Subsea Soil Exploration System

Abstract

Provided is a subsea ground exploration system capable of generating surface waves at a desired position on the seabed. 【Solution means】The subsea ground exploration system includes a device that holds a weight at a predetermined height from the seabed and remotely releases and drops the weight, and a vibration receiver disposed in the vicinity of the device for measuring the vibration of the seabed.

Description

Technical Field

[0001] The present disclosure relates to a subsea ground exploration system.

Background Art

[0002] Non-Patent Document 1 describes a technique for performing surface wave exploration by arranging subsea seismometers in a linear array and dropping a weight from the water surface onto the seabed at shallow water depths.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when dropping a weight from the water surface, the weight is carried away by ocean currents before reaching the seabed. Therefore, it has been difficult to drop the weight at a desired position on the seabed. In particular, ground exploration is required at the seabed at large water depths, but it is even more difficult to generate surface waves at a desired position on the seabed at large water depths.

[0005] In view of this point, an object of the present disclosure is to provide a subsea ground exploration system capable of generating surface waves at a desired position on the seabed.

Means for Solving the Problems

[0006] A subsea ground exploration system according to a first aspect of the present disclosure is (1) a device that holds a weight at a predetermined height from the seabed and detaches and drops the weight by remote operation, A vibration receiver that is arranged near the device and measures the vibration of the seabed, is provided.

[0007] A seabed ground exploration system as one embodiment of the present disclosure, (2) wherein the device includes a placement part placed on the seabed, a suspension part connected to the placement part and detachably holding the weight, a buoyancy generation part that applies an upward force to the suspension part, is provided, is the seabed ground exploration system according to (1) above.

[0008] A seabed ground exploration system as one embodiment of the present disclosure, (3) the device is configured to cut off the connection between the placement part and the suspension part by remote operation, so that the suspension part and the buoyancy generation part can move, is the seabed ground exploration system according to (2) above.

[0009] A seabed ground exploration system as one embodiment of the present disclosure, (4) wherein the device includes a gantry placed on the seabed, a suspension part fixed to the gantry and detachably holding the weight, is provided, is the seabed ground exploration system according to (1) above.

[0010] A seabed ground exploration system as one embodiment of the present disclosure, (5) the device and the vibration receiver are separably connected by remote operation, is the seabed ground exploration system according to (4) above.

[0011] A seabed ground exploration system as one embodiment of the present disclosure, (6) Further comprising a float connected to the vibration receiver, The seafloor ground exploration system according to any one of (1) to (5) above.

[0012] A seafloor ground exploration system as one embodiment of the present disclosure, (7) A plurality of the vibration receivers are provided, and the plurality of vibration receivers are linearly connected. The seafloor ground exploration system according to any one of (1) to (6) above.

[0013] A seafloor ground exploration system as one embodiment of the present disclosure, (8) The vibration receiver includes a storage unit that stores the measured vibration of the seabed. The seafloor ground exploration system according to any one of (1) to (7) above.

Advantages of the Invention

[0014] According to the present disclosure, surface waves can be generated at a desired position on the seabed for ground exploration.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the components shown in the following drawings, the same components are denoted by the same reference numerals.

[0017] Referring to FIGS. 1 to 4, a seabed ground exploration system 100 according to a first embodiment of the present invention will be described. The seabed ground exploration system 100 is installed by a ship 1000.

[0018] The ship 1000 may tow part or all of the seabed ground exploration system 100 to the installation position. Since the seabed ground exploration system 100 is lightweight, it can be towed by a ship 1000 with a gross tonnage of about 20 tons. The ship 1000 may be provided with means for raising or lowering part or all of the seabed ground exploration system 100. The means may be a winch.

[0019] The ship 1000 may be provided with means such as a GPS for measuring its own position. The ship 1000 may be provided with an acoustic positioning system for measuring the position of the seabed ground exploration system 100.

[0020] The ship 1000 may be provided with a transceiver for communicating with the seabed ground exploration system 100.

[0021] The seabed ground exploration system 100 includes a device 10 and vibration receivers 20 (20A, 20M, 20N). The seabed ground exploration system 100 may further include a weight 30 and a float (buoy) 40.

[0022] The device 10 holds the weight 11 at a predetermined height from the seabed 2000. The height may be set according to on-site conditions such as the hardness of the seabed 2000 ground or the exploration depth. The height is, for example, 3 to 5 meters. The weight of the weight 11 is, for example, 50 kg. Specifically, the device 10 may include a mounting portion 12, a suspension portion 13, and a buoyancy generating portion 14. In the present disclosure, the seabed includes the lake bottom.

