JP6389450B2 - Submarine cable position search method and submarine pipe position search method - Google Patents

Description

  The present invention relates to a submarine cable position search method and a submarine pipe position search method.

  Submarine cables such as submarine cables and submarine water pipes laid in relatively shallow sea areas are usually buried to avoid damage caused by dredging. Moreover, even if it is not buried, it will be difficult to visually recognize the laid submarine cables and pipes after many years have passed since the laying on the seabed. In order to perform maintenance work and repair work on such submarine cables and submarine pipes, it is first necessary to search for the positions of the submarine cables and submarine pipes.

  Conventionally, an AC magnetic field detection method is known as one of methods for exploring submarine cables. In this method, an alternating magnetic field generated around the submarine cable is caused to flow by applying a low-frequency alternating current to the submarine cable including the position detection line for detecting the buried position as shown in FIG. To detect the cable position. A magnetic sensor for detecting an alternating magnetic field is attached to, for example, an underwater robot (ROV: Remotely Operated Vehicle). The underwater robot is connected to a control device mounted on the mother ship at sea by a control line, and is controlled from the mother ship. The control device causes the underwater robot to travel along the submarine cable, and the absolute position of the mother ship obtained from GPS, the relative position of the underwater robot relative to the mother ship, the horizontal distance and the vertical distance of the submarine cable obtained from the magnetic sensor. To get. From the results obtained in this manner, the buried position information of the submarine cable, that is, the position information on the bottom of the sea and the buried depth information therefrom can be obtained.

JP 2003-77348 A

  However, among the submarine cables already laid on the seabed, there are submarine cables that do not have position detection lines, such as those laid several decades ago. Even with such a submarine cable, if an AC current for position detection can be passed through a transmission line for power or communication at the core, it is possible to search for a position by an AC magnetic field detection method. However, when the transmission line is in use, an AC current for position detection may not be allowed to flow.

  On the other hand, as a conventional method of exploring the submarine pipe, a diver uses a magnetic probe or the like to search for the submarine pipe, relying on the track information of the laid ship when laying the submarine pipe and the exposed location of the submarine pipe on the seabed. There is a way to search. However, the track of the laid ship and the bottom point of the submarine pipe may not match, or it may be necessary to remove the gold dust that the magnetic probe responds one by one on the seabed. It is not easy to find out where the pipe is buried. Furthermore, even if the exposed part of the submarine pipe is found partially, on the seabed with poor visibility, the diver cannot find the exposed part at a distant place, and accurately knows where the submarine pipe extends. Can not. For this reason, in the conventional method, much time and labor are required to search the position of the submarine tube.

  Then, an object of this invention is to provide the position search method which can search the position of a submarine cable or a submarine pipe easily.

  Submarine cables and submarine pipes are usually equipped with armored iron wires or steel strips. These armored iron wires, steel strips, and the like play a role in making submarine cables and submarine pipes less susceptible to damage by increasing the strength against external forces and internal forces. The inventors of the present application pay attention to the fact that members such as armored iron wires and steel strips that are not provided for the purpose of energization can be energized, and these cannot be used for the AC magnetic field detection method. I thought. The present invention has been made from such a viewpoint.

That is, a submarine cable position exploration method according to an aspect of the present invention includes a current-carrying conductor that forms a transmission path for power or communication, an insulator that covers the current-carrying conductor, and a periphery of the insulator A submarine cable comprising a covering portion covering the submarine cable, wherein the covering portion has a reinforcing portion that can be energized to increase the strength of the submarine cable. A step of causing an alternating current to flow through the reinforcing portion of the submarine cable, and a magnetic field in which an alternating magnetic field generated around the submarine cable by the alternating current flowing through the reinforcing portion is disposed in the vicinity of the submarine cable on the seabed. a step of detecting by a sensor, from said alternating magnetic field detected by the magnetic sensor, see containing and a step of acquiring a position of the submarine cable, the step of flowing the alternating current, before In the land where one end of the submarine cable is located, it is a step of applying an alternating current to the reinforcing portion, and as the distance along the submarine cable from the application point of the alternating current to the magnetic sensor increases, the reinforcing portion The method further includes the step of amplifying the effective value of the alternating current to be applied. Here, “in the vicinity of the submarine cable” refers to a range in which an AC magnetic field generated around the submarine cable can be detected.

According to the above method, since an alternating current is passed through the energized reinforcing part, the generated AC magnetic field is detected, and the position information of the submarine cable is acquired. Even if it is a cable, an AC magnetic field detection system can be employed for position exploration. Further, as the distance along the submarine cable from the application point of the alternating current to the magnetic sensor increases, the alternating current flowing through the reinforcing portion is attenuated, and the detection of the alternating magnetic field by the magnetic sensor becomes difficult. However, according to this method, an alternating magnetic field that can be sufficiently detected by the magnetic sensor can be generated even when the distance from the application point increases.

