Air suction foundation, supply device, construction method, and removal method

Abstract

The present invention provides an air suction foundation having a reaction force against external forces and enabling easy removal operations and a construction method thereof. The air suction foundation (1A) comprises a main structure (10) having a structure forming a space inside, and a part of the main structure (10) is buried in a seabed foundation (G). Granular matter (GM) is added to the remaining space (RS) inside the part of the main structure (10) protruding from the seabed foundation (G).

Description

Technical Field

[0001] The invention relates to an air suction foundation and a construction method thereof. Background Art

[0002] In the past, there is a known foundation structure that is constructed on a bottom foundation such as the seabed to serve as a foundation for supporting a structure above water. As one such foundation structure, an air suction foundation is constructed, for example, by penetrating a cylindrical peripheral wall portion (skirt portion) extending downward from the periphery of an upper plate portion into the bottom foundation using air suction force (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2004-339695 Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] Generally, when constructing an air suction foundation, the cylindrical peripheral wall portion may not completely penetrate into the underwater foundation due to various reasons, resulting in a decrease in the stability of the air suction foundation. In this case, as described in Patent Document 1, a grouting material (concrete, etc.) is injected into the interior of the air suction foundation and the grouting material is solidified, thereby improving the stability of the air suction foundation.

[0008] However, when the vacuum foundation containing the solidified grouting material inside is to be completely dismantled after the service life has expired, for example, difficult operations such as dismantling the vacuum foundation underwater and recovering the grouting material underwater are required.

[0009] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an air suction foundation and a construction method thereof which has a reaction force against an external force and can facilitate the work during removal.

[0010] (II) Technical solution

[0011] In order to solve the above-mentioned problems, an air suction foundation of one embodiment of the present invention is characterized in that it has a main structure part, which has a structure forming a space inside, and a part of the main structure part is buried in the foundation, and granular matter is added to the space of the part of the main structure part protruding from the foundation.

[0012] (III) Beneficial effects

[0013] According to one aspect of the present invention, it is possible to provide an air suction foundation and a construction method thereof that has a reaction force against an external force and can facilitate work during removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram schematically showing the air suction basis according to the first embodiment of the present invention.

[0015] Figure 2 It is a schematic top view of the above-mentioned air suction foundation.

[0016] Figure 3 It is a schematic diagram for explaining a construction method for constructing an air suction foundation according to the first embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram schematically showing the main structural part for constructing the air suction foundation according to the second embodiment of the present invention.

[0018] Figure 5 It is a schematic diagram for explaining a method for removing the air suction foundation according to the third embodiment of the present invention.

[0019] Figure 6 It is a schematic diagram schematically showing the air suction basis according to the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0020] The shapes and dimensions (length, width, etc.) of the structures described in the drawings of this application do not necessarily reflect the actual shapes and dimensions, and are appropriately changed for clarity and simplification of the drawings. In addition, in this specification, the downward direction in the vertical direction is set as the positive direction of the Z axis, and the X axis and the Y axis are set as the horizontal direction, thereby defining the mutually orthogonal X axis, Y axis and Z axis in the three-dimensional space for description.

[0021] [Implementation method 1]

[0022] The following uses Figure 1 to Figure 3 One embodiment of the present invention will be described.

[0023] In this embodiment, the foundation of a ground-based aquatic structure set at sea, that is, an air suction foundation constructed as a separate foundation is taken as an example for explanation. In addition, the air suction foundation of one embodiment of the present invention is not limited to being constructed on a seabed foundation, and can also be constructed on various underwater foundations such as the river bottom, lake bottom, and pool bottom. If the state of the underwater foundation (strength, flatness, etc.) is suitable, the air suction foundation can be constructed even in a location with a relatively shallow water depth. In addition, a plurality of air suction foundations of one embodiment of the present invention can also be set up to form a plurality of separate foundations.

[0024] (Structure of air suction foundation)

[0025] The following reference Figure 1 and Figure 2 The structure of the air suction base 1A according to the present embodiment will be described. Figure 1 1 is a schematic diagram schematically showing an air suction foundation 1A in a state of being constructed on a seabed foundation (foundation) G. FIG. Figure 2 It is a top view of the air suction base 1A. Figure 1 The air suction foundation 1A is shown in a state of supporting the above-water structure 2. Figure 2 The above-water structure 2 is omitted to show the air suction foundation 1A.

