Exploration system

Abstract

An exploration system (1) comprises: a ground penetrating radar (10) that explores underground; and a control device (40) that acquires known distance information indicating a distance from one point on the ground to one point underground and reference time information indicating the reference time required for a first electromagnetic wave to reach the one point underground from the one point on the ground, calculates the relative permittivity underground, calculates the propagation speed of the first electromagnetic wave by using the relative permittivity, and calculates, by using the propagation speed, the propagation distance of the first electromagnetic wave when the ground penetrating radar (10) conducts the exploration at a point different from the one point on the ground.

Description

Exploration system

[0001] This disclosure relates to an exploration system.

[0002] Ground Penetrating Radar (GPR) is a known device capable of investigating underground structures. GPR can explore the underground by transmitting electromagnetic waves into the ground and receiving the reflected waves (see, for example, Non-Patent Document 1).

[0003] Tsutomu Suzuki, "Exploration of Subterranean and Underwater Environments Using Radio Waves," Measurement and Control, Vol. 20, No. 8, pp. 762-772, 1981.

[0004] In surveys using GPR, the propagation speed of electromagnetic waves varies depending on the ground material, making it sometimes impossible to accurately determine the distance to the measurement target. GPR measures the propagation time t of a pulse wave transmitted from the ground surface into the ground, reflected in the ground, and returning to the ground surface, thereby determining the electromagnetic wave propagation speed v. ｐ Therefore, the electromagnetic wave propagation distance L is calculated using Equation 1.

[0005] Electromagnetic wave propagation speed v ｐ This can be calculated from the relative permeability μ, relative permittivity ε, and the speed of light c in free space using Equation 2. Since Equation 2 is described, for example, in Non-Patent Document 1, a detailed explanation is omitted.

[0006] The relative permeability μ can be considered to be μ = 1 for typical soil materials, and the speed of light c is a known constant c = 3 × 10⁻⁶ ８Although it can be approximated by (m / s), the relative permittivity ε varies greatly depending on the ground material. Therefore, in the conventional GPR measurement principle using equations 1 and 2, there is a risk that the electromagnetic wave propagation distance L will be output as an inaccurate value. GPR is used in civil engineering works in the preliminary survey process before the excavation process. If buried objects are detected in the area where construction is planned using GPR, manual excavation can be performed to avoid damaging the buried objects. In this case, if the true location of the buried object is deeper than the location of the buried object calculated by GPR using the electromagnetic wave propagation distance L, the manual excavation range will increase, significantly reducing work efficiency and leading to delays in the construction period. Also, if the true location of the buried object is shallower than the location of the buried object detected by GPR, there is a risk of accidents causing damage to the buried object due to mechanical excavation.

[0007] In light of these circumstances, the purpose of this disclosure is to improve the technology of ground penetration exploration using GPR.

[0008] An exploration system according to one embodiment comprises a ground-penetrating radar positioned on the ground and transmitting a first electromagnetic wave into the ground to conduct an exploration of the ground, and a control device connected to the ground-penetrating radar, wherein the control device acquires known distance information indicating the distance from one point on the ground to one point in the ground, acquires reference time information indicating the time from when the ground-penetrating radar transmits the first electromagnetic wave from one point on the ground until the first electromagnetic wave reaches one point in the ground as a reference time, calculates the relative permittivity of the ground based on the known distance information and the reference time information, calculates the propagation speed of the first electromagnetic wave using the relative permittivity, and calculates the propagation distance of the first electromagnetic wave when the ground-penetrating radar conducts the exploration at a point other than the one on the ground using the propagation speed.

[0009] This disclosure can improve the technology for ground penetration exploration using GPR.

[0010] This is a diagram showing the configuration of the exploration system according to the first embodiment. This is a diagram illustrating the initial arrangement of the ground-penetrating radar and the receiving device according to the first embodiment. This is a flowchart showing an example of the operation of the exploration system according to the first embodiment. This is a diagram showing the configuration of the exploration system according to the second embodiment. This is a flowchart showing an example of the operation of the exploration system according to the second embodiment. This is a flowchart showing an example of the operation of the exploration system according to the second embodiment.

[0011] (First Embodiment) The first embodiment of this disclosure will be described below with reference to the figures.

[0012] In each figure, identical or corresponding parts are denoted by the same reference numeral. In the description of this embodiment, the description of identical or corresponding parts will be omitted or simplified as appropriate. In the drawings, the direction along the ground surface GR is shown as the X direction and the Y direction, and the direction perpendicular to the ground surface GR is shown as the Z direction.

[0013] The exploration system 1 comprises a ground-penetrating radar 10, a receiving device 20, a signal generator 30, and a control device 40. The ground-penetrating radar 10, the signal generator 30, and the control device 40 are connected via a network 50.

