Ground-penetrating radar system and ground-penetrating drilling method

Abstract

To provide an underground radar device that suppresses wear and damage to protective plates that protect a transmitting antenna part and a receiving antenna part, and maintains detection accuracy of underground conditions in front of an underground tunneling machine.SOLUTION: The present invention comprises a transmitting antenna part 31 for transmitting electromagnetic waves to the ground in front of an underground tunneling machine 1 having a face plate 2 with a cutter 20, a receiving antenna part 32 for receiving electromagnetic waves, a transmitting antenna protection plate 30a made of a material that transmits electromagnetic waves and provided on the face plate 2 to protect the transmitting antenna part 31, and a receiving antenna protection plate 30b made of a material that transmits electromagnetic waves and provided on the face plate 2 to protect the receiving antenna part 32. A front surfaces of the transmitting antenna protection plate 30a and the receiving antenna protection plate 30b are arranged so as to be recessed from the front surface of the face plate 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a ground radar device installed in a tunneling machine for detecting the situation of the ground ahead and a tunneling method.

Background Art

[0002] In order to safely construct a tunnel or the like by a tunneling machine, the excavation conditions must be appropriately set, and for this purpose, it is necessary to know the soil quality of the excavation route. As a technique for detecting and discriminating the soil quality of the excavation route, a radar device, so-called a ground radar device, is known, which is provided with a transmitting antenna and a receiving antenna for transmitting and receiving electromagnetic waves on a rotating face plate having a cutter at the front end of the tunneling machine.

[0003] This ground radar device emits electromagnetic waves forward from the transmitting antenna, and receives, by the receiving antenna, the reflected waves reflected by hitting a reflector ahead and the surface electromagnetic waves propagated through the ground near the surface of the face plate. Then, the presence or absence and position of the reflector can be discriminated by the reflected waves, and the soil quality near the surface of the face plate can be discriminated by the propagation speed and attenuation rate of the surface propagated waves.

[0004] Conventionally, as described in Patent Document 1, a protective plate that transmits electromagnetic waves is integrally attached to a part of the face plate, a transmitting antenna part and a receiving antenna part are installed on the back surface side of the protective plate, and the space between the transmitting antenna part and the receiving antenna part of the protective plate is partitioned by an electromagnetic wave shielding part, and a ground radar device that blocks leakage electromagnetic waves propagated from the transmitting antenna part to the receiving antenna part through the protective plate has been proposed. The transmitting antenna and the receiving antenna are installed on the face plate provided at the front end of the tunneling machine, and are protected from earth pressure, water pressure, wear, etc. by a protective plate disposed on the front surface side thereof.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In ground-penetrating radar systems like the one described in Patent Document 1, the front surface of the protective plate is positioned in the same plane as the front surface of the faceplate, and since FRP or similar materials are often used for the protective plate that transmits electromagnetic waves, the protective plate is prone to wear and damage during excavation. This can cause the transmitting and receiving antenna installed on the back side to malfunction, or the transmitted electromagnetic waves to be affected by the wear and damage of the protective plate, leading to a decrease in detection performance. This effect can be particularly significant when the excavated ground is hard gravel or bedrock, or during long-distance construction.

[0007] The problem that this invention aims to solve is to provide a ground-penetrating radar device and a ground-penetrating drilling method that suppresses wear and damage to protective plates protecting the transmitting antenna and receiving antenna sections, and maintains the accuracy of detecting underground conditions in front of the ground-penetrating drilling machine. [Means for solving the problem]