[0023] The placement part 12 is placed on the seabed 2000. The placement part 12 may be composed of a weight.

[0024] The suspension part 13 is connected to the placement part 12. Specifically, the suspension part 13 may include a rope 13R, and one end of the rope 13R may be connected to the placement part 12. By changing the length of the rope 13R, the height of the suspension part 13 from the seabed 2000, and thus the height of the weight 11 held by the suspension part 13 from the seabed 2000, can be adjusted.

[0025] The suspension part 13 detachably holds the weight 11 that generates surface waves. The suspension part 13 may detachably hold a plurality of weights 11. For example, the suspension part 13 includes a separation mechanism 13S1 in which a screw hole is formed and a means for rotatably turning a screw inserted into the screw hole is provided. The weight 11 is connected to the screw. When the separation mechanism 13S1 turns the screw, the screw comes out of the screw hole. As a result, the weight 11 is separated from the suspension part 13. The separation mechanism 13S1 may include a motor.

[0026] The device 10 remotely operates to disconnect and drop the weight 11 from the suspension part 13. For example, the separation mechanism 13S1 includes a receiver that receives sound waves. The transmitter and receiver of the ship 1000 transmit a sound wave including an instruction to disconnect the weight 11. When the separation mechanism 13S1 receives the instruction, the separation mechanism 13S1 disconnects and drops the weight 11 from the suspension part 13. The separation mechanism 13S1 may receive an instruction from a location other than the ship 1000.

[0027] Referring to FIG. 2, when the weight 11 falls from the suspension part 13 of the device 10 and collides with the seabed 2000, surface waves 2100 are generated on the seabed 2000. By observing and analyzing the surface waves 2100 with the vibration receiver 20, for example, the S-wave velocity structure of the seabed 2000 can be estimated. When the weight is dropped from above the water surface, it is impossible to grasp where the weight will collide with the seabed 2000 as it will be washed away. In contrast, by dropping the weight 11 from the device 10, the weight 11 can be made to collide near the device 10 on the seabed 2000. Generally, when a plurality of vibration receivers 20 are linearly connected, it is preferable from the viewpoint of data quality, etc. to drop the weight 11 near the end of the row of vibration receivers 20, or preferably on the extension of the row of vibration receivers 20. The position where the weight 11 collides can be adjusted by the length of the rope 20R1 connecting the placement part 12 and the row of vibration receivers 20. In a configuration where a plurality of weights 11 are held by the device 10, usually, the weights 11 are dropped one by one.

[0028] Note that by connecting the device 10 and the weight 11 with a rope 13R or the like, referring to FIG. 4, even after the weight 11 has fallen, the weight 11 can be recovered together with the device 10. As another example, the weight 11 may not be connected to the buoyancy generation part 14 and may be connected to the placement part 12 and the suspension part 13.

[0029] The buoyancy generation part 14 exerts an upward force on the suspension part 13. With this configuration, even if a vertically downward force is applied to the suspension part 13, the device 10 can be prevented from tipping over. The buoyancy generation part 14 is connected to the suspension part 13. The buoyancy generation part 14 may be composed of a plurality of floats 14A, 14B, and 14C. The uppermost float among the floats 14A and 14B is connected by a rope 14R1. The plurality of floats 14B are connected to each other by a rope 14R2. The lowermost float among the plurality of floats 14B and each of the two floats 14C are connected by ropes 14R3 and 14R4.

[0030] In this embodiment, the float 14A floats on the water surface 3000. The float 14A can indicate the position of the seabed exploration system 100.

[0031] The vibration sensor 20 is arranged near the device 10 and measures the vibration of the seabed 2000. For example, the vibration sensor 20 can measure the surface wave 2100 generated when the weight 11 collides with the seabed 2000. The vibration sensor 20 may acquire the horizontal / vertical spectrum ratio of the vibration at the installation position. The vibration sensor 20 may be provided with sensors for measuring the vertical component and the horizontal component of the vibration, and calculate the S-wave velocity based on the horizontal / vertical spectrum ratio. The S-wave velocity indicates the softness of the ground of the seabed 2000 and is used as a parameter for seismic design and liquefaction judgment.

[0032] The vibration sensor 20 is connected to the mounting portion 12 via a rope 20R1. With this configuration, the distance between the vibration sensor 20 and the mounting portion 12 is maintained at a predetermined value. A plurality of vibration sensors 20 may be provided. A plurality of vibration sensors 20A ··· 20M and 20N may be linearly connected via a rope 20R2. With this configuration, the distance between adjacent vibration sensors 20 is maintained at a predetermined value. The distance between adjacent vibration sensors 20 may be 2.5 meters or 5 meters.