[0014] The ground-penetrating radar 10 transmits a first electromagnetic wave into the ground from the surface, receives the reflected wave of the first electromagnetic wave (hereinafter referred to as the first reflected wave) that has hit an underground structure, and measures the propagation distance of the first electromagnetic wave based on the time from the transmission of the first electromagnetic wave to the reception of the first reflected wave. The ground-penetrating radar 10 transmits the first electromagnetic wave to the receiving device 20 in accordance with the synchronization signal received from the signal generator 30. The ground-penetrating radar 10 is placed on a cart and moved to the measurement position by a worker pushing or pulling the cart.

[0015] The receiving device 20 is installed inside an underground structure by workers or the like. In this embodiment, the structure is a pipeline P. The receiving device 20 receives the first electromagnetic wave transmitted from the ground-penetrating radar 10.

[0016] The signal generator 30 transmits a synchronization signal to the ground-penetrating radar 10 and the receiving device 20, synchronizing the measurement timing of the ground-penetrating radar 10 and the receiving device 20.

[0017] The control device 40 is, for example, a general-purpose computer such as a PC or tablet, a server computer such as a cloud server, or a dedicated computer. "PC" is an abbreviation for personal computer.

[0018] Network 50 includes the Internet, at least one WAN, at least one MAN, or a combination thereof. "WAN" is an abbreviation for wide area network. "MAN" is an abbreviation for metropolitan area network. Network 50 may also include at least one wireless network, at least one optical network, or a combination thereof. Wireless networks are, for example, ad hoc networks, cellular networks, wireless LANs, satellite communication networks, or terrestrial microwave networks. "LAN" is an abbreviation for local area network.

[0019] The outline of this embodiment will be described with reference to Figure 1. The exploration system 1 comprises a ground-penetrating radar 10 and a control device 40. The control device 40 acquires known distance information indicating the distance from a point on the ground to a point underground. The control device 40 acquires reference time information indicating the time from when the ground-penetrating radar transmits a first electromagnetic wave from a point on the ground until the first electromagnetic wave reaches a point underground, as the reference time. The control device 40 calculates the relative permittivity of the ground based on the known distance information and the reference time information. The control device 40 calculates the propagation speed of the first electromagnetic wave using the relative permittivity. The control device 40 calculates the propagation distance of the first electromagnetic wave when the ground-penetrating radar conducts exploration at a point other than the point on the ground, using the propagation speed.

[0020] In this embodiment, the position of the ground-penetrating radar 10 and the position of the receiving device 20 installed inside the conduit P in the initial setup described below correspond to a point on the ground and a point underground, respectively. The receiving device 20 is positioned such that its receiving antenna 23 is in contact with the inner surface of the conduit P on the ground side, or is located near the inner surface of the conduit P on the ground side. The conduit P is a conduit containing resin, such as a vinyl pipe, through which the incident wave of the first electromagnetic wave (hereinafter referred to as the first incident wave) can pass. The target of the ground-penetrating radar 10's exploration may be other structures located underground, different from the conduit P, in addition to the conduit P. Other structures may include metal conduits such as iron. According to this embodiment, the synchronization signal transmitted from the signal generator 30 ensures that the operation of measuring the reference time until the first electromagnetic wave transmitted from the ground-penetrating radar 10 reaches the receiving device 20 (hereinafter referred to as the time measurement operation) is performed accurately. As described below, the control device 40 uses the reference time to calculate the relative permittivity inherent to the ground where the pipeline P is installed, and further calculates the propagation speed of the first electromagnetic wave in the ground. Using the calculated propagation speed, the control device 40 can accurately calculate the propagation distance of the first electromagnetic wave when the ground-penetrating radar moves from its initial position and performs ground exploration at another location, separately from the propagation distance measured by the ground-penetrating radar 10. According to this embodiment, compared to the case where only the propagation distance measured by the ground-penetrating radar 10 is used, it becomes possible to grasp the accurate propagation distance to underground structures, and as a result, the accurate distance to the structure can be measured. Therefore, the excavation process when a structure is detected can be made more efficient. Thus, the technology of ground-penetrating exploration using GPR can be improved.

[0021] Referring to Figure 1, the configuration of the ground-penetrating radar 10 according to this embodiment will be described. The ground-penetrating radar 10 comprises a control unit 11, a communication unit 12, an output unit 13, a transmitting antenna 14, and a receiving antenna 15.