[0008] The invention according to claim 1 is a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are recessed and positioned behind the front surface of the faceplate, and the electromagnetic wave shielding unit protrudes from the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate. The invention according to claim 2 is a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate. The ground-penetrating radar device is characterized in that the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are recessed from the front surface of the faceplate, an external protective plate is provided which is detachably attached to the recess and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, the external protective plate consists of a transmitting-side external protective plate that covers the front surface of the transmitting antenna protective plate and a receiving-side external protective plate that covers the front surface of the receiving antenna protective plate, and the electromagnetic wave shielding section separates the transmitting-side external protective plate and the receiving-side external protective plate and protrudes from the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate. The invention according to claim 3 is a ground-penetrating radar device according to claim 1, characterized in that it comprises an external protective plate that is detachably attached to the recess and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate. The invention according to claim 4 is a ground-penetrating radar device according to claim 2 or 3, characterized in that the front surface of the external protective plate and the front surface of the faceplate are arranged in the same plane. The invention according to claim 5 is a ground-penetrating radar device according to claim 2 or 3, characterized in that the front surface of the external protective plate is positioned set back from the front surface of the faceplate. The invention according to claim 6 is a ground-penetrating radar device according to any one of claims 2 to 5, characterized in that the external protective plate is an electromagnetic wave-transmitting protective plate made of a material that transmits electromagnetic waves. The invention according to claim 7 is a ground-penetrating radar device according to any one of claims 2 to 5, characterized in that the external protective plate is an electromagnetic wave shielding protective plate made of a material that does not transmit electromagnetic waves. The invention according to claim 8 is a method for underground excavation, characterized in that the underground excavation machine is equipped with a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of the underground excavation machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the underground excavation machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are set back from the front surface of the faceplate and have recesses, and the electromagnetic wave shielding unit is set back from the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate to have recesses, and the underground excavation machine is equipped with an underground radar device that protrudes from the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate. The invention according to claim 9 comprises: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a tunnel boring machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the tunnel boring machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, wherein the transmitting antenna protective The underground excavation method is characterized by the following: the front surfaces of the plate and the receiving antenna protective plate are positioned recessed from the front surface of the faceplate, and an external protective plate is provided in the recess, which is detachably attached and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, the external protective plate consists of a transmitting-side external protective plate that covers the front surface of the transmitting antenna protective plate and a receiving-side external protective plate that covers the front surface of the receiving antenna protective plate, and the electromagnetic wave shielding section is equipped with a ground-penetrating radar device that separates the transmitting-side external protective plate and the receiving-side external protective plate and protrudes from the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate, and is used for excavation. The invention according to claim 10 is a method for underground excavation according to claim 8, characterized in that an external protective plate covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate is detachably attached to the recess and excavation is carried out. The invention according to claim 11 is an underground excavation method according to claim 9 or 10, characterized in that the external protective plate is an electromagnetic wave-transmitting protective plate made of a material that transmits electromagnetic waves. The invention according to claim 12 is an underground excavation method according to claim 9 or 10, characterized in that the external protective plate is an electromagnetic wave shielding plate made of a material that does not transmit electromagnetic waves. The invention according to claim 13 is a method of underground excavation according to any one of claims 9 to 12, characterized in that the external protective plate is attached to the recess and excavation is carried out, and then the external protective plate is removed and excavation is carried out. The invention according to claim 14 is a method of underground excavation according to any one of claims 9 to 12, characterized in that the external protective plate is attached to the recess and excavation is carried out, and then the external protective plate is removed and a new external protective plate is attached and excavation is carried out. The invention according to claim 15 is a ground-penetrating radar device for drilling, comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine having a rotating faceplate with a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-transmitting material and provided on the faceplate to protect the transmitting antenna unit; and a receiving antenna protective plate made of an electromagnetic wave-transmitting material and provided on the faceplate to protect the receiving antenna unit, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are set back from the front surface of the faceplate and have recesses, wherein an electromagnetic wave-transmitting protective plate made of an electromagnetic wave-transmitting material is detachably attached to the recess, and an external protective plate covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate is detachably attached to the recess, wherein an electromagnetic wave-transmitting protective plate made of an electromagnetic wave-transmitting material is detachably attached to the recess, and the external protective plate covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate. In a state where detection is possible underground After excavation, remove the external protective plate. In a state where detection is possible underground This is a method of underground excavation characterized by digging. The following are also acceptable alternative inventions. Means 1 is a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; and a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are recessed and positioned behind the front surface of the faceplate.

[0009] Means 2is characterized in that an external protection plate is detachably attached to the concave portion and covers the front surfaces of the transmission antenna protection plate and the reception antenna protection plate Means 1 It is the ground penetrating radar device according to

[0010] Means 3 is characterized in that the front surface of the external protection plate and the front surface of the face plate are arranged in the same plane Means 2 It is the ground penetrating radar device according to

[0011] Means 4 is characterized in that the front surface of the external protection plate is arranged to retreat from the front surface of the face plate Means 2 It is the ground penetrating radar device according to

[0012] Means 5 is characterized in that the external protection plate is an electromagnetic wave transmission protection plate made of a material that transmits electromagnetic waves Any of means 2 through means 4 It is the ground penetrating radar device described in

[0013] Means 6 is characterized in that the external protection plate is an electromagnetic wave blocking protection plate made of a material that does not transmit electromagnetic waves Any of means 2 through means 4 It is the ground penetrating radar device according to

[0014] Means 7 is characterized in that it includes an electromagnetic wave blocking portion that separates the transmission antenna protection plate and the reception antenna protection plate, and the electromagnetic wave blocking portion protrudes from the front surfaces of the transmission antenna protection plate and the reception antenna protection plate Any of the means 1 through means 6 It is the ground penetrating radar device according to

[0015] Means 8The external protective plate is characterized by comprising an electromagnetic wave shielding section that separates the transmitting antenna protective plate and the receiving antenna protective plate, the transmitting side external protective plate comprising a transmitting side external protective plate that covers the front surface of the transmitting antenna protective plate and a receiving side external protective plate that covers the front surface of the receiving antenna protective plate, and the electromagnetic wave shielding section that separates the transmitting side external protective plate and the receiving side external protective plate and protrudes from the front surfaces of the transmitting side external protective plate and the receiving side external protective plate. Any of means 2 through means 7 This is the ground-penetrating radar device described.

[0016] Means 9 is, A ground-penetrating radar device is provided for excavation, characterized by the use of a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves from the electromagnetic waves that have struck an obstacle in front and have been reflected, and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; and a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are set back from the front surface of the faceplate and have recesses. by law be.

[0017] means 10 This method is characterized by detachably attaching an external protective plate that covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate to the recess and then excavating. Means 9 This is the underground excavation method described in [the relevant document].

[0018] Means 11 The method is characterized by detachably attaching an electromagnetic wave-transmitting protective plate, made of an electromagnetic wave-transmitting material, to the recess, and covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, before excavation. Means 9 or 10 This is the underground excavation method described in [the relevant document].

