JP7022025B2 - Suction foundation and its installation method - Google Patents

Description

The techniques disclosed herein relate to suction foundations and their installation methods.

Conventionally, suction foundations installed in underwater ground have been known. For example, Patent Document 1 discloses a suction foundation having a ceiling portion and a peripheral wall portion and having a partition wall having an open bottom. The partition wall is supported by the ground by penetrating the peripheral wall into the bottom ground. A structure such as a skeleton is installed on the partition wall.

Japanese Unexamined Patent Publication No. 2005-23730

The above-mentioned suction foundation is supported by the ground in which the peripheral wall is intruded. When this ground becomes loose, the bearing capacity of the ground decreases and the stability of the suction foundation also decreases.

The technique disclosed herein has been made in view of this point, and its purpose is to improve the stability of the suction foundation.

The suction foundation disclosed herein has a ceiling portion and a peripheral wall portion connected to the ceiling portion, and is formed so that the bottom is open. It is provided with a release portion that penetrates the partition wall to communicate the inside and the outside of the partition wall and releases the pore water pressure between the soil particles inside the partition wall.

According to the suction foundation, the stability of the suction foundation can be improved.

FIG. 1 is a schematic diagram of a suction foundation. FIG. 2 is a bottom view of the suction foundation. FIG. 3 is a flowchart showing the procedure of how to install the suction foundation. FIG. 4 is an explanatory diagram showing a state before the suction foundation is sunk in step S1. FIG. 5 is an explanatory diagram showing a state after the suction foundation is sunk in step S1. FIG. 6 is a schematic diagram of the suction foundation according to the modified example 1. FIG. 7 is a schematic diagram of the suction foundation according to the modified example 2. FIG. 8 is a schematic diagram of the suction foundation according to the modified example 3. FIG. 9 is a schematic diagram of the suction foundation according to the modified example 4.

Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a suction foundation 100. FIG. 2 is a bottom view of the suction foundation 100.

The suction foundation 100 is a foundation for installing a structure on or under water, and is sunk in the ground G underwater. In the example of FIG. 1, the suction foundation 100 is a foundation for installing the wind turbine 40 at sea. The suction foundation 100 includes a partition wall 10 on which the wind turbine 40 is installed, and a release portion 30 that releases the pore water pressure between the soil particles inside the partition wall 10.

The partition wall 10 is formed in the shape of a container in which the ceiling is closed and the bottom is open. Specifically, the partition wall 10 has a substantially disk-shaped ceiling portion 11 and a substantially cylindrical peripheral wall portion 12 connected to the peripheral edge of the ceiling portion 11. A support column 15 is provided on the ceiling portion 11. The support column 15 is arranged at the center X of the ceiling portion 11 and extends upward in the vertical direction. The upper end of the support column 15 is located above the water surface when the partition wall 10 is submerged in the ground G. A wind turbine 40 is installed on the support column 15.

As shown in FIG. 2, the space inside the partition wall 10, that is, the space surrounded by the ceiling portion 11 and the peripheral wall portion 12, is divided into three spaces P by the three partition wall portions 13. The partition wall portion 13 extends in the radial direction from the center X of the ceiling portion 11. The three partition wall portions 13 are arranged at equal intervals in the circumferential direction around the center X. The partition wall 10 (specifically, the ceiling portion 11, the peripheral wall portion 12, and the partition wall portion 13) is made of a steel plate.

The peripheral wall portion 12 and the partition wall portion 13 penetrate into the ground G. At this time, the inside of the partition wall 10, that is, the space P is filled with soil particles constituting the ground G. Here, "filling" means not only a state in which the space P is completely filled with soil particles, but also a state in which water remains above the soil particles in the space P. In the suction foundation 100 installed on the ground G, a frictional force acts on the peripheral wall portion 12 and the partition wall portion 13. As a result, the suction foundation 100 is firmly fixed to the ground G. In addition, when an external force acts on the suction foundation 100, a negative pressure is generated inside the partition wall 10, and the pull-out resistance increases. This ensures the stability of the suction foundation 100.

The release unit 30 has three drain pipes 31 and a valve 32 provided in each drain pipe 31. The release unit 30 releases the pore water pressure between the soil particles filled in the space P.