[0022] The control unit 11 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for specific processing such as a DSP. "CPU" is an abbreviation for Central Processing Unit. "GPU" is an abbreviation for Graphics Processing Unit. "DSP" is an abbreviation for Digital Signal Processor. The programmable circuit is, for example, an FPGA. "FPGA" is an abbreviation for Field-Programmable Gate Array. The dedicated circuit is, for example, an ASIC. "ASIC" is an abbreviation for Application Specific Integrated Circuit. The control unit 11 controls each part of the ground-penetrating radar 10 and executes processing related to the operation of the ground-penetrating radar 10.

[0023] The communication unit 12 includes at least one communication module. The communication module is, for example, a module compatible with a wired LAN communication standard such as Ethernet (registered trademark), a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G, or 5G. "IEEE" is an abbreviation for Institute of Electrical and Electronics Engineers. "LTE" is an abbreviation for Long Term Evolution. "4G" is an abbreviation for 4th generation. "5G" is an abbreviation for 5th generation. The communication unit 12 receives information used for the operation of the ground-penetrating radar 10 and transmits information obtained by the operation of the ground-penetrating radar 10.

[0024] The output unit 13 includes at least one output interface. The output interface is, for example, a display or a speaker. The display is, for example, an LCD or an organic EL display. "LCD" is an abbreviation for Liquid Crystal Display. "EL" is an abbreviation for Electro Luminescent. The output unit 13 outputs information obtained by the operation of the ground penetrating radar 10. Instead of being provided in the ground penetrating radar 10, the output unit 13 may be connected to the ground penetrating radar 10 as an external output device. As a connection method, for example, any method such as USB, HDMI (registered trademark), or Bluetooth (registered trademark) can be used. "USB" is an abbreviation for Universal Serial Bus. "HDMI (registered trademark)" is an abbreviation for High-Definition Multimedia Interface.

[0025] The transmitting antenna 14 emits a first electromagnetic wave.

[0026] The receiving antenna 15 receives the reflected wave of the first electromagnetic wave. The receiving antenna 15 can generate an electrical signal based on the intensity of the received first reflected wave and output it to the control unit 11.

[0027] Referring to FIG. 1, the configuration of the receiving device 20 according to the present embodiment will be described. The receiving device 20 includes a control unit 21, a communication unit 22, and a receiving antenna 23. [[ID=ll]]

[0028] The control unit 21 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or a GPU, or a dedicated processor specialized for specific processing such as a DSP. The programmable circuit is, for example, an FPGA. The dedicated circuit is, for example, an ASIC. While controlling each part of the receiving device 20, the control unit 21 executes processing related to the operation of the receiving device 20.

[0029] The communication unit 22 includes at least one communication module. The communication module is a module corresponding to a wired LAN communication standard such as Ethernet (registered trademark), a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G standard, or 5G standard. The communication unit 22 receives information used for the operation of the receiving device 20 and transmits information obtained by the operation of the receiving device 20.

[0030] The receiving antenna 23 receives the incident wave of the first electromagnetic wave transmitted by the ground penetrating radar 10. The receiving antenna 23 can generate an electrical signal based on the intensity of the received first electromagnetic wave and output it to the control unit 21.

[0031] Referring to FIG. 1, the configuration of the signal generation device 30 according to the present embodiment will be described. The signal generation device 30 includes a control unit 31 and a communication unit 32.

[0032] The control unit 31 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for a specific process. The programmable circuit is, for example, an FPGA. The dedicated circuit is, for example, an ASIC. The control unit 31 executes processes related to the operation of the signal generation device 30 while controlling each part of the signal generation device 30.

[0033] The communication unit 32 includes at least one communication module. The communication module is a module corresponding to a wired LAN communication standard such as Ethernet (registered trademark), a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G standard, or 5G standard. The communication unit 32 receives information used for the operation of the signal generation device 30 and transmits information obtained by the operation of the signal generation device 30.

[0034] Referring to FIG. 1, the configuration of the control device 40 according to the present embodiment will be described. The control device 40 includes a control unit 41, a storage unit 42, a communication unit 43, an input unit 44, and an output unit 45.

[0035] The control unit 41 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for a specific process. The programmable circuit is, for example, an FPGA. The dedicated circuit is, for example, an ASIC. The control unit 41 controls each part of the control device 40 and executes processes related to the operation of the control device 40.

[0036] The memory unit 42 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or any combination thereof. The semiconductor memory is, for example, RAM, ROM, or flash memory. "RAM" is an abbreviation for Random Access Memory. "ROM" is an abbreviation for Read Only Memory. The RAM is, for example, SRAM or DRAM. "SRAM" is an abbreviation for Static Random Access Memory. "DRAM" is an abbreviation for Dynamic Random Access Memory. The ROM is, for example, EEPROM. "EEPROM" is an abbreviation for Electrically Erasable Programmable Read Only Memory. The flash memory is, for example, SSD. "SSD" is an abbreviation for Solid-State Drive. The magnetic memory is, for example, HDD. "HDD" is an abbreviation for Hard Disk Drive. The storage unit 42 functions, for example, as a main memory, auxiliary memory, or cache memory. The storage unit 42 stores information used for the operation of the control device 40 and information obtained through the operation of the control device 40.

