1 is a double-walled cylindrical steel plate shell structure; the mud-inserting steel structure 2 is a single-walled cylindrical steel plate shell structure.

[0027] Specifically, the counterweight to be installed is placed inside the upper opening structure 16 of the base structure 1.

[0028] Optionally, the counterweight to be installed may include iron ore or cement. In this embodiment of the invention, the type of counterweight to be installed can be selected according to actual needs.

[0029] Specifically, the inner wall of the base structure 1 is provided with a structure that matches different counterweights to be installed, for fixing the counterweights to be installed and for transferring the weight of the counterweights to be installed to the base structure 1.

[0030] In this embodiment of the invention, the cylindrical structure of the base structure 1 can be used to support the counterweight to be installed, thereby improving the axial pull-out resistance of the suction pile anchor foundation. The separate design and distributed installation of the counterweight eliminates the need for the base structure 1 to support the counterweight during construction, launching, and offshore installation phases, thus optimizing the design of the base structure 1. The base structure 1 is self-floating, reducing the transportation costs of the suction pile anchor foundation and lowering the demand for offshore installation equipment by avoiding the use of large floating cranes.

[0031] Figure 2 This is a side view of a base structure provided according to an embodiment of the present utility model. Figure 2 As shown, a ballast tank 3 is installed inside the base structure, and a ballast system is installed inside the ballast tank 3. Specifically, as... Figure 2 As shown, the ballast system includes a first pipeline 4 and a first sea valve 5; wherein, the first sea valve 5 is disposed on the outer wall of the base structure 1, and the first pipeline 4 is connected to the first sea valve 5.

[0032] Figure 3 This is a top view of the distribution of a first pipeline inside a ballast tank according to an embodiment of the present invention. Figure 3 As shown, in this embodiment of the invention, one end of the first pipeline 4 is connected to the first sea valve 5, and the other end of the first pipeline 4 is provided with multiple ports and evenly distributed at multiple points inside the ballast tank 3, so as to guide the ballast water of the first sea valve 5 through the first pipeline 4 and relatively evenly penetrate the ballast water in the ballast tank 3.

[0033] Optionally, at least one ballast tank 3, a first sea valve 5, and a first pipeline 4 are provided, with one first sea valve 5 installed on the side wall of each ballast tank 3. After the first sea valve 5 is opened underwater, seawater enters the interior of the ballast tank 3 through the first pipeline 4.

[0034] Specifically, the ballast system is used to adjust the ballast water and buoyancy of the base structure 1, so that the base structure 1 can float or sink during the installation process.

[0035] like Figure 2 As shown, the base structure 1 also includes a buoyancy chamber 13, which is located on top of the ballast tank 3. Specifically, the buoyancy chamber 13 has an internally hollow structure, with a second sea valve 14 and a second pipeline 15 connected to the second sea valve 14 installed on its outer wall. The second pipeline 15 passes through the outer and inner walls of the buoyancy chamber 13 and connects to the interior of the upper opening structure 16 of the base structure 1. After the second sea valve 14 is opened, seawater will enter the space inside the upper opening structure 16 of the base structure 1 through the second pipeline 15.

[0036] in, Figure 2 The dashed lines in the diagram indicate the orientation of the first pipeline 4 and the second pipeline 15.

[0037] It should be noted that one end of the second pipeline 15 is connected to the second sea valve 14, and the other end of the second pipeline 15 passes through the buoyancy chamber 13 and connects to the inner wall. The middle section of the second pipeline 15 connected to the second sea valve 14 inside the buoyancy chamber 13 is closed, so seawater will not be pumped into the buoyancy chamber 13. The second pipeline 15 is only used to establish a channel connecting the sea valve on the outer wall and the inner wall.

[0038] Optionally, such as Figure 2 As shown, the ballast system also includes a vent pipe 6, one end of which extends into the interior of the ballast tank 3, and the other end of which passes through the top of the base structure 1 and communicates with the outside of the ballast tank 3.