A submarine cable position exploration method according to another aspect of the present invention includes a current-carrying conductor that forms a transmission path for power or communication, an insulator that covers the current-carrying conductor, and a periphery of the insulator. A submarine cable comprising a covering portion for covering, wherein the covering portion has a reinforcing portion that can be energized to increase the strength of the submarine cable, and is a method for exploring the position of the submarine cable, A step of passing an alternating current through the reinforcing portion of the submarine cable; and a magnetic sensor in which an alternating magnetic field generated around the submarine cable by the alternating current flowing through the reinforcing portion is disposed in the vicinity of the submarine cable on the seabed. a step of detecting by, from said alternating magnetic field detected by the magnetic sensor, and a step of acquiring the position of the submarine cable, the step of flowing the alternating current, an alternating magnetic field By generating a plurality of magnetic field generators that cause an alternating current to flow through the reinforcing portion, the distance along the submarine cable from the magnetic field generator to the magnetic sensor increases, and the alternating magnetic field detected by the magnetic sensor installed in every case to be below a certain threshold value, the plurality of including the step of supplying alternating current to the reinforcing portion by generating an AC magnetic field around the submarine cable by the magnetic field generator. According to this method, since an alternating current is passed through the energized reinforcing part, the generated alternating magnetic field is detected, and the position information of the submarine cable is acquired, so the submarine does not include the position detection line for detecting the buried position. Even if it is a cable, an AC magnetic field detection system can be employed for position exploration. In addition, an induced current can flow through the reinforcing part by the magnetic field generated by the magnetic field generator, thereby generating an alternating current in the reinforcing part to the extent that dielectric breakdown does not occur in the insulator in the submarine cable. Can be located. Furthermore, the absolute position of the submarine cable can be measured from one end side to the other end side without amplifying the current applied at one end of the submarine cable.

  In the step of flowing the alternating current in the submarine cable position exploration method, the reinforcing portion to which the alternating current is passed may be a steel strip, an armored iron wire, or a steel pipe. According to this method, for example, even a submarine cable that has already been laid can be located using the AC magnetic field detection method.

A submarine tube position exploration method according to an aspect of the present invention is a submarine tube including a conduit that forms a flow path of liquid or gas, and a covering portion that covers the periphery of the conduit, and the covering portion includes: A method for exploring the position of the submarine pipe, comprising a reinforcing portion capable of energization for increasing the strength of the submarine pipe, wherein an alternating current is passed through the reinforcing section of the submarine pipe laid on the seabed, A step of detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through a reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine tube on the sea floor, and from the alternating magnetic field detected by the magnetic sensor, It is seen containing a step of acquiring the position of the undersea pipe, the step of flowing the alternating current in the land to which one end of said undersea pipe is located, a step of applying an alternating current to the reinforcing portion, of the alternating current Before application point Indeed distance along the seabed tube until the magnetic sensor is large, further comprising the step of amplifying the effective value of the alternating current applied to the reinforcing portion. Here, “in the vicinity of the submarine tube” refers to a range in which an alternating magnetic field generated around the submarine tube can be detected.

According to the above method, an alternating current is passed through the energized reinforcing portion, the alternating magnetic field generated thereby is detected, and the position information of the submarine tube is acquired. For this reason, it is possible to search the position of the submarine tube by the AC magnetic field detection method. Further, as the distance along the seabed tube from the application point of the alternating current to the magnetic sensor increases, the alternating current flowing through the reinforcing portion is attenuated, and the detection of the alternating magnetic field by the magnetic sensor becomes difficult. However, according to this method, an alternating magnetic field that can be sufficiently detected by the magnetic sensor can be generated even when the distance from the application point increases.

According to another aspect of the present invention, there is provided a submarine tube position exploration method, comprising: a conduit that forms a liquid or gas flow path; and a covering portion that covers the periphery of the conduit. A method for exploring the position of the submarine pipe, comprising a reinforcing portion capable of energization for increasing the strength of the submarine pipe, and passing an alternating current through the reinforcing section of the submarine pipe laid on the seabed; A step of detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through the reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine tube on the sea floor, and from the alternating magnetic field detected by the magnetic sensor, and a step of obtaining a position of the undersea pipe, the step of flowing the previous SL alternating current, a plurality of magnetic field generator supplying an alternating current to the reinforcing portion by generating an alternating magnetic field, from the magnetic field generator Magnetic sensor Wherein the alternating magnetic field distance along the seabed pipe is detected by increased and the magnetic sensor is installed in each case to be below a certain threshold, an AC magnetic field around the undersea pipe by the plurality of magnetic field generators in including the step of supplying alternating current to the reinforcing portion by generating. According to this method, an alternating current is passed through the energized reinforcing part, the alternating magnetic field generated thereby is detected, and the position information of the submarine tube is acquired. For this reason, it is possible to search the position of the submarine tube by the AC magnetic field detection method. In addition, the magnetic field generated by the magnetic field generator can cause an induced current to flow through the reinforcement, and the position of the submarine pipe is searched while generating an alternating current in the reinforcement so that dielectric breakdown does not occur in the insulation in the submarine pipe. be able to. Furthermore, the absolute position of the submarine tube can be measured from one end side to the other end side without amplifying the current applied at one end of the submarine tube.

