JP2012237677A - Sensor installation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bury a sensor in the seafloor with high positional accuracy in a manner that ensures measurement accuracy.SOLUTION: A sensor installation method: moves an excavation steel pipe 200, for installing an earthquake measurement device therein, to a predetermined position on the seafloor to bury the earthquake measurement device by using an unmanned submersible capable of moving on the seafloor; excavates the seafloor below the excavation steel pile 200 while pressing the same onto the seafloor and removes excavated surplus soil outside the excavated steel pile 200 through an upper face thereof in a manner that an internal space of the excavation steel pile 200 extends downward in an almost vertical direction using an excavation control function as well as a surplus soil removal function mounted on the unmanned submersible; inserts the earthquake measurement device in the internal space of the excavation steel pile 200 buried in the seafloor using the unmanned submersible; and fills soil in a space between an inner surface of the excavation steel pile 200 and a surface of the earthquake measurement device as well as a space between a bottom surface of a burial hole and the earthquake measurement device using a soil spreading function mounted on the unmanned submersible.

Description

  The present invention relates to a sensor installation method, and more particularly to a sensor installation method in which a seabed installation sensor is embedded in the seabed.

  Conventionally, seismometers including seismic sensors have been installed on the seabed, and seismic waves have been measured at observation points other than the ground. When such sensors are installed on the seabed, they are widely installed on the seafloor (see Patent Documents 1 and 2).

  However, if the seismometer device is installed in the water on the bottom of the sea, the seismometer device is not fixed to the sea floor, so there is a possibility that accurate seismic waves cannot be measured. For example, there was a possibility of measuring long-period large noise caused by the bottom current of the seabed shaking the seismometer device, or the seismometer device measuring movements different from ground motion during a large earthquake. . For this reason, embedding of seismometers in the seabed is becoming common.

  As a technique for embedding such a seismometer in the seabed, a technique for embedding a seismometer in the hole by an unmanned submersible after making a hole in the seabed has been proposed (see Non-Patent Document 1: It is called “conventional example”). In this conventional technique, a hole for embedding the seismometer device is formed by a free fall type piston corer system.

JP 2000-193755 A JP 62-025281 A

Eiichiro Araki and nine others, “Towards high-precision broadband seismic observation on the seabed” [online], 2008, 24th Shinkai Symposium Oral presentation S03, [April 28, 2011 search], Internet <URL: http://www.jamstec.go.jp/jamstec-j/maritec/rvod/blue_earth/2008/program/pdf/S03.pdf>

  In the conventional technique described above, a hole for embedding the seismometer device is drilled by a free fall type piston corer system. As a result, due to factors such as changes in the depth direction of tidal currents in the sea, the drilling position may deviate from within the allowable range of the drilling position determined from the position where the signal can be connected to the submarine cable for sending measurement signals to the ground. Often occurs. For this reason, in order to make the perforation position within the permissible range, there have been cases in which perforation has to be performed many times.

  Moreover, in the drilling by the free fall type piston corer method, the drilling direction could not be accurately set to the vertical direction. As a result, the seismic wave component in the vertical direction, which is more difficult to calibrate after installation, cannot be measured with high accuracy.

  For this reason, while being able to improve the embedding position accuracy of the sensor for seabed installation, such as an earthquake sensor, the technique which can improve the inclination precision of the said sensor for seabed installation is awaited.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a sensor installation method that can embed a seabed installation sensor on the seabed with high positional accuracy and ensure measurement accuracy.

  The present invention is a sensor installation method for burying a sensor for seabed installation on the seabed, using a submersible that can move the seabed, at a predetermined seafloor position where the sensor for seabed installation is to be buried, A moving step of moving a tubular member for disposing a sensor case in which an undersea sensor is housed in an internal space; and a predetermined excavation control function and a residual sand removal function installed in the submersible craft. The bottom of the tubular member is excavated below the tubular member while pressing the tubular member against the sea bottom so that the direction in which the internal space of the tubular member extends is substantially vertically downward. By removing the excavated residual sand from the upper surface of the tubular member to the outside of the tubular member, the tubular member is removed from the inner space of the tubular member in a state where the excavated residual sand is removed. A sensor placement hole forming step to be embedded; and a sensor insertion step of inserting the sensor case into the internal space of the tubular member embedded in the sea floor from the side that should be vertically below the sensor case using the submersible craft. And a space between the inner surface of the tubular member and the surface of the sensor case, and a bottom surface of the hole formed in the sensor arrangement hole forming step, using a sediment spreading function mounted on the submarine. And a sensor fixing step of filling the space between the bottom surface of the sensor case with earth and sand. Here, the submarine installation sensor may include at least one of an earthquake sensor and a water pressure sensor.

