Coaxial waveguide multi-point deformation sensor in rock-soil and variable gauge length measurement method

Abstract

The application discloses a coaxial waveguide rock-soil internal multipoint deformation sensor and a variable gauge length measuring method. The coaxial waveguide rock-soil internal multipoint deformation sensor comprises an outer conductor, which is hollow inside and open at both ends; a metal support frame, which is arranged in the outer conductor, each metal support frame is sequentially and spacedly arranged along the axial direction of the outer conductor, and a through hole is arranged on each metal support frame; an inner conductor, which is arranged in the outer conductor, penetrates through the through holes of each metal support frame and is in contact with each through hole; and a magnetic ring, each magnetic ring is arranged on the outer conductor and can move relative to the outer conductor and drive the nearest metal support frame to move. The application is provided with a plurality of metal support frames, each metal support frame is a reflection point, a sensing gauge length can be formed between each two metal support frames, the deformation of a layer position where the sensing gauge length is located can be obtained by acquiring the change of interference spectrum signals of different sensing gauge lengths, and thus the deformation condition of an arbitrary layer position can be obtained according to requirements.

Description

Technical Field

[0001] This application relates to the field of soil and rock deformation monitoring technology, and in particular to a coaxial waveguide multi-point deformation sensor inside soil and rock and a variable gauge length measurement method. Background Technology

[0002] Deformation information at different depths within soil and rock masses is a crucial basis for analyzing the catastrophic mechanisms and evolution of various geotechnical engineering hazards (such as slope slippage, mine overburden deformation, roadbed settlement or arching, and tunnel surrounding rock deformation), as well as for evaluating and issuing early warnings for soil and rock mass stability. Traditional layered deformation monitoring methods involve burying settlement gauges or single-point displacement gauges at different depths in multiple boreholes. This measurement technique is complex to install and requires manual readings, making long-term real-time monitoring impossible. Currently, there is a lack of simple and automated devices capable of long-term monitoring.

[0003] In recent years, some new types of devices for measuring layered deformation in soil and rock have emerged. For example, Chinese Patent Application No. 200910069372.9 discloses a magnetic ring-type layered settlement level testing system based on the principle of electromagnetic induction. This system detects the positional changes of a magnetic ring in the soil and rock mass by stretching a magnetic probe with a graduated cable, thereby calculating the layered deformation. However, this method requires manual reading, is complex to operate, and suffers from low measurement accuracy due to the limited induction range between the probe and the magnetic ring. Another example is Chinese Patent Application No. 201710787646.2. A method and system for measuring layered settlement of soil and rock based on the Hall effect are disclosed. This system uses a Hall integrated sensor array to detect the magnetic induction intensity of a magnetic ring embedded in the soil and rock mass, thereby determining the position of the magnetic ring and obtaining deformation information at different depths. This method can achieve high-precision online continuous measurement, but it is susceptible to electromagnetic interference. Chinese patent application number 201510215836.8 discloses a hydraulic layered settlement meter, which calculates the layered settlement of soil by measuring the hydraulic difference between a reference tube and a measuring tube using a hydraulic sensor. This device is complex to install and has low measurement stability. Chinese patent application number 201310399092.0 discloses a fiber optic method for measuring layered deformation of soil and rock mass. This method uses distributed fiber optic sensors embedded in a borehole to measure the strain distribution of the borehole profile, and integrates the strain measurements to obtain the deformation of soil layers at different depths. However, this method has drawbacks such as the fiber being brittle and difficult to deploy, strain measurements being easily affected by temperature changes, strain-to-displacement conversion leading to large cumulative errors, and expensive demodulation equipment.

[0004] While the aforementioned existing technologies can all measure deformation at different depths within soil and rock masses, they each have their own shortcomings. Importantly, the measurement gauge length of these technologies needs to be preset in advance and remains fixed. However, the location and thickness of each rock layer within a soil or rock mass are difficult to predict, and the layer thickness may change over time (e.g., mudstone layers expand and deform when exposed to water). In such cases, it is difficult to match the measurement gauge length with the location and thickness of different rock layers, making it impossible to accurately characterize the deformation amount and deformation evolution process of a particular rock layer.