[0019] Means 12The method is characterized by detachably attaching an electromagnetic wave shielding plate, made of a material that does not transmit electromagnetic waves, to the recess, and having an external protective plate that covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, before excavation. Means 9 or 10 This is the underground excavation method described in [the relevant document].

[0020] Means 13 This method is characterized by attaching the external protective plate to the recess and excavating, and then removing the external protective plate and continuing to excavate. Any of means 10 to means 12 This is the underground excavation method described.

[0021] Means 14 This method is characterized by attaching the external protective plate to the recess and excavating, then removing the external protective plate and attaching a new external protective plate before continuing to excavate. Any of means 10 to means 12 This is the underground excavation method described. [Effects of the Invention]

[0022] According to the present invention, the transmitting antenna protective plate and the receiving antenna protective plate are provided with recesses that are set back from the front surface of the faceplate. This suppresses wear and damage to the transmitting antenna protective plate and the receiving antenna protective plate that rotate with the rotation of the faceplate, maintains the protective function of the transmitting and receiving antennas, prevents failure of the transmitting and receiving antennas, and prevents the electromagnetic wave transmission performance of the transmitting and receiving antenna protective plate from being affected, thereby preventing a decrease in the accuracy of detecting underground conditions.

[0023] In addition, by detachably attaching external protective plates that cover the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate to the faceplate in the recesses, wear and damage to the transmitting antenna protective plate and the receiving antenna protective plate can be prevented, especially when an underground excavator is drilling through hard ground such as gravel or bedrock, where the protective plates are prone to wear and damage.

[0024] In addition, if the front surface of the external protective plate and the front surface of the faceplate are positioned on the same plane, the rotational resistance of the faceplate can be reduced, thereby lowering the cutter torque.

[0025] In addition, by positioning the front of the external protective plate set back from the front of the faceplate, wear and damage to the external protective plate can be suppressed.

[0026] In addition, if the external protective plate is made of a material that transmits electromagnetic waves, it is possible to detect underground conditions by transmitting and receiving electromagnetic waves even with the external protective plate installed.

[0027] In addition, if the external protective plate is made of a material that does not transmit electromagnetic waves, it can provide a higher level of protection, especially when excavating through hard ground, as it prioritizes protecting the protective plate over detecting objects in the ground.

[0028] In addition, if an electromagnetic wave shielding section is provided to separate the transmitting antenna protective plate and the receiving antenna protective plate, and the electromagnetic wave shielding section protrudes from the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, the reception of surface-propagated waves that penetrate the ground loosened by the recess can be reduced, so that surface-propagated waves containing undisturbed and accurate ground information can be received, thereby improving the detection accuracy for soil type discrimination of the ground.

[0029] In addition, the external protective plate is an electromagnetic wave-transmitting protective plate made of a material that transmits electromagnetic waves, and is equipped with an electromagnetic wave shielding section that separates the transmitting antenna protective plate and the receiving antenna protective plate. The external protective plate consists of a transmitting-side external protective plate that covers the front of the transmitting antenna protective plate and a receiving-side external protective plate that covers the front of the receiving antenna protective plate. The electromagnetic wave shielding section separates the transmitting-side external protective plate and the receiving-side external protective plate, and protrudes from the front of the transmitting-side external protective plate and the receiving-side external protective plate. This blocks the direct transmission of electromagnetic waves from the transmitting-side external protective plate to the receiving-side external protective plate, and reduces the reception of surface-propagated waves that penetrate the loosened ground in front of the transmitting-side external protective plate and the receiving-side external protective plate. As a result, surface-propagated waves containing accurate, undisturbed ground information are received, improving the detection accuracy for soil type discrimination of the ground.

[0030] According to the underground drilling method of the present invention, since the ground-penetrating radar device is equipped with a transmitting antenna protective plate and a receiving antenna protective plate whose front surfaces are set back from the front surface of the faceplate and have recesses, wear and damage to the transmitting antenna protective plate and the receiving antenna protective plate that rotate with the rotation of the faceplate are suppressed, the protective function of the transmitting antenna and the receiving antenna is maintained and the transmitting and receiving antennas do not fail, and the electromagnetic wave transmission performance of the transmitting antenna protective plate and the receiving antenna protective plate is not affected, and drilling can be performed without reducing the accuracy of detecting underground conditions.

[0031] In addition, external protective plates that cover the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are detachably attached to the recesses before excavation. Therefore, depending on the excavation distance and the type of soil being excavated, the external protective plates can be attached to protect the transmitting antenna protective plate and the receiving antenna protective plate during excavation.

[0032] In addition, an electromagnetic wave-transmitting protective plate made of an electromagnetic wave-transmitting material is detachably attached to the recess, and an external protective plate covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate is installed before excavation. This protects the transmitting antenna protective plate and the receiving antenna protective plate, and allows excavation to proceed while detecting the conditions ahead in the ground.

[0033] In addition, an electromagnetic wave shielding plate made of a material that does not transmit electromagnetic waves is detachably attached to the recess, and an external protective plate covering the front of the transmitting antenna protective plate and the receiving antenna protective plate is attached before excavation. Therefore, especially when excavating through hard ground, if the protection of the protective plate is prioritized over detection of what is in front of the ground, the excavation can be carried out in a way that provides a higher level of protection.