  In this sensor installation method, when submerging the seabed installation sensor, first, in the moving process, using a submersible that can move the seabed, the seabed installation sensor is installed at a predetermined seafloor position where the seabed installation sensor should be embedded. The tubular member for arranging the sensor case in which the sensor is accommodated in the internal space is moved. As a result, the tubular member is accurately positioned on the seabed position where the seabed installation sensor is to be embedded.

  Next, using the excavation control function and the residual soil removal function installed in the submersible in the sensor arrangement hole forming step, the tubular member is Excavation below the tubular member is performed while pressing against the surface, and excavation residual soil generated by excavation is removed from the upper surface of the tubular member to the outside of the tubular member. As a result, the excavation residual sand is removed (that is, filled only with seawater), and the tubular member is embedded in the seabed so that the direction in which the internal space extends accurately matches the vertical direction.

  Next, in the sensor insertion step, the sensor case is inserted into the internal space of the tubular member embedded in the sea floor from the side that should be vertically below the sensor case using the submersible craft. As a result, the sensor case can be arranged in the internal space of the tubular member in a state in which an inclination error from the direction to face the vertical direction as the sensor case is reduced.

  Next, in the sensor fixing step, the space between the inner surface of the tubular member and the surface of the sensor case, and the holes formed in the sensor arrangement hole forming step, using the earth and sand spreading function mounted on the submersible craft. The space between the bottom surface and the bottom surface of the sensor case is filled with earth and sand. As a result, the sensor for seabed installation is buried in the seabed in a state where the coupling between the sensor case and the seabed is enhanced.

  Therefore, according to the sensor installation method of the present invention, it is possible to embed the seabed installation sensor in the seabed so that the position accuracy can be ensured and the measurement accuracy can be ensured.

  In the sensor installation method of the present invention, the tubular member is cylindrical, one end is fixed to the inner surface of the tubular member at the lower end of the tubular member, and the center of the lower end of the tubular member is A plurality of excavating blades whose other end portions are fixed to the provided central member are arranged, and excavation in the sensor arrangement hole forming step is performed by pressing the tubular member against the sea bottom while the tubular member and the plurality of excavating This can be done by rotating the blade in a predetermined direction. In this case, it is not necessary to prepare a drilling blade as a drilling facility equipped in the submersible for drilling the sensor arrangement hole on the sea floor, so that the configuration of the drilling facility can be simplified and reduced in weight. Can be planned.

  In the sensor installation method of the present invention, the residual sand removal in the sensor arrangement hole forming step is inserted into the inner space of the tubular member, and the upper surface of the inner pipe member that extends from the upper end portion to the vicinity of the lower end portion of the tubular member. By supplying pressurized running water from the side, seawater containing excavation residual soil near the lower end of the tubular member is passed through a flow path formed by the inner surface of the tubular member and the outer surface of the inner pipe member. Through the top surface of the tubular member. In this case, as a facility for removing residual sand that is installed in the submersible for drilling the sensor arrangement hole on the sea floor, an inner pipe member and a pressurized water supply for supplying pressurized water to the inside of the inner pipe member It is sufficient to prepare a means, and the simplification and weight reduction of the configuration of the residual sand removal equipment can be achieved.

  As described above, according to the sensor installation method of the present invention, there is an effect that the sensor for seabed installation can be embedded in the seabed so as to ensure the position accuracy and the measurement accuracy.

