Method for controlling frozen soil thickness, frozen soil thickness control system, and temperature measuring pipe

Abstract

To provide a frozen soil thickness control method, a frozen soil thickness control system, and a temperature measuring tube capable of suppressing excessive freezing in a predetermined range of frozen soil.SOLUTION: A frozen soil thickness control system 2 comprising a freezing tube 3 installed on the ground 1, a freezing device 4 that circulates a freezing refrigerant in the freezing tube 3, an electromagnetic wave generator 5, and a plurality of antennas 6 for irradiating the ground 1 spaced apart from the freezing tube 3 by a predetermined distance with electromagnetic waves generated by the electromagnetic wave generator 5, is formed in the ground 1. Also, a temperature measuring tube 7 capable of measuring the thickness of a frozen soil 8 and emitting electromagnetic waves is installed on the ground 1. The temperature measuring tube 7 has a temperature sensor 11 for temperature measurement and the antenna 6 for irradiating electromagnetic waves arranged inside a tubular body 10. Electromagnetic waves generated by the electromagnetic wave generator 5 are applied to the ground 1 to heat the vicinity of a target formation surface 15 of the frozen soil 8, thereby suppressing the growth of the frozen soil 8 beyond the target formation surface 15.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for controlling frozen soil thickness, a system for controlling frozen soil thickness, and a temperature measuring tube. [Background technology]

[0002] Conventionally, frozen soil created by freezing methods has been used to maintain the strength and watertightness of the ground. In freezing methods, a freezing refrigerant such as a coolant or liquefied carbon dioxide is circulated through freezing pipes placed at intervals in the ground, freezing the ground around the pipes, creating frozen soil.

[0003] During the creation and operation of frozen soil, the formation status of frozen soil is managed by measuring the underground temperature using thermometer pipes buried around the freezing pipes. For example, if excessive freezing occurs in the ground, there is a risk of ground heaving due to excessive freezing and ground subsidence when thawing. Therefore, to prevent excessive freezing of the ground, there are methods such as switching the flow rate or temperature of the freezing refrigerant based on the temperature measured by the thermometer pipes, or operating the freezing pipes in a thinned or intermittent manner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-108766 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above methods are not effective enough to prevent excessive freezing when used alone. Furthermore, although there are methods that combine thinning operation and temperature switching, it is difficult to accurately prevent excessive freezing within a specified range of the frozen soil.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a method for controlling frozen soil thickness, a frozen soil thickness control system, and a temperature measuring tube that can suppress excessive freezing within a specified range of frozen soil. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the first invention is a method for controlling the thickness of frozen soil formed on the ground, in which the vicinity of a target formation surface of the frozen soil is heated by a heating device, and the frozen soil is prevented from growing beyond the target formation surface of the frozen soil. the heating device is an electromagnetic wave generator, and irradiates electromagnetic waves near the target formation surface of the frozen soil to form an electromagnetic wave irradiation area so as to cover a predetermined range of the target formation surface of the frozen soil, and by raising the temperature of the ground in the electromagnetic wave irradiation area, the growth of the frozen soil in the predetermined range is suppressed; multiple antennas connected to the electromagnetic wave generator are inserted into the ground at predetermined intervals, and the electromagnetic waves are irradiated from the antennas in a direction at least approximately parallel to the target formation surface of the frozen soil; a temperature measuring tube for measuring the thickness of the frozen soil is arranged in a direction that penetrates the target formation surface of the frozen soil; the antenna is arranged inside the temperature measuring tube, and the electromagnetic waves are irradiated from the temperature measuring tube midway along the temperature measuring tube. This is a method for controlling frozen soil thickness.

[0008] In the first aspect of the present invention, by using a heating device to heat the vicinity of the target formation surface of the frozen soil, it is possible to prevent overfreezing, in which the frozen soil grows beyond the target formation surface.