  In the step of flowing the alternating current in the submarine tube position exploration method, the reinforcing portion to which the alternating current flows may be a steel strip, an armored iron wire, or a steel pipe. According to this method, even a submarine pipe that does not have a signal line already laid can be searched for position by the AC magnetic field detection method.

According to still another aspect of the present invention, there is provided a submarine tube position exploration method, which is a submarine tube position exploration method including an energizable conduit that forms a liquid or gas flow path, wherein the submarine pipe is laid on the seabed. Flowing an alternating current through the conduit of the tube; detecting an alternating magnetic field generated around the submarine tube by the alternating current flowing through the conduit by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed; , from the alternating magnetic field detected by the magnetic sensor, see containing and a step of acquiring a position of the undersea pipe, the step of flowing the alternating current in the land to which one end of said undersea pipe is located, alternating in the conduit A step of amplifying the effective value of the alternating current applied to the conduit as the distance along the submarine tube from the application point of the alternating current to the magnetic sensor increases. To prepare for. Here, “in the vicinity of the submarine tube” refers to a range in which an alternating magnetic field generated around the submarine tube can be detected.

According to the above method, an alternating current is passed through a conduit that can be energized, the alternating magnetic field generated thereby is detected, and the position information of the submarine tube is acquired. For this reason, it is possible to search the position of the submarine tube by the AC magnetic field detection method. Further, as the distance along the seabed tube from the application point of the alternating current to the magnetic sensor increases, the alternating current flowing through the conduit is attenuated, and the detection of the alternating magnetic field by the magnetic sensor becomes difficult. However, according to this method, an alternating magnetic field that can be sufficiently detected by the magnetic sensor can be generated even when the distance from the application point increases.

A submarine tube position exploration method according to another aspect of the present invention is a submarine tube position exploration method including an energizable conduit that forms a liquid or gas flow path, wherein the submarine pipe is laid on the seabed. Flowing an alternating current through the conduit; and detecting an alternating magnetic field generated around the submarine tube by the alternating current flowing through the conduit by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed; from the alternating magnetic field detected by the magnetic sensor, and a step of obtaining a position of the undersea pipe, the step of flowing the previous SL alternating current, a plurality of passing an alternating current to the conduit by generating an alternating magnetic field A magnetic field generator is installed each time the distance along the seabed tube from the magnetic field generator to the magnetic sensor increases and the alternating magnetic field detected by the magnetic sensor falls below a certain threshold. And, including the step of flowing an alternating current to the reinforcing portion by generating an alternating magnetic field around said undersea pipe by the plurality of magnetic field generators. According to this method, an alternating current is passed through a conduit that can be energized, an alternating magnetic field generated thereby is detected, and position information of the submarine tube is acquired. For this reason, it is possible to search the position of the submarine tube by the AC magnetic field detection method. In addition, an induced current can be caused to flow through the conduit by the magnetic field generated by the magnetic field generator, and the submarine tube can be located while generating an alternating current in the conduit to the extent that dielectric breakdown does not occur in the insulator in the submarine tube. it can. Furthermore, the absolute position of the submarine tube can be measured from one end side to the other end side without amplifying the current applied at one end of the submarine tube.

  In the step of flowing the alternating current in the submarine tube position exploration method, the conduit through which the alternating current flows may be a steel pipe. According to this method, for example, even a submarine tube that does not have a signal line that has already been laid can be searched for position by the AC magnetic field detection method.

  In the submarine pipe position exploration method, for example, the submarine pipe is a submarine water pipe that feeds water.

  An object of the present invention is to provide a position search method that can easily search the position of a submarine cable or a submarine tube.

It is a schematic block diagram of the system using the position search method of the submarine cable of this invention. It is sectional drawing of the submarine cable which is a search object of the position search method of the submarine cable of this invention. It is a figure for demonstrating the modification of the position search method of the submarine cable used for the system of FIG. It is sectional drawing of the seabed water pipe which is the search object of the position search method of the seabed water pipe of this invention.