[0026] like Figure 1 As shown, the air suction foundation 1A is a foundation for setting up an above-water structure 2. The air suction foundation 1A is sunk to the seabed foundation G at the bottom of the ocean 4. The above-water structure 2 supported by the air suction foundation 1A is not particularly limited, and examples thereof include a windmill (wind turbine), a caisson main structure, a bridge pier, etc. The caisson main structure can also be applied to a breakwater, a quay wall, etc. The structure supported by the air suction foundation 1A is not limited to the above-water structure 2, and may also be an underwater structure set in the sea that does not protrude from the sea surface of the ocean 4.

[0027] like Figure 1 and Figure 2 As shown, the air suction foundation 1A has a main structure portion 10. The main structure portion 10 is a construction component at the moment before the air suction foundation 1A is constructed. The main structure portion 10 of the present embodiment includes: a roughly disc-shaped upper wall portion 11 on which the above-water structure 2 is set, and a roughly cylindrical side wall portion 12 extending from the periphery of the upper wall portion 11. The main structure portion 10 of the present embodiment is a shape with a closed top side and an open bottom side, in other words, a container (barrel) shape with a bottom. A portion of the main structure portion 10 of the air suction foundation 1A (at least a portion of the side wall portion 12) is buried in the seabed foundation G.

[0028] The upper wall 11 is made of reinforced concrete, for example. The upper wall 11 has no particular limitation on the material and shape as long as it has the strength and shape to be able to set the water structure 2. The upper wall 11 can be made of prestressed concrete, steel or other materials. The upper wall 11 can have a shape such as a square or polygonal shape when viewed from above.

[0029] The side wall 12 may be formed of the same material as the upper wall 11, or may be integrally formed with the upper wall 11. The side wall 12 may also be formed of a material different from that of the upper wall 11. The side wall 12 may be in any hollow shape as long as the main structure 10 is in the shape of a bottomed container, and is not limited to a cylindrical shape. The side wall 12 may also be in the shape of a square cylinder, for example.

[0030] Here, the main structure 10 is manufactured according to the specifications designed based on (i) the state (strength, etc.) of the seabed foundation G investigated in advance, and (ii) the shape and weight of the above-water structure 2, etc. That is, the diameter, height, wall thickness, etc. of the upper wall 11 and the side wall 12 are set according to the strength, etc. required as the air suction foundation 1A. In addition, the height (length in the Z-axis direction) of the side wall 12 is designed to correspond to the depth to be penetrated into the seabed foundation G. The side wall 12 may also have a shape in which the height varies locally.

[0031] When constructing the suction foundation 1A, the main structure 10 is lowered to the location where the water structure 2 is planned to be set up, for example using a crane, and the side wall 12 is penetrated into the seabed foundation G by suction (the construction method will be described in detail later).

[0032] At this time, even if the state of the seabed foundation G is analyzed in advance, it is not easy to make the side wall portion 12 completely penetrate into the seabed foundation G. For example, due to the presence of a foundation layer having a strength different from that of the previous analysis result in the seabed foundation G, the main structure portion 10 may sometimes be incompletely (insufficiently) penetrated. In this case, the incompletely penetrated main structure portion 10 is in a state where the space inside it has a portion filled with the seabed foundation G and a portion other than the portion, that is, a remaining space RS.

[0033] If the portion of the seabed foundation G surrounded (surrounded) by the side wall portion 12 is regarded as the inner foundation IG, the remaining space RS is a portion defined in three-dimensional space by the surface of the inner foundation IG, the bottom surface of the upper wall portion 11, and the inner side wall surface of the side wall portion 12. In other words, the remaining space RS is the inner space of the portion of the main structure portion 10 protruding from the seabed foundation G. The remaining space RS is filled with seawater, or a mixture of seawater and the seabed foundation G, or the like.

[0034] The remaining space RS reduces the stability of the vacuum foundation. Therefore, in the past, grouting material was injected into the remaining space RS to improve the stability of the vacuum foundation. This will cause the following problem: it will be difficult to remove the vacuum foundation containing the solidified grouting material in the future.

[0035] Therefore, the air suction foundation 1A of this embodiment has a supplementary portion 13 formed by supplementing the granular matter GM to the residual space RS. The supplementary portion 13 contacts the surface of the internal foundation IG, and also contacts the bottom surface (the surface on the vertically downward side) of the upper wall portion 11 and a part of the inner side wall surface of the side wall portion 12 (the portion protruding from the internal foundation IG).

