Radio wave shielding apparatus and radio wave shielding method in tunnel construction

Abstract

To prevent mutual adverse effects inside and outside a tunnel by shielding radio waves by providing an electromagnetic wave shielding function in the tunnel.SOLUTION: The radio wave shielding device 1 is installed in a tunnel during tunnel construction. The radio wave shielding device 1 is composed of a radio wave shielding body having a radio wave shielding effect arranged so as to partition a tunnel inside hollow part in the axial direction. The radio wave shielding body is a radio wave shielding door 2 installed at the entrance of the tunnel or a radio wave shielding curtain 10 installed in the tunnel. By the radio wave shielding device 1, the radio wave used in the tunnel is shielded and is not emitted to the outside of the tunnel, the influence on the periphery is suppressed, the radio wave outside the tunnel is shielded and does not intrude into the tunnel, and the interference to the equipment in the tunnel is suppressed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a radio wave shielding device and radio wave shielding method that are installed in a tunnel during tunnel construction to prevent radio waves used inside the tunnel from being emitted outside the tunnel and to prevent radio waves from outside the tunnel from entering the tunnel. [Background technology]

[0002] In recent years, measuring and control devices equipped with wireless communication have been rapidly developed for use in tunnel construction, and efforts are being made to put them to practical use (for example, Patent Document 1 below). This is because, for tunnels that are excavated daily, wired communication devices require the wiring of communication cables to be changed as the excavation progresses, which is time-consuming, and the presence of communication cables places restrictions on the movement and freedom of the device, depending on the device.

[0003] Recently, the range of applications of measuring equipment that uses radio waves (electromagnetic waves) has expanded to include remote wireless operation of heavy machinery, remote detonation using wireless blasting detonators, measuring the thickness of lining concrete, checking for air bubbles and defects inside lining concrete, and measuring the anchorage of rock bolts, the condition of the lower half, and the soundness of the face.

[0004] Devices that use radio waves require a high-output transmitter that can achieve a sufficient S / N ratio (signal / noise ratio) to prevent communication interference and ensure reliable communication. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-165494 Summary of the Invention [Problem to be solved by the invention]

[0006] However, many of the communication devices and measuring instruments that use radio waves use the same or similar frequency bands as those used by the communication devices and measuring instruments in private homes, factories, hospitals, and medical facilities around the tunnel construction site, so care must be taken to avoid affecting them. For example, a high-power transmitter is likely to affect television viewing and home appliances in nearby private homes outside the tunnel.

[0007] The impact of electromagnetic waves (radio waves) emitted outside the tunnel on surrounding electronic devices and communications varies depending on the frequency, but it is important to keep the values ​​measured for each frequency outside the tunnel exit below the levels shown in Figure 16 so that they do not fall under the restrictions of the Radio Law.

[0008] In addition, some wireless communication devices that use microwaves (e.g., Wi-Fi (registered trademark, same below)) can affect weather observation radars on aircraft flying overhead, and are becoming subject to regulation under the Radio Law.

[0009] Therefore, it is necessary to prevent radio waves used inside the tunnel from being emitted outside the tunnel.

[0010] Furthermore, if radio waves entering the tunnel from outside interfere with communication equipment inside the tunnel, this could lead to malfunctions of equipment, heavy machinery, and electronic detonators installed inside the tunnel, which could result in a serious accident.

[0011] Therefore, it is also necessary to prevent radio waves from outside the tunnel from entering the tunnel.

[0012] Therefore, the main objective of the present invention is to provide a radio wave shielding device and radio wave shielding method for tunnel construction that provides an electromagnetic wave shielding function that blocks radio waves inside the tunnel, thereby preventing radio waves from adversely affecting both the inside and outside of the tunnel. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention according to claim 1 provides a radio wave shielding device to be installed in a tunnel during tunnel construction, The radio wave shielding device for tunnel construction is characterized in that it comprises a radio wave shielding body having a radio wave shielding effect that is installed so as to separate the tunnel interior in the axial direction.

[0014] In the invention described in claim 1 above, during tunnel construction, a radio wave shield having a radio wave shielding effect is installed inside the tunnel so as to separate the hollow space of the tunnel in the axial direction, so that radio waves used inside the tunnel are blocked by the radio wave shield and do not escape outside the tunnel, suppressing their impact on the surrounding area, and radio waves outside the tunnel are blocked by the radio wave shield and do not enter the tunnel, suppressing interference with equipment inside the tunnel. Therefore, by blocking radio waves with the radio wave shield, it becomes possible to prevent mutual adverse effects of radio waves inside and outside the tunnel.