It is a block diagram which shows the schematic structure of the seafloor observation system containing the seismometer device embed | buried by the sensor installation method of one Embodiment of this invention. It is a figure for demonstrating the structure of the excavation steel pipe utilized with the sensor installation method of one Embodiment of this invention. It is a figure for demonstrating the structure of the excavation steel pipe drive part utilized with the sensor installation method of one Embodiment of this invention. It is a figure for demonstrating the engagement state of the excavation steel pipe of FIG. 2, and the excavation steel pipe drive part of FIG. It is a figure for demonstrating the structure of the seismometer apparatus embed | buried under the seabed with the sensor installation method of one Embodiment of this invention. It is FIG. (1) for demonstrating the embedding process of the seismometer apparatus by the sensor installation method of one Embodiment of this invention. It is FIG. (2) for demonstrating the embedding process of the seismometer apparatus by the sensor installation method of one Embodiment of this invention. It is FIG. (3) for demonstrating the embedding process of the seismometer apparatus by the sensor installation method of one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

FIG. 1 is a block diagram showing a schematic configuration of a seafloor observation system 900 including a seismometer device embedded in the seabed by a sensor installation method according to an embodiment of the present invention. As shown in FIG. 1, the seafloor observation system 900 includes a data collection device 910 and branching devices (BU) 920 ₁ ,..., 920 _M.

Here, the data collection device 910 is installed in a building on land. Further, the branching devices 920 ₁ ,..., 920 _M are arranged on the sea bottom.

A data collecting device 910 and the branching unit 920 ₁ of the data collection device 910 side terminals are connected by trunk signal cable. The branch unit _{920 j (j = 1, ...} ) and one terminal of the branching device 920 _{j + 1} side, a branching unit 920 _j terminal of the branching device 920 _{j + 1} is the base signal cable and the Specifications Connected by a signal cable. Then, one terminal of the opposite side of the branching unit 920 _M-1 side of the branching unit 920 _M is Shiasu connected. These branching devices 920 ₁ ,..., 920 _M , a signal cable connecting them, and a backbone signal cable connecting the data collecting device 910 and the branching device 920 ₁ constitute a backbone signal path.

The other terminal of the branching device 920 j + ₁ side branch device 920 _j, terminating device disposed on the sea floor (TE) 930 _j are connected by a signal cable. In addition, a node device 940 _j disposed on the sea floor is connected to the termination device 930 _j by a signal cable. Then, sensor devices 100 _j1 ,... Installed on the sea floor are connected to the node device 940 _j by signal cables. Here, the sensor device 100 _j1 is a seismometer device.

In this seafloor observation system 900, a signal carrying the measurement results of the sensor devices 100 _j1 ,... (J = 1 to M) is sequentially sent to the basic signal path via the node device 940 _j and the termination device 930 _j . Then, the signal is sent to the data collection device 910 via the basic signal path.

  FIG. 2 shows a configuration of a drilled steel pipe 200 used in the sensor installation method according to the embodiment of the present invention. Here, FIG. 2A is a perspective view when the excavated steel pipe 200 is viewed from an obliquely upward direction, and FIG. 2B is a perspective view when the excavated steel pipe 200 is viewed from an obliquely downward direction. . FIG. 2C is a longitudinal sectional view (XZ sectional view) of the excavated steel pipe 200.

  2A to 2C, the excavated steel pipe 200 includes a cylindrical steel pipe 210 as a tubular member. At the upper end (+ Z direction end) of the cylindrical steel pipe 210, a flange portion 210H is provided.

In addition, one end is fixed to the central member 230 at the lower end (−Z direction end) of the cylindrical steel pipe 210 and extends radially from the central member 230, and the other end is cylindrical. Four excavation blades 220 _{1 to} 220 ₄ fixed to the inner surface of the steel pipe 210 are provided. For this reason, the excavating blades 220 _{1 to} 220 ₄ together with the cylindrical steel pipe 200 are arranged on the sea bottom and rotated in a predetermined rotation direction (hereinafter referred to as “excavation rotation direction”) while being pressed against the sea bottom, thereby excavating. The bottom of the steel pipe 200 is excavated.

  A positioning hole extending downward from the upper surface is formed in the center of the central member 230. The member positioned by this positioning hole will be described later.

  FIG. 3 shows a configuration of a drilled steel pipe drive unit 300 used in the sensor installation method according to the embodiment of the present invention. Here, FIG. 3 (A) is a perspective view when the excavated steel pipe drive unit 300 is viewed from an obliquely upward direction, and FIG. 3 (B) is a view when the excavated steel pipe drive unit 300 is viewed from an obliquely downward direction. It is a perspective view. FIG. 3C is a longitudinal sectional view (XZ sectional view) of the excavated steel pipe drive unit 300.