[0033] Hereinafter, the hardware configuration of the vibration sensor 20 will be described in detail. The vibration sensor 20 may be covered with a protective member. The protective member may be made of, for example, glass. Referring to FIG. 3, the vibration sensor 20 includes a control unit 21, a storage unit 22, an attitude control unit 23, and a transponder 24.

[0034] The control unit 21 is one or more processors. The processor may be, for example, a general-purpose processor or a dedicated processor specialized for specific processing, but is not limited thereto and can be any processor. The control unit 21 controls the operation of the entire vibration sensor 20.

[0035] The memory unit 22 stores the vibrations of the seabed 2000 measured by the vibration receiver 20. The memory unit 22 may also store the measurement time of the vibrations. The memory unit 22 is, for example, a storage device including one or more memories. The memory may be, for example, a semiconductor memory, a magnetic memory, an optical memory, etc., but is not limited thereto and can be any memory. The memory unit 22 functions as, for example, a primary storage device or a secondary storage device. By the ship 1000 pulling up the vibration receiver 20, the vibrations of the seabed 2000 stored by the vibration receiver 20 can be read out.

[0036] The attitude control unit 23 controls the attitude of the vibration receiver 20. The attitude control unit 23 may be configured by a gimbal. Note that by lowering the center of gravity of the vibration receiver 20, the lower surface of the vibration receiver 20 may be placed on the seabed 2000.

[0037] When the transponder 24 receives a specific acoustic vibration, it transmits a response signal. By receiving the response signal of the transponder 24, the position of the transponder 24 can be measured.

[0038] The vibration receiver 20 can also perform a micro-vibration array exploration for measuring the micro-vibrations of the seabed 2000. Note that the micro-vibrations of the seabed 2000 are considered to be caused by natural phenomena such as waves. Here, when the suspension part 13 or the buoyancy generation part 14 is carried away by the ocean current and moves, the seabed 2000 vibrates through the placement part 12. This vibration may interfere with the micro-vibration array exploration.

[0039] Referring to FIG. 4, the device 10 can remotely disconnect the connection between the mounting part 12 and the suspending part 13. More specifically, the suspending part 13 includes a second separation mechanism 13S2 in which a second screw hole is formed and a means for rotating a screw inserted into the second screw hole is provided. The mounting part 12 is connected to the screw. The second separation mechanism 13S2 rotates the screw, so that the screw is removed from the second screw hole. As a result, the connection between the mounting part 12 and the suspending part 13 is disconnected. The second separation mechanism 13S2 may include a motor. After the disconnection, vibration of the seabed 2000 caused by the movement of the suspending part 13 or the buoyancy generating part 14 can be suppressed. Therefore, the accuracy of the microtremor array exploration can be improved. After the disconnection, the ship 1000 can recover the suspending part 13 and the buoyancy generating part 14 connected to the suspending part 13. In a configuration in which the weight 11 is connected to the suspending part 13, the ship 1000 can also recover the weight 11.

[0040] 1, the sinker 30 is placed on the seabed 2000. The receiver 20 is connected to the sinker 30 via a rope 20R3. The weight of the sinker 30 is, for example, 50 kg.

[0041] The float 40 is connected to the sinker 30 via a rope 40R. The configuration of the float 40 may be similar to that of the floats 14A or 14B. The float 40 may indicate the position of the geophone 20.

[0042] Next, a seabed exploration system 200 according to a second embodiment of the present disclosure will be described with reference to Figures 5 and 6, focusing on differences from the first embodiment. Note that components having the same configurations in the first and second embodiments are denoted by the same reference numerals.

[0043] The apparatus 210 of the seafloor ground surveying system 200 further includes a mount 215 and a weight 250 .

[0044] The pedestal 215 is placed on the seabed 2000. Referring to FIG. 6, the pedestal 215 is composed of rod-shaped members. The rod-shaped members may be rectangular parallelepiped-shaped or circular tubular. Specifically, the pedestal 215 includes three vertical members 215V extending along the falling direction of the weight 11, three (a total of nine) horizontal members 215H1 extending in each of the three planes perpendicular to the falling direction of the weight 11 and three horizontal members 215H2, and three support members 215I. The members are connected by connecting members 215C.