[0034] In addition, since the external protective plate is attached to the recess and excavation is started, and then the external protective plate is removed and excavation continues, even if the external protective plate is worn or damaged due to long-distance construction or soil conditions, it can be removed and excavation can continue while detecting what is happening in the ground ahead.

[0035] In addition, since the external protective plate is attached to the recess and excavation is carried out, and then the external protective plate is removed and a new external protective plate is attached and excavation continues, even when long-distance construction is required in bedrock, if the external protective plate is worn or damaged, it can be removed and a new external protective plate is attached, i.e., replaced, so that the transmitting antenna protective plate and the receiving antenna protective plate can continue to be protected while excavation is carried out. [Brief explanation of the drawing]

[0036] [Figure 1] This is a front view of a ground tunneling machine according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view of a ground-penetrating radar device showing a first embodiment of the present invention. [Figure 3] This is a cross-sectional view of a ground-penetrating radar device showing a second embodiment of the present invention. [Figure 4] This is a cross-sectional view of a ground-penetrating radar device showing a third embodiment of the present invention. [Figure 5] This is an explanatory diagram of a subsurface excavation method according to a fourth embodiment of the present invention. [Modes for carrying out the invention]

[0037] Embodiments of the present invention will be described below with reference to the drawings. It goes without saying that the present invention is not limited to these embodiments.

[0038] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to Figures 1 and 2.

[0039] Figure 1 is a front view of a ground tunneling machine according to the first embodiment, and Figure 2 is a cross-sectional view of a ground-penetrating radar device showing the first embodiment. In the following explanation, the direction in which the underground tunneling machine moves is referred to as "forward," and the opposite direction is referred to as "backward."

[0040] As shown in Figure 1, the underground tunneling machine 1 is a shield tunneling machine used in the shield tunneling method, and has a circular faceplate 2 on its front end. Multiple cutters 20, each consisting of numerous bits 20a arranged in a row, are attached radially to the surface of the faceplate 2, and slits 21 are formed adjacent to the cutters 20. Then, the underground tunneling machine 1 moves forward by rotating the faceplate 2 to excavate the ground with the cutter 20 and taking in soil through the slit 21.

[0041] A ground-penetrating radar device 3 is installed on the faceplate 2. The ground-penetrating radar device 3 transmits electromagnetic waves forward from its transmitting antenna and receives reflected waves that are reflected off reflective objects in front of it, as well as surface-propagated waves that propagate through the ground near the surface in front of the faceplate 2, with its receiving antenna. The presence and location of obstacles can be determined by the reflected waves, and the soil type near the surface of the faceplate 2 can be determined by the propagation speed and attenuation rate of the surface-propagated waves.

[0042] As shown in Figure 2, the ground-penetrating radar device 3 comprises two protective plates, a transmitting antenna protective plate 30a and a receiving antenna protective plate 30b, a transmitting antenna section 31 and a receiving antenna section 32, a rear-side electromagnetic wave shielding material 33, and an electromagnetic wave shielding section 34.

[0043] Since the faceplate 2 is usually made of a tough material such as iron that does not easily transmit electromagnetic waves, an opening 35 is formed at the location where the transmitting antenna section 31 and the receiving antenna section 32 are installed. The opening 35 is formed while avoiding the areas where the cutter 20 and slit 21 are provided.

[0044] The transmitting antenna protective plate 30a and the receiving antenna protective plate 30b are made of a tough, electromagnetic wave-transmitting material such as FRP, and are fitted into the opening 35 in a circumferential direction of the faceplate 2, adjacent to each other with a gap 300 between them.

[0045] The transmitting antenna protective plate 30a and the receiving antenna protective plate 30b are positioned so that their front surfaces are set back from the front surface of the panel 2.

[0046] The transmitting antenna unit 31 transmits electromagnetic waves for ground detection and is attached in close contact with the back side of the transmitting antenna protective plate 30a, protecting it from soil pressure, water pressure, and sediment. The transmitting antenna protective plate 30a is sized to protrude from the outer front edge of the transmitting antenna section 31, completely covering the front surface of the transmitting antenna section 31.

[0047] The receiving antenna unit 32 receives electromagnetic waves transmitted by the transmitting antenna unit 31, and is attached in close contact with the back side of the receiving antenna protective plate 30b, protecting it from soil pressure, water pressure, and sediment. The receiving antenna protective plate 30b is sized to protrude from the outer front edge of the receiving antenna section 32, completely covering the front surface of the receiving antenna section 32.

[0048] The ground-penetrating radar device 3 transmits electromagnetic waves from the transmitting antenna unit 31 and receives them with the receiving antenna unit 32, and for example, makes judgments about the underground conditions 360 times during one rotation of the faceplate 2.

[0049] The rear electromagnetic wave shielding material 33 is made of a material that does not allow electromagnetic waves to pass through, such as iron, and has an open front. It is provided on the back surface of the panel 2 so as to cover the opening 35 of the panel 2 from the rear side. The rear electromagnetic wave shielding material 33 also functions as a housing that houses the transmitting antenna section 31 and the receiving antenna section 32. It is formed in a box shape and has a partition wall 330 that separates the transmitting antenna section 31 and the receiving antenna section 32. Therefore, the rear electromagnetic wave shielding material 33 is provided to surround the rear side of the transmitting antenna section 31, preventing electromagnetic waves from leaking to the rear side of the transmitting antenna section 31.