As comprehensively shown in FIGS. 3A to 3C, the excavated steel pipe driving unit 300 includes a cylindrical inner pipe member 310. An upper end portion (+ Z direction end portion) of the inner pipe member 310 is used for supplying or collecting flowing oil to a flowing water pipe 710 for supplying pressurized water to the inner pipe member 310 and a hydraulic motor 320 described later. A flange portion 310H is provided as a lid through which the fluid flow pipes 720 ₁ and 720 ₂ penetrate.

  The outer diameter of the inner pipe member 310 other than the flange 310H is smaller than the inner diameter of the cylindrical steel pipe 210 described above.

In addition, the excavated steel pipe drive unit 300 includes a hydraulic motor 320. The hydraulic motor 320 is fixed to the inner surface of the inner pipe member 310 by fixing members 330 _{1 to} 330 ₄ at the lower end portion (−Z direction end portion) of the inner pipe member 310. In the hydraulic motor 320, the rotating shaft member protrudes downward, and the rotating shaft member rotates by supplying and collecting the flowing oil using the flowing oil pipes 720 ₁ and 720 ₂ .

In addition, the excavated steel pipe driving unit 300 further includes an attachment member 340 fixed to the rotating shaft member of the hydraulic motor 320. The attachment member 340 includes a disk-shaped base member 341 that is fixed to the rotating shaft member at the center. A positioning projection 342 extending downward is provided at the center of the bottom surface of the base member 341. In addition, two driving protrusions 343 ₁ and 343 ₂ extending downward are provided at the radial center of the base member 341.

In the present embodiment, when the flowing oil is supplied through the flowing oil pipe 720 ₁ and the flowing oil is collected through the flowing oil pipe 720 ₂ , the rotating shaft member rotates together with the attachment member 340 for excavation rotation. It is designed to rotate in the direction. In addition, when the flowing oil is supplied through the flowing oil pipe 720 ₂ and the flowing oil is collected through the flowing oil pipe 720 ₁ , the rotating shaft member and the attachment member 340 are opposite to the excavation rotation direction. It is designed to rotate in the direction.

The flowing water pipe 710 can be connected to a pressurized flowing water supply unit provided in an unillustrated unmanned submersible craft. The fluid flow pipes 720 ₁ , 720 ₂ can be connected to a hydraulic pressure adjustment unit provided in the unmanned submersible craft.

  In this embodiment, excavation steel pipe drive part 300 is provided with a pair of clamp arms (not shown) which can be opened and closed for grasping excavation steel pipe 200. A rotary bearing is disposed in a portion of the clamp arm that contacts the side surface of the excavated steel pipe 200, and the excavated steel pipe 200 can freely rotate even in a clamped state by the clamp arm.

  FIG. 4 shows a state where the above-described excavated steel pipe 200 and the excavated steel pipe driving unit 300 are engaged. Here, FIG. 4A is a perspective view when the state where the excavated steel pipe 200 and the excavated steel pipe driving unit 300 are engaged is seen from the obliquely upward direction, and FIG. 4B is the excavated steel pipe 200. It is a longitudinal cross-sectional view (XZ cross-sectional view) of the state which and the excavation steel pipe drive part 300 were engaged.

4A and 4B, the positioning protrusion 342 of the attachment member 340 of the excavating steel pipe driving unit 300 is inserted into the positioning hole of the central member 230 of the excavating steel pipe 200, and excavation is performed. The driving projections 343 ₁ and 343 ₂ of the attachment member 340 of the steel pipe driving unit 300 are inserted into the space between the excavating blades of the excavating steel pipe 200, whereby the excavating steel pipe 200 and the excavating steel pipe driving unit 300 are engaged. Combined.

  Such an engagement state is realized by inserting the excavated steel pipe drive unit 300 into the internal space of the excavated steel pipe 200 from above and adjusting the relative positional relationship. The maintenance of the engaged state is achieved by supporting the flange 210H of the drilled steel pipe 200 from below by two openable and closable clamp arms provided in the drilled steel pipe drive unit 300 after realizing the engaged state once. This is achieved by maintaining the positional relationship between the excavated steel pipe 200 and the excavated steel pipe drive unit 300.

