JP6902190B2 - Intrusive foundation penetration method and penetration management device - Google Patents

Description

The present invention relates to a method of penetrating a suction foundation installed on the bottom ground of the sea or the like.

As shown in FIG. 8, the suction foundation 1 includes a tubular main body portion 2 and a skirt portion 3 provided on the lower end side of the main body portion 2 and having a wider cross-sectional area than the main body portion 2. The skirt portion 3 is a cup-shaped body composed of a top plate 31 and a tubular vertical wall (skirt) 32 extending downward from the top plate.

The suction foundation 1 penetrates the skirt 32 of the skirt portion 3 into the bottom ground to ensure stability, and is utilized as a foundation for a water structure such as a wind turbine. To penetrate the suction foundation 1, first, as shown in FIG. 8, the skirt portion 3, which is a cup-shaped body, is grounded on the bottom ground with its own weight. Then, water is drained from the hollow portion 21 of the main body portion 2 communicating with the skirt inner region 33 surrounded by the skirt portion 3 and the ground surface of the bottom of the water by the pump 4 to generate suction pressure due to the difference in water level to generate the skirt portion. 3 is penetrated to a predetermined position on the bottom ground.

Japanese Unexamined Patent Publication No. 64-52921

However, when the water depth at which the suction foundation 1 is installed is shallow, there is a problem that the suction pressure required for the penetration of the suction foundation 1 cannot be obtained. Further, even when the penetration resistance is large, the suction foundation 1 cannot be penetrated by the obtained suction pressure. In particular, when the concrete skirt portion 3 is used, the wall thickness becomes thick and the tip resistance becomes large, so that the force required for penetration is further required.

As a solution to this problem, a penetration method for reducing the penetration resistance of the bottom ground using a water jet has been proposed (see, for example, Patent Document 1). However, in the method using a water jet together, excessive pressure is applied to the bottom ground, which disturbs the bottom ground, and there is a risk that the strength of the bottom ground required for the suction foundation 1 cannot be obtained.

The present invention has been made in view of such a situation, and solves the above-mentioned problems, and is a suction foundation without lowering the strength of the bottom ground even when the water depth to be installed is shallow or the penetration resistance is large. It is an object of the present invention to provide a suction foundation intrusion method and an intrusion management device capable of intruding into the submerged ground.

The method for penetrating the skirt suction foundation of the present invention includes a tubular main body that serves as a leg of an offshore structure, and a skirt that is provided on the lower end side of the main body and has a wider cross-sectional area than the main body. Suction that penetrates the suction foundation into the bottom ground using the weight of the suction foundation and the suction pressure generated by draining water from the hollow portion of the main body whose lower end communicates with the inside of the skirt. The method of penetrating the foundation, wherein the communication means for communicating the hollow portion of the main body portion with the external space is provided, and the hollow portion of the main body portion and the external space are communicated with each other by the communication means. After the suction foundation is penetrated into the bottom ground using the suction pressure generated by draining water from the hollow portion of the main body portion, the air in the hollow portion of the main body portion is forcibly exhausted from the communication means. As a result, a negative pressure is generated in the hollow portion of the main body portion, and the suction pressure is increased by the generated negative pressure .
Also, penetration managing apparatus of the present invention is a penetration management apparatus for managing the penetration method suction foundation above, a pressure gauge that is disposed on the lower end side of the hollow portion of the main body, the hollow of the body portion a barometer arranged on the upper end side of the section, the based on the pressure measured by by water pressure and the air pressure gauge measuring the pressure gauge, the body of water level detecting unit that detect the water level in the hollow portion of the It is characterized by having and .

According to the present invention, the suction pressure can be increased by the negative pressure generated in the hollow portion of the main body portion, so that the strength of the bottom ground can be reduced even when the water depth to be installed is shallow or the penetration resistance is large. It has the effect of allowing the suction foundation to penetrate the underwater ground.