The drainage pipe 31 penetrates the partition wall 10 to communicate the inside and the outside of the partition wall 10. Specifically, the drainage pipe 31 communicates the space P with the atmosphere above the water surface. One end of the drainage pipe 31 opens inside the partition wall 10, that is, the space P, and the other end opens outside the partition wall 10 and above the water surface. The drainage pipe 31 is provided in each of the three spaces P. That is, each space P is opened to the atmosphere by a separate drain pipe 31. The drainage pipe 31 is provided along the support column 15 and is supported by the support column 15. The drainage pipe 31 is an example of a pipe of the opening portion.

The valve 32 switches communication and shutoff between the inside and the outside of the partition wall 10, that is, opening and shutting off the drain pipe 31. The valve 32 is installed in a portion of the drain pipe 31 above the water surface.

Although not shown, the suction foundation 100 may further have a drainage mechanism for draining the water in the partition wall 10 when the partition wall 10 is sunk. This drainage mechanism has three drainage pipes communicating with each of the three spaces P and a drainage pump provided in each drainage pipe. By operating the drainage pump and draining the water in the space P through the drainage pipe, the penetration of the partition wall 10 into the ground G is promoted.

The wind turbine 40 is an example of a structure installed on the suction foundation 100. The wind turbine 40 has a tower 41 and a rotor 42 provided in the tower 41. The tower 41 is installed on the support column 15 of the partition wall 10. The rotor 42 is rotatably provided at the tip of the tower 41.

Subsequently, a method of installing the suction foundation 100 will be described. FIG. 3 is a flowchart showing the procedure of the installation method of the suction foundation 100. FIG. 4 is an explanatory diagram showing a state before the suction foundation 100 is sunk in step S1. FIG. 5 is an explanatory diagram showing a state after the suction foundation 100 is sunk in step S1.

First, in step S1, as shown in FIG. 4, the suction foundation 100 in a state where the wind turbine 40 is not installed is towed to the installation site. After that, the subduction of the suction foundation 100 to the ground G is started. Specifically, the suction foundation 100 sinks to the seabed due to its own weight or ballast load. The lower end portions of the peripheral wall portion 12 and the partition wall portion 13 penetrate into the ground G to some extent by the own weight of the suction foundation 100 or the ballast load. At this time, the valve 32 is closed.

After that, the drainage pump of the drainage mechanism is operated, and the water inside the partition wall 10 (space P) is drained. As a result, a suction load acts on the partition wall 10, and the peripheral wall portion 12 further penetrates into the ground G. As shown in FIG. 5, when the peripheral wall portion 12 penetrates into the ground G to a predetermined depth (for example, the depth at which the ceiling portion 11 is in contact with the ground G), drainage by the drainage pump is stopped. Step S1 is an example of a step of penetrating the peripheral wall portion into the underwater ground.

As the peripheral wall portion 12 and the partition wall portion 13 penetrate into the ground G in this way, the inside of the partition wall 10, that is, the space P is filled from below by the soil particles constituting the ground G. At this time, the water above the ground G and the interstitial water between the soil particles are discharged by the drainage pump or discharged from the lower end of the partition wall 10 to the outside of the partition wall 10.

Next, in step S2, the wind turbine 40 is installed on the partition wall 10. Specifically, the wind turbine 40 is installed on the support column 15. Step S2 is an example of a step of installing the structure on the partition wall after the penetration of the peripheral wall portion.