(Submarine cable location method)
Hereinafter, an embodiment of a submarine cable position search method according to the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic configuration diagram of an exploration system 1A using the method for exploring the position of a submarine cable 30 according to this embodiment. The submarine cable 30 to be searched extends from the first landing station 2 on the land where one end is located, and extends to the second landing station 3 on the land where the other end is located along the bottom surface 4. . The submarine cable 30 is buried at the time of laying.

  The exploration system 1A includes a mother ship 10 that navigates the sea between the first and second landing stations 2 and 3 substantially along the submarine cable 30, a control device 11 mounted on the mother ship 10, and a control line to the control device 11. 12 has an underwater robot 20 connected at 12.

  The mother ship 10 is provided with a GPS 13 for positioning and a plurality of acoustic transducers 14. The underwater robot 20 is provided with two magnetic sensors 21, a transponder 22, an altimeter 23, and a video camera (not shown).

  Each of the two magnetic sensors 21 is a three-axis magnetic sensor, and is spaced apart from each other at symmetrical positions with respect to the body of the underwater robot 20. Information on the three-axis components of the magnetic field detected by each magnetic sensor 21 is sent to the control device 11 on the mother ship 10 via the control line 12. Based on the information detected by the magnetic sensor 21, the control device 11 acquires the relative position (direction, horizontal distance, vertical distance) of the submarine cable 30 with respect to the underwater robot 20.

  The plurality of acoustic transducers 14 on the mother ship 10 side and the transponder 22 on the underwater robot 20 side constitute an SSBL (Super Short Base Line) underwater position measurement system for measuring the relative position of the underwater robot 20 with respect to the mother ship 10. The acoustic signals transmitted from the transponder 22 on the underwater robot 20 side are received by the plurality of acoustic transducers 14 on the mother ship 10 side, and arrival time differences and phase differences of the received signals are measured. The relative position of the underwater robot 20 with respect to the mother ship 10 is obtained from the result, and this relative position information is sent to the control device 11. However, the underwater position positioning system for measuring the relative position of the underwater robot 20 with respect to the mother ship 10 is not limited to the positioning system configured as described above.

  The altimeter 23 is provided below the underwater robot 20 and measures the vertical distance of the underwater robot 20 from the sea floor 4. This distance information is sent to the control device 11.

  Next, the structure of the submarine cable 30 that is a search target of the position search method according to this embodiment will be described with reference to FIG.

  FIG. 2 is a cross-sectional view of the submarine cable 30 that is a search target of the position search method according to this embodiment. The submarine cable 30 is a three-core cable including three wire cores 31. Each of the wire cores 31 includes a current-carrying conductor 32 that forms a transmission path for power or communication, and an insulator 33 provided on the outer peripheral surface so as to cover the periphery of the current-carrying conductor 32. The energizing conductor 32 is configured by twisting copper strands, for example, and the insulator 33 is configured by polyethylene, for example.

  The wire core 31 includes a first covering portion 34 provided on the outer peripheral surface so as to cover the periphery of the insulator 33. The 1st coating | coated part 34 has the water-impervious layer 35 and the anti-corrosion layer 36 in order from the inner side. The water shielding layer 35 includes, for example, a lead coating layer.

  Further, the submarine cable 30 includes an optical fiber communication line 37.

  The three wire cores 31 and the optical fiber communication line 37 are integrally covered with the second covering portion 39 through the inclusions 38. The inclusion 38 is, for example, a plastic string. The 2nd coating | coated part 39 has the steel strip 40, the armored iron wire 41, and the protective layer 42 in order from the inner side. In the submarine cable 30, the first covering portion 34 and the second covering portion 39 constitute the covering portion of the present invention.

  The steel strip 40 is, for example, a stainless steel strip. The armored iron wire 41 is obtained by twisting iron wires. Both the steel strip 40 and the armored iron wire 41 serve to increase the strength of the submarine cable 30 and are conductive conductors. In this submarine cable 30, both the steel strip 40 and the armored iron wire 41 correspond to the reinforcing portion of the present invention. The protective layer 42 is, for example, plastic.

  Next, a method for searching for the position of the submarine cable 30 according to this embodiment will be described. The position search method for the submarine cable 30 of the search system 1A employs an AC magnetic field detection method.

  In the first landing station 2, an AC transmitter (not shown) is directly connected to the steel strip 40, which is a reinforcing part of the submarine cable 30, and an alternating current is passed from the AC transmitter to the steel strip 40. Although the alternating current to apply is not limited, For example, it is a low frequency around 20 Hz, for example, is a rectangular wave or a sine wave.