It is a side sectional view which shows the structure of the suction foundation which concerns on this invention. It is explanatory drawing explaining the penetration method of the suction foundation which concerns on this invention. It is explanatory drawing explaining the penetration method of the suction foundation which concerns on this invention. It is explanatory drawing explaining the penetration method of the suction foundation which concerns on this invention. It is a figure which shows the transition of the suction pressure according to the penetration depth when the vacuum pressure is applied in the middle of penetration. It is a figure which shows the transition of the suction pressure according to the penetration depth when the suction pressure is applied with the air valve shown in FIG. 1 closed. It is a block diagram which shows the structure of the penetration management apparatus which manages the penetration method of the suction foundation which concerns on this invention. It is explanatory drawing explaining the penetration method of the conventional suction foundation.

Next, an embodiment for carrying out the present invention (hereinafter, simply referred to as “embodiment”) will be specifically described with reference to the drawings.

As shown in FIG. 1, the suction foundation 1a penetrating into the bottom ground in the present embodiment is provided on the tubular main body 2a which is the leg of an offshore structure such as a wind turbine and on the lower end side of the main body 2a. It includes a skirt portion 3 having a wider cross-sectional area than the main body portion 2a. The skirt portion 3 is a cup-shaped body composed of a top plate 31 and a tubular vertical wall (skirt) 32 extending downward from the top plate.

The hollow portion 21 of the main body portion 2a communicates with the skirt inner region 33 whose lower end side is surrounded by the skirt portion 3 and the bottom ground surface, and the upper end side is closed by the top plate 22.

An air valve 23 is provided on the top plate 22. By opening the air valve 23, the hollow portion 21 of the main body 2a and the external space are communicated with each other, and by closing the air valve 23, the hollow portion 21 of the main body 2a is sealed. That is, the air valve 23 functions as a communication opening / closing means for opening / closing the communication between the hollow portion 21 of the main body 2a and the external space. Further, the air valve 23 may be configured to be remotely controllable by using, for example, an electromagnetic valve.

Further, a pump 4, a water pressure gauge 5, and a barometer 6 are arranged in the hollow portion 21 of the main body portion 2a.

The pump 4 is arranged on the lower end side of the hollow portion 21. A drainage pipe 41, one end of which is connected to the pump 4, penetrates the top plate 22 and extends to the outside. As a result, by driving the pump 4, the water in the hollow portion 21 is drained to the outside of the suction foundation 1a.

The water pressure gauge 5 is arranged on the lower end side of the hollow portion 21, and the barometer 6 is arranged on the upper end side of the hollow portion 21.

Next, the method of penetrating the suction foundation 1a will be described in detail with reference to FIGS. 2 to 6.
The suction foundation 1a is manufactured, for example, in a production yard near the construction site of the foundation, towed to the construction site, positioned at a predetermined position, and submerged in water.

When the skirt portion 3 (skirt 32) provided at the tip of the suction foundation 1a reaches the bottom ground B, the skirt 32 penetrates into the bottom ground B due to the weight of the suction foundation 1a, as shown in FIG. The penetration by its own weight is performed in a state where the air valve 23 is opened and the hollow portion 21 of the main body portion 2a and the external space are communicated with each other.

When the penetration by its own weight is completed, the pump 4 is driven in a state where the air valve 23 is opened and the hollow portion 21 of the main body 2a and the external space are communicated with each other, and the water in the hollow portion 21 is moved to the outside of the suction foundation 1a. Drain. As shown in FIG. 3, this drainage lowers the water level outside the main body 2a (hereinafter referred to as the _{water level S 2 ) as compared with the water level outside the main body 2a (referred to as the external water level S 1).} A suction pressure is generated due to the difference in water level, and the skirt portion 3 is further penetrated by the suction load acting on the top plate 31 of the skirt portion 3. Incidentally, the suction pressure becomes stronger as the water level difference between the external water level S ₁ and body water level S ₂ is increased. Therefore, it is possible to control the magnitude of the suction load acting on the top plate 31 by the water level in the body water level S _2.

Or when the water depth is shallow, if penetration resistance is large, even if the maximum water level difference between the external water level S ₁ and body water level S _2, before reaching the predetermined depth, it will end intrusive by suction pressure. In this case, the drive of the pump 4 is temporarily stopped, and as shown in FIG. 4, the exhaust hose 71 connected to the vacuum pump 7 is connected to the open air valve 23 to forcibly exhaust the air in the main body 2a. Then, a vacuum pressure (negative pressure) is generated in the upper space in the main body 2a. As a result, the suction pressure can be further increased by the vacuum pressure (negative pressure) (maximum 10 m), and the increased suction load further penetrates the skirt portion 3 to a predetermined depth.