When the wind turbine 40 is installed, the weight of the partition wall 10 including the wind turbine 40 becomes large. As a result, the pressure inside the partition wall 10 becomes high, and the pore water pressure between the soil particles inside the partition wall 10 becomes high. When the pore water pressure becomes high, the frictional force between the soil particles decreases, and the ground G loosens. As a result, the bearing capacity of the partition wall 10 due to the ground G is reduced. However, the interstitial water between the soil particles inside the partition wall 10 can be discharged from the bottom of the partition wall 10, that is, the lower end of the peripheral wall portion 12. Therefore, the excess pore water pressure inside the partition wall 10 (the water pressure increased from the pore water pressure between the soil particles outside the partition wall 10 at the same water depth) is eventually reduced. However, in the ground G, not only the permeable layer S made of sandy soil or the like but also the impermeable layer C made of cohesive soil or the like may be present. In step S1, the peripheral wall portion 12 may penetrate into the impermeable layer C in the ground G. When the peripheral wall portion 12 penetrates into the impermeable layer C, the impermeable layer C hinders the discharge of the pore water in the portion above the impermeable layer C. Pore water in the portion above the impermeable layer C may permeate into the impermeable layer C and be gradually drained from the bottom of the partition wall 10, but the pore water pressure inside the partition wall 10 remains high for a long time. Will continue.

Therefore, after the installation of the wind turbine 40, the release of the excess pore water pressure is executed in step S3. Step S3 is an example of a step of releasing the pore water pressure between the soil particles inside the partition wall, which increases due to the installation of the structure.

Specifically, the operator opens the valve 32 after installing the wind turbine 40. Due to the excess pore water pressure increased by the mounting of the wind turbine 40, the water in the space P is discharged through the drain pipe 31 as a matter of course. As a result, the difference between the pore water pressure outside the partition wall 10 and the pore water pressure inside the partition wall 10 at the same water depth is reduced. Eventually, drainage from the drainage pipe 31 is stopped at a point where the water head of the portion of the drainage pipe 31 protruding above the water surface and the pore water pressure of the soil particles in the space P are balanced. The operator closes the valve 32 after the drainage is stopped. As a result, the suction foundation 100 is installed as shown in FIG. 1, and the installation of the suction foundation 100 is completed.

As a result, the excess pore water pressure between the soil particles inside the partition wall 10 is reduced at an early stage, and the bearing capacity of the partition wall 10 by the ground G is improved at an early stage. Even when the peripheral wall portion 12 does not penetrate into the impermeable layer C, the water inside the partition wall 10 is discharged not only from the bottom of the partition wall 10 but also through the release portion 30, so that the partition wall 10 is discharged. The excess pore water pressure inside the wall is reduced at an early stage, and the bearing capacity of the partition wall 10 by the ground G is improved at an early stage.

Further, by closing the valve 32 after the excess pore water pressure inside the partition wall 10 is reduced, the communication between the inside and the outside of the partition wall 10 via the drain pipe 31 is cut off. As described above, the suction foundation 100 increases the pull-out resistance against an external force due to the negative pressure generated inside the partition wall 10. If the drain pipe 31 is left open, the function of generating negative pressure is weakened to some extent. By closing the valve 32, the closing property of the partition wall 10 can be enhanced and the deterioration of the negative pressure generation function can be suppressed. The "obstructiveness" referred to here is the obstructiveness based on the fact that the bottom of the partition wall 10 is open, and is the obstructiveness due to the ceiling portion 11 and the peripheral wall portion 12.

In addition, step S2 and step S3 may be performed in parallel. That is, the wind turbine 40 may be installed with the valve 32 open. When the pore water pressure inside the partition wall 10 increases due to the installation of the wind turbine 40, the water in the partition wall 10 is discharged through the drain pipe 31 according to the increase. The valve 32 is closed after the wind turbine 40 is installed. The valve 32 may be opened before the installation of the wind turbine 40 is started, for example, from the time when the partition wall 10 of step S1 is penetrated.

Further, the valve 32 may not be closed after the excess pore water pressure inside the partition wall 10 is released, and the drain pipe 31 may be left open. By opening the drainage pipe 31, it is possible to alleviate an increase in pore water pressure inside the partition wall 10 due to tides, secular changes in the consolidation state of the ground G, and the like. For example, when the tide level drops, the pore water pressure outside the partition wall 10 becomes lower than the pore water pressure inside the partition wall 10. As a result, the water inside the partition wall 10 is discharged from the drain pipe 31, and the difference in pore water pressure between the inside and the outside of the partition wall 10 is reduced. On the contrary, when the tide level rises, the pore water pressure outside the partition wall 10 becomes higher than the pore water pressure inside the partition wall 10. As a result, the water level in the drain pipe 31 is lowered, and the difference in pore water pressure between the inside and the outside of the partition wall 10 is reduced. If the drainage pipe 31 is open, the blockage of the partition wall 10 is lowered, but since the cross-sectional area of the drainage pipe 31 is smaller than the cross-sectional area of the space P, the blockage of the partition wall 10 is lowered. Is few. That is, the decrease in the negative pressure generation function of the partition wall 10 due to the opening of the drainage pipe 31 is not so large.