[0009] In the first invention, The heating device is an electromagnetic wave generating device, and irradiates electromagnetic waves near the target formation surface of the frozen soil to form an electromagnetic wave irradiation area so as to cover a predetermined range of the target formation surface of the frozen soil, and by raising the temperature of the ground in the electromagnetic wave irradiation area, the growth of the frozen soil in the predetermined range is suppressed. 。 By irradiating a predetermined area of ​​the target formation surface of the frozen soil with electromagnetic waves to raise the temperature of the ground, it is possible to prevent excessive freezing of the ground in the electromagnetic wave irradiated area.

[0010] In the first invention, A plurality of antennas connected to the electromagnetic wave generator are inserted into the ground at predetermined intervals, and the electromagnetic waves are irradiated from the antennas in a direction substantially parallel to at least the target formation surface of the frozen soil. 。 By using an antenna, it is possible to form an electromagnetic wave irradiation area by propagating electromagnetic waves within the ground while minimizing the attenuation of electromagnetic wave energy. Furthermore, a temperature measuring tube that measures the thickness of the frozen soil is positioned in a direction that penetrates the target formation surface of the frozen soil, the antenna is positioned inside the temperature measuring tube, and the electromagnetic waves are irradiated from the temperature measuring tube midway along the temperature measuring tube. The use of a temperature measuring tube makes it easier to position the antenna and allows electromagnetic waves to be emitted in the desired direction while measuring the thickness of the frozen soil.

[0011] The antenna may be, for example, a ground plane antenna or a waveguide antenna. These antennas allow for highly controlled direction of electromagnetic waves.

[0013] The frozen soil may be formed on the outer periphery of an underground tunnel, and the temperature measuring pipe may be disposed relative to the ground from inside the underground tunnel. The frozen soil may be a frozen soil wall formed underground, and the antenna may be disposed relative to the ground from above ground. This allows for control of the thickness of the frozen soil surrounding the underground tunnel and the frozen soil walls that form underground.

[0014] The electromagnetic waves are controlled based on temperature information obtained by the temperature measuring tube, and when the temperature information determines that the frozen soil is growing beyond the target formation surface of the frozen soil, the electromagnetic waves are irradiated for a predetermined period of time, and after the predetermined period of time has elapsed, or when the temperature information determines that the frozen soil that has exceeded the target formation surface of the frozen soil has disappeared, it is desirable to stop the electromagnetic waves. This makes it possible to efficiently prevent excessive freezing of the ground.

[0015] The electromagnetic waves may be continuously irradiated to the vicinity of the target formation surface of the frozen soil, thereby preventing the frozen soil from growing beyond the target formation surface of the frozen soil. This makes it easy to prevent excessive freezing of the ground.

[0016] The second invention is a method for controlling the thickness of frozen soil formed on the ground, comprising heating an area near a target formation surface of the frozen soil with a heating device to prevent the frozen soil from growing beyond the target formation surface of the frozen soil, the heating device being an electromagnetic wave generating device that irradiates electromagnetic waves near the target formation surface of the frozen soil to form an electromagnetic wave irradiation area that covers a predetermined range of the target formation surface of the frozen soil, and raising the temperature of the ground in the electromagnetic wave irradiation area to prevent the growth of the frozen soil in the predetermined range, irradiating the electromagnetic waves from at least two separated positions, and controlling the phase of the electromagnetic waves so that the position where the electromagnetic waves interfere constructively is near the target formation surface of the frozen soil. No. 3 The invention is a control system for the thickness of frozen soil formed in the ground, comprising a freezing pipe installed in the ground, a freezing device that circulates a freezing refrigerant in the freezing pipe, an electromagnetic wave generator, and a plurality of antennas that irradiate the electromagnetic waves generated from the electromagnetic wave generator onto the ground at a predetermined distance from the freezing pipe. The electromagnetic waves are irradiated from at least two separate positions so that the electromagnetic waves interfere with each other constructively, thereby forming an electromagnetic wave irradiation region where the electromagnetic waves interfere with each other constructively. This is a frozen soil thickness control system characterized by the following.