FIG. 5 shows a configuration of a seismometer apparatus 100 _j1 (j = 1 to M) embedded in the seabed by the sensor installation method according to the embodiment of the present invention. Here, FIG. 5A is an external perspective view when the seismometer apparatus 100 _j1 is viewed obliquely from above, and FIG. 5B is a block diagram showing a functional configuration of the seismometer apparatus 100 _j1 . is there.

As shown in FIG. 5A, the seismometer apparatus 100 _j1 includes a chassis 110 as a sensor case having a cylindrical outer shape. Further, suspension arch portions 111 ₁ and 111 ₂ are provided on the upper bottom surface of the chassis 110. A signal cable 800 for sending a measurement result signal to the node device 940 _j passes through the upper bottom surface.

  In the internal space of the chassis 110, an earthquake sensor 120 and an electrical / optical conversion unit 130 are accommodated. The seismic sensor 120 and the electrical / optical conversion unit 130 are directly or indirectly fixed to the inner surface of the chassis 110.

In the seismometer apparatus 100 _j1 , the earthquake sensor 120 measures a seismic wave and sends the measurement result as an electric signal to the electric / optical conversion unit 130. The electrical / optical conversion unit 130 that has received the electrical signal carrying the measurement result converts the electrical signal into an optical signal, and sends the converted optical signal to the node device 940 _j via the signal cable 800. It has become.

  The unmanned submersible used in the present embodiment can be equipped with a sandbag in which buried sand is stored, and has a first manipulator having a tip portion capable of gripping the sandbag, a sandbag bag cutting and a rope. And a second manipulator having a tip portion capable of cutting. The unmanned submersible is equipped with a lift, and the lift is equipped with a hydraulic cylinder that also functions as an actuator that moves the excavated steel pipe drive unit 300 up and down.

Next, the embedding method of the seismometer apparatus by the sensor installation method of this embodiment using the elements described above will be described. Given, branching unit 920 ₁ constituting the submarine observation system 900, ..., and 920 _M, terminating device 930 _1, ..., and 930 _M, the node device 940 _1, ..., and 940 _M, with already placed on the seabed It is assumed that the signal cable connecting them is already laid. Further, base signal cable for connecting between the data collection device 910 and the branching unit 920 ₁ as well as a over installed, one terminal of the opposite side of the branching unit 920 _M-1 side of the branching unit 920 _M is Shiasu connected It shall be.

  In the sensor installation method of the present embodiment, first, the excavated steel pipe 200 and the excavated steel pipe drive unit 300 are engaged on the deck of a ship navigating on the sea surface (see FIG. 4). Subsequently, the excavation steel pipe 200 and the excavation steel pipe drive unit are held by holding the outer surface of the excavation steel pipe 200 while supporting the flange 210H of the excavation steel pipe 200 from below by the openable / closable clamp arm included in the excavation steel pipe drive unit 300. The engagement state with 300 is maintained.

Next, the excavated steel pipe 200 gripped by the clamp arm and the excavated steel pipe drive unit 300 including the clamp arm are submerged on the sea floor together with the unmanned submersible using a crane equipped with the ship. Subsequently, the unmanned submersible is driven on the sea floor by remote control, and the seismometer apparatus 100 _j1 is moved to a position where the seabed is to be buried. Then, the excavated steel pipe 200 and the excavated steel pipe driving unit 300 in the engaged state are placed on the sea bottom so that the lower surface of the excavated steel pipe 200 becomes the sea bottom (see FIG. 6A).

Next, by operating the unmanned submersible by remote control, a force is applied to the excavating steel pipe drive unit 300 to push downward using the hydraulic cylinder described above, and the pressurized water is supplied to the inner pipe via the water pipe 710. While supplying to the internal space of the member 310, by supplying and collecting oil through the flow oil pipes 720 ₁ and 720 ₂ , the rotary shaft member of the hydraulic motor 320 is driven to rotate in the excavation rotation direction. As a result, the attachment member 340 fixed to the rotating shaft member is rotationally driven, so that the excavation steel pipe 200 is rotationally driven in the excavation rotation direction. As a result, the lower surface side of the excavated steel pipe 200 (that is, the tip of the excavating blade) is pressed against the sea bottom, while the excavated steel pipe 200 (that is, the excavated blade) is excavated and rotated as indicated by the black arrow in FIG. Since it rotates in the direction, the bottom surface of the excavated steel pipe 200 is excavated, and the excavated steel pipe 200 is inserted into the excavated hole.