[0037] The communication unit 43 includes at least one communication module. The communication module is, for example, a module compatible with a wired LAN communication standard such as Ethernet®, a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G, or 5G. The communication unit 43 receives information used for the operation of the control device 40 and transmits information obtained through the operation of the control device 40. The communication unit 43 enables the control device 40 to send and receive information with other devices via a network.

[0038] The input unit 44 includes at least one input interface. The input interface may be, for example, a physical key, a capacitive key, a pointing device, a touchscreen integrated with a display, or a microphone. The input unit 44 accepts operations to input information used for the operation of the control device 40. Instead of being provided in the control device 40, the input unit 44 may be connected to the control device 40 as an external input device. Any connection method can be used, for example, USB, HDMI®, or Bluetooth®.

[0039] The output unit 45 includes at least one output interface. The output interface is, for example, a display or a speaker. The display is, for example, an LCD or an organic EL display. The output unit 45 outputs information obtained by the operation of the control device 40. Instead of being provided in the control device 40, the output unit 45 may be connected to the control device 40 as an external output device. Any connection method can be used, for example, USB, HDMI®, or Bluetooth®.

[0040] The functions of the control device 40 are realized by executing the program according to this embodiment on the processor acting as the control unit 41. In other words, the functions of the control device 40 are realized by software. The program causes the computer to perform the operations of the control device 40, thereby causing the computer to function as the control device 40. That is, the computer functions as the control device 40 by performing the operations of the control device 40 according to the program.

[0041] The program can be stored on a non-temporary computer-readable medium. Examples of non-temporary computer-readable mediums include flash memory, magnetic recording devices, optical discs, magneto-optical recording media, or ROM. The program can be distributed, for example, by selling, transferring, or lending portable media such as SD cards, DVDs, or CD-ROMs containing the program. "SD" is an abbreviation for Secure Digital. "DVD" is an abbreviation for Digital Versatile Disc. "CD-ROM" is an abbreviation for Compact Disc Read Only Memory. The program may also be distributed by storing it in server storage and transferring it from the server to other computers. The program may also be provided as a program product.

[0042] A computer, for example, stores a program stored on a portable medium or a program transferred from a server in its main memory. Then, the computer reads the program stored in the main memory with its processor and executes the processing according to the read program. The computer may also read the program directly from the portable medium and execute the processing according to the program. The computer may also execute the processing according to the received program sequentially each time a program is transferred to it from a server. Processing may also be performed by a so-called ASP type service, which does not transfer programs from the server to the computer, but realizes its function only through execution instructions and result acquisition. "ASP" is an abbreviation for Application Service Provider. A program includes information used for processing by an electronic computer that is equivalent to a program. For example, data that is not a direct instruction to the computer but has the nature of defining the computer's processing falls under "equivalent to a program".

[0043] Some or all of the functions of the control device 40 may be implemented by a programmable circuit or a dedicated circuit as a control unit 41. In other words, some or all of the functions of the control device 40 may be implemented by hardware.

[0044] Next, the operation of the exploration system 1 according to this embodiment will be described with reference to Figures 2 and 3.

[0045] Before step S101 in Figure 3, the receiving device 20 is positioned by workers or the like at the end of the pipeline P, which is an underground structure. The ground-penetrating radar 10 is positioned on the ground at a location corresponding to the position of the receiving device 20, and on the same vertical line as the receiving device 20. Figure 2 shows the initial positioning of the receiving device 20 and the ground-penetrating radar 10. As shown in Figure 2, the receiving device 20 is positioned at the end of the pipeline P connected to the manhole M, and the ground-penetrating radar 10 is positioned on the ground at a location corresponding to the position of the receiving device 20.

[0046] In step S101, the control unit 31 of the signal generator 30 transmits a synchronization signal to both the ground-penetrating radar 10 and the receiving device 20 via the communication unit 32. The control unit 31 may also receive instructions from the control device 40 via the communication unit 32 and transmit a synchronization signal in accordance with those instructions. The signal generator 30 may also transmit a synchronization signal to the control device 40.

[0047] In step S102, the ground-penetrating radar 10 and the receiving device 20 receive a synchronization signal and perform time measurement operations at the same timing based on the synchronization signal. Specifically, when the synchronization signal is ON, the transmitting antenna 14 of the ground-penetrating radar 10 transmits a first electromagnetic wave into the ground. The control unit 21 of the receiving device 20 starts measuring time from when the synchronization signal is ON and stops the measurement when the receiving antenna 23 receives the first electromagnetic wave. In Figure 2, the first electromagnetic wave transmitted by the transmitting antenna 14 of the ground-penetrating radar 10 and received by the receiving antenna 23 of the receiving device 20 is shown by a dashed line.