[0017] No. 3In the invention, by using an antenna to irradiate electromagnetic waves onto the ground at a predetermined distance from the freezing pipe, it is possible to prevent excessive freezing of the ground and control the thickness of frozen soil.

[0018] No. 4 The invention is a temperature measuring tube that can measure frozen soil thickness and irradiate electromagnetic waves, characterized in that a temperature sensor for temperature measurement and an antenna for irradiating electromagnetic waves are arranged inside the tube body, a window portion through which the electromagnetic waves are irradiated is formed near the tip of the antenna in the tube body, and an electromagnetic wave reflector is arranged on the tip side of the window portion, and the electromagnetic waves irradiated from the antenna are reflected by the reflector and irradiated from the window portion to the outside of the tube body.

[0019] No. 4 By using the temperature measuring tube of the present invention, a temperature sensor and an antenna are placed inside the tube body, so that the frozen soil thickness can be measured while irradiating electromagnetic waves in the desired direction. [Effects of the Invention]

[0020] According to the present invention, a method for controlling frozen soil thickness, a system for controlling frozen soil thickness, and a temperature measuring tube can be provided that can suppress excessive freezing within a predetermined range of frozen soil. [Brief explanation of the drawings]

[0021] [Figure 1] A diagram showing the vicinity of the widened section 17 of the tunnel 9. [Figure 2] A diagram showing a cross section of the tunnel 9 and frozen soil 8. [Figure 3] 1 is a diagram showing an overview of the frozen soil thickness control system 2. [Figure 4] FIG. 2 is a diagram showing a cross section near the tip of the temperature measuring pipe 7. [Figure 5] FIG. 2 is a diagram showing a cross section near the tip of the temperature measuring pipe 7. [Figure 6] A diagram showing a cross section along a target formation surface 15 of frozen soil 8. [Figure 7] A diagram showing the state in which the growth of permafrost 8 is not inhibited. [Figure 8]FIG. 10 is a diagram showing an example in which a frozen soil thickness control system 2a is applied to a frozen soil wall 8a. [Figure 9] A diagram showing an overview of the frozen soil thickness control system 2b. [Figure 10] A diagram showing an overview of the frozen soil thickness control system 2c. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0023] [First embodiment] Fig. 1 is a diagram showing the vicinity of the widening section 17 of the tunnel 9, and Fig. 2 is a diagram showing a cross section of the tunnel 9 and frozen soil 8 before the widening section 17 is constructed. Fig. 3 is a diagram showing an overview of the frozen soil thickness control system 2, and is an enlarged view of the area A shown in Fig. 2.

[0024] To construct the branch section of tunnel 9 shown in Fig. 1 , tunnel 9 is constructed in ground 1, and frozen soil 8 is formed in the ground 1 around tunnel 9. Then, with the ground 1 around tunnel 9 reinforced with frozen soil 8, the frozen soil 8 is excavated from within tunnel 9 to construct widened section 17, and branch tunnel 18 is constructed from widened section 17. In the first embodiment, a system and method for controlling the thickness of frozen soil 8 formed around the outer periphery of tunnel 9 when constructing widened section 17 and branch tunnel 18 will be described.

[0025] As shown in Figures 2 and 3, the frozen soil thickness control system 2 is composed of freezing pipes 3, freezing devices 4, electromagnetic wave generators 5, antennas 6, and temperature measuring pipes 7. The freezing pipes 3 are installed at intervals around the periphery of a tunnel 9 constructed in the ground 1, and the freezing devices 4 are connected to the freezing pipes 3. Frozen soil 8 around the tunnel 9 is formed by circulating a freezing refrigerant through the freezing pipes 3 using the freezing devices 4. Multiple temperature measuring pipes 7 are installed in a direction that penetrates from the inside of the tunnel 9 through a target formation surface 15 of the frozen soil 8. The temperature measuring pipes 7 are installed toward the ground 1 in a predetermined range 16 on at least the upper half of the tunnel 9, which is the target for controlling the thickness of the frozen soil 8, and measure the thickness of the frozen soil 8.