[0050] Furthermore, the electromagnetic wave shielding material 33 on the back side may be configured to further fill the space in which the box-shaped transmitting antenna section 31 and receiving antenna section 32 are housed with a material with a high dielectric constant to prevent diffuse reflection of electromagnetic waves.

[0051] The partition wall 330 of the rear electromagnetic wave shielding material 33 is provided on the back surface of the faceplate 2 at a position that coincides with the gap 300 between the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b.

[0052] Flanges are formed on the front part (upper part in Figure 2) of the inner circumferential surface of the side wall of the rear electromagnetic wave shielding material 33 and on the front part (upper part in Figure 2) of the partition wall 330 on the transmitting antenna section 31 and receiving antenna section 32 side, respectively. The front surfaces of the flanges are stepped portions 350a and 350b that are set back from the front surface of the faceplate 2. The peripheral edges of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b are placed on and fixed to the front surfaces of these stepped sections 350a and 350b.

[0053] The electromagnetic wave shielding section 34 is made of a material that does not transmit electromagnetic waves, such as iron, and is provided on the front end surface of the partition wall 330 and positioned in the gap 300 between the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b. This electromagnetic wave shielding section 34 separates the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b and is provided protruding from the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b. Specifically, its front end surface protrudes so that it is flush with the front surface of the faceplate 2.

[0054] By providing the electromagnetic wave shielding section 34, it is possible to block the propagation of electromagnetic waves transmitted from the transmitting antenna section 31 through the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b to the receiving antenna section 32. The electromagnetic wave shielding section 34 may be integrated with the partition wall 330, or a separate electromagnetic wave shielding section 34 may be fixed to the partition wall 330 by welding or the like.

[0055] Furthermore, since the depth from the front surface of the panel 2 to the front surfaces of the stepped portions 350a and 350b is set to be greater than the thickness of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b, the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b are positioned set back from the front surface of the panel 2. In other words, a recess 36 is formed between the opening 35 of the panel 2 and the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b.

[0056] In this embodiment, the recess 36 is formed by the opening 35 of the faceplate 2 and the front surfaces of the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b. However, it is not limited to this, and the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b may be set back so that the recess 36 is formed by the opening 35 of the faceplate 2, the inner circumferential surface of the side wall of the rear electromagnetic wave shielding material 33 and the front surfaces of the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b.

[0057] The protruding electromagnetic wave shielding portion 34 divides the recess 36 into a transmitting recess 36a and a receiving recess 36b.

[0058] The transmitting antenna unit 31 transmits electromagnetic waves into the ground in front of it through the transmitting antenna protective plate 30a. The electromagnetic waves transmitted from the transmitting antenna unit 31 are received by the receiving antenna unit 32. The electromagnetic waves received by the receiving antenna unit 32 include reflected waves that are reflected after hitting obstacles in front of it, and surface-propagated waves that propagate near the front surface of the faceplate 2. The presence or absence of reflected waves can be used to detect obstacles, and the distance to the obstacle can be calculated by evaluating the arrival time of the reflected waves. Furthermore, by evaluating the voltage value and arrival time of surface-propagated waves, the soil type in the ground that the waves passed through can be determined.

[0059] As the faceplate 2 rotates and excavates the ground, the ground-penetrating radar device 3 also rotates. However, the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b, which are exposed on the front of the ground-penetrating radar device 3, are positioned set back from the front of the faceplate 2 and have recesses. This reduces wear and damage due to friction with the ground, and prevents damage to the transmitting antenna section 31 and the receiving antenna section 32, which are protected by the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b.

[0060] Furthermore, since the electromagnetic wave shielding section 34 separates the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b, and protrudes from the front surfaces of the transmitting antenna shielding plate 30a and the receiving antenna shielding plate 30b within the recess 36, the reception of surface-propagated waves that penetrate the loosened ground by the recess 36 can be reduced. As a result, surface-propagated waves containing undisturbed and accurate ground information can be received, improving the detection accuracy for soil type discrimination of the ground.

[0061] In this embodiment, the electromagnetic wave shielding section 34 is configured to protrude so that its front end surface is flush with the front surface of the faceplate 2, but it is not limited to this configuration, and it may also protrude from the front surface of the faceplate 2. For example, if it is configured to protrude to a height that takes into account the height of the cutter 20 and the thickness of the cut, the ground will have been disturbed by the excavation up to this position, so surface-propagated waves containing accurate, undisturbed ground information will be received, further improving the detection accuracy for soil type discrimination of the ground.

[0062] Furthermore, the electromagnetic wave shielding section 34 may be provided so as not to protrude from the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b, that is, so as to be flush with the front surfaces of the antenna protective plates. In this case, the resistance caused by the electromagnetic wave shielding section 34 can be reduced when the faceplate rotates.

[0063] [Second Embodiment] A second embodiment of the present invention will be described below with reference to Figure 3. Note that the same parts as in the first embodiment will be omitted from the description, and only the differences will be explained.