[0048] In step S103, the control unit 21 of the receiving device 20 determines the reference time t, which is the time from when the time measurement starts until the first electromagnetic wave is received and the measurement is stopped. ｔ Reference time information indicating this is transmitted to the control device 40 via the communication unit 22. The receiving device 20 may also transmit information indicating the time when the first electromagnetic wave was received to the control device 40.

[0049] In step S104, the control unit 41 of the control device 40 receives reference time information from the receiving device 20 via the communication unit 43. The control unit 41 may also receive information indicating the time when the receiving device 20 received the first electromagnetic wave. In this case, the control unit 41 calculates the difference from the time when the synchronization signal was turned on to the time indicated by the information, and sets this difference to the reference time t ｔ The data may be obtained as follows. The control unit 41 may determine the time when the synchronization signal was turned on based on the synchronization signal received from the signal generator 30, or it may determine the time when the first electromagnetic wave was transmitted from the ground-penetrating radar 10.

[0050] In step S105, the control unit 41 determines the known distance LＤ Obtain known distance information indicating it. The known distance L Ｄ is the distance between the underground exploration radar 10 and the receiving device 20 in the initial arrangement. In FIG. 2, the known distance L between the receiving device 20 and the underground exploration radar 10 Ｄ is shown. The known distance L Ｄ is measured by an operator when the receiving device 20 is arranged at the end of the pipeline P, and the control unit 41 may receive the input of the information indicating the known distance L Ｄ via the input unit 44. Not limited to this, the control unit 41 may receive the known distance information from an external device. The known distance L Ｄ may be the burial depth of the pipeline P. For example, the control unit 41 searches a database indicating the burial depth of each of a plurality of pipelines buried underground, and obtains, as the known distance L, the burial depth of the pipeline P where the receiving device 20 is arranged, which is specified from the database Ｄ as well.

[0051] In step S106, the control unit 41 uses the reference time t indicated by the reference time information received in step S104 ｔ and the known distance L indicated by the known distance information obtained in step S105 Ｄ to calculate the relative permittivity ε of the underground Ｃ . The following formula 3 may be used to calculate the relative permittivity ε Ｃ . In the following formula, ε Ｃ is the relative permittivity of the underground, and c indicates the speed of light in free space. The speed of light c may use the known constant c = 3×10 ８ (m / s).

[0052] In step S107, the control unit 41 uses the calculated relative permittivity ε Ｃ to calculate the propagation speed v Ｃ of the first electromagnetic wave. The control unit 41 calculates the propagation speed v Ｃ using, for example, the following formula 4. In formula 4, the relative permeability μ may be set to 1, or a preset value may be used. The speed of light c may use the known constant c = 3×10 ８ (m / s).

[0053] In step S108, the ground-penetrating radar 10 moves to a position where it will perform ground-penetrating exploration. The ground-penetrating radar 10 may be moved by a worker pushing a cart on which the ground-penetrating radar 10 is mounted.

[0054] In step S109, the ground-penetrating radar 10 starts exploring the ground. Specifically, the control unit 11 of the ground-penetrating radar 10 transmits radar time information, which indicates the propagation time t from the time the first electromagnetic wave is transmitted by the transmitting antenna 14 until the first reflected wave is received by the receiving antenna 15, to the control device 40 via the communication unit 12. The control unit 11 may further transmit radar propagation distance information, which indicates the electromagnetic wave propagation distance L calculated using the above-described equations 1 and 2, to the control device 40 via the communication unit 12. In this case, the relative permittivity ε in equation 2 is a value preset for the ground-penetrating radar 10, and the velocity v in equation 1 is... ｐ This value may be calculated from Equation 2 using the relative permittivity ε. The radar propagation distance information may also include the distance L / 2 to the underground structure measured by the ground-penetrating radar 10, which is obtained by dividing the electromagnetic wave propagation distance L by 2.

[0055] In step S110, the control unit 41 of the control device 40 receives radar time information from the ground-penetrating radar 10 via the communication unit 43. The control unit 41 may also receive radar propagation distance information from the ground-penetrating radar 10 via the communication unit 43.

[0056] In step S111, the control unit 41 derives the propagation distance L of the first electromagnetic wave based on the radar time information. Ｃ The control unit 41 calculates the derived propagation distance Lc using, for example, the following equation 5. That is, the control unit 41 calculates the propagation speed v calculated in step S107 for the propagation time t indicated by the radar time information. ｃ Multiply by this to obtain the derived propagation distance L. Ｃ Calculate.