[0005] Therefore, it is still necessary to explore a technical solution to address or at least mitigate the aforementioned shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a coaxial waveguide multi-point deformation sensor inside rock and soil to at least solve one of the above-mentioned technical problems.

[0007] This invention provides the following solution:

[0008] According to one aspect of the present invention, a multi-point deformation sensor for the interior of coaxial waveguide rock and soil is provided, the multi-point deformation sensor for the interior of coaxial waveguide rock and soil comprising:

[0009] An outer conductor, which is open at both ends and hollow inside;

[0010] A plurality of metal support frames are provided inside the outer conductor, and each metal support frame is arranged at intervals along the axial direction of the outer conductor, and each metal support frame is provided with a through hole;

[0011] An inner conductor is disposed within the outer conductor and extends from one end of the outer conductor to the other end. The inner conductor passes through the through holes of each of the metal support frames and contacts each of the through holes respectively.

[0012] Multiple magnetic rings are provided, each ring being fitted onto the outer conductor and capable of movement relative to it. When a magnetic ring moves, it drives the nearest metal support frame to move as well.

[0013] The central axis of the inner conductor, the central axis of the outer conductor, and the central axis of the through hole coincide.

[0014] Optionally, the coaxial waveguide soil-rock multi-point deformation sensor further includes:

[0015] A first radio frequency coaxial connector is mounted on one end of the outer conductor, and one end of the inner conductor is in contact with the first radio frequency coaxial connector.

[0016] Optionally, the coaxial waveguide soil-rock multi-point deformation sensor further includes:

[0017] A second radio frequency coaxial connector is mounted on the other end of the outer conductor, and the other end of the inner conductor is in contact with the second radio frequency coaxial connector.

[0018] The radio frequency terminal load is connected to the second radio frequency coaxial connector.

[0019] Optionally, the coaxial waveguide soil-rock multi-point deformation sensor further includes:

[0020] A signal demodulation and analysis device is connected to the first radio frequency coaxial connector via a coaxial signal transmission line.

[0021] Optionally, each of the magnetic rings has a groove on its inner wall;

[0022] The outer conductor has at least one grooved guide rail extending along the axial direction of the outer conductor, and the position where the grooved guide rail contacts the magnetic ring is located within the groove.

[0023] Optionally, the outer conductor is filled with an insulator.

[0024] Optionally, the center of one of the magnetic rings coincides with the center of the metal support frame that the magnetic ring can drive.

[0025] Optionally, both the outer conductor and the inner conductor are made of copper.

[0026] This application also provides a variable gauge length measurement method for use with a coaxial waveguide soil-rock multi-point deformation sensor as described above, the variable gauge length measurement method comprising:

[0027] The interference spectrum between any two of the metal support frames is continuously acquired within a preset time period.

[0028] The deformation of the layer where the two metal support frames are located is obtained by continuously acquiring the interference spectrum between any two of the metal support frames within a preset time period.

[0029] The coaxial waveguide soil-rock internal multi-point deformation sensor of this application is equipped with multiple metal support frames spaced apart along the axial direction of the outer conductor. Each metal support frame is a reflection point, and a sensing gauge length can be formed between every two metal support frames. By acquiring the changes in the interference spectrum signal of different sensing gauge lengths, the deformation of the layer where the sensing gauge length is located can be obtained. Thus, the deformation of any layer can be acquired as needed, without the need to set up a separate sensor for each layer for layer monitoring. Furthermore, the monitoring of various layers can be generated by adjusting the position of each metal support frame.