[0064] In the second embodiment, external protective plates consisting of a transmitting-side external protective plate 40a and a receiving-side external protective plate 40b are detachably attached to recesses 36a and 36b, where the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b are positioned set back from the front surface of the faceplate 2.

[0065] The opening 35 of the panel 2 is larger than the outer circumference of the stepped portions 350a and 350b of the rear electromagnetic wave shielding material 33, and the front end of the side wall of the rear electromagnetic wave shielding material 33 and the front end of the partition wall 330 on the transmitting antenna portion 31 and the receiving antenna portion 32 side are formed as front stepped portions 351a and 351b that are set back from the front surface of the panel 2. The front stepped portions 351a and 351b are flush with the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b.

[0066] The recesses 36a and 36b are formed by the opening 35, the front stepped portions 351a and 351b, and the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b.

[0067] The depth from the front surface of the panel 2 to the bottom of the recesses 36a and 36b (the front surfaces of the front stepped portions 351a and 351b and the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b) is equal to the thickness of the transmitting external protective plate 40a and the receiving external protective plate 40b that are to be installed. Therefore, the front surfaces of the installed transmitting external protective plate 40a and the receiving external protective plate 40b are positioned in the same plane as the front surface of the panel 2. Since the front surfaces of the transmitting external protective plate 40a and the receiving external protective plate 40b and the front surface of the faceplate 2 are arranged in the same plane, the rotational resistance of the faceplate can be reduced, thereby lowering the cutter torque.

[0068] The transmitting-side external protective plate 40a and the receiving-side external protective plate 40b are electromagnetic wave-transmitting protective plates made of a material that transmits electromagnetic waves, such as FRP. The transmitting-side external protective plate 40a and the receiving-side external protective plate 40b are slightly wider in shape to protect the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b.

[0069] The transmitting-side external protective plate 40a and the receiving-side external protective plate 40b are mounted with their outer edges on the front surface of the front stepped portions 351a and 351b and are detachably attached with screws or the like. The space between the transmitting external protective plate 40a and the receiving external protective plate 40b is blocked by an electromagnetic wave shielding portion 34 that protrudes to the front surface of the faceplate 2. In this embodiment, the tip of the partition wall 330, which is located between the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b and separates them, corresponds to an electromagnetic wave shielding portion that blocks electromagnetic waves from passing directly from the transmitting antenna protective plate 30a to the receiving antenna protective plate 30b.

[0070] Since the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b are transparent to electromagnetic waves, the ground-penetrating radar device 3 can perform its detection function even when installed in front of the transmitting antenna unit 31 and the receiving antenna unit 32.

[0071] Therefore, when the underground tunneling machine 1 is drilling through ground of varying hardness, the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b can always be attached. Furthermore, when the underground tunneling machine 1 is drilling through soft ground or clayey ground where there is little need to protect the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b, the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b may be removed, and when drilling through hard ground such as gravel ground or bedrock where protection is highly necessary, the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b may be attached.

[0072] Furthermore, when performing long-distance construction, the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b may be installed from the beginning. When the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b are worn or damaged after excavating a predetermined distance, they may be removed and either left removed or replaced before continuing the excavation.

[0073] In this embodiment, the front surfaces of the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b were arranged on the same plane as the front surface of the faceplate 2. However, the invention is not limited to this configuration, and the front surfaces of the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b may be positioned set back from the front surface of the faceplate 2. Doing so can suppress wear and damage to the external protective plates.

[0074] Furthermore, in this embodiment, the opening 35 of the faceplate 2 was made wider and front stepped portions 351a and 351b were provided so that the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b were made slightly wider than the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b to provide sufficient protection. However, the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b and the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b may be the same size. In this case, the front stepped portions 351a and 351b are not provided, and the outer circumference of the stepped portions 350a and 350b and the opening 35 will be the same size as in the first embodiment.

[0075] In this embodiment, the electromagnetic wave shielding section 34 is configured to protrude so that its front end surface is flush with the front surface of the faceplate 2, similar to the first embodiment. However, it is not limited to this configuration, and it goes without saying that it may also protrude from the front surfaces of the faceplate 2, the transmitting-side external protective plate 40a, and the receiving-side external protective plate 40b, similar to the modified configuration described in the note to the first embodiment.

[0076] [Third Embodiment] A third embodiment of the present invention will be described below with reference to Figure 4. Note that the same parts as those in the first and second embodiments will be omitted from the description, and only the differences will be explained.

[0077] In the third embodiment, the difference from the second embodiment is that the transmitting-side external protective plate 40a' and the receiving-side external protective plate 40b' are electromagnetic wave shielding protective plates made of a material that does not transmit electromagnetic waves. Materials that do not transmit electromagnetic waves include iron and iron alloys. When the transmitting-side external protective plate 40a' and the receiving-side external protective plate 40b' are attached in front of the transmitting antenna unit 31 and the receiving antenna unit 32, electromagnetic waves cannot be transmitted or received.

[0078] Therefore, it is effective when prioritizing the protection of the protective plate over forward detection underground. For example, when excavating bedrock. In addition, in long-distance construction, the transmitting-side external protective plate 40a' and the receiving-side external protective plate 40b' can be installed from the beginning, and excavation can be started. When the transmitting-side external protective plate 40a' and the receiving-side external protective plate 40b' are worn or damaged after excavating a predetermined distance, they can be removed and either left removed or replaced, and excavation can continue from there.