[0036] As described in detail later, the granular material GM is replenished into the remaining space RS through the conveying device and the conveying pipe. The granular material GM may be an aggregate of multiple particles. The granular material GM is not particularly limited in specific composition as long as it can be replenished into the remaining space RS in a manner that makes the replenishing portion 13 water-permeable to form the replenishing portion 13. The granular material GM may be an aggregate of artificial particles that do not exist in nature. The granular material GM is preferably an aggregate of particles (such as soil) produced from nature as natural objects. If particles as natural objects are used as granular material GM to form the replenishing portion 13, the environmental load on the internal foundation IG caused by setting up the air suction foundation 1A can be reduced. The granular material GM may contain, for example, a sand component or a gravel component, or may be a mixture of a sand component and a gravel component. The granular material GM may also contain coarse-grained soil or fine-grained soil. The particle size of the granular material GM may be measured, for example, by conducting a test based on JIS A 1204.

[0037] In this specification, coarse-grained soil may contain fine-grained components, that is, it may be gravel mixed with fine-grained components, sand mixed with fine-grained components, etc. Fine-grained components refer to particles with a particle size of less than 0.075 mm. In addition, fine-grained soil refers to silt, clay, organic soil (such as organic clay, organic volcanic ash soil), volcanic ash clay (such as volcanic ash clay type I, volcanic ash clay type II), etc. Sand component refers to soil particles with a particle size of more than 0.075 mm and less than 2 mm. Gravel component refers to soil particles with a particle size of more than 2 mm and less than 75 mm. From the viewpoint of the size of the inner diameter of the pipe for conveying granular material GM and the ease of operation, the granular material GM preferably has particles (soil particles) with a particle size of less than 40 mm as the main body (that is, when gravel components are included, soil particles with a particle size of more than 2 mm and less than 40 mm are preferred as gravel components).

[0038] The granular material GM preferably has appropriate water permeability and a low content of organic matter. The granular material GM is preferably a debris, and more preferably silica sand. When the replenishing portion 13 is formed using the granular material GM including silica sand with a low organic content, the possibility of the following problem can be reduced, that is, the problem of the existence ratio of the granular material GM in the replenishing portion 13 being reduced due to the decomposition of organic matter.

[0039] In addition, the granular material GM needs to have a bearing capacity capable of transmitting the stress from the upper wall portion 11 to the foundation. The granular material GM may be a collection of particles of a material that will not solidify until the vacuum foundation 1A is removed. The granular material GM may also be a collection of particles of a material that has good compatibility with the underlying foundation (internal foundation IG) and is water-permeable. The granular material GM is preferably a material that can form a supplementary portion 13 in a manner that can transfer the weight of the water structure 2 carried on the vacuum foundation 1A to the foundation, and can form a supplementary portion 13 that has the property of pressurizing the inside of the vacuum foundation 1A by supplying water to the supplementary portion 13 when the vacuum foundation 1A is removed. In addition, it is preferred to study the water permeability of the area including the inside of the vacuum foundation 1A (i.e., the surface of the supplementary portion 13 and the internal foundation IG) and the foundation below the seabed foundation G in advance. Thus, the structure of the granular material GM can be appropriately selected according to the properties of the internal foundation IG (water permeability of the above-mentioned area) and the degree of transmission of stress transmitted to the internal foundation IG by the granular material GM replenished to the replenishing portion 13, and the structure of the granular material GM is not particularly limited.

[0040] As described above, the granular matter GM is an aggregate of particles different from the internal foundation IG, and comes into contact with the internal foundation IG and is replenished in the surplus space RS.

[0041] like Figure 2 As shown, the upper wall portion 11 has two opening and closing portions, which can connect and block the internal space of the upper wall portion 11 from the outside (i.e., the ocean 4). One of the two opening and closing portions is a feeding opening and closing portion 14 for supplying (feeding) granular matter GM to the remaining space RS, and the other is a water-passing opening and closing portion 15 for discharging water from the internal space of the main structure portion 10.

[0042] The air suction foundation 1A of this embodiment has a replenishing portion 13, and the replenishing portion 13 is formed in the following manner: the granular matter GM is replenished into the residual space RS through the feeding opening and closing portion 14, and the seawater is discharged from the residual space RS through the water-passing opening and closing portion 15. In addition, seawater or the bottom sediment of the internal foundation IG may remain in the replenishing portion 13. Therefore, the granular matter GM, seawater, and the bottom sediment of the internal foundation IG may be mixed in the replenishing portion 13. Most of the replenishing portion 13 is filled with the granular matter GM.