[0026] The antenna 6 is disposed within the temperature measuring tube 7 and irradiates the electromagnetic waves generated by the electromagnetic wave generator 5 onto the ground 1, which is located a predetermined distance from the freezing tube 3. The electromagnetic waves generated by the electromagnetic wave generator 5 are, for example, microwaves with a frequency of 300 MHz to 300 GHz. Microwaves generate thermal energy by directly exciting the molecules of a substance, thereby raising the temperature. The frequency of the microwaves irradiated onto the ground 1 is selectively selected from a band in which energy absorption by water is high, with 0.9 to 6 GHz being particularly desirable. By irradiating microwaves of such a frequency onto the ground 1 containing water, the ground 1 is efficiently heated. In other words, the electromagnetic wave generator 5 functions as a heating device that heats the ground.

[0027] 4 and 5 are diagrams showing a cross section near the tip of the temperature measuring pipe 7, with Fig. 4 being an enlarged view of range B shown in Fig. 3, and Fig. 5 being a cross section taken along arrow CC shown in Fig. 3. Fig. 6 is a diagram showing a cross section along the target formation surface 15 of the frozen soil 8.

[0028] As shown in Figures 4 and 5, the temperature measuring pipe 7 is a double pipe, with a waveguide antenna 6 placed inside a steel pipe body 10, and a temperature sensor 11 for measuring temperature placed in the space between the pipe body 10 and the antenna 6. The temperature sensors 11 are placed at multiple locations at intervals along the extension direction of the pipe body 10, and acquire temperature information from each location. The temperature measuring pipe 7 measures the thickness of the frozen soil 8 by determining the position where the temperature of the ground 1 is 0 degrees (the boundary position between the frozen soil 8 and the unfrozen ground 1) from the temperature information acquired by each temperature sensor 11. Note that optical fiber sensors may be used as the temperature sensors 11 to acquire the temperature distribution along the extension direction of the pipe body 10.

[0029] The antenna 6 is used to radiate electromagnetic waves. A window 12 is formed in the tubular body 10 near the tip 21 of the antenna 6. The window 12 is made of a material such as fluororesin that allows electromagnetic waves to pass through without attenuation. A reflector 13 for the electromagnetic waves is arranged on the tip 22 side of the window 12. The reflector 13 is, for example, conical in shape, and the electromagnetic waves radiated from the antenna 6 are reflected by the reflector 13 and radiated from the window 12 to the outside of the tubular body 10, as shown by the arrow in Figure 4.

[0030] As shown in FIG. 4, the temperature measuring pipe 7 is placed in the ground 1 so that the window portion 12 is located at the target formation surface 15 of the frozen soil 8. The angle of the reflecting surface of the reflecting portion 13 is set so that the electromagnetic waves from the antenna 6 are irradiated in a direction approximately parallel to the target formation surface 15 of the frozen soil 8. As shown in FIG. 5, the windows 12 are formed at intervals around the circumferential direction of the pipe body 10. The electromagnetic waves irradiated from the multiple windows 12 form an electromagnetic wave irradiation area 14 approximately centered on the temperature measuring pipe 7. As shown in FIG. 6, the multiple temperature measuring pipes 7 are arranged, for example, so that the positions at which they penetrate the target formation surface 15 of the frozen soil 8 are staggered. This allows the electromagnetic wave irradiation area 14 to be formed along the target formation surface 15 without any gaps.