[0057] In step S112, the control unit 41 determines the derived propagation distance L Ｃ Derived propagation distance information, which indicates the derived propagation distance L, is output via the output unit 45. ＣThe derived distance L to the underground structure is obtained by dividing by 2. Ｃ This includes / 2. If radar propagation distance information is received from the ground-penetrating radar 10 in step S110, the control unit 41 may also output the radar propagation distance information via the output unit 45. After that, the operation of the exploration system 1 returns to step S108.

[0058] The control unit 41 may transmit the derived propagation distance information to the ground-penetrating radar 10 via the communication unit 43. In this case, the control unit 11 of the ground-penetrating radar 10 receives the derived propagation distance information via the communication unit 12 and outputs it via the output unit 13. By viewing the derived propagation distance information output to the output unit 45 of the control device 40 or the output unit 13 of the ground-penetrating radar 10, the worker can determine the exact distance to the pipeline P. As described above, according to this embodiment, in step S102, the reference time t ｔ For the same soil used when the measurement was taken, i.e., soil with the same relative permittivity, the derived propagation distance L Ｃ And the derived distance L to the underground structure. Ｃ The / 2 can be repeatedly calculated each time the ground-penetrating radar 10 moves from its initial position and performs ground-penetrating exploration at a different location.

[0059] (Second Embodiment) A second embodiment of the present disclosure will be described below.

[0060] Referring to Figure 4, the exploration system 1 according to this embodiment will be described. The exploration system 1 according to this embodiment further includes a transmitting device 60. The transmitting device 60 is positioned inside the pipeline P, which is an underground structure, and transmits a second electromagnetic wave to the surface. In Figure 4, the first electromagnetic wave transmitted and received by the ground-penetrating radar 10 is shown by a solid arrow, and the second electromagnetic wave transmitted and received by the receiving device 20 and the transmitting device 60 is shown by a dashed arrow. In this embodiment, the ground-penetrating radar 10, the receiving device 20 and the transmitting device 60 perform exploration for buried objects O existing between the pipeline P and the surface at their respective positions on the same vertical line above and below ground.

[0061] Referring to Figure 4, the configuration of the transmitting device 60 according to this embodiment will be described. The transmitting device 60 comprises a control unit 61, a communication unit 62, and a transmitting antenna 63.

[0062] The control unit 61 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for specific processing such as a DSP. The programmable circuit is, for example, an FPGA. The dedicated circuit is, for example, an ASIC. The control unit 61 controls each part of the transmitting device 60 and executes processing related to the operation of the transmitting device 60.

[0063] The communication unit 62 includes at least one communication module. The communication module is, for example, a module compatible with a wired LAN communication standard such as Ethernet®, a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G, or 5G. The communication unit 62 receives information used for the operation of the transmitting device 60 and transmits information obtained through the operation of the transmitting device 60.

[0064] The transmitting antenna 63 transmits a second electromagnetic wave to the ground.

[0065] In this embodiment, the receiving antenna 23 of the receiving device 20 receives, in addition to the first reflected wave, a reflected wave (hereinafter referred to as the second reflected wave) that is reflected when the second electromagnetic wave transmitted by the transmitting device 60 strikes an underground buried object O. The receiving antenna 23 can generate an electrical signal based on the intensity of the received second reflected wave and output it to the control unit 21.

[0066] The transmitting device 60 and the receiving device 20 according to this embodiment are housed in the same housing B. A towing device R is provided in the housing B. Specifically, the towing device R includes a rope or wire. Wheels that contact the inner surface of the pipeline P may be provided in the housing B. Inside the manhole to which the end of the pipeline P is connected, a worker pulls the towing device R, causing the transmitting device 60 and the receiving device 20 to move inside the pipeline P toward the manhole. However, the towing device R may be wound by a winding device, for example, which has a drum on its outer circumference for winding the towing device R and a motor for rotating the drum.

[0067] The configuration of other devices included in the exploration system 1 according to this embodiment is the same as that of the first embodiment, so a description will be omitted.

[0068] The operation of the exploration system 1 according to the second embodiment will be described with reference to Figures 4 to 5B.

[0069] Steps S201 to S207 in Figure 5A are the same as steps S101 to S107 in Figure 2, so their explanation is omitted.

[0070] In step S208, the ground-penetrating radar 10 moves to a position where it will perform underground exploration. In this embodiment, the ground-penetrating radar 10 is moved by a worker pushing a cart carrying the radar 10 along the white arrows in Figure 4 for a predetermined distance.