[0039] Specifically, such as Figure 1 As shown, a drainage pipe 7 is also installed inside the base structure 1. One end of the drainage pipe 7 passes through the bottom of the base structure 1 and connects to the interior of the mud-filled steel structure 2. The other end of the drainage pipe 7 passes through the top of the base structure 1 and connects to the water pump 8.

[0040] In one optional embodiment of this utility model, a flange is provided at the top port of the drainage pipeline 7 connecting the base structure 1, and the top port of the drainage pipeline 7 is connected to the external pipeline 12 connecting the water pump 8 through the flange.

[0041] In this embodiment of the invention, the drainage pipeline 7 and the external pipeline 12 are detachable.

[0042] Specifically, the drainage pipeline 7 and the water pump 8 can pump out the seawater in the closed space between the mud-filled steel structure 2 and the seabed soil, forming an internal and external pressure difference to enhance the horizontal force resistance and axial pull-out resistance of the tension leg platform suction pile anchor foundation.

[0043] Specifically, an ear plate structure is provided on the side wall of the base structure 1.

[0044] Figure 3 This is a top view of a base structure provided according to an embodiment of the present utility model. Figure 4 This is a partially enlarged view of the side wall portion of a base structure provided according to an embodiment of the present utility model. For example... Figure 3 and Figure 4 As shown, the ear plate structure includes a horizontal eye plate 9 disposed on the outer wall of the base structure 1 and a vertical eye plate 10 disposed on the top edge of the base structure 1.

[0045] Specifically, the horizontal eyeplate 9 is used to connect the mooring cable or mooring chain;

[0046] The vertical eyeplate 10 is used to assist in fixing the device for installing the counterweight. For example, the vertical eyeplate 10 can be used to fix the flexible tube for installing the counterweight.

[0047] Optionally, such as Figure 3 As shown, multiple horizontal eye plates 9 are evenly arranged circumferentially on the outer side wall of the base structure 1, for example, three. The horizontal eye plates 9 are connected to the mooring cable or mooring chain of the tugboat 11.

[0048] In one optional embodiment of this utility model, the outer wall diameter of the base structure is 15m, the inner wall diameter is 10m, the total height of the base structure is 15m, the inner wall height is 10m, and the length of the steel structure embedded in the mud is 15m.

[0049] This utility model provides a method for offshore construction of a tension leg platform suction pile anchor foundation, which includes the following implementation methods:

[0050] Implementation method 1:

[0051] (1) Set the ballast tank to be empty or partially empty so that the base structure can float on the sea surface by relying on the buoyancy of the ballast tank.

[0052] (2) The tension leg platform suction pile anchoring structure is towed from the launching site to the operating sea area by tugboat.

[0053] Specifically, the base structure can be equipped with one or more ballast tanks and ballast systems inside, depending on the specific application conditions. Ear plate structures can be installed on the outer side wall of the base structure to give the base structure buoyancy, self-stability and load adjustment capabilities. After launching, the horizontal eye plates on the side wall of the base structure can be connected to the tow hook of the tugboat using tow cables, and the tugboat can then wet-tow it from the launching site to the operating sea area.

[0054] (3) In the operating sea area, the base structure is limited by tugboats and towing cables, and the ballast water in the ballast tank is increased at a preset rate by the ballast system, so that the base structure and the mud-penetrating steel structure gradually sink to the seabed anchoring point and penetrate into the seabed soil.

[0055] Specifically, at the installation site, three tugboats can be used. Each tugboat is connected to the horizontal eye plate on the side wall of the base structure via tow cables. The three tugboats are arranged in a triangular pattern around the base structure so that the horizontal position of the base structure in the sea can be controlled by the cooperation of the three tugboats.

[0056] Then, the ballast water in the ballast tank is increased at a preset rate through the ballast system, and under the coordinated control of the three tugboats adjusting the tension of the towing cables, the base structure and the steel structure embedded in the mud are gradually sunk to the seabed anchorage point and penetrate into the seabed soil.