As described above, the suction foundation 100 is formed so as to have a ceiling portion 11 and a peripheral wall portion 12 connected to the ceiling portion 11 so that the bottom is opened, and the peripheral wall portion 12 penetrates into the underwater ground G. The partition wall 10 is provided with a partition wall 10 and a release portion 30 that penetrates the partition wall 10 to communicate the inside and the outside of the partition wall 10 and releases the pore water pressure between the soil particles inside the partition wall 10.

According to this configuration, even if the pore water pressure inside the partition wall 10 increases due to the installation of the structure such as the wind turbine 40 on the partition wall 10, the increased pore water pressure is reduced at an early stage by the release portion 30. As a result, the decrease in the bearing capacity of the ground G due to the excessive pore water pressure can be eliminated at an early stage, and the stability of the suction foundation 100 can be improved at an early stage.

Further, the release portion 30 has a valve 32 capable of switching communication and disconnection between the inside and the outside of the partition wall 10.

According to this configuration, the communication and disconnection between the inside and the outside of the partition wall 10 can be switched by the valve 32. When the valve 32 is opened to allow the inside and the outside of the partition wall 10 to communicate with each other through the release portion 30, there is an advantage that the increase in the pore water pressure inside the partition wall 10 due to tide or the like can be alleviated. On the other hand, closing the valve 32 to block communication between the inside and the outside of the partition wall 10 via the release portion 30 has an advantage of improving the blockage property of the partition wall 10. By providing the valve 32, it becomes possible to select which advantage is prioritized.

Further, the release portion 30 has a drainage pipe 31 (pipe) having one end opened inside the partition wall 10 and the other end open outside the partition wall 10 and above the water surface, and the valve 32 is a drainage pipe. It is provided in the portion of 31 above the water surface.

According to this configuration, the valve 32 is provided at a position above the water surface. Therefore, when the valve 32 is manually opened and closed, it is not necessary to perform the work underwater, so that the workability of opening and closing the valve 32 is improved.

Further, the release portion 30 releases the excess pore water pressure generated inside the partition wall 10 due to the installation of the wind turbine 40 (structure) on the partition wall 10.

According to this configuration, the release portion 30 can release the excess pore water pressure generated inside the partition wall 10 after installing a structure such as a wind turbine 40 on the partition wall 10. That is, it is possible to suppress a decrease in the bearing capacity of the ground G after installing a structure such as a wind turbine 40 on the partition wall 10.

Further, the peripheral wall portion 12 penetrates into the impermeable layer C in the ground G.

According to this configuration, since the water inside the partition wall 10 is prevented from being discharged from the bottom of the partition wall 10, it is particularly effective to release the excess pore water pressure inside the partition wall 10 by the release portion 30.

Further, in a method of installing a suction foundation 100 having a ceiling portion 11 and a peripheral wall portion 12 connected to the ceiling portion 11 and having a partition wall 10 formed so that the bottom is open, the peripheral wall portion 12 is placed in water. Between the step of penetrating into the ground G, the step of installing the windmill 40 (structure) in the partition wall 10 after the penetration of the peripheral wall portion 12, and the soil particles inside the partition wall 10 that increase due to the installation of the windmill 40. It includes a step of releasing the pore water pressure.

According to this configuration, the release portion 30 can reduce the excess pore water pressure generated inside the partition wall 10 due to the installation of the structure such as the wind turbine 40 at an early stage. As a result, the decrease in the bearing capacity of the ground G due to the excessive pore water pressure can be suppressed at an early stage, and the stability of the suction foundation 100 can be improved at an early stage.

Further, in the step of penetrating the peripheral wall portion 12, the peripheral wall portion 12 is penetrated into the impermeable layer C of the ground G.