  Also, as shown in FIG. 6B, when pressurized water is supplied to the inner space of the inner pipe member 310 from above, a water flow is generated in the direction indicated by the white arrow, so that the excavation residue generated as a result of excavation is generated. Seawater containing earth and sand flows upward through the gap between the inner surface of the cylindrical steel pipe 210 and the outer surface of the inner pipe member 310 of the excavated steel pipe 200 and is discharged from the upper surface of the cylindrical steel pipe 210 to the outside. . As a result, no excavated soil is left in the excavated steel pipe 200 inserted into the excavated hole.

  And excavation is continued until it becomes the state (refer FIG.6 (C)) in which the excavation steel pipe 200 was inserted in the excavation hole. When the excavation is thus completed, the grip of the excavated steel pipe 200 by the clamp arm is released.

When all of the excavated steel pipe 200 is inserted into the excavation hole, the supply of the pressurized water to the inner space of the inner pipe member 310 via the flowing water pipe 710 is stopped. Subsequently, by collecting and supplying oil through the flow oil pipes 720 ₁ and 720 ₂ , excavation is performed using a hydraulic cylinder while the rotary shaft member of the hydraulic motor 320 is driven to rotate in a direction opposite to the excavation rotation direction. The excavated steel pipe drive unit 300 is taken out from the internal space of the excavated steel pipe 200 by pulling the steel pipe drive unit 300 upward (see FIG. 7A).

  And using the crane with which the ship on the sea surface is equipped, the excavation steel pipe drive part 300 is pulled up to the sea together with the unmanned submersible craft, and is collected on the ship. As a result, the excavated steel pipe 200 is embedded in the seabed while only seawater is present in the internal space (FIG. 7B).

Next, the excavated steel pipe drive unit 300 is removed from the elevator of the unmanned submersible on the deck of the ship. At this time, the water pipe 710 and the oil pipes 720 ₁ and 720 ₂ are also removed from the unmanned submersible craft. Subsequently, the seismometer apparatus 100 _j1 is suspended by a rope on an elevator equipped on the unmanned submersible craft. Such suspension is performed using the suspension arch portions 111 ₁ and 111 ₂ in the seismometer apparatus 100 _j1 . In addition, the sandbag containing the filling earth and sand is mounted on the unmanned submersible. Then, with the seismometer apparatus 100 _j1 suspended from the elevator, the unmanned submersible is submerged on the sea floor using a crane equipped with the ship.

The seismometer device 100 _j1 is submerged in the seabed with the signal cable 800 having a connector attached to the other end to be connected to the node device 940 _j connected to the seismometer device 100 _j1 (see FIG. 5). It is done.

Next, the unmanned submersible is driven on the sea bottom by remote control, and the seismometer apparatus 100 _j1 is moved directly above the embedded excavated steel pipe 200 (see FIG. 7C). Incidentally, seismometer device 100 _j1 is generally horizontal directivity after embedding (e.g., direction to face the north) because is defined, as to satisfy the horizontal directivity, a seismometer device 100 _j1 Then, it is moved directly above the excavated steel pipe 200.

In this way, after the seismometer apparatus 100 _j1 moves right above the excavated steel pipe 200, the elevator of the unmanned submersible is lowered to insert the seismometer apparatus 100 _j1 into the internal space of the excavated steel pipe 200. When the bottom surface of the seismometer device 100 _j1 reaches the lower end of the excavated steel pipe 200, the second manipulator described above is operated to cut the rope that has suspended the seismometer device 100 _j1 . As a result, the seismometer apparatus 100 _j1 is placed in the internal space of the excavated steel pipe 200 (see FIG. 8A).

Next, the sandbag is grasped using the first manipulator described above, and the sandbag is moved to the upper part of the gap between the seismometer device 100 _j1 and the excavated steel pipe 200. Subsequently, the second manipulator is operated to cut the lower side or lower surface of the sandbag (see FIG. 8B). As a result, the filling soil spread from the sandbag is filled in the gap between the seismometer apparatus 100 _j1 and the excavated steel pipe 200.