[0015] As a second aspect of the present invention, there is provided a radio wave shielding device for tunnel construction according to the first aspect, wherein the radio wave shielding body includes a radio wave shielding door installed at the entrance of the tunnel.

[0016] In the invention described in claim 2 above, a radio wave shielding door is installed at the entrance to the tunnel as the radio wave shielding body, and by opening and closing this radio wave shielding door, heavy machinery and the like can enter and exit, while when radio waves are to be emitted inside the tunnel or when it is desired to prevent radio waves from entering from outside the tunnel, the radio wave shielding door can be closed to prevent radio waves from being emitted outside the tunnel and radio waves from entering the tunnel.

[0017] According to a third aspect of the present invention, there is provided a radio wave shielding device for tunnel construction according to the first aspect, wherein the radio wave shielding body includes a radio wave shielding curtain installed in the tunnel.

[0018] In the invention described in claim 3, a radio wave shielding curtain is installed in the tunnel as the radio wave shield. By opening and closing this radio wave shielding curtain, heavy machinery and the like can pass through, and when radio waves are to be emitted in a specific area in the tunnel or when it is desired to prevent radio waves from entering the specific area, by closing the radio wave shielding curtain, it becomes possible to prevent radio waves from being emitted outside the specific area and radio waves from entering the specific area.

[0019] The present invention according to claim 4 provides a radio wave shielding device for tunnel construction according to claim 1, in which a radio wave shielding shield having a radio wave shielding effect and breathability is arranged within the flow path of the tunnel ventilation duct so as to divide the flow path in the axial direction.

[0020] In the invention described in claim 4, in order to prevent the emission and intrusion of radio waves through the tunnel ventilation duct, a radio wave shield that has radio wave shielding effect and is breathable is arranged inside the flow path so as to divide the flow path in the axial direction. The radio wave shield is made of a mesh structure or a shutter structure made of an electrically conductive material and is arranged midway through the flow path of the tunnel ventilation duct, thereby preventing the emission and intrusion of radio waves through the tunnel ventilation duct while ensuring breathability.

[0021] As the present invention according to claim 5, there is provided a radio wave shielding device for tunnel construction according to claim 1, in which a bent portion is provided midway along the flow path of the tunnel ventilation duct so that the flow path does not proceed in a straight line.

[0022] In the invention described in claim 5 above, since radio waves have little attenuation and tend to travel in a straight line when the flow path is straight, a bend is provided in the middle of the flow path to prevent the radio waves from traveling in a straight line in the duct axis direction, thereby preventing the emission and intrusion of radio waves through the tunnel ventilation duct.

[0023] The present invention according to claim 6 provides a radio wave shielding method for tunnel construction, characterized in that during tunnel construction, a radio wave shielding body having a radio wave shielding effect is installed within the tunnel, dividing the tunnel interior in the axial direction.

[0024] The present invention according to claim 7 provides a radio wave shielding method for tunnel construction according to claim 6, in which a radio wave shielding shield having radio wave shielding effect and breathability is arranged within the flow path of the tunnel ventilation duct so as to separate the flow path in the axial direction.

[0025] The present invention according to claim 8 provides a radio wave shielding method for tunnel construction according to claim 6, in which a bent section is provided midway along the flow path of the tunnel ventilation duct so that the flow path does not proceed in a straight line.

[0026] The inventions described in claims 6 to 8 above provide for a method of shielding radio waves from the tunnel entrance by installing a radio wave shield inside the tunnel, and a method of shielding radio waves passing through a tunnel ventilation duct by arranging a radio wave shield or installing a bent section. [Effects of the Invention]

[0027] As explained above in detail, according to the present invention, by providing an electromagnetic wave shielding function inside the tunnel, radio waves can be blocked and mutual adverse effects of radio waves between the inside and outside of the tunnel can be prevented. [Brief explanation of the drawings]