[0057] In one optional embodiment of this utility model, three tugboats are arranged in a triangular pattern around the base structure to fix the relative position of the base structure in the operating sea area; then the ballast water inside the base structure is gradually increased to gradually submerge the base structure; some fixed ballast can be set inside the base structure so that when the base structure is fully submerged, the center of gravity of the entire structure, including the mud-entry steel structure, the ear plate structure and the eye plate auxiliary structure, is lower than the center of buoyancy, thus forming sufficient self-stability.

[0058] Then, after the base structure is filled with all the ballast water, the steel structure is driven into the seabed soil by its own weight.

[0059] In this embodiment of the invention, the process of injecting ballast water into the ballast tank to allow the anchoring foundation to gradually sink into the seabed is a slow and controlled process, which ensures that the base structure can sink to the preset location.

[0060] (4) Construct a counterweight placement channel and place the counterweight to be installed into the upper opening of the base structure through the counterweight placement channel to increase the depth of the steel structure penetrating the seabed soil.

[0061] Specifically, a counterweight placement channel is established using surface vessels and hoses, connecting the surface vessel to the counterweight placement point in the base structure. Vertical eyeplates on the upper part of the base structure are used to secure the hoses. Counterweights such as iron ore or cement are transported to the counterweight placement point in the base structure via hoses or other structures with equivalent functions. The increasing weight of the counterweights further increases the depth of the steel structure penetrating the seabed soil.

[0062] (5) The seawater between the steel structure and the seabed soil is discharged by pumping and drainage pipelines to increase the depth of the steel structure penetrating the seabed soil.

[0063] Specifically, the flanges on the top of the surface vessel and the base structure can be connected by hoses or other structures with equivalent functions. The liquid in the closed space formed by the steel structure and the seabed soil can be pumped out, creating an internal and external pressure difference, which further increases the depth of the steel structure penetrating the seabed soil.

[0064] In one optional embodiment of this utility model, the above steps (4) and (5) can be performed alternately or in steps until the steel structure penetrating the seabed reaches the designed depth and the counterweight in the base structure reaches the designed weight.

[0065] Implementation Method 2:

[0066] (1) The tension leg platform suction pile anchor foundation is towed to the operating sea area by a work vessel.

[0067] Specifically, depending on the specific application conditions, such as the crane's capacity and the size and weight of the base structure, it can be decided whether to place some iron ore or cement as counterweights in advance in the part of the base structure where counterweights are placed.

[0068] (2) The crane of the working vessel is connected to the ear plate structure, and the tension leg platform suction pile anchor foundation is lowered from the water surface to the seabed anchoring point by the crane. At this time, the steel structure for entering the mud is driven into the seabed soil by the self-weight of the base structure.

[0069] (3) Construct a counterweight placement channel and place the counterweight to be installed into the upper opening of the base structure through the counterweight placement channel to increase the depth of the steel structure penetrating the seabed soil.

[0070] (4) The seawater between the steel structure and the seabed soil is discharged by pumping and drainage pipelines to increase the depth of the steel structure penetrating the seabed soil.

[0071] In one optional embodiment of this utility model, the above steps (3) and (4) can be performed alternately or in steps until the steel structure penetrating the seabed reaches the designed depth and the counterweight in the base structure reaches the designed weight.

[0072] The tension leg platform suction pile anchorage foundation provided by this utility model has the following advantages compared with the prior art:

[0073] (1) A counterweight that can be permanently placed in the base structure was added to the base structure. The axial pull-out capacity of the suction pile anchor foundation was improved by the counterweight. This solved the problem that the axial pull-out capacity of the traditional suction pile anchor foundation was limited by soil conditions, structural design and installation method and was not suitable for tension leg platforms. This expanded the application range of suction pile anchor foundation.

[0074] (2) By using counterweights to be installed, the load conditions of the base structure during construction, transportation, and offshore installation were optimized, thus achieving structural design optimization. The form of the counterweights to be installed makes the base structure itself lighter, reducing the structural self-weight's limitation on the length design of the embedded steel structure. Specifically, the deeper the embedded steel structure penetrates the soil, the better its pull-out and horizontal resistance. However, the length design of the embedded steel structure needs to consider the effects of loads such as the self-weight of the anchoring foundation. The separable counterweights make the base structure and embedded steel structure lighter, and during the installation of the anchoring points, the counterweights can be gradually and slowly loaded onto the base structure, thus allowing for the design of a longer embedded steel structure, enhancing the structure's resistance to horizontal and pull-out forces.