[0045] The vertical members 215V are connected to each other via the horizontal members 215H1. The support members 215I connect the horizontal members 215H2 and the vertical members 215V. More specifically, the horizontal members 215H1 constitute each side of three small triangles that overlap each other in the direction in which the weight 11 falls. The three vertical members 215V constitute each vertex of the small triangles. The horizontal members 215H2 constitute each side of a large triangle. The support members 215I constitute line segments connecting the vertices of the large triangle and the vertices of the triangle in the middle in the vertical direction among the three small triangles.

[0046] The suspension part 213 is fixed to the pedestal 215. More specifically, the suspension part 213 includes a rod-shaped member 213H extending from one vertex of the uppermost triangle in the vertical direction among the three small triangles to the side opposite to the vertex in the triangle.

[0047] The suspension part 213 may separably hold a plurality of weights 11. More specifically, the suspension part 213 includes a mechanism 213D in which screw holes are formed and means for rotatably turning screws inserted into the screw holes is provided. The mechanism 213D is fixed to the rod-shaped member 213H. The weight 11 is connected to the screw.

[0048] The lower suspension part 213 releases and drops the weight 11 from the lower suspension part 213 by remote control. For example, the lower suspension part 213 includes a receiver 213R that receives sound waves. The transmitter-receiver of the ship 1000 transmits a sound wave including an instruction to release the weight 11. When the receiver 213R receives the instruction, the device 210 releases and drops the weight 11. The receiver 213R may receive an instruction from a location other than the ship 1000.

[0049] The weight 250 is placed on the seabed 2000. The separation mechanism 215S of the gantry 215 is connected to the weight 250 via the rope 250R0. The vibration receiver 20 is connected to the weight 250 via the rope 250R1.

[0050] The device 210 and the vibration receiver 20 may be separably connected by remote control. Specifically, the gantry 215 further includes a separation mechanism 215S. The separation mechanism 215S includes a receiver that receives sound waves. The transmitter-receiver of the ship 1000 transmits a sound wave including an instruction to separate the device 210 and the vibration receiver 20. When the receiver receives the instruction, the device 210 separates the vibration receiver 20. After separation, the lower suspension part 213 and the gantry 215 can be left on the seabed 2000, and the vibration receiver 20 can be recovered. Therefore, the accuracy of the microarray exploration by the vibration receiver 20 can be improved.

[0051] The device 210 may further include a transponder 260. When the transponder 260 receives a specific acoustic vibration, it transmits a response signal. By receiving the response signal of the transponder 260, the position of the transponder 260 can be measured.

[0052] Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or corrections based on the present disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means or steps, etc. can be combined into one or divided.

Description of Reference Numerals

[0053] 100,200: Submarine Seabed Exploration System 10,210: Device 11,30,250: Hammer 12: Placing Part 13,213: Suspended Part 13S1,13S2,215S: Separation Mechanism 13R,14R1,14R2,14R3,14R4,20R1,20R2,20R3,40R,250R0,250R1: Rope 213H: Rod-shaped Member 213R: Receiver 213D: Mechanism 14: Buoyancy Generation Part 14A,14B,14C,40: Float 20,20A,20M,20N: Vibration Receiver 21: Control Part 22: Memory Part 23: Attitude Control Part 24,260: Transponder 215: Stand 215H1,215H2: Horizontal Member 215V: Vertical Member 215I: Support Member 215C: Connecting Member 215S: Separation Mechanism 1000: Ship 2000: Seabed 2100: Surface Wave 3000: Water Surface

Claims

1. An apparatus that holds a weight at a predetermined height from the seabed and remotely detaches and drops the weight, A vibration receiver disposed near the apparatus for measuring vibrations of the seabed, Comprising, The apparatus is, A placement part placed on the seabed, A suspension part connected to the placement part for separably holding the weight, A buoyancy generation part that exerts an upward force on the suspension part, Comprising, The apparatus is, Remotely cuts the connection between the placement part and the suspension part, The suspension part and the buoyancy generation part are movable, A seabed ground exploration system.

2. An apparatus that holds a weight at a predetermined height from the seabed and remotely detaches and drops the weight, A vibration receiver disposed near the apparatus for measuring vibrations of the seabed, Comprising, The apparatus is, A gantry placed on the seabed, A suspension part fixed to the gantry for separably holding the weight, Comprising, A seabed ground exploration system in which the apparatus and the vibration receiver are separably connected by remote operation.

3. Further comprising a float connected to the vibration receiver, The seabed ground exploration system according to claim 1 or 2.

4. A plurality of the vibration receivers are provided, and the plurality of vibration receivers are linearly connected, The seabed ground exploration system according to claim 1 or 2.

5. The vibration receiver includes a storage unit for storing the measured vibrations of the seabed, The seabed ground exploration system according to claim 1 or 2.

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