[0043] Regarding the replenishing section 13, based on the volume of the remaining space RS before the granular matter GM is introduced, it is preferred that the granular matter GM in the remaining space RS occupy a ratio of 70% or more. In this case, the remaining space less than 30% (hereinafter referred to as the unreplenished space US) can be processed as follows. For example, in a state where the external force generated by the deadweight of the water structure 2 (windmill, etc.) carried on the air suction foundation 1A is applied to the replenishing section 13 via the upper wall 11, the water is re-sucked (re-discharged) through the water opening and closing section 15, so that the unreplenished space US can be reduced to set up the air suction foundation 1A. In addition, for example, depending on the situation, auxiliary construction methods such as vibrators (using vibration to reduce the friction between the soil of the foundation and the side wall 12) are combined, so that the unreplenished space US can also be reduced to set up the air suction foundation 1A. In addition, it is also possible to appropriately combine with the above-mentioned exemplified methods to add and replenish the granular matter GM.

[0044] As for the replenishing portion 13 , it is more preferable that the occupancy rate of the granular matter GM in the surplus space RS is approximately 100%.

[0045] Furthermore, in the vacuum foundation 1A of the present embodiment, liquid (for example, water) is injected into the replenishing portion 13 through the feeding opening and closing portion 14 or the water-passing opening and closing portion 15 during removal, so that the main structure portion 10 can be easily removed.

[0046] In this regard, the granular material GM of this embodiment is preferably such that the water permeability coefficient of the replenishing portion 13 is 10 -7 above 10 -1 The above water permeability coefficient can be measured by conducting an indoor test (test in a facility) under virtually the same conditions as those of the replenishing part 13. The replenishing part 13 can be filled with appropriate granular material GM in consideration of compatibility with the ground properties.

[0047] By making the water permeability coefficient of the granular material GM 10 -7 above 10 -1 Then, the supplementary portion 13 in which the granular matter GM is appropriately supplemented to the surplus space RS can be obtained. Thus, the stability of the air suction base 1A can be effectively improved, and when the air suction base 1A is removed, the liquid can be easily infiltrated into the supplementary portion 13.

[0048] The liquid injected into the replenishing portion 13 may be a liquid in which a solute is dissolved in a solvent (water), and may be seawater, for example. Alternatively, a liquid having high fluidity (low viscosity) may be used.

[0049] In addition, for the air suction base 1A, the main structure part 10 can be easily removed by feeding a fluid into the replenishing part 13. The fluid can be a liquid or a gas. In addition, the fluid can also be a mixture of a liquid and a gas. The fluid can also contain a solid as a dispersed substance.

[0050] As described above, the air suction base 1A of the present embodiment has a replenishing portion 13, thereby, compared with a state in which the remaining space RS is filled with water or the like, the supporting force and the horizontal reaction force can be increased, and the stability can be improved. Furthermore, when the air suction base 1A is dismantled, a fluid can be fed into the replenishing portion 13 to make it easier to dismantle. In addition, by utilizing substances existing in nature or substances that will not pollute or contaminate the environment as the granular matter GM and the solids (dispersoids) contained in the fluid to be replenished in the replenishing portion 13, there is no need to recover the granular matter GM and the solids. Therefore, the air suction base 1A of the present embodiment has a reaction force against external forces, and can facilitate the dismantling operation.

[0051] (Other structures)

[0052] The specific structure of the feed opening and closing part 14 and the water flow opening and closing part 15 is not particularly limited as long as they can switch between a state in which the internal space of the main structure part 10 is connected to the outside and a state in which it is isolated from each other. As the structure of the feed opening and closing part 14 and the water flow opening and closing part 15, a known structure can be adopted.

[0053] In addition, refer again Figure 2 The air suction foundation 1A is provided with both the feed opening and closing part 14 and the water flow opening and closing part 15 in an area where the upper surface of the upper wall part 11 is divided into two parts of equal area by a line segment passing through the center (center point C) when the upper wall part 11 is viewed from above. Typically, the granular material GM is supplied by a conveying pipe inserted into the remaining space RS through the feed opening and closing part 14 (refer to the construction method described later). Seawater is discharged from the water flow opening and closing part 15 configured as above, and the granular material GM is supplied through the feed opening and closing part 14.