[0031] The frozen soil thickness control system 2 shown in Fig. 2 and other figures measures the thickness of the frozen soil 8 from temperature information acquired by a temperature sensor 11 in a temperature measuring pipe 7 in a predetermined range 16 targeted for controlling the thickness of the frozen soil 8 during the formation of the frozen soil 8 or during operation. Furthermore, electromagnetic waves are continuously emitted from an antenna 6 in the temperature measuring pipe 7 through a window 12 in a direction substantially parallel to a target formation surface 15 of the frozen soil 8, forming an electromagnetic wave irradiation region 14 that covers the predetermined range 16 of the target formation surface 15 of the frozen soil 8. In the electromagnetic wave irradiation region 14, the temperature of the ground 1 rises, and the growth of the frozen soil 8 beyond the target formation surface 15 is suppressed.

[0032] Thus, according to the first embodiment, by forming an electromagnetic wave irradiation area 14 to cover a predetermined range 16 of the target formation surface 15 of the frozen soil 8 and raising the temperature of the ground 1, it is possible to prevent excessive freezing of the ground 1. Furthermore, by using the antenna 6, it is possible to precisely control the direction of the electromagnetic waves and propagate the electromagnetic waves into the ground 1 while minimizing energy attenuation, thereby forming the electromagnetic wave irradiation area 14. This makes it possible to maintain a 0-degree boundary area (the boundary area between the frozen soil 8 and the unfrozen ground 1) in any range of the ground 1 and precisely control the thickness of the frozen soil 8. In this case, unlike control using intermittent operation, thinning operation, temperature switching, etc., the freezing capacity for frozen soil formation is not reduced, and the frozen soil formation capacity can be sufficiently maintained.

[0033] In the first embodiment, the antenna 6 is disposed inside the temperature measuring pipe 7, which allows the antenna 6 to be easily installed in the ground 1. Furthermore, the temperature measuring pipe 7 can measure the thickness of the frozen soil 8 while irradiating electromagnetic waves onto the ground 1. In the first embodiment, by continuously irradiating electromagnetic waves when the frozen soil 8 is formed or during operation, excessive freezing of the ground 1 can be easily and reliably suppressed.

[0034] The antenna 6 does not have to be a waveguide type, and other types of antennas such as a coaxial cable or ground plane type may be arranged inside the tube body 10 of the temperature measuring tube 7. Also, the single-tube tube body 10 may be used as a waveguide and as both a temperature measuring tube and an antenna.

[0035] In the first embodiment, the range 16 for controlling the thickness of the frozen soil 8 was limited to the upper half of the tunnel 9, but the range is not limited to this and is set according to various conditions such as the surrounding environment of the site and the properties of the ground 1.

[0036] Other examples of the present invention will be described below as second to fifth embodiments. Each embodiment will be described by focusing on differences from the previously described embodiments, and similar configurations will be denoted by the same reference numerals in the drawings and will not be described again. Furthermore, the configurations described in each embodiment, including the first embodiment, can be combined as necessary.

[0037] [Second embodiment] The second embodiment uses a frozen soil thickness control system 2 similar to that of the first embodiment, but the method of controlling electromagnetic waves is different. Figure 7 is a diagram showing a state in which the growth of frozen soil 8 is not suppressed in range B of Figure 3.

[0038] In the second embodiment, frozen soil 8 is formed without irradiating electromagnetic waves from antenna 6, and the thickness of frozen soil 8 is measured from temperature information acquired by temperature sensor 11 in temperature measuring pipe 7. Then, if it is determined from the temperature information that frozen soil 8 has grown beyond target formation surface 15 as shown in FIG. 7, electromagnetic waves are irradiated from antenna 6 in temperature measuring pipe 7, forming electromagnetic wave irradiation area 14 (FIG. 4) so ​​as to cover a predetermined area of ​​target formation surface 15 of frozen soil 8, thereby raising the temperature of ground 1 in electromagnetic wave irradiation area 14. Thereafter, if it is determined from the temperature information acquired by temperature sensor 11 that frozen soil 8 beyond target formation surface 15 has disappeared as shown in FIG. 4, irradiation of electromagnetic waves from antenna 6 is stopped. The growth of frozen soil 8 beyond target formation surface 15 is suppressed in a similar manner during frozen soil 8 operation.