According to this configuration, since the water inside the partition wall 10 is prevented from being discharged from the bottom of the partition wall 10, it is particularly effective to release the excess pore water pressure inside the partition wall 10 by the release portion 30.

Subsequently, a modification of the suction foundation 100 will be described. In the following description, the same configuration as the suction basic 100 will be described with the same reference numerals, the description thereof will be omitted, and different parts will be mainly described.

<Modification example 1>
The suction foundation 200 according to the first modification will be described. FIG. 6 is a schematic diagram of the suction foundation 200 according to the modified example 1. The suction foundation 200 is different from the suction foundation 100 in that the opening and closing of the valve 32 is automatically controlled.

The release unit 230 of the suction foundation 200 further has a control unit 35 for controlling the valve 32 in addition to the drain pipe 31 and the valve 32. The control unit 35 controls the opening and closing of the valve 32 when the suction foundation 200 is installed.

The suction foundation 200 is installed according to the procedure shown in the flowchart of FIG. 3 described above. The processes up to steps S1 and S2 are the same as in the case of the suction basis 100.

In step S3, the operator operates the control unit 35 after installing the wind turbine 40. The control unit 35 opens the valve 32. Due to the excess pore water pressure increased by the installation of the wind turbine 40, the water in the space P is discharged through the drain pipe 31 as a matter of course. As a result, the difference between the pore water pressure outside the partition wall 10 and the pore water pressure inside the partition wall 10 at the same water depth is reduced. Eventually, drainage from the drainage pipe 31 is stopped at a point where the water head of the portion of the drainage pipe 31 protruding above the water surface and the pore water pressure of the soil particles in the space P are balanced. The control unit 35 waits for a time expected to balance the head and the pore water pressure, and then closes the valve 32. The control unit 35 controls the three valves 32 in the same manner and in parallel.

As a result, the excess pore water pressure between the soil particles inside the partition wall 10 is reduced at an early stage, and the bearing capacity of the partition wall 10 by the ground G is improved at an early stage. Further, by closing the valve 32 after the excess pore water pressure inside the partition wall 10 is reduced, the closing property of the partition wall 10 can be enhanced and the deterioration of the negative pressure generation function can be suppressed.

In addition, step S2 and step S3 may be performed in parallel. That is, the wind turbine 40 may be installed with the valve 32 open. The valve 32 may be opened before the installation of the wind turbine 40 is started, for example, from the time when the partition wall 10 of step S1 is penetrated.

<Modification 2>
FIG. 7 is a schematic diagram of the suction foundation 300 according to the modified example 2. The control content of the valve 32 of the suction foundation 300 is different from that of the suction foundation 200 according to the first modification.

The release unit 330 of the suction foundation 300 further includes a wave height sensor 36 for detecting the wave height and a wind speed sensor 37 for detecting the wind speed, in addition to the drain pipe 31, the valve 32, and the control unit 35. The detection results of the wave height sensor 36 and the wind speed sensor 37 are input to the control unit 35. The control unit 35 controls the opening and closing of the valve 32 when the suction foundation 300 is installed, and also controls the opening and closing of the valve 32 according to changes in the external environment even after the suction foundation 300 is installed.

The suction foundation 300 is installed according to the procedure shown in the flowchart of FIG. 3 described above. The processes up to steps S1 and S2 are the same as in the case of the suction basis 100.

The control unit 35 opens the valve 32 after installing the wind turbine 40 in step S3, as in the modification 2. However, after releasing the excess pore water pressure inside the partition wall 10, the control unit 35 controls the opening and closing of the valve 32 based on the detection results of the wave height sensor 36 and the wind speed sensor 37. Specifically, the control unit 35 controls the valve 32 when the wave height detected by the wave height sensor 36 is higher than the predetermined wave height threshold value or when the wind speed detected by the wind speed sensor 37 is larger than the predetermined wind speed threshold value. Close. On the other hand, when the wave height detected by the wave height sensor 36 is equal to or less than the predetermined wave height threshold value and the wind speed detected by the wind speed sensor 37 is equal to or less than the predetermined wind speed threshold value, the control unit 35 keeps the valve 32 open. do. The control unit 35 controls the three valves 32 in the same manner and in parallel.