[0054] Thus, in the air suction base 1A of the present embodiment, the feed opening and closing portion 14 and the water flow opening and closing portion 15 are arranged at positions close to each other. In this case, the water flow opening and closing portion 15 is located near the position where the granular matter GM is finally filled into the residual space RS. Thus, compared with the case where the water flow opening and closing portion 15 is arranged at a position away from the feed opening and closing portion 14, the amount of granular matter GM flowing out of the water flow opening and closing portion 15 during the process of filling the granular matter GM into the residual space RS can be reduced.

[0055] In addition, the feed opening and closing section 14 and the water flow opening and closing section 15 are not limited to the above-mentioned arrangement relationship, and may be arranged away from each other.

[0056] In addition, for the conveying pipe inserted into the remaining space RS through the feeding opening and closing part 14, one end is inserted into the remaining space RS, and the other end is connected to the supply device for supplying the granular material GM. A winding device for the conveying pipe is provided at a position between the two ends of the conveying pipe, for example, near the above-mentioned supply device.

[0057] <Construction method>

[0058] The following uses Figure 3 A construction method for constructing the air suction foundation 1A of the present embodiment will be described. Figure 3 This is a schematic diagram for explaining the construction method of the air suction foundation 1A. Figure 3 The figure indicated by the mark 3001 in FIG. 1 is a schematic diagram schematically showing the state before the main structure part 10 is penetrated into the seabed foundation G. Figure 3 The figure indicated by the mark 3002 in FIG. 1 is a schematic diagram for explaining the penetration process of the main structure part 10 into the seabed foundation G. Figure 3 The figure indicated by reference numeral 3003 in FIG. 1 is a schematic diagram for explaining a replenishing process of replenishing the remaining space RS with the granular matter GM.

[0059] First, if Figure 3 As shown in the mark 3001, the main structure 10 is sunk to the seabed where the water structure 2 is planned to be installed. In this example, the state where the water structure 2 is installed on the upper wall 11 is shown for explanation, but the water structure 2 can also be installed on the upper wall 11 after the air suction foundation 1A is constructed. The main structure 10 can be prefabricated and transported, for example, it can be assembled on a ship.

[0060] Before sinking to the seabed, the delivery pipe 6 is connected to the delivery opening and closing portion 14 on the main structure portion 10. The delivery pipe 6 is connected to the supply device 20 on the side opposite to the side connected to the delivery opening and closing portion 14. The delivery pipe 6 may be inserted into the delivery opening and closing portion 14, and a part of it may enter the internal space of the main structure portion 10. The delivery pipe 6 is, for example, a flexible hose with a diameter of 80 mm or more and 150 mm or less.

[0061] The supply device 20 is a device for supplying granular material GM. The supply device 20 includes: a granular material supply silo 21, a pressure pump 22, and a crane 23. The granular material supply silo 21 is a device for storing granular material GM. The pressure pump 22 is a device that uses a pressure difference to suck up the granular material GM and pressure-feeds the granular material GM to the internal space of the main structure part 10 through the conveying pipe 6. The crane 23 supports the conveying pipe 6 and has a storage part for accommodating the long conveying pipe 6. The crane 23 has a winch for sending the conveying pipe 6 from the storage part or winding the conveying pipe 6 in the storage part.

[0062] Before sinking to the seabed, the water pipe 7 is connected to the water opening and closing part 15 on the main structure part 10. The water pipe 7 is connected to the water pressure pump 30 on the side opposite to the water opening and closing part 15. The water pressure pump 30 is a device that sucks up water using a pressure difference and discharges it.

[0063] Then, if Figure 3 As shown in the mark 3002, the main structure 10 is penetrated into the seabed foundation G (penetration process). After a part of the side wall 12 (front end) of the main structure 10 is penetrated into the seabed foundation G by its own weight, the water pressure pump 30 is used to suck up seawater from the internal space of the main structure 10. Thus, air suction force is generated, so that the main structure 10 is further penetrated into the seabed foundation G.

[0064] When the side wall portion 12 can be completely penetrated into the seabed foundation G, that is, when the main structure portion 10 can be penetrated into the seabed foundation G until the bottom surface of the upper wall portion 11 and the internal foundation IG are in contact with each other, the following operation is performed. That is, when a part of the delivery pipe 6 enters the internal space of the main structure portion 10, the delivery pipe 6 is wound just before the bottom surface of the upper wall portion 11 is set on the internal foundation IG. The air suction foundation constructed in this case does not have the supplementary portion 13.

[0065] On the other hand, when the side wall portion 12 has not completely penetrated the seabed foundation G and a surplus space RS exists inside the main structure portion 10 , the following operation is performed.