[0039] In this way, in the second embodiment, excessive freezing of the ground 1 can be efficiently suppressed by starting and stopping the irradiation of electromagnetic waves from the antenna 6 based on the temperature information obtained from the temperature measuring tube 7.

[0040] In the second embodiment, the radiation of electromagnetic waves from the antenna 6 is stopped based on the temperature information acquired by the temperature sensor 11, but the radiation of electromagnetic waves may also be stopped based on the elapsed time since the radiation of electromagnetic waves began.

[0041] [Third embodiment] Figure 8 is a diagram showing an example in which the frozen soil thickness control system 2a is applied to a frozen soil wall 8a. Figure 8(a) is a perspective view of a vertical cross section of the frozen soil wall 8a, and Figure 8(b) is a diagram showing an overview of the frozen soil thickness control system 2a. The third embodiment differs from the first embodiment mainly in that the frozen soil thickness of the frozen soil wall 8a is controlled.

[0042] As shown in Figure 8, the frozen soil thickness control system 2a is composed of freezing pipes 3a, freezing devices 4, electromagnetic wave generators 5, antennas 6a, etc. The freezing pipes 3a are installed horizontally at intervals in a substantially vertical direction within the ground 1. The frozen soil wall 8a is formed in a wall-like shape within the ground 1 by circulating a freezing refrigerant through the freezing pipes 3a using freezing devices 4. The antennas 6a are, for example, coaxial cables, and multiple antennas are arranged from the ground surface to the ground 1. The antennas 6a are installed facing the ground 1 within a predetermined range 16a on one side that is to be controlled for the thickness of the frozen soil wall 8a, and form an electromagnetic wave irradiation area approximately centered on the antenna 6a.

[0043] During the formation of the frozen soil wall 8a or during operation, the frozen soil thickness control system 2a irradiates electromagnetic waves from the antenna 6a in a direction substantially parallel to the target formation surface 15 of the frozen soil wall 8a in a predetermined range 16a on the target formation surface 15, the target range 16a being the target for controlling the thickness of the frozen soil wall 8a, to form an electromagnetic wave irradiation region 14 that covers the predetermined range 16a. In the electromagnetic wave irradiation region 14, the temperature of the ground 1 rises, preventing the frozen soil wall 8a from growing beyond the target formation surface 15. The electromagnetic waves may be irradiated continuously, as in the first embodiment, or may be controlled based on temperature information from a temperature measuring tube (not shown), as in the second embodiment.

[0044] In this way, also in the third embodiment, by forming the electromagnetic wave irradiation area 14 so as to cover a predetermined range 16a of the target formation surface 15 of the frozen soil wall 8a and raising the temperature of the ground 1, it is possible to prevent excessive freezing of the ground 1. Furthermore, by using the antenna 6a, it is possible to highly control the irradiation direction of the electromagnetic waves and to form the electromagnetic wave irradiation area 14 by propagating the electromagnetic waves within the ground 1 while minimizing energy attenuation.

[0045] 8, multiple antennas 6a are placed bent into the ground 1, but multiple antennas may also be placed approximately vertically along the target formation surface 15 of the frozen soil wall 8a. In this case, electromagnetic waves are irradiated from the antennas in two directions (toward the front and the back of the page) approximately parallel to the target formation surface 15 of the frozen soil wall 8a, and an electromagnetic wave irradiation area 14 is formed so as to cover a predetermined range 16a of the target formation surface 15 of the frozen soil wall 8a.

[0046] [Fourth embodiment] Fig. 9 is a diagram showing an overview of a frozen soil thickness control system 2b. Fig. 9 corresponds to the cross section shown in Fig. 3 in the first embodiment. The fourth embodiment differs from the first embodiment mainly in that the frozen soil thickness is controlled using a frozen soil thickness control system 2b that does not install an antenna on the ground 1.