[0079] [Fourth Embodiment] A fourth embodiment of the present invention will be described below with reference to Figure 5. Note that the same parts as those in the first to third embodiments will be omitted from the description, and only the differences will be explained.

[0080] The fourth embodiment is a method of underground excavation using the ground-penetrating radar device 3 according to the first to third embodiments.

[0081] Figure 5 is a longitudinal section diagram illustrating the general shape of the ground along the excavation path by the underground tunneling machine 1. The soil type changes in the order of ordinary ground (a) such as clayey ground, bedrock (b) which is particularly hard hard ground, and gravelly ground (c) which is hard ground with slightly lower hardness (from left to right in Figure 5). Additionally, an intermediate shaft A is constructed from the ground at the boundary between the normal ground a and the bedrock b, and an intermediate shaft A' is constructed from the ground at the boundary between the bedrock b and the gravelly ground c.

[0082] A shaft (not shown) is formed above ground at the starting position of the underground tunneling machine 1, and the underground tunneling machine 1, equipped with a ground-penetrating radar device 3 in which the transmitting side external protective plates 40a, 40a' and receiving side external protective plates 40b, 40b' are not attached, that is, recesses 36a, 36b as in the first embodiment are exposed, is installed in the shaft and drills through the normal ground a following the shaft.

[0083] After the underground tunneling machine 1 reaches the intermediate shaft A, the underground tunneling machine 1, equipped with a ground-penetrating radar device 3 mounted on a ground-penetrating radar device 3 that is protected by covering the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b as in the third embodiment, launches from the intermediate shaft A and drills through the bedrock b.

[0084] After the underground tunneling machine 1 reaches the intermediate shaft A', the transmitting-side external protective plate 40a' and the receiving-side external protective plate 40b' made of a material that does not transmit electromagnetic waves are removed, and the transmitting-side external protective plate 40a and the receiving-side external protective plate 40b made of a material that transmits electromagnetic waves are attached to the recesses 36a and 36b, that is, the underground tunneling machine 1 equipped with the underground radar device 3, which is protected by covering the front surfaces of the transmitting antenna protective plate 30a and the receiving antenna protective plate 30b as in the second embodiment, launches from the intermediate shaft A' and drills through the gravelly ground c.

[0085] In this embodiment, ordinary ground a, such as clayey ground, is an example of ground to which the first embodiment applies; hard rock b, which is hard ground with high hardness, is an example of ground to which the third embodiment applies; and gravelly ground c, which is hard ground with low hardness, is an example of ground to which the second embodiment applies. However, the appropriate embodiment is to be applied depending on the situation, and the combination of specific ground conditions and the embodiment to which it is applied is not mandatory.

[0086] [Other variations] The present invention is not limited to the embodiments described above. For example, the following are also included.

[0087] In this embodiment, the underground tunneling machine is a shield tunneling machine used in the shield tunneling method, but is not limited to this. Any underground tunneling machine equipped with a rotating faceplate and cutter may be an underground tunneling machine used in the pipe jacking method or the TBM method.

[0088] In this embodiment, the transmitting antenna and the receiving antenna are arranged side by side in the circumferential direction of the panel, but they may also be installed side by side in the radial direction of the panel.

[0089] In the second and third embodiments, the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate are flush with the front surface of the panel. However, the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate may be set back from the front surface of the panel.

[0090] In this fourth embodiment, the external protective plates for the transmitting and receiving sides are attached and detached within an intermediate shaft. However, the invention is not limited to this, and the attachment and detachment work may be performed by securing a workspace for the work through ground improvement, without providing an intermediate shaft.

[0091] In this embodiment, the transmitting and receiving external protective plates are normally removed when excavating through the ground. However, it is also possible to excavate with the transmitting and receiving external protective plates, which are made of a material that transmits electromagnetic waves, attached and detached. Furthermore, when drilling through bedrock, it is possible to attach external protective plates made of materials that transmit electromagnetic waves, rather than external protective plates made of iron or iron alloy.

[0092] In this embodiment, the external protective plate was composed of separate components for the transmitting and receiving sections, but it may also be composed of a single component.

[0093] Each technical aspect of any embodiment may be applied to other embodiments to form examples. [Explanation of symbols]

[0094] 1 Underground digging machine 2 face plates 20 cutters 20a bit 21 slits 3. Ground-penetrating radar system 30a Transmitting antenna protective plate 30b Receiving antenna protective plate 300 gap 31 Transmitting antenna section 32 Receiving antenna section 33. Electromagnetic wave shielding material on the back side 330 Bulkhead 34 Electromagnetic wave shielding section 35 Opening 35a Transmitter side opening 35b Receiving side opening 350a,350b Stepped section 351a,351b Front step 36 recesses 40a, 40a' Transmitter side external protective plate 40b, 40b' Receiver side external protective plate a Normal ground b. Bedrock c. Gravelly ground A,A' Intermediate shaft

Claims

1. A ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves from the electromagnetic waves that have struck an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, The front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are provided with recesses that are set back from the front surface of the panel, The ground-penetrating radar device is characterized in that the electromagnetic wave shielding section protrudes from the front surface of the transmitting antenna protective plate and the receiving antenna protective plate.