  With the mother ship 10 stopped near the coast of the land where the first landing station 2 is located, the underwater robot 20 with the magnetic sensor 21 attached is dropped into the sea from the mother ship 10 and operated from the mother ship 10, and the submarine cable 30 in the vicinity. At this time, the underwater robot 20 is disposed in a range where at least an AC magnetic field generated around the submarine cable can be detected by an AC current flowing through the steel strip 40.

  The magnetic sensor 21 of the underwater robot 20 disposed in the vicinity of the submarine cable 30 detects an AC magnetic field generated around the submarine cable 30 by an AC current flowing through the steel strip 40.

  Then, the position of the submarine cable 30 is obtained from the AC magnetic field detected by the magnetic sensor 21.

  Specifically, information on the three-axis components of the magnetic field detected by each magnetic sensor 21 is sent from the AC magnetic field detected by the magnetic sensor 21 to the control device 11 on the mother ship 10 via the control line 12. . Based on the information detected by the magnetic sensor 21, the control device 11 acquires the relative position (direction, horizontal distance, vertical distance) of the submarine cable 30 with respect to the underwater robot 20.

  On the other hand, the control device 11 receives the relative position information of the underwater robot 20 with respect to the mother ship 10 obtained by the plurality of acoustic transducers 14 on the mother ship 10 side and the transponder 22 on the underwater robot 20 side. In addition, the control device 11 receives the absolute position of the mother ship 10 acquired by the GPS 13.

  Based on the relative position of the submarine cable 30 with respect to the underwater robot 20, the relative position of the underwater robot 20 with respect to the mother ship 10, and the absolute position of the mother ship 10, the position information of the submarine cable 30 is obtained.

  Further, the control device 11 receives the vertical distance information from the sea floor 4 of the underwater robot 20 acquired by the altimeter 23. The embedment depth of the submarine cable 30 is obtained by subtracting the vertical distance obtained by the altimeter 23 from the vertical distance from the underwater robot 20 to the submarine cable 30 obtained by the magnetic sensor 21.

  In this way, while detecting the alternating magnetic field by the magnetic sensor 21, the underwater robot 20 is moved along with the mother ship 10 along the submarine cable 30 toward the second landing station 3, and the absolute position of the submarine cable 30 is measured.

  As described above, in the method of searching for the position of the submarine cable 30 according to this embodiment, an alternating current is passed through the steel strip 40 that can be energized to detect the alternating magnetic field generated thereby, and the position information of the submarine cable 30 is obtained. get. For this reason, even if the submarine cable 30 does not include the position detection line for detecting the embedded position, the position search can be performed by employing the AC magnetic field detection method.

  The AC magnetic field detected by the magnetic sensor 21 becomes weaker as the distance along the submarine cable 30 from the first landing station 2 to which the AC current is applied to the magnetic sensor 21 increases. For this reason, when an alternating current is passed through the steel strip 40 in the position search method, the effective value of the alternating current applied to the steel strip 40 may be amplified as the distance increases. Thereby, even if the distance from the application point of alternating current becomes large, the alternating current magnetic field which can fully be detected by the magnetic sensor 21 can be generated. The effective value of the alternating current applied to the steel strip 40 may be continuously amplified along with the distance along the submarine cable 30 from the first landing station 2 to the magnetic sensor 21, or may be amplified in stages. Also good.

(Modification)
In the above submarine cable position exploration method, it is possible to expand the cable exploration possible range from the application point of the alternating current by amplifying the effective value of the alternating current applied to the steel strip 40 as described above. . However, it is necessary to suppress the applied current to such an extent that dielectric breakdown does not occur in the insulator of the submarine cable. Therefore, an alternating current for exploration of the submarine cable 30 may be generated on the seabed by electromagnetic induction.

  FIG. 3 is a schematic configuration diagram of an exploration system 1B using the submarine cable 30 position exploration method according to this modification. In this exploration system 1B, magnetic field generators 24 and 26 for generating an alternating magnetic field around the submarine cable 30 are installed in the vicinity of the submarine cable 30 on the seabed in order to cause an alternating current to flow through the reinforcing portion by electromagnetic induction. The magnetic field generators 24 and 26 are of a battery power type and have a pressure-proof waterproof structure. Hereinafter, a method for searching for the position of the submarine cable 30 according to this modification will be described. In this exploration system 1B, the AC magnetic field detection method is adopted as in the exploration system 1A.

  Also in this modified example, first, in the first landing station 2, an AC transmitter (not shown) is directly connected to the steel strip 40 which is the reinforcing portion of the submarine cable 30, and the AC transmitter An alternating current is passed through the belt 40. Although the alternating current to apply is not limited, For example, it is a low frequency around 20 Hz, for example, is a rectangular wave or a sine wave.

  Similar to the exploration system 1A, with the mother ship 10 stopped near the coast of the land where the first landing station 2 is located, the underwater robot 20 to which the magnetic sensor 21 is attached is dropped from the mother ship 10 into the sea. And is arranged in the vicinity of the submarine cable 30.