[0071] In step S209, the ground-penetrating radar 10 starts exploring the ground. Specifically, the control unit 11 of the ground-penetrating radar 10 transmits radar time information, which indicates the propagation time t from the time the transmitting antenna 14 transmits the first electromagnetic wave until the receiving antenna 15 receives the first reflected wave, and first reflected wave information, which indicates the signal strength of the first reflected wave received by the receiving antenna 15, to the control device 40 via the communication unit 12. However, if there are no buried objects O in the ground, the control unit 11 transmits radar time information indicating that the propagation time has not been measured, and first reflected wave information indicating that the signal strength has not been detected, to the control device 40. The control unit 11 may further transmit radar propagation distance information, which indicates the electromagnetic wave propagation distance L calculated using the above-described equations 1 and 2, to the control device 40 via the communication unit 12. In this case, the relative permittivity ε in equation 2 is a value preset in the ground-penetrating radar 10, and the velocity v in equation 1 ｐ This value may be calculated from Equation 2 using the relative permittivity ε. The radar propagation distance information may include the distance L / 2 to the underground buried object O measured by the ground-penetrating radar 10, which is obtained by dividing the electromagnetic wave propagation distance L by 2.

[0072] In step S210, the control unit 41 of the control device 40 receives radar time information and first reflected wave information from the ground-penetrating radar 10 via the communication unit 43. The control unit 41 may also receive radar propagation distance information from the ground-penetrating radar 10 via the communication unit 43.

[0073] In step S211, the receiving device 20 and the transmitting device 60 move to a position in the ground corresponding to the position of the ground-penetrating radar 10 on the ground, and to a position in the ground on the same vertical line as the ground-penetrating radar 10, and begin underground exploration. Specifically, by having a worker pull the towing device R by a predetermined distance equal to the distance the ground-penetrating radar 10 has moved, the housing B in which the transmitting device 60 and the receiving device 20 are housed in Figure 4 moves in the direction of the white arrow. The transmitting antenna 63 of the transmitting device 60 transmits a second electromagnetic wave to the ground side.

[0074] In step S212, the control unit 21 of the receiving device 20 transmits second reflected wave information, which indicates the signal strength of the second reflected wave received by the receiving antenna 23, to the control device 40 via the communication unit 22. However, if there are no buried objects O in the ground, the control unit 21 transmits second reflected wave information to the control device 40 indicating that no signal strength has been detected.

[0075] In step S213, the control unit 41 of the control device 40 receives the second reflected wave information from the receiving device 20.

[0076] In step S214, the control unit 41 determines whether or not buried object O exists based on the first reflected wave information and the second reflected wave information. If it is determined that buried object O exists, that is, if the presence of buried object O is detected, the operation of the exploration system 1 proceeds to step S215. If it is determined that buried object O does not exist, the operation of the exploration system 1 proceeds to step S217.

[0077] Specifically, the control unit 41 determines that there is an object O buried underground when the intensity of the first reflected wave is equal to or greater than a first predetermined value and the intensity of the second reflected wave is equal to or greater than a second predetermined value (hereinafter referred to as the first pattern). The first predetermined value and the second predetermined value may be set in advance and stored in the memory unit 42. The control unit 41 determines that there is an object O buried underground in an area closer to the ground than the pipeline P when the intensity of the first reflected wave is equal to or greater than a first predetermined value and the intensity of the second reflected wave is less than a second predetermined value (hereinafter referred to as the second pattern). The control unit 41 may also determine that there is an object O buried underground in an area closer to the ground than the pipeline P when the intensity of the first reflected wave is equal to or greater than a first predetermined value and the second reflected wave information indicates that the signal intensity has not been detected. The control unit 41 determines that there is an object O buried underground in an area closer to the pipeline P than above ground level when the intensity of the first reflected wave is less than a first predetermined value and the intensity of the second reflected wave is equal to or greater than the second predetermined value (hereinafter referred to as the third pattern). The control unit 41 may also determine that there is an object O buried underground in an area closer to the pipeline P than above ground level when the first reflected wave information indicates that the signal intensity is not detected and the intensity of the second reflected wave is equal to or greater than the second predetermined value. The control unit 41 determines that there is no object O buried underground when the intensity of the first reflected wave is less than a first predetermined value and the intensity of the second reflected wave is less than the second predetermined value (hereinafter referred to as the fourth pattern). The control unit 41 may also determine that there is no object O buried underground when the first reflected wave information indicates that the signal intensity is not detected and the second reflected wave information also indicates that the signal intensity is not detected.

[0078] In step S215, the control unit 41 derives the propagation distance L of the first electromagnetic wave based on the radar time information received in step S210. Ｃ The control unit 41 calculates the derived propagation distance Lc using equation 5, similar to step S111 described above.