[0028] [Figure 1] 1A and 1B show a tunnel equipped with a radio wave shielding device 1 according to the present invention, in which (A) is a cross-sectional view of the tunnel and (B) is a view taken along line BB. [Figure 2] 10A and 10B show a tunnel equipped with a radio wave shielding device 1 according to a modified example, in which (A) is a cross-sectional view of the tunnel and (B) is a view taken along line BB. [Figure 3] 1A is a cross-sectional view of a tunnel, and FIG. 1B is a view taken along line BB, for explaining the radio wave shielding device 1 in detail. [Figure 4]FIG. 1 is an axial cross-sectional view of a tunnel in which a radio wave shielding curtain 10 is installed. [Figure 5] FIG. 10 is a system configuration diagram in which an open / close detection mechanism 11 is provided in the radio wave shielding door 2. [Figure 6] 1A and 1B show a tunnel ventilation duct 20, in which (A) is a cross-sectional view of the tunnel, and (B) is a view taken along line BB. [Figure 7] 10A and 10B show a modified example of the radio wave shield 21, in which (A) is a cross-sectional view in the duct axial direction, and (B) is a front view of the radio wave shield 21. FIG. [Figure 8] 10 is a cross-sectional view of a modified example of the radio wave shield 21 taken along the duct axis. FIG. [Figure 9] FIG. 2 is an axial cross-sectional view of a tunnel ventilation duct 20 provided with a bent portion 23. [Figure 10] FIG. 10 is a cross-sectional view of a tunnel in the axial direction showing an embodiment in which a wireless detonator 31 is used. [Figure 11] 1 is an axial cross-sectional view of a tunnel showing an embodiment in which a wireless communication system is used. FIG. [Figure 12] FIG. 1 is an axial cross-sectional view of a tunnel showing an embodiment in which a ground-penetrating radar system 50 is used. [Figure 13] FIG. 10 is a cross-sectional view of a tunnel in the axial direction showing an embodiment in which a microwave moisture meter 55 is used. [Figure 14] FIG. 10 is a cross-sectional view of a tunnel in the axial direction showing an embodiment in which a microwave measuring device 62 is used. [Figure 15] FIG. 10 is a cross-sectional view of a tunnel in the axial direction showing an embodiment in which a remotely operated heavy machine 70 is used. [Figure 16] 10 is a graph showing the allowable electric field strength for weak radio signals at a distance of 3 m. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0030] <Radio wave shielding device> The radio wave shielding device 1 of the present invention is installed in the hollow space inside the tunnel and, if necessary, in the flow path of the tunnel ventilation duct 20 to prevent radio waves used inside the tunnel from being emitted outside the tunnel during tunnel construction and to prevent radio waves from outside the tunnel from entering the tunnel.

[0031] The radio wave shielding device 1 for shielding radio waves passing through the tunnel interior and entering and exiting the tunnel entrance can be constructed from a radio wave shielding body having a radio wave shielding effect that is installed to separate the tunnel interior in the axial direction.

[0032] By installing the radio wave shielding body in the hollow part of the tunnel, almost perpendicular to the tunnel axis, radio waves traveling in the axial direction inside the tunnel are reflected or absorbed by the radio wave shielding body, thereby blocking the progression of the radio waves, thereby preventing radio waves used inside the tunnel from being emitted outside the tunnel and preventing radio waves from outside the tunnel from entering the tunnel.

[0033] The radio wave shield will be described in detail below. The radio wave shield may be of any type as long as it is configured to block the progression of radio waves inside the tunnel. As an example of an embodiment of the radio wave shield, as shown in Figures 1 and 2, it can be configured with a radio wave shielding door 2 installed at the tunnel entrance and a frame 3 that supports the radio wave shielding door 2.

[0034] The radio wave shielding door 2 is made of a material that has the property of reflecting or absorbing electromagnetic waves, but since reflection without attenuation of the electromagnetic waves may affect other devices, it is desirable to make it of a material that has the property of attenuating electromagnetic waves by absorbing them. Materials that reflect or absorb electromagnetic waves include metals such as steel, copper, aluminum, and silver, conductive polymers, and conductive coating materials that have been applied to the surface with paint or spray containing conductive substances such as silver or carbon.

[0035] The radio wave shielding door 2 is installed near the tunnel entrance (portal), preferably within a range of about 0.1 to 50 m from the tunnel entrance.

[0036] The radio wave shielding door 2 may be opened and closed by a double or single swinging door using hinges as shown in Fig. 1, or by a sliding door that runs on a rail as shown in Fig. 2. A double swinging door that allows for a large opening area is preferable.