  Similar to the exploration system 1A, the magnetic sensor 21 of the underwater robot 20 disposed in the vicinity of the submarine cable 30 detects an AC magnetic field generated around the submarine cable 30 by an AC current flowing through the steel strip 40. Then, while detecting the alternating magnetic field by the magnetic sensor 21 and measuring the absolute position of the submarine cable 30, the underwater robot 20 is moved along with the mother ship 10 to the second landing station 3 side along the submarine cable 30. .

  The AC magnetic field detected by the magnetic sensor 21 becomes weaker as the distance along the submarine cable 30 from the first landing station 2 to which the AC current is applied to the magnetic sensor 21 increases. When the detected AC magnetic field falls below a certain threshold, a first magnetic field generator 24 that generates an AC magnetic field around the submarine cable 30 is installed in the vicinity of the submarine cable 30 on the seabed. Here, “in the vicinity of the submarine cable 30” refers to a range in which an alternating current that generates an alternating magnetic field sufficient to be detected by the magnetic sensor 21 can flow. When the submarine cable 30 is embedded, the magnetic field generator 24 is preferably installed immediately above the embedded submarine cable 30 on the bottom surface 4.

  After the magnetic field generator 24 is installed, an alternating magnetic field is generated around the submarine cable 30 by the magnetic field generator 24, and an alternating current flows through the submarine cable 30 by electromagnetic induction. An alternating magnetic field generated by the alternating current is detected by the magnetic sensor 21. Then, while measuring the absolute position of the submarine cable 30, the underwater robot 20 is moved along the submarine cable 30 to the second landing station 3 side while leaving the magnetic field generator 24 at the installation location. Go.

  Thereafter, when the distance along the submarine cable 30 from the magnetic field generator 24 to the magnetic sensor 21 is increased and the detected AC magnetic field is equal to or less than a certain threshold value, the second magnetic field generator 26 is connected to the seabed at the seabed. Installed in the vicinity of the cable 30. Thus, the absolute position of the submarine cable 30 is measured up to the second landing station 3 side by sequentially installing the magnetic field generator.

  For example, as shown in FIG. 3, the magnetic field generators 24 and 26 can be installed by being suspended from the mother ship 10 with a rope 15 or the like. When the magnetic field generators 24 and 26 are suspended from the mother ship 10, for example, an acoustic transmitter (not shown) is attached to the magnetic field generator 24 in order to install the magnetic field generator 24 near the submarine cable 30. It may be left. Then, while confirming the position of the magnetic field generator 24 by the signal from the acoustic transmitter, the magnetic field generator 24 is installed at a known position of the submarine cable 30 where the underwater robot 20 has already passed and the absolute position has been measured. It may be installed by being guided by the mother ship 10 as described above.

  In order to collect the magnetic field generators 24 and 26 after the position survey of the submarine cable 30 is completed, buoys 25 and 27 floating on the sea surface are connected to the magnetic field generators 24 and 26 by ropes 25a and 27a, respectively. ing.

  Also in this modified example, even when the submarine cable 30 does not include a position detection line for detecting the embedded position, the position search can be performed using the AC magnetic field detection method. In this modification, even if the distance from the land on the first landing station 2 side to the land on the second landing station 3 side is large (for example, several tens of kilometers or more), the magnetic field generator is It can be installed in the vicinity of the submarine cable 30 and an induced current can be passed through the reinforcing portion by a magnetic field generated around the submarine cable 30. Thereby, the absolute position of the submarine cable 30 is measured from the land on the first landing station 2 side to the land on the second landing station 3 side without amplifying the current applied on the first landing station 2 side. Can do. This modification can also be applied to a submarine tube position exploration method described later.

(Submarine pipe location exploration method)
Next, an embodiment of a submarine tube position exploration method according to the present invention will be described. In this embodiment, an exploration system similar to the exploration system 1A for the submarine cable 30 described above is used. For this reason, the overlapping description about the specific position search method by a search system or an alternating magnetic field detection system is abbreviate | omitted.

  The submarine pipe to be searched by the position search method according to this embodiment is, for example, a submarine water pipe that supplies water to a remote island or the like. FIG. 4 is a cross-sectional view of the submarine water pipe 50 that is the object of the position exploration method according to this embodiment. The seabed water pipe 50 includes a conduit 52 that forms a water channel 51 and a covering portion 53 that is provided on the outer peripheral surface of the conduit 52 so as to cover the periphery of the conduit 52. The conduit 52 is made of, for example, polyethylene.

  The covering portion 53 includes a floor layer 54, a steel strip 55, an anticorrosion layer 56, an armored iron wire 57, and a protective layer 58 in order from the inside.