[0030] The beneficial effects of this invention are: by burying a multi-point deformation sensor inside the soil and rock as described in this invention, real-time monitoring of the deformation of rock strata at different depths inside the soil and rock mass can be achieved. Moreover, the measuring gauge length of the sensor can be continuously adjusted as the deformation of the rock strata evolves, and deformation measurement can always be performed with the most suitable gauge length, thereby achieving refined measurement of the deformation of each rock stratum. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a coaxial waveguide rock and soil multi-point deformation sensor in one embodiment of this application.

[0032] Figure 2 This is a schematic diagram of the structure of a coaxial waveguide multi-point deformation sensor embedded in the soil and rock according to an embodiment of this application.

[0033] Figure 3 This is a cross-sectional schematic diagram of a coaxial waveguide rock and soil multi-point deformation sensor according to an embodiment of this application.

[0034] Figure 4 This is a schematic diagram of the principle of a coaxial waveguide rock and soil multi-point deformation sensor in one embodiment of this application.

[0035] Figure label:

[0036] 1. Outer conductor; 2. Metal support frame; 3. Inner conductor; 4. Magnetic ring; 5. First RF coaxial connector; 6. RF terminal load; 7. Signal demodulation and analysis device; 11. Groove guide rail. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Figure 1 This is a schematic diagram of the structure of a coaxial waveguide rock and soil multi-point deformation sensor in one embodiment of this application. Figure 2 This is a schematic diagram of the structure of a coaxial waveguide multi-point deformation sensor embedded in the soil and rock according to an embodiment of this application. Figure 3 This is a cross-sectional schematic diagram of a coaxial waveguide rock and soil multi-point deformation sensor according to an embodiment of this application.

[0039] like Figures 1 to 3 The coaxial waveguide soil-rock multi-point deformation sensor shown includes an outer conductor 1, a metal support frame 2, an inner conductor 3, and magnetic rings 4. The outer conductor 1 is open at both ends and hollow inside. There are multiple metal support frames 2, which are arranged inside the outer conductor 1. Each metal support frame 2 is arranged at intervals along the axial direction of the outer conductor 1, and each metal support frame has a through hole. The inner conductor 3 is arranged inside the outer conductor 3 and extends from one end of the outer conductor to the other end. The inner conductor passes through the through holes of each metal support frame 2 and contacts each through hole. There are multiple magnetic rings 4, each of which is sleeved on the outer wall of the outer conductor 1 and can move relative to the outer conductor 1. When a magnetic ring moves, the moving magnetic ring can drive the nearest metal support frame 2 to move. The central axis of the inner conductor 3, the central axis of the outer conductor 1, and the central axis of the through hole coincide.

[0040] In this embodiment, the outer circle of each metal support frame 2 is in contact with the inner wall of the outer conductor 1.

[0041] The coaxial waveguide soil-rock internal multi-point deformation sensor of this application is provided with multiple metal support frames 2 spaced apart along the axial direction of the outer conductor 1. Each metal support frame 2 is a reflection point, and a sensing gauge length can be formed between every two metal support frames 2. By acquiring the changes in the interference spectrum signal of different sensing gauge lengths, the deformation of the layer where the sensing gauge length is located can be obtained. Thus, the deformation of any layer can be acquired as needed, without the need to set up a separate sensor for each layer for layer monitoring. Furthermore, the monitoring of various layers can be generated by adjusting the position of each metal support frame 2.

[0042] In this embodiment, the coaxial waveguide rock and soil internal multi-point deformation sensor further includes a first radio frequency coaxial connector 5, which is installed at one end of the outer conductor 1 and at one end of the inner conductor 3 in contact with the first radio frequency coaxial connector 5.

[0043] In this embodiment, the coaxial waveguide rock and soil internal multi-point deformation sensor further includes a second radio frequency coaxial connector and a radio frequency terminal load 6. The second radio frequency coaxial connector 6 is installed at the other end of the outer conductor 1, and the other end of the inner conductor 3 is in contact with the second radio frequency coaxial connector.