[0037] The frame 3 is made of a material that has the property of reflecting or absorbing electromagnetic waves, and is a wall-like member that is placed so as to fill the hollow space inside the tunnel between the radio wave shielding door 2 and the inner wall surface of the tunnel. The frame 3 is fixed by welding or screw connection to anchors driven into the bedrock surrounding the tunnel.

[0038] The frame 3 is electrically connected to an earth 4 driven into the bedrock surrounding the tunnel, so that electricity stored in the frame 3 can be discharged to the ground.

[0039] If a gap occurs between the frame 3 and the tunnel inner wall surface due to unevenness of the tunnel inner wall surface, it is advisable to seal the gap and prevent radio waves from leaking through it by suspending an electrically conductive shielding member 9 such as an iron plate or copper plate between the frame 3 and the tunnel inner wall surface in the gap or around the entire circumference of the tunnel, as shown in Figure 3(B).

[0040] The radio wave shielding door 2, which employs the aforementioned double-door swing-type opening and closing mechanism, will be described in more detail with reference to FIG. 3. The outer side of the radio wave shielding door 2 is supported on the frame 3 so as to be rotatable with hinges 5 as fulcrums.

[0041] In addition, the radio wave shielding door 2 and frame 3 are connected by a flexible conductor (bonding wire 6) such as mesh wire or twisted wire, so that electromagnetic waves absorbed by the radio wave shielding door 2 can pass through the bonding wire 6 and travel to the frame 3.

[0042] To keep the double-hinged radio wave shielding door 2 closed, as shown in Figure 3, a door fixing means such as a latch 7 suspended between the left and right radio wave shielding doors 2, 2 is provided while the left and right radio wave shielding doors 2 are closed.

[0043] 3(B), it is preferable to prevent radio waves from leaking from the gap where the left and right radio wave shielding doors 2, 2 meet by providing a receiving plate 8 made of a material with radio wave shielding effect. Furthermore, if a gap occurs between the radio wave shielding door 2 and the frame 3, it is also preferable to provide the receiving plate 8 in this gap to prevent radio waves from leaking.

[0044] The radio wave shielding door 2 is provided in one stage at the tunnel entrance or in multiple stages spaced apart in the tunnel axial direction.

[0045] The radio wave shielding door 2 can be installed not only at the tunnel entrance, but also at any location within the tunnel to partition the hollow space within the tunnel in the axial direction, for example, when the tunnel is long or when work areas within the tunnel need to be partitioned, as shown in Figure 4.

[0046] Another embodiment of the radio wave shielding body can be configured as a radio wave shielding curtain 10 installed inside a tunnel, as shown in Fig. 4. The radio wave shielding curtain 10 can be installed more easily than the radio wave shielding door 2 when the tunnel is long or when work areas inside the tunnel need to be partitioned.

[0047] The radio wave shielding curtain 10 is made of a sheet material that has the property of reflecting or absorbing electromagnetic waves, but since reflection without attenuation of the electromagnetic waves may affect other devices, it is preferable to make it of a material that has the property of attenuating electromagnetic waves by absorbing them. Such a material can be a sheet material made of a plastic base material such as polyester plated with a soft magnetic metal.

[0048] The radio wave shielding curtain 10 may be arranged in the same manner as the radio wave shielding door 2 by placing a frame 3 around it and closing the opening, or by providing a frame on the inner wall surface of the surrounding tunnel and fixing the radio wave shielding curtain 10 directly to the frame.

[0049] In order to prevent radio waves from being generated inside the tunnel when the radio wave shielding body (radio wave shielding door 2, radio wave shielding curtain 10) is left open, it is recommended to provide an open / close detection mechanism 11 on the radio wave shielding body as shown in FIG. 5, and also provide an interlock device on the radio wave generating device or an alarm device to issue an alarm to workers.

[0050] The open / close detection mechanism 11 is a device that detects the open / close state of the radio wave shield using a sensor attached to the radio wave shield or the frame 3, and transmits the detection signal to an interlock device 12. This interlock device 12 is connected to a radio wave generator 13 that generates radio waves, and when the open / close detection mechanism 11 detects that the radio wave shield is in an open state, it performs an operation to interlock the radio wave generator 13 so that it does not emit radio waves. Reference numeral 14 denotes a radio wave emitting antenna that irradiates the radio waves generated by the radio wave generator 13.