[0047] As shown in Figure 9, frozen soil thickness control system 2b is composed of a freezing pipe 3, a freezing device 4, an electromagnetic wave generator 5, a window 12a, etc. Window 12a is made of a material such as fluororesin that allows electromagnetic waves to pass through without attenuation, and is formed in the lining of tunnel 9. Window 12a irradiates electromagnetic waves generated by electromagnetic wave generator 5 onto ground 1.

[0048] In the frozen soil thickness control system 2b, electromagnetic waves generated by the electromagnetic wave generator 5 are irradiated from the window 12a toward the target formation surface 15 of the frozen soil 8 in the ground 1 during the formation of the frozen soil 8 or during operation. The phase of the electromagnetic waves is controlled so that the position where the electromagnetic waves irradiated from at least two windows 12a interfere constructively is located near the target formation surface 15 of the frozen soil 8. This forms an electromagnetic wave irradiation region 14a where the electromagnetic waves constructively interfere with each other, covering a predetermined area of ​​the target formation surface 15 of the frozen soil 8. In the electromagnetic wave irradiation region 14a, the temperature of the ground 1 rises, preventing the frozen soil 8 from growing beyond the target formation surface 15. The electromagnetic waves may be continuously irradiated as in the first embodiment, or may be controlled based on temperature information from a temperature measuring tube (not shown) as in the second embodiment.

[0049] In this way, in the fourth embodiment, excessive freezing of the ground 1 can be prevented by forming an electromagnetic wave irradiation area 14a to cover a predetermined range of the target formation surface 15 of the frozen soil 8 and raising the temperature of the ground 1.

[0050] [Fifth embodiment] Fig. 10 is a diagram showing an overview of a frozen soil thickness control system 2c. Fig. 10 corresponds to the cross section shown in Fig. 2 in the first embodiment. The fifth embodiment differs from the first embodiment mainly in that frozen soil thickness is controlled using a frozen soil thickness control system 2c that does not have an electromagnetic wave generator.

[0051] As shown in Figure 10, the frozen soil thickness control system 2c is composed of a freezing pipe 3, a freezing device 4, a pipe 19, a heating device 20, etc. The pipe 19 is arranged in a direction that penetrates the target formation surface 15 of the frozen soil 8, and may also serve as a temperature measuring pipe. The heating device 20 is, for example, a heater, and is arranged near the tip of the pipe 19.

[0052] In the frozen soil thickness control system 2c, when frozen soil 8 is formed or during operation, a heating device 20 heats the portion of the pipe body 19 located near the target formation surface 15 of the frozen soil 8, thereby raising the temperature of the ground 1 near the target formation surface 15 and suppressing the growth of the frozen soil 8.

[0053] In this way, in the fifth embodiment, by heating the vicinity of the target formation surface 15 of the frozen soil 8 with the heating device 20, it is possible to prevent the ground 1 from being over-freezed.

[0054] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas disclosed in this application, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0055] 1……ground 2, 2a, 2b, 2c...Frozen soil thickness control system 3, 3a……Freezing tube 4……Freezing device 5...Electromagnetic wave generator 6, 6a... Antenna 7……Temperature tube 8...Frozen soil 8a……Frozen earth wall 9...Tunnel 10...Tube body 11...Temperature sensor 12, 12a...Window section 13……Reflector 14, 14a……Electromagnetic wave irradiation area 15……Goal formation aspect 16, 16a...range 17………Wide section 18...Branch tunnel 19...Tube body 20……Heating device 21……Tip 22...Tip