Then, using the first manipulator, the sandbag is moved on the circumference where the gap between the seismometer apparatus 100 _j1 and the excavated steel pipe 200 is formed. As a result, the entire gap between the seismometer apparatus 100 _j1 and the excavated steel pipe 200 is filled with the filling earth and sand, and the coupling between the seismometer apparatus 100 _j1 and the seabed is improved, and the seismometer apparatus 100 _j1 is _placed on the seabed. Buried.

Thereafter, using the first manipulator, the end of the signal cable 800 connected to the seismometer apparatus 100 _j1 is gripped, and then the unmanned submersible is moved to the vicinity of the node apparatus 940 _j . . Then, the signal cable 800 is connected to the node device 940 _j by operating the first manipulator.

As described above, in the present embodiment, when embedding the seabed seismometer apparatus 100 _{j1 in} the seabed, first, the seismometer apparatus 100 _j1 should be embedded using an unmanned submersible that can move the seabed. The excavated steel pipe 200 for placing the chassis 110 in which the earthquake sensor 120 is housed in the inner space is moved to the seabed position. As a result, the excavated steel pipe 200 is accurately positioned on the seabed position where the seismometer apparatus 100 _j1 is to be embedded.

  Next, the direction in which the inner space of the excavated steel pipe 200 extends is substantially vertical by utilizing the excavation control function (function of the hydraulic control unit) and the residual sand removal function (function of the pressurized water generation unit) implemented in the unmanned submersible craft. While excavating the excavated steel pipe 200 against the bottom of the sea so as to be downward, excavation of the lower part of the excavated steel pipe 200 is performed, and excavated residual soil generated by excavation is removed from the upper surface of the excavated steel pipe 200 to the outside of the excavated steel pipe 200 . As a result, the excavated residual sand is removed (that is, filled only with seawater), and the excavated steel pipe 200 is embedded in the seabed so that the direction in which the internal space extends coincides with the vertical direction with high accuracy.

Next, using the unmanned submersible craft, the seismometer device 100 _j1 is inserted into the internal space of the excavated steel pipe 200 embedded in the seabed from the side that should be vertically below the seismometer device 100 _j1 . As a result, the seismometer device 100 _j1 can be placed in the internal space of the excavated steel pipe 200 in a state where the tilt error from the direction to face the vertical direction is reduced as the seismometer device 100 _j1 .

Next, using the earth and sand spreading function implemented in the unmanned submersible (the earth and sand filling function from the sandbag), the space between the inner surface of the excavated steel pipe 200 and the surface of the seismometer device 100 _j1 , and The space between the bottom of the buried hole and the seismometer apparatus 100 _j1 is filled with earth and sand. As a result, the seismometer device 100 _j1 is embedded in the seabed in a state where the coupling between the seismometer device 100 _j1 and the bottom of the sea is enhanced.

  Therefore, according to the sensor installation method of the present embodiment, it is possible to embed the seismometer device on the seabed so that the position accuracy can be ensured and the measurement accuracy can be ensured.

In the present embodiment, the excavated steel pipe 200 is cylindrical, and one end is fixed to the inner surface of the excavated steel pipe 200 at the lower end of the excavated steel pipe 200, and the center of the lower end of the excavated steel pipe 200 A plurality of excavating blades 220 _{1 to} 220 ₄ whose other ends are fixed to a central member 230 provided on the excavating steel pipe 200 are excavated below the excavating steel pipe 200 while the excavating steel pipe 200 is pressed against the sea bottom. It is performed by rotating 200 excavation blades 220 _{1 to} 220 ₄ in the excavation rotation direction. For this reason, it is not necessary to prepare a drilling blade as a drilling facility equipped in an unmanned submersible for drilling a seismometer device arrangement hole on the sea floor, so the configuration of the drilling facility is simplified and lightened. Can be achieved.