[0051] Furthermore, as shown in Figure 5, it is desirable to install a radio wave level meter 15 and a radio wave receiving antenna 16 outside the tunnel entrance to measure the level of radio waves emitted from the tunnel entrance, and to constantly measure the level of radio waves leaking from the tunnel entrance. If there is a risk that the level will exceed the standards set forth in the Radio Law, a warning will be issued or measures will be taken to stop the use of the radio wave generating device 13 using the interlock device 12.

[0052] The radio wave shielding device 1 according to the present invention can also have a form that shields radio waves from entering or exiting through a tunnel ventilation duct 20 that ventilates the inside of a tunnel, such as a wind pipe. This form will be described in detail below.

[0053] As shown in FIG. 6, one embodiment of the radio wave shielding device 1 provided in such a tunnel ventilation duct 20 can be configured by a radio wave shielding shield 21 that has radio wave shielding effect and is breathable and is arranged within the flow path of the tunnel ventilation duct 20 so as to divide the flow path in the axial direction.

[0054] The radio wave shield 21 may be of any shape as long as it can block radio waves traveling through the flow path in the duct axial direction and is breathable. To cite a specific embodiment, as shown in Fig. 7(B), the inner space of the duct may be formed in a mesh shape by weaving conductive wires at intervals in both the vertical and horizontal directions, or in a punched metal shape by forming numerous fine holes in a flat plate, thereby ensuring breathability. In this case, the mesh spacing or the diameter of the fine holes is formed to be sufficiently small relative to the frequency and wavelength of the electromagnetic waves in question.

[0055] The radio wave shield 21 may be installed in one stage as shown in FIG. 6(B), or in multiple stages (three stages in the illustrated example) spaced apart in the duct axial direction as shown in FIG. 7(A).

[0056] Furthermore, the radio wave shield 21 may have a shutter structure 22 in which multiple conductive blades are arranged at a fixed inclination and interval, as shown in Fig. 8. The gaps between the blades ensure ventilation, and the blades also provide shielding against radio waves traveling in a straight line. The spacing between the blades is formed to be sufficiently small compared to the frequency and wavelength of the electromagnetic waves in question.

[0057] Another embodiment of the radio wave shielding device 1 provided in the tunnel ventilation duct 20 can be configured by providing a bent section 23 in the middle of the flow path of the tunnel ventilation duct 20 so that the flow path does not go straight, as shown in FIG.

[0058] By providing the bent portion 23, radio waves traveling straight in the axial direction within the flow path collide with the conductive duct wall surface of the bent portion 23 and are absorbed or attenuated, thereby reducing the level of radio waves flowing downstream.

[0059] In the illustrated example, the bent portion 23 is configured as a meandering portion, but it may be a bent portion that is simply bent at a predetermined angle, or may have a maze structure that combines multiple bent portions.

[0060] <Radio wave shielding method> The radio wave shielding method of the present invention involves installing the above-mentioned radio wave shielding body, which has a radio wave shielding effect, at an appropriate position at the entrance to the tunnel and / or inside the tunnel so as to separate the hollow space inside the tunnel in the axial direction, in order to prevent radio waves used inside the tunnel from being emitted outside the tunnel and to prevent radio waves from outside the tunnel from entering the tunnel during tunnel construction.

[0061] Furthermore, in the event that radio waves are emitted or intruded through the tunnel ventilation duct 20, the above-mentioned radio wave shielding shield 21, which has radio wave shielding effect and is breathable, is placed within the flow path of the tunnel ventilation duct 20 so as to separate the flow path in the axial direction.

[0062] In addition to or instead of the configuration in which the radio wave shielding shield 21 is arranged, the above-mentioned bent section 23 can be provided midway along the flow path of the tunnel ventilation duct 20, bending the flow path so that the flow path does not proceed in a straight line, thereby preventing the emission and intrusion of radio waves through the tunnel ventilation duct 20.

[0063] <Example of using a radio wave shielding device> Next, a specific example of using the radio wave shielding device 1 described above in tunnel construction will be given below.

[0064] (Usage example 1) FIG. 10 shows an example of the use of the radio wave shielding device 1 when a wireless detonator (wireless detonating electric detonator) is used as the detonation method for explosives used in tunnel blasting.