  The steel strip 55 is, for example, a stainless steel strip. The armored iron wire 57 is obtained by twisting iron wires. Both the steel strip 55 and the armored iron wire 57 serve to increase the strength of the seabed water pipe 50 and are conductive conductors. In this submarine water pipe 50, both the steel strip 55 and the armored iron wire 57 correspond to the reinforcing portion of the present invention.

  Also in the position exploration method for the submarine water pipe 50 according to this embodiment, as in the position exploration method for the submarine cable 30 described above, an alternating current is passed through the energizable steel strip 55 to detect the alternating magnetic field generated thereby. The position information of the seabed water pipe 50 is acquired. For this reason, the position of the seabed water pipe 50 can be searched by the AC magnetic field detection method.

  Also in the position exploration method of this embodiment, when an alternating current is passed through the steel strip 55, the distance along the submarine water pipe 50 from the first landing station 2 that is the application point of the alternating current to the magnetic sensor 21 increases. The effective value of the alternating current applied to the steel strip 55 may be amplified. Thereby, even if the distance from the application point of alternating current becomes large, the alternating current magnetic field which can fully be detected by the magnetic sensor 21 can be generated.

(Other embodiments)
The above-described embodiment is an example in all respects, and should be considered not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, although the submarine water pipe has been described as the exploration target of the position exploration method of the above embodiment, the submarine pipe that is the exploration target of the position exploration method of the present invention is not limited to the submarine water supply pipe. For example, the submarine pipe to be searched by the position search method of the present invention may be a submarine pipe that sends a liquid or gas other than water, or may be a submarine pipe laid as a pipeline.

  In the said embodiment, although the position search method of the submarine cable 30 and the submarine water pipe 50 was described taking the example of the method of searching the position by flowing an alternating current through the steel strips 40 and 55, the armored iron wires 41 and 57 The position may be searched by passing an alternating current.

  The submarine cable 30 and the submarine water pipe 50 described in the above embodiment are illustrated for the purpose of explanation, and the search target of the position search method of the present invention is the submarine cable 30 and the submarine water pipe 50 having the above structure. It is not limited to.

  For example, the submarine cable to be surveyed may be a single-core cable or a two-core cable, and an insulator is provided around the current-carrying conductor of the submarine cable via an inclusion such as a semiconductive tape. It may be. Moreover, a submarine cable and a submarine pipe may include a steel pipe as a reinforcing portion capable of energizing, for example, to increase the strength of the covering portion. In this case, the position search of the submarine cable and the submarine pipe can be executed by passing an alternating current through the steel pipe.

  For example, the conduit that forms the liquid or gas flow path of the submarine tube to be probed may be an energizable conduit such as a steel tube. In this case, even if it is a submarine tube that does not have a covering part that covers the conduit or does not have a reinforcing part that can be energized in the covering part, the position of the submarine pipe is searched by passing an alternating current through the conduit. can do. It is desirable that the conduit that can be energized has an insulating coating.

2 First landing station (application point of alternating current)
21 Magnetic sensor 30 Submarine cable 32 Conducting conductor 33 Insulator 34 First covering part (covering part)
39 Second covering part (covering part)
40 Steel strip (reinforcement part)
41 Armored iron wire (reinforcement part)
50 Submarine water pipe (submarine pipe)
51 water channel
52 Polyethylene pipe (conduit)
53 Covering part 55 Steel strip (reinforcing part)
57 Armored Iron Wire (Reinforcement)

Claims (10)