When the wave height or the wind speed is large, the external force acting on the suction foundation 300 becomes large. In such a case, the control unit 35 closes the valve 32 to block communication between the inside and the outside of the partition wall 10 via the release unit 330. As a result, the blockage of the partition wall 10 can be enhanced, and the resistance of the suction foundation 300 to an external force can be improved. On the other hand, when the wave height and the wind speed are small, the external force acting on the suction foundation 300 is small. Therefore, by opening the valve 32, the inside of the partition wall 10 is caused by the tide and the secular change of the consolidation state of the ground G. The increase in pore water pressure can be alleviated.

In addition, step S2 and step S3 may be performed in parallel. That is, the wind turbine 40 may be installed with the valve 32 open. The valve 32 may be opened before the installation of the wind turbine 40 is started, for example, from the time when the partition wall 10 of step S1 is penetrated.

<Modification 3>
FIG. 8 is a schematic diagram of the suction foundation 400 according to the modified example 3. The suction foundation 400 differs from the suction foundation 100 in that it does not have a valve 32.

The release portion 430 has a drain pipe 31 and does not have a valve 32. That is, the drain pipe 31 of the release portion 430 is always open.

The suction foundation 400 is installed according to the procedure shown in the flowchart of FIG. 3 described above. The processing in step S1 is the same as in the case of the suction basis 100.

Then, the installation of the wind turbine 40 in step S2 and the release of the excess pore water pressure in step S3 are always performed in parallel. Further, after the installation of the wind turbine 40, the drain pipe 31 remains open. By opening the drainage pipe 31, it is possible to alleviate an increase in pore water pressure inside the partition wall 10 due to tides, secular changes in the consolidation state of the ground G, and the like.

<Modification example 4>
FIG. 9 is a schematic diagram of the suction foundation 500 according to the modified example 4. The suction foundation 500 differs from the suction foundation 100 in that the release portion 530 has a drainage pump 33. Here, a configuration modified from the suction foundation 300 will be described. However, the configuration that is the base of the modified example 4 is not limited to the suction foundation 300, and may be the suction foundation 100, 200, 400, or the like.

The release portion 530 of the suction foundation 500 includes a drain pipe 31, a valve 32, a control unit 35, a wave height sensor 36, and a wind speed sensor 37, as well as a drain pump 33 for discharging the pore water inside the partition wall 10, and each drain pipe 31. Further has a pressure sensor 34 provided in the above and an inclination sensor 38 for detecting the inclination of the partition wall 10. The detection results of the pressure sensor 34, the tilt sensor 38, the wave height sensor 36, and the wind speed sensor 37 are input to the control unit 35. The drainage pump 33 drains the water in the space P through the drainage pipe 31. The drainage pump 33 is installed in a portion of the drainage pipe 31 above the water surface. The pressure sensor 34 detects the water pressure in the drain pipe 31.

The suction foundation 500 is installed according to the procedure shown in the flowchart of FIG. 3 described above. The processes up to steps S1 and S2 are the same as in the case of the suction basis 100.

The control unit 35 discharges the water in the space P by opening the valve 32 in step S3 and operating the drainage pump 33 based on the detection result of the pressure sensor 34. The control unit 35 discharges water so that the difference between the pore water pressure outside the partition wall 10 and the pore water pressure inside the partition wall 10 at the same water depth is reduced. Specifically, the pore water pressure inside the partition wall 10 can be known from the detected pressure of the pressure sensor 34 and the height difference between the pressure sensor 34 and the partition wall 10 (for example, the lower end of the drain pipe 31). The control unit 35 controls the drainage pump 33 so that the detected pressure of the pressure sensor 34 falls within the pressure range corresponding to the range of the target pore water pressure. When the detected pressure of the pressure sensor 34 falls within the target pressure range, the control unit 35 stops the drainage pump 33 and closes the valve 32. The control unit 35 performs such control for the three sets of valves 32 and the drainage pump 33 in parallel.

Since the suction foundation 500 forcibly discharges the water inside the partition wall 10 by the drainage pump 33, the excess pore water pressure inside the partition wall 10 is set earlier than in the case where the water inside the partition wall 10 is discharged as it is. Can be reduced to.