[0065] The reason for using wireless detonators is that, traditionally, at tunnel construction sites where blasting is used to excavate, electric detonators or fuse-equipped detonators have been used to detonate explosives; however, electric detonators require the connection of lead wires, and fuse-equipped detonators require the fuse to be bundled. In both cases, the preparation work for detonation required work to be done close to the tunnel face, which posed a high risk of being involved in an accident such as a collapse of the tunnel face. Therefore, by using wireless detonators, the process of connecting lead wires and bundling fuses is eliminated, and wireless detonators are used to improve the safety of blasting workers.

[0066] In the detonation method using the wireless detonator, as shown in Figure 10, a wireless detonator 31 is placed at the end of the borehole 30 into which explosives are loaded, a parent die 32 consisting of an explosive for detonation or a water-containing explosive placed next to the wireless detonator 31, an additional die 33 consisting of an explosive for reinforcement or a water-containing explosive, and a filler 34 that seals the opening of the borehole.

[0067] The wireless detonator 31 is equipped with an electromagnetic wave receiving unit that receives power to activate the built-in electronic circuit, and a transmitter 36 that irradiates electromagnetic waves to the electromagnetic wave receiving unit and a detonation antenna 37 are connected by a coaxial cable 38 to an initiation device 35, which is installed at a predetermined distance from the working face S. The initiation device 35 is also equipped with an ignition and detonation control device 40 in a partitioned ignition location 39, and is connected to the transmitter 36 by a control cable 41.

[0068] When the ignition and detonation control device 40 of the detonator 35 issues a detonation signal, the transmitter 36 emits an electromagnetic wave via the detonation antenna 37 toward the wireless detonator 31. When the electromagnetic wave is irradiated to the electromagnetic wave receiving section of the wireless detonator 31, the detonation order is determined in the built-in electronic circuit, and the detonations occur one by one.

[0069] Because blasting scatters a large amount of rubble near the tunnel face S, the detonator 35 must be installed at a location far enough away from the tunnel face S. However, as the distance between the wireless detonator 31 and the detonation antenna 37 increases, the level of the electromagnetic waves transmitted to the wireless detonator 31 decreases in inverse proportion to the distance. Therefore, to perform safe blasting by separating the detonation antenna 37 from the tunnel face S, a transmitter 36 with a large radio wave output that can ensure a sufficient S / N ratio (signal / noise ratio) is required. For this reason, if the radio wave output becomes too high, there is a risk that the electromagnetic waves required to detonate the wireless detonator 31 will leak outside the tunnel.

[0070] Therefore, as shown in Figure 10, a radio wave shielding door 2 is installed at the tunnel entrance to prevent radio waves from leaking out of the tunnel. This prevents the radio waves from affecting nearby houses and prevents radio waves from leaking into pyrotechnic magazines, pyrotechnic factories, explosives handling facilities, etc. installed outside the tunnel and accidentally detonating wireless detonators 31 stored inside.

[0071] (Usage example 2) Figure 11 shows an example of a communication system inside a tunnel during construction.

[0072] During tunnel construction, a wide variety of parameters are measured, such as the positions of workers and heavy machinery inside the tunnel, images of the work situation, the environment inside the tunnel (temperature, humidity, carbon dioxide concentration, nitrogen oxide concentration), the amount of spring water, and rock displacement, and these are transmitted to offices outside the tunnel.As such, it is important to have an advanced communications environment in place throughout tunnel construction.

[0073] Radio waves of various frequencies are used as a communication method, and currently Wi-Fi communication is widely used, but there are limits to the frequency bands and number of channels that can be used for communication. In order to increase the number of channels, frequency bands that are restricted for outdoor use, such as radar waves used by aircraft, may be used. In such cases, measures must be taken to prevent radio waves from being emitted outside the tunnel so as not to affect aircraft passing overhead.

[0074] Therefore, as shown in FIG. 11, a radio wave shielding device 1 according to the present invention, which installs a radio wave shielding door 2 at the entrance of the tunnel, is an effective countermeasure.

[0075] 11, a communication cable 42 is laid extending from the outside of the mine into the mine, and a plurality of Wi-Fi repeaters 43 are connected to the end of the cable in a daisy chain at intervals of approximately 100 to 300 m via LAN cables 44. Either a LAN cable or an optical fiber cable, or a combination of these, can be used as the communication cable 42, and a commonly used mode is to lay an optical fiber cable up to the mine entrance and a LAN cable inside the mine.