[0066] That is, Figure 3 As shown in the mark 3003, the granular material GM is transported to the surplus space RS through the transport pipe 6 using the supply device 20, thereby forming the replenishment part 13 (replenishment process). When the surplus space RS exists, the height of the part of the side wall part 12 protruding from the seabed foundation G is less than 1m, for example.

[0067] In addition, for the air suction foundation 1A, the height of the portion of the main structure 10 protruding from the seabed foundation G (i.e., the height from the surface of the seabed foundation G to the surface of the upper wall 11) can be determined according to the state of the seabed foundation G and the size of the main structure 10, and there is no particular limitation. From the perspective of the stability of the air suction foundation 1A, the height is preferably 50 cm or less.

[0068] (Inspection method)

[0069] After the vacuum foundation 1A of the present embodiment is constructed, it is difficult to confirm the following from the appearance: that is, in appearance, (i) the vacuum foundation 1A having the supplementary portion 13 inside the main structure portion 10 and (ii) the existing vacuum foundation in which the remaining space RS is filled with concrete or the like may be identical to each other.

[0070] An example of an inspection method for confirming the air suction foundation 1A is described below. For example, by opening the feed opening and closing portion 14 or the water flow opening and closing portion 15, the existence of the supplementary portion 13 can be confirmed. In addition, for example, by pre-installing a sensor such as a load meter that can communicate with the outside inside the main structure portion 10, the inside of the main structure portion 10 can be measured from the outside. In this case, it can be confirmed based on the information sent from the above-mentioned sensor whether the inside of the main structure portion 10 has the supplementary portion 13 or is filled with concrete.

[0071] (Variation Example)

[0072] (a) The supply device 20 can generate a mixed fluid in which the particulate matter GM is mixed with a liquid (seawater, etc.), and can deliver the mixed fluid to the remaining space RS through the delivery pipe 6 and the delivery opening and closing portion 14.

[0073] (b) Generally speaking, a foundation with high permeability is prone to liquefaction. For example, in the case where the seabed foundation G is a foundation with high permeability, for a modified example of the air suction foundation 1A, it is preferable to use a granular material GM containing relatively fine particles (such as fine particles) to form the supplementary portion 13. In this case, the fine particles contained in the granular material GM enter between the particles of the soil particles on the surface of the foundation. Thus, in a modified example of the air suction foundation 1A, the supplementary portion 13 is in contact with the internal foundation IG having a lower permeability than the seabed foundation G. According to such a modified example of the air suction foundation 1A, the liquefaction of the internal foundation IG can be reduced, and the passive air suction can be increased (also refer to embodiment 4 described later).

[0074] [Implementation method 2]

[0075] In the following, another embodiment of the present invention will be described. In addition, for the sake of convenience of description, the same reference numerals are attached to components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0076] Figure 4 This is a schematic diagram schematically showing a main structure portion 10B which is a construction member for constructing an air suction foundation 1B according to the present embodiment. Figure 4 The figure indicated by reference numeral 4001 in FIG. 1 is a figure showing the state of the main body structure portion 10B before the supplementary portion 13 is formed, as viewed from the positive direction side of the Z axis. Figure 4 The figure indicated by reference numeral 4002 is a cross-sectional view taken along line AA′ in the figure indicated by reference numeral 4001 . Figure 4 The figure indicated by reference numeral 4003 in FIG. 1 is a schematic diagram schematically showing a state in which the replenishing portion 13 is formed while the transport tube 6 is being pulled out.

[0077] like Figure 4 As shown in the marks 4001 and 4002 in FIG. 1 , the main structure portion 10B of the vacuum base 1B of the present embodiment has a guide portion 16 formed on the bottom surface of the upper wall portion 11B. The guide portion 16 guides the arrangement or movement of the conveying pipe 6. In the present embodiment, the guide portion 16 is provided in a spiral shape. However, the specific shape of the guide portion 16 is not particularly limited.

[0078] With the delivery pipe 6 disposed in advance in the guide portion 16 of the main structure portion 10B, a penetration step is performed to penetrate the upper wall portion 11 of the main structure portion 10B into the seabed foundation G. Next, a supplementary step is performed to form the supplementary portion 13 of the suction foundation 1B of this embodiment. The supplementary step is described below.

[0079] like Figure 4 As shown by the mark 4003 in FIG. 1 , in the replenishing process, the conveying pipe 6 is guided and pulled out by the guide portion 16, and the granular material GM is replenished to the remaining space RS. The supply device 20 continuously or intermittently pulls out the conveying pipe 6 using the winch on the crane 23, and the granular material GM is conveyed through the conveying pipe 6. Thus, the granular material GM can be replenished to the remaining space RS substantially uniformly to form the replenishing portion 13.