In addition, step S2 and step S3 may be performed in parallel. That is, the wind turbine 40 may be installed while opening the valve 32 and draining water with the drainage pump 33. The valve 32 may be opened before the installation of the wind turbine 40 is started, for example, from the time when the partition wall 10 of step S1 is penetrated.

In addition, the control unit 35 may adjust the inclination of the partition wall 10 when releasing the excess pore water pressure. When the water inside the partition wall 10 is discharged, not only the pore water pressure decreases, but also the peripheral wall portion 12 can further penetrate into the ground G. The control unit 35 adjusts the drainage amount of the three drainage pumps 33 based on the detection result of the tilt sensor 38. Specifically, the control unit 35 relatively increases the amount of drainage of the drainage pump 33 in the space P corresponding to the relatively high portion of the ceiling portion 11 based on the detection result of the tilt sensor 38. At this time, the control unit 35 adjusts the drainage amount of the three drainage pumps 33 within the range in which the detected pressures of the three pressure sensors 34 fall within the above-mentioned pressure range. Thereby, the inclination of the partition wall 10 can be adjusted while reducing the excess pore water pressure inside the partition wall 10.

Further, the control unit 35 may control the valve 32 and the drainage pump 33 based on the detection results of the wave height sensor 36 and the wind speed sensor 37 during normal operation after the suction base 500 is installed. Specifically, the control unit 35 controls the valve 32 when the wave height detected by the wave height sensor 36 is higher than the predetermined wave height threshold value or when the wind speed detected by the wind speed sensor 37 is larger than the predetermined wind speed threshold value. And operate the drainage pump 33. The control unit 35 continues draining by the drainage pump 33 until the pressure detected by the pressure sensor 34 becomes equal to or lower than a predetermined pressure. This predetermined pressure is a value smaller than the pressure range in the release of the above-mentioned excess pore water pressure. After the drainage pump 33 is stopped, the valve 32 is closed. On the other hand, when the wave height detected by the wave height sensor 36 is equal to or less than the predetermined wave height threshold value and the wind speed detected by the wind speed sensor 37 is equal to or less than the predetermined wind speed threshold value, the control unit 35 closes the valve 32 and drains the pump. Keep 33 stopped. The control unit 35 controls the three valves 32 and the drainage pump 33 in the same manner and in parallel.

When the wave height or the wind speed is large, the external force acting on the suction foundation 500 becomes large. In such a case, the control unit 35 opens the valve 32 and drains the water inside the partition wall 10 by the drainage pump 33. As a result, the pore water pressure inside the partition wall 10 is reduced, and the bearing capacity of the ground G is enhanced. As a result, the resistance of the suction foundation 500 to an external force can be improved. On the other hand, when the wave height and the wind speed are small, the external force acting on the suction foundation 300 is small. Therefore, by opening the valve 32, the inside of the partition wall 10 is caused by the tide and the secular change of the consolidation state of the ground G. The increase in pore water pressure can be alleviated.

As described above, the release portion 530 of the suction foundation 500 has a drainage pump 33 for draining the interstitial water inside the partition wall 10.

According to this configuration, the water inside the partition wall 10 can be drained earlier than in the case of draining the water inside. As a result, the decrease in the bearing capacity of the ground G due to the excessive pore water pressure can be suppressed earlier, and the stability of the suction foundation 100 can be improved earlier.

In the suction foundation 500, tilt control and control of the valve 32 and the drainage pump 33 by the external environment may be omitted.

Further, the control unit 35 controls the drainage pump 33 based on the detection result of the pressure sensor 34, but the control unit 35 is not limited to this. For example, the release portion 530 may employ a drainage pump 33 having a lift corresponding to the pore water pressure inside the target partition wall 10, and the pressure sensor 34 may be omitted. In that case, when the excess pore water pressure is released after the wind turbine 40 is installed, the control unit 35 may discharge as much water as possible by the drainage capacity of the drainage pump 33. When the drainage pump 33 discharges a possible amount of water, the pore water pressure inside the partition wall 10 becomes a target value.