Claims

1. A method for controlling frozen soil thickness formed on the ground, comprising: Heating the vicinity of the target formation surface of the frozen soil with a heating device to prevent the frozen soil from growing beyond the target formation surface of the frozen soil; the heating device is an electromagnetic wave generating device, and irradiates electromagnetic waves near the target formation surface of the frozen soil to form an electromagnetic wave irradiation area so as to cover a predetermined range of the target formation surface of the frozen soil, and by increasing the temperature of the ground in the electromagnetic wave irradiation area, the growth of the frozen soil in the predetermined range is suppressed; Inserting a plurality of antennas connected to the electromagnetic wave generator into the ground at predetermined intervals, and irradiating the electromagnetic waves from the antennas in a direction substantially parallel to at least the target formation surface of the frozen soil; A method for controlling frozen soil thickness, characterized in that a temperature measuring tube for measuring the thickness of the frozen soil is arranged in a direction that penetrates the target formation surface of the frozen soil, the antenna is arranged inside the temperature measuring tube, and the electromagnetic waves are irradiated from the temperature measuring tube midway along the temperature measuring tube.

2. 2. The method for controlling frozen soil thickness according to claim 1, wherein the antenna is a ground plane antenna or a waveguide antenna.

3. The frozen soil is formed on the outer periphery of the underground tunnel, 2. The method for controlling frozen soil thickness according to claim 1, wherein the temperature measuring pipe is disposed in relation to the ground from inside the underground tunnel.

4. The frozen soil is a frozen soil wall formed underground, 3. The method for controlling frozen soil thickness according to claim 1, wherein the antenna is disposed on the ground from above.

5. the electromagnetic waves are controlled based on temperature information obtained by the temperature measuring tube; When it is determined based on the temperature information that the frozen soil has grown beyond the target formation surface of the frozen soil, the electromagnetic waves are irradiated for a predetermined period of time, A method for controlling frozen soil thickness as described in claim 1, characterized in that the electromagnetic waves are stopped after a predetermined time has passed or when the temperature information determines that the frozen soil beyond the target formation surface of the frozen soil has disappeared.

6. A method for controlling frozen soil thickness according to claim 1, characterized in that the electromagnetic waves are continuously irradiated near the target formation surface of the frozen soil, thereby preventing the frozen soil from growing beyond the target formation surface of the frozen soil.

7. A method for controlling frozen soil thickness formed on the ground, comprising: Heating the vicinity of the target formation surface of the frozen soil with a heating device to prevent the frozen soil from growing beyond the target formation surface of the frozen soil; the heating device is an electromagnetic wave generating device, and irradiates electromagnetic waves near the target formation surface of the frozen soil to form an electromagnetic wave irradiation area so as to cover a predetermined range of the target formation surface of the frozen soil, and by increasing the temperature of the ground in the electromagnetic wave irradiation area, the growth of the frozen soil in the predetermined range is suppressed; A method for controlling frozen soil thickness, characterized by irradiating the electromagnetic waves from at least two separated positions and controlling the phase of the electromagnetic waves so that the position where the electromagnetic waves interfere and reinforce each other is near the target formation surface of the frozen soil.

8. A control system for frozen soil thickness formed on the ground, a freezing pipe installed in the ground; a freezing device that circulates a freezing refrigerant through the freezing tube; An electromagnetic wave generator; a plurality of antennas that irradiate the electromagnetic waves generated by the electromagnetic wave generating device onto the ground at a predetermined distance from the freezing tube; Equipped with A frozen soil thickness control system characterized by being capable of irradiating electromagnetic waves from at least two separated positions so that the electromagnetic waves interfere with each other and reinforce each other, thereby forming an electromagnetic wave irradiation area where the electromagnetic waves interfere with each other and reinforce each other.

9. A temperature measuring tube that can measure frozen soil thickness and irradiate electromagnetic waves, A temperature sensor for measuring temperature and an antenna for irradiating electromagnetic waves are placed inside the tube. a window portion through which electromagnetic waves are irradiated is formed in the tubular body near the tip of the antenna, an electromagnetic wave reflector is disposed on the tip side of the window; A temperature measuring tube characterized in that electromagnetic waves radiated from the antenna are reflected by the reflecting portion and radiated to the outside of the tube body through the window portion.

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