[0080] [Implementation method 3]

[0081] In the following, another embodiment of the present invention will be described. In addition, for the sake of convenience of description, the same reference numerals are attached to components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0082] Figure 5The reference numerals 5001, 5002, and 5003 in FIG. 1 are diagrams showing an outline of a method for dismantling the air suction foundation 1 of the present embodiment. The air suction foundation 1 may be the air suction foundation 1A of the first embodiment or the air suction foundation 1B of the second embodiment.

[0083] like Figure 5 As shown by the mark 5001 in FIG. 1 , one end of the water pipe 7 is connected to the water pressure pump 30, and the other end of the water pipe 7 is connected to the water opening and closing part 15. Then, water is sent to the replenishing part 13 by the water pressure pump 30. Thus, the water pressure inside the main structure part 10 can be increased.

[0084] When the water pressure inside the main structure 10 is made substantially the same as the water pressure outside the supplementary part 13 (the ocean 4), or higher than the water pressure outside the supplementary part 13 (the ocean 4), the suction force acting on the main structure 10 is reduced. Figure 5 As shown by mark 5002 in FIG. 1 , the main structure portion 10 can be pulled out from the seabed foundation G.

[0085] Afterwards, if Figure 5 As shown by the mark 5003 in the figure, the main structure part 10 is completely pulled out from the seabed foundation G, so that the air suction foundation 1 can be removed (removal process). In addition, in the above-mentioned removal process, a fluid (water and / or air) can be sent to the replenishment part 13 by pressurizing a gas such as air from the hydraulic pump 30.

[0086] [Implementation method 4]

[0087] Hereinafter, another embodiment of the present invention will be described. For the sake of convenience, components having the same functions as those described in the above-mentioned Embodiments 1 to 3 are denoted by the same reference numerals and their description will not be repeated.

[0088] The air suction foundation of one embodiment of the present invention can also be used as an anchor of a floating structure on water. In addition, in this specification, an air suction structure such as an air suction anchor is also referred to as an air suction foundation.

[0089] In this embodiment, an air suction foundation constructed as a foundation (anchor) applied to a floating water structure is described. The water structure is connected to the anchor by a mooring lock, for example, by a catenary mooring to fix the position. The air suction foundation of one embodiment of the present invention can be used as an anchor in various floating forms (semi-submersible form, single column form, etc.).

[0090] The following reference Figure 6 The structure of the air suction base 1C according to this embodiment will be described. Figure 61 is a schematic diagram schematically showing an air suction foundation 1C constructed on a seabed foundation (foundation) G. The floating body 40 is moored at multiple points by a plurality of air suction foundations 1C, and Figure 6 An air suction base 1C is shown.

[0091] like Figure 6 As shown, the suction foundation 1C is provided with a connection portion 8 on the upper wall portion 11. One end of a mooring lock 50 is connected to the connection portion 8. The other end of the mooring lock 50 is connected to the column 41 of the floating body 40 on which the above-water structure 2 is installed. As the mooring lock 50, a known material can be used, and it is preferably formed of a material having elasticity. The suction foundation 1C is installed on the seabed at a water depth of 50 m or more, for example.

[0092] The suction foundation 1C is typically subjected to an external force in an inclined direction. Due to the component of the upward vertical direction (negative direction of the Z axis) (i.e., the pulling force) of the external force in the inclined direction, friction is generated in the side wall portion 12 through the seabed foundation G in the suction foundation 1C, and passive suction occurs. This passive suction occurs because the internal pressure of the main structure portion 10 is lower than the hydrostatic pressure.

[0093] Here, if the amount of seawater flowing into the main structure portion 10 can be reduced, passive air suction can be increased. However, generally, in a soft sandy soil foundation near the seabed, there are cases where the gaps between particles are large and the water permeability is high.

[0094] The air suction foundation 1C of this embodiment has a supplementary portion 13 inside the main structure portion 10. For example, the supplementary portion 13 is formed by granular material GM containing fine particles, so that the gaps between soil particles on the surface of the internal foundation IG can be filled with the fine particles.

[0095] Therefore, the air suction foundation 1C can increase the passive air suction generated by the external force. In addition, it is possible to reduce the liquefaction of the internal foundation IG caused by earthquakes and the like.