_{When the water level S 2 in the} main body rises due to the vacuum pressure (negative pressure), the pump 4 is driven again to drain the water in the hollow portion 21 to the outside of the suction foundation 1a, and the external water level S ₁ and the water level in the main body are drained. A water level difference from S _{2 is generated.} As a result, the effect of vacuum pressure (negative pressure) can be obtained even at a depth of 10 m or deeper.

FIG. 5 shows the transition of the suction pressure according to the penetration depth when the suction foundation 1a is penetrated into the bottom ground B to a predetermined depth (6 m). In the example shown in FIG. 5, suction pressure was started from a penetration depth of 1 m, and a vacuum pressure (negative pressure) was generated in the upper space in the main body 2a at a penetration depth of 4.6. According to FIG. 5, it can be seen that when the vacuum pressure (negative pressure) is generated in the upper space in the main body 2a at the penetration depth of 4.6, the suction pressure increases by the vacuum pressure (negative pressure).

In a state where the air valve 23 is closed and the hollow portion 21 of the main body portion 2a is sealed, the pump 4 may be driven to drain the water in the hollow portion 21 to the outside of the suction base 1a. In this case, as shown in FIG. 6, with the drainage (decrease in body water level S _2), vacuum pressure (negative pressure) is generated in the upper space in the main body portion 2a, generated vacuum pressure (negative pressure) The suction pressure can be increased. Note that FIG. 5 shows an example in which suction pressure is started to be applied with the air valve 23 closed from a penetration depth of 2.9 m.

The intrusion of the suction foundation 1a into the submerged ground B can be managed by using the intrusion management device 8 as shown in FIG. 7. The intrusion management device 8 is an information processing device such as a personal computer, and includes a control unit 81, an input unit 82 such as a keyboard, and an output unit 83 such as a liquid crystal display.

The control unit 81 is an information processing unit such as a microcomputer equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. A control program for controlling the operation of the intrusion management device 8 is stored in the ROM. The CPU of the control unit 81 reads the control program stored in the ROM and expands the control program in the RAM to execute the control according to the instruction input from the input unit 82. Further, the control unit 81 functions as a water level detection unit 91, a drainage control unit 92, an exhaust control unit 93, and an operation monitoring unit 94.

Water level detection unit 91, a water pressure measured by the pressure meter 5, based on the pressure measured by the pressure gauge 6 to detect a body water level S _2. Pressure measured by the barometer 6 to if it was atmospheric pressure, can be accurately detected the body water level S ₂ based on only the pressure measured by the pressure meter 5. However, in the present embodiment, since a vacuum pressure (negative pressure) is generated in the upper space in the main body 2a, this vacuum pressure (negative pressure) is measured by the barometer 6 and measured by the water pressure gauge 5. by correcting the water pressure to detect an accurate body water level S _{2. The water level S 2} inside the main body detected by the water level detecting unit 91 is not an absolute water level with respect to the external water level S ₁ , but a relative water level inside the hollow portion 21.

The drainage control unit 92 drives the pump 4 based on the drainage instruction input from the input unit 82 to drain the water in the hollow portion 21. The drainage control unit 92 accepts the setting of the _{water level S 2 in} the main body as a drainage instruction, and controls the amount of drainage by the pump 4 so as to maintain the _{set water level S 2 in the main body.} As a result, the suction pressure due to the difference in water level can be easily controlled. When it is not necessary to control the suction pressure, the drainage control unit 92 may accept the setting of the drainage amount per hour and maintain the set drainage amount.

The exhaust control unit 93 drives the vacuum pump 7 based on the exhaust instruction input from the input unit 82 to exhaust the air in the hollow portion 21.

The operation monitoring unit 94, main body and the water level S ₂ detected by the water level detection unit 91 outputs the operation status of the discharge control unit 92 and the exhaust control unit 93 by the output unit 83. As a result, the work manager can monitor the intrusive work of the suction foundation 1a.