<< Other Embodiments >>
As described above, the above-described embodiment has been described as an example of the technology disclosed in the present application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. are made as appropriate. It is also possible to combine the components described in the above embodiment to form a new embodiment. Further, among the components described in the attached drawings and the detailed description, not only the components essential for solving the problem but also the components not essential for solving the problem in order to exemplify the above-mentioned technology. Can also be included. Therefore, the fact that those non-essential components are described in the accompanying drawings or detailed description should not immediately determine that those non-essential components are essential.

For example, the embodiment may have the following configuration.

The shape of the partition wall 10 is not limited to a substantially cylindrical shape. The partition wall 10 can be formed into any shape as long as it has a ceiling portion and a peripheral wall portion and does not have a bottom. For example, the partition wall 10 may be formed in the shape of a square cylinder having a substantially quadrangular cross section or a substantially pentagonal cross section. Further, the partition wall 10 may be formed in a dome shape having a curved ceiling portion.

Further, although the inside of the partition wall 10 is partitioned into a plurality of spaces by the partition wall portion 13, the partition wall portion 13 may be omitted. That is, a single space may be formed inside the partition wall 10.

The partition wall 10 may not be provided with the support column 15.

Further, the structure installed on the suction foundation 100 is not limited to the wind turbine 40. The structure may be a wind condition observation tower, a caisson, or the like.

Communication between the inside and the outside of the partition wall 10 may be realized by a configuration other than the drainage pipe 31. For example, a through hole formed in the partition wall 10 may realize communication between the inside and the outside of the partition wall 10.

Although one drainage pipe 31 is provided for each space P inside the partition wall 10, a plurality of drainage pipes 31 may be provided for each space P. Further, although the upper end of the drain pipe 31 is located above the water surface, it may be located below the water surface. Further, although the drainage pipe 31 penetrates the ceiling portion 11, it may penetrate the peripheral wall portion 12.

When the valve 32 and / or the drainage pump 33 is provided, the valve 32 and / or the drainage pump 33 may be provided in a portion of the drainage pipe 31 below the water surface.

As described above, the techniques disclosed herein are useful for suction foundations and their installation methods.

100,200,300,400,500 Suction foundation 10 Partition 11 Ceiling part 12 Peripheral wall part 30,230,330,430,530 Release part 31 Drainage pipe (pipe)
32 Valve 33 Drainage pump 40 Wind turbine (structure)
G Ground C Impermeable layer

Claims (7)

A partition wall having a ceiling portion and a peripheral wall portion connected to the ceiling portion and formed so that the bottom is open, and the peripheral wall portion penetrates into the underwater ground.
It is provided with a release portion that penetrates the partition wall to communicate the inside and the outside of the partition wall and releases the pore water pressure between the soil particles inside the partition wall .
The release portion is a suction foundation that releases the pore water pressure inside the partition wall after the structure is installed on the partition wall after the penetration of the peripheral wall portion . In the suction basis according to claim 1,
The release portion is a suction foundation having a valve capable of switching communication and cutoff between the inside and the outside of the partition wall. In the suction basis according to claim 2,
The release portion has a tube having one end open inside the partition and the other end outside the partition and above the water surface.
The valve is a suction foundation provided in a portion of the pipe above the water surface. In the suction basis according to any one of claims 1 to 3,
The release portion is a suction foundation having a drainage pump for draining the interstitial water inside the partition wall. In the suction basis according to any one of claims 1 to 4 ,
The peripheral wall is a suction foundation that penetrates the impermeable layer of the ground. It is a method of installing a suction foundation having a ceiling portion and a peripheral wall portion connected to the ceiling portion and having a partition wall formed so that the bottom is open.
The process of penetrating the peripheral wall into the underwater ground,
The step of installing the structure on the partition wall after the penetration of the peripheral wall portion, and
A method for installing a suction foundation, which comprises a step of releasing the pore water pressure between soil particles inside the partition wall after installing the structure. In the method of installing the suction foundation according to claim 6 ,
In the step of penetrating the peripheral wall portion, a method of installing a suction foundation that penetrates the peripheral wall portion into the impermeable layer of the ground.

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