[0076] When PHS (registered trademark, hereinafter the same: Personal Handy-phone System) terminals 46 are used inside the tunnel, PHS repeaters 45 are installed at intervals of approximately 100 to 300 m.

[0077] In addition, when establishing communications in a location where LAN cables cannot be laid, such as near the working face S, a specific low-power repeater 47 is installed and communication is carried out via radio waves with a device 48 that transmits and receives data at specific low power.

[0078] (Usage example 3) FIG. 12 shows an example of using the radio wave shielding device 1 when using an underground radar system 50 during tunnel construction.

[0079] In the past, elastic wave exploration methods and boring surveys were widely used to investigate the geological conditions of the ground where a tunnel is to be excavated, but there were limitations to the detailed geological investigations they could perform. For this reason, ground-penetrating radar methods are beginning to be put into practical use. This method involves emitting microwaves (electromagnetic waves) from the tunnel face S forward and receiving the microwaves that are reflected by cavities, cracks, the groundwater table, etc. to investigate the geological conditions. This ground-penetrating radar method can measure the geological conditions not only in front of the tunnel face S, but also around the tunnel, making it effective for investigating the integrity of the tunnel.

[0080] In order to expand the exploration range in geological surveys using the underground radar method, it is effective to increase the output of the microwaves irradiated onto the ground. However, these microwaves may leak out of the tunnel and cause communication problems for surrounding mobile phones or affect aircraft radar, so radio wave shielding by the radio wave shielding device 1 of the present invention is necessary.

[0081] As shown in Figure 12, the underground radar system 50 used in the underground radar method has a built-in transmitter / receiver circuit 51 that transmits and receives microwaves, and microwaves 53 are irradiated toward the ground from an antenna 52 provided at the front, and microwaves reflected by cavities 54 in the ground are received by the antenna 52, making it possible to measure the position and size of underground cavities 54, etc.

[0082] In order to prevent microwaves irradiated to the ground by the underground radar system 50 from being reflected inside the tunnel and emitting radio waves outside the tunnel from the tunnel entrance, measures can be taken to install the radio wave shielding door 2 at the tunnel entrance.

[0083] (Usage example 4) FIG. 13 shows an example of using the radio wave shielding device 1 when measuring the moisture content and pore water in various parts of a tunnel using a microwave moisture meter 55 during tunnel construction.

[0084] Conventionally, in civil engineering works, devices have been put to practical use to measure moisture content by using radioisotopes that emit neutrons and radioisotopes that emit gamma rays, and measuring moisture content based on the difference in their absorption ratios. However, handling these devices, including for radiation exposure management, has been extremely time-consuming. In contrast, microwave moisture meters 55, which use microwaves, can perform measurements without using radioisotopes and are therefore easy to use. However, to achieve a sufficient search range, powerful microwaves must be irradiated, which necessitates radio wave shielding by the radio wave shielding device 1 of the present invention.

[0085] As shown in Figure 13, the microwave moisture meter 55 has a built-in transmitter / receiver circuit 56 that transmits and receives microwaves, and microwaves 58 are irradiated toward the ground from an antenna 57 provided at the front, and microwaves 60 reflected from particularly high-moisture areas 59 in the ground or water veins are received by the antenna 57, making it possible to measure the position and size of high-moisture areas 59, etc.

[0086] In order to prevent microwaves irradiated to the ground by the microwave moisture meter 55 from being reflected inside the tunnel and emitting radio waves outside the tunnel from the tunnel entrance, measures can be taken to install the radio wave shielding door 2 at the tunnel entrance.

[0087] (Usage example 5) FIG. 14 shows an example of using the radio wave shielding device 1 when a microwave measuring device 62 is used to manage the lining concrete 61.

[0088] Traditionally, pouring concrete for lining has required improvements such as increasing the fluidity of the concrete used to pour it, in order to prevent air bubbles and incomplete filling of the concrete. Furthermore, the concrete was carefully poured by vibrating it with a vibrator during pouring to prevent air bubbles and unfilled areas from remaining inside the poured concrete. Inspecting internal defects during pouring has drawbacks: concrete is not optically transparent, making it impossible to inspect, and unhardened concrete has poor ultrasonic reflection characteristics, making it impossible to inspect using ultrasonic waves. Therefore, a microwave measuring device 62 is effective for detecting the thickness and internal defects of the lining concrete by irradiating short-wavelength electromagnetic waves such as microwaves from the outer surface of the formwork 63 using materials that transmit radio waves, such as wood or FRP, and measuring the reflected waves.