[0096] When the vacuum foundation 1C is subjected to external forces in the inclined direction, it is subjected to external forces in the horizontal direction in addition to the pull-out forces in the vertical direction. When the vacuum foundation 1C is subjected to external forces in the horizontal direction, a reaction force caused by soil pressure is generated in the vacuum foundation 1C.

[0097] The suction foundation 1C has the supplementary portion 13, and can transmit stress to the internal ground IG through the granular matter GM supplemented in the supplementary portion 13. As a result, the suction foundation 1C can increase the reaction force to the external force in the horizontal direction.

[0098] Furthermore, the suction foundation 1C can be easily dismantled similarly to the suction foundations 1, 1A, and 1B of the above-mentioned Embodiments 1 to 3. Therefore, the suction foundation 1C has a reaction force to the external force and can facilitate the work at the time of dismantling.

[0099] [Additional Notes]

[0100] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0101] Description of Reference Numerals

[0102] 1, 1A, 1B, 1C-air suction foundation; 6-transportation pipe; 10, 10B-main structural part; 14-feeding opening and closing part (opening and closing part); 15-water opening and closing part (opening and closing part); 16-guiding part; 20-supply device; G-seabed foundation (foundation); GM-granular matter.

Claims

1. An air suction foundation, characterized in that: A main structure part is provided, the main structure part has a structure forming a space inside, and a part of the main structure part is buried in the foundation, A part of the space of the portion of the main structure protruding from the foundation is delimited by the surface of the inner foundation in the foundation surrounded by a part of the main structure, and is supplemented with granular matter, The main structure part includes an opening and closing part, which can connect and isolate the space from the outside. The opening and closing part includes: an inlet opening and closing part connected to a conveying pipe for conveying the granular material and conveying the granular material into the space; and a water-passing opening and closing part for discharging water from the space. The water can be discharged from the space to the outside through the water-passing opening and closing part, and the granular matter can be replenished into the space through the feeding opening and closing part. In a state where a part of the space is replenished with the granular matter, the feed opening and closing portion and the water flow opening and closing portion are in a state where the space is isolated from the outside.

2. An air suction foundation, characterized in that: A main structure part is provided, the main structure part has a structure forming a space inside, and a part of the main structure part is buried in the foundation, The main structure part comprises: an upper wall part, on which a structure is arranged; and a side wall part, which extends from the periphery of the upper wall part and at least a part of which penetrates into the foundation. The space of the portion of the main structure protruding from the foundation is supplemented with granular material, which is a collection of particles different from the foundation. The replenishing portion in the space replenished with the granular material is in contact with at least a portion of the surface of the foundation, the bottom surface of the upper wall portion, and the inner side wall surface of the side wall portion. The upper wall portion covers the supplementary portion from above, The supplementary portion is located only between the surface of the foundation and the bottom surface of the upper wall portion.

3. The air suction foundation according to claim 1 or 2, characterized in that: The granular material contains sand or gravel.

4. The air suction foundation according to claim 1 or 2, characterized in that: The water permeability coefficient of the granular material is 10 -7 above 10 -1 the following.

5. The air suction foundation according to claim 2, characterized in that: The main body structure portion includes an opening and closing portion capable of connecting and blocking the space from the outside.

6. The air suction foundation according to claim 1 or 5, characterized in that: The main body structure portion includes a guide portion that guides placement or movement of a transport tube that is inserted into the opening and closing portion and transports the granular material.

7. The air suction foundation according to claim 5, characterized in that: The opening and closing portion includes: a supply opening and closing portion that supplies the granular matter to the space; and a water flow opening and closing portion that discharges water from the space.

8. The air suction foundation according to claim 1 or 5, characterized in that: The occupancy rate of the granular matter in the space is 70% or more.

9. A supply device for supplying the granular material to the space through a conveying pipe connected to the opening and closing portion of the air suction base according to any one of claims 1 and 5 to 7, characterized in that: The granular material is conveyed while the conveying tube is continuously or intermittently drawn out.

10. A method for constructing an air suction foundation, which is a method for constructing the air suction foundation according to any one of claims 1 to 8, characterized in that: include: A penetration step, wherein the main structure is penetrated into the foundation; as well as A replenishing step is to replenish the granular matter into the space.

11. A method for dismantling an air suction foundation, which is a method for dismantling the air suction foundation according to any one of claims 1 to 8, characterized in that: include: The dismantling process is to dismantle the air suction foundation by sending the granular matter into a fluid.

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