  In the present embodiment, the removal of residual sand generated by excavation for forming the buried hole is inserted into the inner space of the excavated steel pipe 200 and extends from the upper end portion of the excavated steel pipe 200 to the vicinity of the lower end portion thereof. By supplying the pressurized water from the upper surface side of 310, seawater containing the excavated residual soil near the lower end of the excavated steel pipe 200 is formed by the inner surface of the excavated steel pipe 200 and the outer surface of the inner pipe member 310. It is performed by blowing up from the upper surface of the excavated steel pipe 200 through the flow path. For this reason, in order to supply the pressurized water to the inner pipe member 310 and the inner space of the inner pipe member 310 as an equipment for removing the residual soil sand that is installed in the unmanned submersible for drilling the seismometer device arrangement hole on the seabed. It is only necessary to prepare a pressurized water supply means, and it is possible to simplify and lighten the configuration of the residual sand removal equipment.

  The present invention is not limited to the above-described embodiment, and various modifications are possible.

  For example, in the above embodiment, the present invention is applied when an earthquake sensor is embedded in the seabed, but the present invention is also applied when another seabed installation sensor such as a water pressure sensor for tsunami observation is embedded in the seabed. Can be applied.

  In the above embodiment, the number of excavating blades attached to the excavated steel pipe 200 is four, but an arbitrary number can be used.

  In the above-described embodiment, the number of driving protrusions in the attachment member 340 of the excavation steel pipe driving unit 300 is two, but may be any number as long as it is equal to or less than the number of excavation blades.

  Further, in the above embodiment, the cable connection form between the node device and the plurality of sensor devices is daisy chained. In this case, it is possible to connect the node device and a plurality of sensor devices to which a twisted cable connection is made via the splicing box.

  The sensor installation method of the present invention can be applied when embedding a sensor for seabed installation on the seabed.

100 ₁₁ to 100 _M1 ... seismometer device, 110 ... chassis (sensor case), 120 ... (sensor undersea installation) seismic sensors, 210 ... cylindrical steel tube (tubular member), 220 220 ₁ -220 ₄ ... digging edge, 230 ... Central member, 310... Inner pipe member.

Claims (4)

A sensor installation method for embedding a sensor for seabed installation in the seabed,
A tubular member for placing a sensor case in which the seabed installation sensor is housed in an internal space at a predetermined seafloor position where the seabed installation sensor is to be embedded, using a submarine capable of moving the seabed. A moving process to move;
Using the excavation control function and residual sand removal function implemented in the submersible craft, the tubular member so that the direction in which the internal space of the tubular member extends is substantially vertically downward at the predetermined seabed position. The bottom of the tubular member is excavated while pressing the bottom surface of the tubular member, and the excavation residual soil generated by the excavation is removed from the upper surface of the tubular member to the outside of the tubular member. A sensor placement hole forming step of embedding the tubular member in the seabed with the excavated soil removed from the space;
A sensor insertion step of inserting the sensor case into the internal space of the tubular member embedded in the sea floor from the side that should be vertically below the sensor case using the submersible craft;
Utilizing the earth and sand spreading function mounted on the submersible craft, the space between the inner surface of the tubular member and the surface of the sensor case, the bottom surface of the hole formed in the sensor arrangement hole forming step, and the sensor A sensor fixing step of filling the space between the bottom of the case with earth and sand;
A sensor installation method comprising:   The sensor installation method according to claim 1, wherein the seabed installation sensor includes at least one of an earthquake sensor and a water pressure sensor. The tubular member is cylindrical,
A plurality of excavations in which one end is fixed to the inner surface of the tubular member and the other end is fixed to a central member provided at the center of the lower end of the tubular member at the lower end of the tubular member The blade is placed,
The excavation in the sensor arrangement hole forming step is performed by rotating the tubular member and the plurality of excavation blades in a predetermined direction while pressing the tubular member against the sea bottom.
The sensor installation method according to claim 1 or 2, wherein The residual sand removal in the sensor arrangement hole forming step is inserted into the inner space of the tubular member, and by supplying pressurized running water from the upper surface side of the inner pipe member extending from the upper end portion of the tubular member to the vicinity of the lower end portion, Seawater containing excavated residual sand near the lower end of the tubular member is blown up from the upper surface of the tubular member through a flow path formed by the inner surface of the tubular member and the outer surface of the inner pipe member. Done by letting
The sensor installation method as described in any one of Claims 1-3 characterized by the above-mentioned.

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