[0079] In step S216, the control unit 41 outputs buried object information indicating the presence of buried object O via the output unit 45. The buried object information may include information indicating whether the buried object O is closer to the surface or to the pipeline P. The control unit 41 may also transmit the buried object information to the ground-penetrating radar 10 via the communication unit 43. In this case, the control unit 11 of the ground-penetrating radar 10 outputs the buried object information via the output unit 13.

[0080] If the control unit 11 determines that a buried object O exists based on the second pattern described above, it outputs buried object information indicating that the buried object O exists in an area close to the surface. If the control unit 11 determines that a buried object O exists based on the third pattern described above, it outputs buried object information indicating that the buried object O exists in an area close to the pipeline P. If the control unit 11 determines that a buried object O exists based on the first pattern described above, it outputs buried object information indicating that the buried object O exists underground, or that there is a possibility that the buried object O exists in both an area close to the surface and an area close to the pipeline P.

[0081] The buried object information is derived from the propagation distance L calculated in step S215. Ｃ Dividing this by 2 gives the derived distance L from the ground to the buried object O. Ｃ It may further include / 2. If the control unit 41 has received radar propagation distance information in steps S210 and S213, it may output the radar propagation distance information via the output unit 45. After that, the operation of the exploration system 1 returns to step S208.

[0082] In step S217, the control unit 41 outputs information indicating that there are areas that cannot be reached by the first electromagnetic wave and the second electromagnetic wave. After that, the operation of the exploration system 1 returns to step S208.

[0083] According to this embodiment, when only the first electromagnetic wave is used, the first electromagnetic wave is attenuated underground, making it impossible to receive the first reflected wave, and consequently reducing the risk of being unable to detect underground buried objects. In other words, the exploration system 1 makes it possible to extend the detectable distance compared to when only a single ground-penetrating radar 10 is used.

[0084] 1. Exploration System 10. Ground Penetrating Radar 11. Control Unit 12. Communication Unit 13. Output Unit 14. Transmitting Antenna 15. Receiving Antenna 20. Receiving Device 21. Control Unit 22. Communication Unit 23. Receiving Antenna 30. Signal Generator 31. Control Unit 32. Communication Unit 40. Control Device 41. Control Unit 42. Memory Unit 43. Communication Unit 44. Input Unit 45. Output Unit 50. Network 60. Transmitting Device 61. Control Unit 62. Communication Unit 63. Transmitting Antenna

Claims

1. A survey system comprising: a ground-penetrating radar positioned on the ground and transmitting a first electromagnetic wave into the ground to conduct a survey of the ground; and a control device connected to the ground-penetrating radar, wherein the control device acquires known distance information indicating the distance from a point on the ground to a point in the ground; acquires reference time information indicating the time from when the ground-penetrating radar transmits the first electromagnetic wave from a point on the ground until the first electromagnetic wave reaches the point in the ground, calculates the relative permittivity of the ground based on the known distance information and the reference time information; calculates the propagation speed of the first electromagnetic wave using the relative permittivity; and calculates the propagation distance of the first electromagnetic wave when the ground-penetrating radar conducts the survey at a point other than the point on the ground, using the propagation speed.

2. The exploration system according to claim 1, wherein the ground-penetrating radar receives the first electromagnetic wave reflected by the underground structure, the control device obtains the time from when the ground-penetrating radar transmits the first electromagnetic wave until it receives the first electromagnetic wave as the propagation time of the first electromagnetic wave, calculates the propagation distance based on the propagation time and the propagation speed, and outputs propagation distance information indicating the calculated propagation distance.

3. The exploration system according to claim 1, further comprising: a transmitting device that transmits a second electromagnetic wave from underground to the surface; and a receiving device that receives a second reflected wave in the ground, which is a reflected wave of the second electromagnetic wave reflected by an underground structure, wherein the transmitting device and the receiving device are provided inside the underground structure; the ground-penetrating radar receives a first reflected wave, which is a reflected wave of the first electromagnetic wave reflected by an underground structure; the control device acquires first reflected wave information indicating the intensity of the first reflected wave from the ground-penetrating radar, acquires second reflected wave information indicating the intensity of the second reflected wave from the receiving device; and, based on the first reflected wave information and the second reflected wave information, detects the presence of an underground structure and outputs buried structure information indicating the presence of the buried structure.

4. The exploration system according to claim 3, wherein the control device outputs information indicating that the buried object is located in the ground, in an area closer to the ground than the structure, when the intensity of the first reflected wave is greater than or equal to a first predetermined value and the intensity of the second reflected wave is less than a second predetermined value, and outputs information indicating that the buried object is located in the ground, in an area closer to the structure than the ground, when the intensity of the first reflected wave is less than a first predetermined value and the intensity of the second reflected wave is greater than or equal to a second predetermined value, as the buried object information.

Images