A submarine cable comprising a current-carrying conductor forming a power or communication transmission line, an insulator covering the periphery of the current-carrying conductor, and a covering portion covering the periphery of the insulator. Is a method for exploring the position of the submarine cable, including a reinforcing portion that can be energized to increase the strength of the submarine cable,
Passing an alternating current through the reinforcing portion of the submarine cable laid on the seabed;
A step of detecting an alternating magnetic field generated around the submarine cable by an alternating current flowing through the reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine cable on the seabed;
Wherein the alternating magnetic field detected by the magnetic sensor, see containing and a step of acquiring a position of the submarine cable,
The step of flowing the alternating current is a step of applying an alternating current to the reinforcing portion on land where one end of the submarine cable is located,
A submarine cable position search method , further comprising a step of amplifying an effective value of an alternating current applied to the reinforcing portion as a distance along the submarine cable from the application point of the alternating current to the magnetic sensor increases . A submarine cable comprising a current-carrying conductor forming a power or communication transmission line, an insulator covering the periphery of the current-carrying conductor, and a covering portion covering the periphery of the insulator. Is a method for exploring the position of the submarine cable, including a reinforcing portion that can be energized to increase the strength of the submarine cable,
Passing an alternating current through the reinforcing portion of the submarine cable laid on the seabed;
A step of detecting an alternating magnetic field generated around the submarine cable by an alternating current flowing through the reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine cable on the seabed;
Obtaining a position of the submarine cable from an AC magnetic field detected by the magnetic sensor,
The step of passing the alternating current increases a distance along the submarine cable from the magnetic field generator to the magnetic sensor by causing a plurality of magnetic field generators that pass an alternating current to the reinforcing portion by generating an alternating magnetic field. Installed whenever the AC magnetic field detected by the magnetic sensor falls below a certain threshold value, and generates an AC magnetic field around the submarine cable by the plurality of magnetic field generators to generate an AC current in the reinforcing portion. A submarine cable location exploration method including a flow process . The method for exploring a position of a submarine cable according to claim 1 or 2, wherein, in the step of passing an alternating current, the reinforcing portion to which the alternating current is passed is a steel strip, an armored iron wire, or a steel pipe. A submarine tube comprising a conduit that forms a liquid or gas flow path and a covering portion that covers the periphery of the conduit, wherein the covering portion is an energizable reinforcing portion for increasing the strength of the submarine tube. A method for exploring the position of the submarine pipe,
Passing an alternating current through the reinforcing portion of the submarine pipe laid on the seabed;
A step of detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through the reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed;
Wherein the alternating magnetic field detected by the magnetic sensor, see containing and a step of acquiring a position of the undersea pipe,
The step of flowing the alternating current is a step of applying an alternating current to the reinforcing portion on land where one end of the submarine tube is located.
A submarine tube position exploration method further comprising a step of amplifying an effective value of an alternating current applied to the reinforcing portion as a distance along the submarine tube from the application point of the alternating current to the magnetic sensor increases . A submarine tube comprising a conduit that forms a liquid or gas flow path and a covering portion that covers the periphery of the conduit, wherein the covering portion is an energizable reinforcing portion for increasing the strength of the submarine tube. A method for exploring the position of the submarine pipe,
Passing an alternating current through the reinforcing portion of the submarine pipe laid on the seabed;
A step of detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through the reinforcing portion by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed;
Obtaining the position of the submarine tube from the AC magnetic field detected by the magnetic sensor,
The step of passing the alternating current increases the distance along the submarine tube from the magnetic field generator to the magnetic sensor by causing a plurality of magnetic field generators to flow an alternating current to the reinforcing portion by generating an alternating magnetic field. Installed whenever the AC magnetic field detected by the magnetic sensor falls below a certain threshold, and generates an AC magnetic field around the submarine tube by the plurality of magnetic field generators, thereby generating an AC current in the reinforcing portion. A method for exploring the position of a submarine pipe , including a flow step . The method for exploring the position of a submarine pipe according to claim 4 or 5, wherein, in the step of passing an alternating current, the reinforcing portion to which the alternating current is passed is a steel strip, an armored iron wire, or a steel pipe. A method of locating a submarine tube with a conducting conduit that forms a liquid or gas flow path, comprising:
Flowing an alternating current through the conduit of the submarine pipe laid on the seabed;
Detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through the conduit by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed;
Wherein the alternating magnetic field detected by the magnetic sensor, see containing and a step of acquiring a position of the undersea pipe,
The step of passing the alternating current is a step of applying an alternating current to the conduit on land where one end of the submarine pipe is located,
The submarine tube position exploration method further comprising a step of amplifying an effective value of the alternating current applied to the conduit as the distance along the submarine tube from the application point of the alternating current to the magnetic sensor increases . A method of locating a submarine tube with a conducting conduit that forms a liquid or gas flow path, comprising:
Flowing an alternating current through the conduit of the submarine pipe laid on the seabed;
Detecting an alternating magnetic field generated around the submarine tube by an alternating current flowing through the conduit by a magnetic sensor disposed in the vicinity of the submarine tube on the seabed;
Obtaining the position of the submarine tube from the AC magnetic field detected by the magnetic sensor,
The step of passing the alternating current increases a distance along the submarine tube from the magnetic field generator to the magnetic sensor by increasing a plurality of magnetic field generators that flow an alternating current through the conduit by generating an alternating magnetic field. A step of installing an alternating current through the conduit by generating an alternating magnetic field around the submarine pipe by the plurality of magnetic field generators installed every time the alternating magnetic field detected by a magnetic sensor becomes a certain threshold value or less. A submarine pipe location method. The method for exploring a position of a submarine pipe according to claim 7 or 8 , wherein, in the step of passing the alternating current, the conduit through which the alternating current is passed is a steel pipe. The submarine tube position exploration method according to any one of claims 4 to 9 , wherein the submarine tube is a submarine water pipe.

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