2. A ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves from the electromagnetic waves that have struck an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, The front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are provided with recesses that are set back from the front surface of the panel, The recess is provided with an external protective plate that is detachably attached and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate. The external protective plate consists of a transmitting-side external protective plate that covers the front surface of the transmitting antenna protective plate and a receiving-side external protective plate that covers the front surface of the receiving antenna protective plate. The electromagnetic wave shielding section is characterized in that it separates the transmitting-side external protective plate and the receiving-side external protective plate, and protrudes from the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate.

3. The ground-penetrating radar device according to claim 1, further comprising an external protective plate that is detachably attached to the recess and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate.

4. The ground-penetrating radar device according to claim 2 or 3, characterized in that the front surface of the external protective plate and the front surface of the faceplate are arranged in the same plane.

5. The ground-penetrating radar device according to claim 2 or 3, characterized in that the front surface of the external protective plate is positioned set back from the front surface of the faceplate.

6. The ground-penetrating radar device according to any one of claims 2 to 5, characterized in that the external protective plate is an electromagnetic wave-transmitting protective plate made of a material that transmits electromagnetic waves.

7. The ground-penetrating radar device according to any one of claims 2 to 5, characterized in that the external protective plate is an electromagnetic wave shielding protective plate made of a material that does not transmit electromagnetic waves.

8. A ground-penetrating drilling method characterized by drilling with a ground-penetrating radar device comprising: a transmitting antenna unit that transmits electromagnetic waves into the ground in front of a ground-penetrating drilling machine equipped with a rotating faceplate having a cutter; a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves strike an obstacle in front of the machine and surface-propagated waves that propagate in the ground near the front of the ground-penetrating drilling machine; a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit; a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit; and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, wherein the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are set back from the front surface of the faceplate and have recesses, and the electromagnetic wave shielding unit protrudes from the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate.

9. The underground tunneling machine, equipped with a rotating faceplate and cutter, includes a transmitting antenna unit that transmits electromagnetic waves into the ground in front of it, a receiving antenna unit that receives reflected waves from obstacles in front of it and surface-propagated waves propagating in the ground near the front of the underground tunneling machine, a transmitting antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the transmitting antenna unit, a receiving antenna protective plate made of an electromagnetic wave-permeable material and provided on the faceplate to protect the receiving antenna unit, and an electromagnetic wave shielding unit that separates the transmitting antenna protective plate and the receiving antenna protective plate, wherein the transmitting antenna protective plate and the front A ground excavation method characterized by the following: the front surface of the receiving antenna protective plate is positioned set back from the front surface of the faceplate and has a recess, an external protective plate is provided in the recess which is detachably attached and covers the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate, the external protective plate consists of a transmitting-side external protective plate which covers the front surface of the transmitting antenna protective plate and a receiving-side external protective plate which covers the front surface of the receiving antenna protective plate, and the electromagnetic wave shielding section is provided with a ground-penetrating radar device which separates the transmitting-side external protective plate and the receiving-side external protective plate and protrudes from the front surfaces of the transmitting-side external protective plate and the receiving-side external protective plate, and the excavation is carried out with the device.

10. The underground excavation method according to claim 8, characterized in that an external protective plate covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate is detachably attached to the recess and excavation is carried out.

11. The underground excavation method according to claim 9 or 10, characterized in that the external protective plate is an electromagnetic wave-transmitting protective plate made of a material that transmits electromagnetic waves.

12. The underground excavation method according to claim 9 or 10, characterized in that the external protective plate is an electromagnetic wave shielding plate made of a material that does not transmit electromagnetic waves.

13. The underground excavation method according to any one of claims 9 to 12, characterized in that the external protective plate is attached to the recess and excavation is carried out, and then the external protective plate is removed and excavation is carried out.

14. The underground excavation method according to any one of claims 9 to 12, characterized in that the external protective plate is attached to the recess and excavation is carried out, and then the external protective plate is removed and a new external protective plate is attached and excavation is carried out.

15. The underground tunneling machine, which has a rotating faceplate with a cutter, comprises a transmitting antenna unit that transmits electromagnetic waves into the ground in front of it, a receiving antenna unit that receives reflected waves that are reflected when the electromagnetic waves hit an obstacle in front of it and surface-propagated waves that propagate in the ground near the front of the underground tunneling machine, a transmitting antenna protective plate made of an electromagnetic wave-transmitting material and provided on the faceplate to protect the transmitting antenna unit, and a receiving antenna protective plate made of an electromagnetic wave-transmitting material and provided on the faceplate to protect the receiving antenna unit, and the A ground-penetrating radar device is provided, which is used for excavation, and the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate are positioned recessed from the front surface of the faceplate, wherein an electromagnetic wave-transmitting protective plate made of an electromagnetic wave-transmitting material is detachably attached to the recess, and an external protective plate covering the front surfaces of the transmitting antenna protective plate and the receiving antenna protective plate is attached to the recess, and excavation is carried out in a state in which the ground can be detected, and then the external protective plate is removed and excavation is carried out in a state in which the ground can be detected.

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