[0089] In order to improve the accuracy of detecting internal defects and to obtain a sufficient inspection range, it is necessary to irradiate a powerful microwave, and therefore it is necessary to shield the radio waves by the radio wave shielding device 1 according to the present invention.

[0090] As shown in Figure 14, the microwave measuring device 62 has a built-in transmitting and receiving circuit 64 that transmits and receives microwaves, and microwaves 66 are irradiated from an antenna 65 provided at the front toward the formwork 63, and microwaves 68 reflected by voids 67 and low-density areas in the covering concrete 61 are received by the antenna 65, making it possible to measure the position and size of voids 67, etc.

[0091] Inspection of the covering concrete 61 using the microwave measuring device 62 can be carried out even when the concrete is in a fluid state before it hardens, so after detecting voids 67, etc. using the microwave measuring device 62, it is possible to take measures to remove the voids 67 by applying additional vibration or pressure.

[0092] In order to prevent the microwaves irradiated by the microwave measuring device 62 from being reflected inside the tunnel and causing radio waves to be emitted outside the tunnel from the tunnel entrance, it is necessary to block radio waves using the radio wave shielding device 1 of the present invention.

[0093] (Usage example 6) FIG. 15 shows an example of using the radio wave shielding device 1 when using a remote-controlled heavy machine 70.

[0094] It is important that the control radio waves of the remotely operated heavy equipment 70 are not interrupted under any circumstances. In the case of specified low-power communication such as Wi-Fi, if a large object such as another heavy equipment exists between the radio wave source and the heavy equipment, the radio waves from the source may be blocked midway, resulting in poor communication. For this reason, it is necessary to use a dedicated control communication device rather than specified low-power communication such as Wi-Fi. In order to ensure communication stability, high-power radio waves may be transmitted, so radio wave shielding by the radio wave shielding device 1 of the present invention is necessary. [Explanation of symbols]

[0095] 1...radio wave shielding device, 2...radio wave shielding door, 3...frame, 4...earth, 5...hinge, 6...bonding wire, 7...lattice, 8...receiving plate, 9...shielding material, 10...shielding curtain, 11...opening / closing detection mechanism, 12...interlock device, 13...radio wave generating device, 14...radio wave emitting antenna, 15...radio wave level measuring device, 16...radio wave receiving antenna, 20...tunnel ventilation duct, 21...radio wave shielding shield, 22...shutter structure, 23...bending portion

Claims

1. A radio wave shielding device installed in a tunnel during tunnel construction, The radio wave shielding device for tunnel construction is characterized in that it consists of a radio wave shielding body having a radio wave shielding effect that is installed so as to separate the tunnel interior in the axial direction.

2. 2. The radio wave shielding device for tunnel construction according to claim 1, wherein the radio wave shielding body includes a radio wave shielding door installed at the entrance of the tunnel.

3. 2. The radio wave shielding device for tunnel construction according to claim 1, wherein the radio wave shielding body includes a radio wave shielding curtain installed in the tunnel.

4. A radio wave shielding device for tunnel construction as described in claim 1, wherein a radio wave shielding shield having radio wave shielding effect and breathability is arranged within the flow path of the tunnel ventilation duct so as to separate the flow path in the axial direction.

5. 2. A radio wave shielding device for tunnel construction according to claim 1, wherein a bent portion is provided midway along the flow path of the tunnel ventilation duct so that the flow path does not proceed in a straight line.

6. A radio wave shielding method for tunnel construction, characterized in that a radio wave shielding body having a radio wave shielding effect is installed within the tunnel during tunnel construction, dividing the tunnel interior in the axial direction.

7. 7. A radio wave shielding method for tunnel construction according to claim 6, wherein a radio wave shielding shield having radio wave shielding effect and air permeability is arranged within the flow path of the tunnel ventilation duct so as to separate the flow path in the axial direction.

8. 7. A radio wave shielding method for tunnel construction according to claim 6, wherein a bent portion is provided midway along the flow path of the tunnel ventilation duct so that the flow path does not proceed in a straight line.

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