[0075] (3) The present invention provides a structure that can permanently bear the counterweight, which can further increase the penetration depth of the suction pile anchor foundation in the seabed soil through the counterweight. This allows the design to achieve the designed depth of the steel structure penetrating the seabed soil through the weight of the counterweight, even in soil conditions such as sandy soil that are not conducive to the suction pile anchor foundation, without the need to use large offshore equipment for piling operations. This improves the adaptability of the suction pile anchor foundation to soil conditions.

[0076] (4) The present invention is equipped with a ballast tank and a buoyancy tank structure, which can realize the self-floating of the base structure. It can be used by tugboats to complete wet towing transportation and offshore installation operations. It can also complete underwater installation by utilizing its own weight, separable counterweight and pressure difference generated by water pump. It does not require the use of large floating cranes or pile driving operations, which reduces the demand for offshore installation equipment, shortens the construction period of offshore installation, and reduces the cost of offshore installation.

[0077] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0078] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A tension leg platform suction pile anchor foundation, characterized by, The utility model relates to a kind of offshore platform, including: Base structure and mud steel structure;The base structure is fixed on the top of the mud steel structure; The base structure is double-wall cylindrical structure, the ballast tank is arranged in the base structure, and the ballast system is arranged in the ballast tank;Drainage pipeline is also arranged in the base structure, one end of the drainage pipeline passes through the bottom of the base structure and communicates with the inside of the mud steel structure, and the other end of the drainage pipeline passes through the top of the base structure and is connected with water pump; Ear plate structure is arranged on the sidewall of the base structure; The mud steel structure is single-wall cylindrical structure, and the opening direction of the cylindrical structure of the mud steel structure is opposite to the opening direction of the cylindrical structure of the base structure;The upper opening structure of the base structure is placed with the weight to be installed.

2. The tension leg platform suction pile anchor foundation of claim 1, wherein: The base structure is steel plate shell structure, and the inner sidewall of the base structure is provided with structure matched with different weights to be installed for fixing the weights to be installed and transmitting the weight of the weights to be installed to the base structure; The mud steel structure is steel plate shell structure.

3. The tension leg platform suction pile anchor foundation of claim 1, wherein: The port of the drainage pipeline connected with the top of the base structure is provided with flange, and the top port of the drainage pipeline is connected with the external pipeline connected with the water pump through the flange.

4. The tension leg platform suction pile anchor foundation of claim 1, wherein: The ear plate structure includes horizontal eye plate arranged on the outer sidewall of the base structure and vertical eye plate arranged on the top edge of the base structure; The horizontal eye plate is used for connecting mooring cable or mooring chain; The vertical eye plate is used for assisting fixing the device for placing the weight to be installed.

5. The tension leg platform suction pile anchor foundation of claim 1, wherein: The ballast system includes first pipeline and first sea valve;Wherein, the first sea valve is arranged on the outer sidewall of the base structure, and the first pipeline is connected with the first sea valve.

6. The tension leg platform suction pile anchor foundation of claim 1, wherein: The ballast system further includes air pipe, one end of the air pipe extends into the ballast tank, and the other end of the air pipe passes through the top of the base structure and communicates with the outside of the ballast tank.

7. The tension leg platform suction pile anchor foundation of claim 1, wherein: The weight to be installed includes iron ore sand or cement.

8. The tension leg platform suction pile anchor foundation of claim 1, wherein: The base structure further includes buoyancy tank, and the buoyancy tank is arranged on the top of the ballast tank;Wherein, the buoyancy tank is hollow structure, second sea valve and second pipeline connected with the second sea valve are arranged on the outer sidewall of the buoyancy tank, the second pipeline passes through the outer sidewall and inner sidewall of the buoyancy tank and communicates with the inside of the upper opening structure of the base structure.

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