Also, the operation monitoring unit 94, when controlling the amount of waste water by the pump - 4 so as to maintain the body water level S ₂ to the discharge control unit 92 is set, body water level S ₂ with the control operation of the discharge control unit 92 _{If the water level S 2 in the} main body rises even if the amount of drainage reaches a preset upper limit, the drive of the pump 4 is stopped and the drainage from the hollow portion 21 of the main body 2a is stopped. To stop. That is, when the amount of drainage per hour exceeds a preset threshold value, the hydraulic gradient due to suction pressure becomes large in the ground around the skirt portion 3, and the surrounding earth and sand may flow into the skirt portion 3 or partially. Since there is a risk that a large amount of water will flow in due to the formation of a water path, drainage will be stopped to check the situation.

Furthermore, the operation monitoring unit 94, when controlling the water pumps 4 so as to maintain the amount of waste water drainage control unit 92 is set, monitoring changes in body water level S ₂ with the control operation of the discharge control unit 92. Then, when the water level S ₂ in the main body reaches the upper limit water level, the operation monitoring unit 94 stops the driving of the pump 4 and stops the drainage from the hollow portion 21 of the main body 2a. The upper limit water level may be set in advance, may be the body water level S ₂ during drainage operation start to set in the reference. That is, when the water level S ₂ in the main body reaches the upper limit water level due to drainage, the hydraulic gradient due to suction pressure becomes large in the ground around the skirt portion 3, and the surrounding earth and sand may flow into the skirt portion 3 or the portion. Since there is a risk that a large amount of water will flow in due to the formation of a typical water path, drainage will be stopped to check the situation.

_{Further, the operation monitoring unit 94 monitors the change in the water level S 2} in the main body due to the control operation of the exhaust control unit 93, and stops the drive of the vacuum pump 7 when the water _{level S 2 in the main body reaches the upper limit water level.} The exhaust from the hollow portion 21 of the main body portion 2a is stopped. The upper limit water level may be set in advance, may be the body water level S ₂ during the discharging operation starts to set in the reference. That is, when the water level S ₂ in the main body reaches the upper limit water level due to the exhaust, the hydraulic gradient becomes larger due to the increase in suction pressure in the ground around the skirt portion 3, and the surrounding earth and sand flow into the skirt portion 3. Or, there is a risk that a large amount of water will flow in due to the formation of a partial water path, so drainage will be stopped to check the situation.

In the present embodiment, the air valve 23, which is a communication opening / closing means, is provided on the top plate 22, but the exhaust hose 71 is connected so as to communicate with the hollow portion 21 of the main body 2a, and the exhaust hose 71 and the exhaust are exhausted. A communication opening / closing means (manual valve or solenoid valve) may be provided on the side of the vacuum pump 7 connected to the hose 71.

As described above, the present embodiment includes a tubular main body portion 2a that serves as a leg portion of an offshore structure, and a skirt portion 3 that is provided on the lower end side of the main body portion 2a and has a wider cross-sectional area than the main body portion 2a. The suction foundation 1a provided with the above is used by the weight of the suction foundation 1a and the suction pressure generated by draining water from the hollow portion 21 of the main body portion 2a whose lower end communicates with the inside of the skirt portion 3. This is a method of penetrating the suction foundation 1a that penetrates into the bottom ground B, in which a negative pressure is generated in the hollow portion 21 of the main body 2a, and the suction pressure is increased by the generated negative pressure.
With this configuration, the suction pressure can be increased by the negative pressure generated in the hollow portion 21 of the main body portion 2a, so that the strength of the bottom ground is reduced even when the water depth to be installed is shallow or the penetration resistance is large. It has the effect of allowing the suction foundation to penetrate the underwater ground without any need.

Further, in the present embodiment, the upper end side of the hollow portion 21 of the main body portion 2a is closed by the top plate 22, and a negative pressure is generated in the upper space in the hollow portion 21 of the main body portion 2a.
With this configuration, in a state in which the negative pressure is generated in the hollow portion 21 of the main body portion 2a, it is possible to control the body water level S _2, it is possible to control the suction pressure.

Further, in the present embodiment, the vacuum pump 7 forcibly exhausts the air in the hollow portion 21 of the main body 2a to generate a negative pressure in the upper space in the hollow portion 21 of the main body 2a.
With this configuration, the generated negative pressure can be controlled, and the suction pressure can be controlled.

Further, in the present embodiment, the air valve 23, which is a communication opening / closing means, is provided on the top plate 22, and by closing the air valve 23 and draining water from the hollow portion 21 of the main body 2a, the hollow of the main body 2a is formed. A negative pressure is generated in the upper space in the portion 21.
With this configuration, a negative pressure can be easily generated with drainage without using the vacuum pump 7.

Further, the present embodiment is a penetration management device 8 that manages the penetration method of the suction foundation 1a, and is a water level detection unit 91 that detects the water _{level in the hollow portion 21 of the main body 2a as the water level S 2 in the main body, and the main body.} so as to maintain the internal water level S ₂ to a set value, the discharge control unit 92 for controlling the amount of water discharged from the hollow portion 21 of the main body portion 2a, the change in body water level S ₂ with the control operation of the discharge control unit 92 It is provided with an operation monitoring unit 94 that monitors and stops the drainage from the hollow portion 21 of the main body portion 2a when the _{water level S 2 in the} main body rises even if the drainage amount reaches a preset upper limit. ..
With this configuration, the inflow of earth and sand and water into the skirt portion 3 can be quickly detected, and the strength of the bottom ground can be prevented from decreasing.

Further, in the present embodiment, when the drainage control unit 92 controls the amount of drainage from the hollow portion 21 of the main body portion 2a to a set value, the operation monitoring unit 94 causes the water level S _{2 in the main body to accompany the control operation of the drainage control unit 92.} When the water level S ₂ in the main body reaches the upper limit water level, the drainage from the hollow portion 21 of the main body 2a is stopped.
With this configuration, the inflow of earth and sand and water into the skirt portion 3 can be quickly detected, and the strength of the bottom ground can be prevented from decreasing.

Further, in the present embodiment, the main body portion 2a hollow part comprising an exhaust control portion 93 for controlling the exhaust from the inside 21, the operation monitoring unit 94, the body water level S ₂ with the control operation of the exhaust control unit 93 The change is monitored, and when the water level S ₂ in the main body reaches the upper limit water level, the exhaust from the hollow portion 21 of the main body 2a is stopped.
With this configuration, the inflow of earth and sand and water into the skirt portion 3 can be quickly detected, and the strength of the bottom ground can be prevented from decreasing.

The present invention has been described above based on the embodiments. This embodiment is an example, and it is understood by those skilled in the art that various modifications are possible in the combination of each of these components, and that such modifications are also within the scope of the present invention.

1, 1a Suction foundation 2, 2a Main body 3 Skirt 4 Pumping pump 5 Water pressure gauge 6 Barometer 7 Vacuum pump 8 Penetration control device 21 Hollow part 22 Top plate 23 Air valve 31 Top plate 32 Vertical wall (skirt)
33 Area inside the skirt 41 Drainage pipe 71 Exhaust hose 81 Control unit 82 Input unit 83 Output unit 91 Water level detection unit 92 Drainage control unit 93 Exhaust control unit 94 Operation monitoring unit

Claims (2)

A suction foundation having a tubular main body that serves as a leg of an offshore structure and a skirt that is provided on the lower end side of the main body and has a wider cross-sectional area than the main body is defined as the weight of the suction foundation. It is a method of penetrating a suction foundation that penetrates into the bottom ground using the suction pressure generated by draining water from the hollow portion of the main body portion whose lower end communicates with the inside of the skirt portion.
A communication means for communicating the hollow portion of the main body and the external space is provided.
With the hollow portion of the main body and the external space communicated by the communication means, the suction foundation is formed on the bottom of the water by using the suction pressure generated by draining water from the hollow portion of the main body. After penetrating the ground
By forcibly exhausting the air in the hollow portion of the main body portion from the communicating means , a negative pressure is generated in the hollow portion of the main body portion, and the suction pressure is increased by the generated negative pressure. How to penetrate the foundation. An intrusive management device that manages the intrusive method of the suction foundation according to claim 1.
A water pressure gauge arranged on the lower end side of the hollow portion of the main body, and
A barometer arranged on the upper end side of the hollow portion of the main body and
Based on the measured pressure by the pressure gauge and the measured pressure by the pressure gauge, and a water level detecting unit that detect the water level in the hollow portion of the main body portion,
An intrusion management device characterized by being equipped with.

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