[0044] The RF terminal load 6 is connected to the second RF coaxial connector.

[0045] In this embodiment, the coaxial waveguide soil-rock multi-point deformation sensor further includes a signal demodulation and analysis device 7, which is connected to the first radio frequency coaxial connector 5 via a coaxial signal transmission line.

[0046] In this embodiment, a groove is provided on the inner wall of each magnetic ring 4;

[0047] The outer conductor 1 has at least one groove guide rail 11 extending along the axial direction of the outer conductor 1 on its outer surface, and the groove guide rail 11 is located in contact with the magnetic ring within the groove.

[0048] In this embodiment, there are four groove guide rails 11 on the outer conductor 1, and each groove guide rail 11 is evenly distributed on the outer conductor 1 along the circumferential direction of the outer conductor 1.

[0049] Specifically, a short internal thread is engraved at each end of the outer conductor 1. One end of the outer conductor 1 is connected to the first RF coaxial connector 5 through the thread, and the other end is connected to the second RF coaxial connector through the thread. The inner conductor 3 is inserted into the inner pin of the RF coaxial connector at both ends, and the RF terminal load 6 is screwed onto the second RF coaxial connector.

[0050] In this embodiment, the outer conductor 1 is filled with an insulator, which is air.

[0051] In this embodiment, the center of a magnetic ring 4 coincides with the center of the metal support frame 2 that the magnetic ring 4 can drive.

[0052] See Figure 1 In this embodiment, the thickness of the magnetic ring 4 is basically the same as the thickness of the metal support frame 2, and the magnetic ring 4 and the metal support frame 2 are coaxial.

[0053] In this embodiment, both the outer conductor 1 and the inner conductor 3 are made of copper.

[0054] In this embodiment, copper wire is used as the inner conductor 3, copper tube is used as the outer conductor 1, and air is used as the insulator to construct the coaxial waveguide. A metal support frame 2 is installed inside the waveguide. The metal support frame 2 is a sliding double-conical iron support frame. Each metal support frame 2 can form a reflection point. A magnetic ring 4 corresponding to each reflection point is set on the outside. The magnetic ring 4 can slide along the pre-made grooved guide rail 11 on the waveguide, thus forming a multi-point deformation sensor inside the coaxial waveguide soil and rock.

[0055] More specifically, the reflection point is created by connecting the inner and outer conductors to form a short circuit. Specifically, copper wire and copper tube are used as the inner and outer conductors, respectively, and air is used as the insulator to construct a coaxial waveguide transmission line. A sliding double-conical iron support frame is set inside the waveguide transmission line to form the reflection point, and neodymium iron boron strong magnetic rings corresponding to the reflection points are set outside the transmission line. The magnetic rings slide along the pre-made protrusions on the waveguide.

[0056] In this embodiment, the working mechanism of the coaxial waveguide soil-rock multi-point deformation sensor is as follows: Electromagnetic waves can propagate forward along the inner and outer conductors. The metal support frame 2 can reflect a portion of the electromagnetic wave energy, i.e., the metal support frame 2 is a reflection point. When two electromagnetic waves reflected from any two reflection points meet, they will form an interference spectrum. When the distance between the two reflection points changes, it will cause a frequency shift in the interference spectrum peak. The frequency shift of the interference spectrum peak is linearly related to the change in the distance between the two reflection points. The deformation between the two reflection points can be calculated from the frequency shift of the spectrum peak. When the deformation of the soil-rock mass causes the magnetic ring 4 to move, the magnetic ring 4 relies on the magnetic field to drive the internal reflection points to move synchronously. By extracting the interference spectrum of any two reflection points, the deformation of the soil-rock mass between the two reflection points can be obtained.

[0057] In this embodiment, any two reflection points can constitute a sensing gauge length. The idea of ​​performing variable gauge length deformation measurement is to construct a time-domain gating function to select any two reflection point signals, and then reconstruct the interference spectrum of the corresponding sensing gauge length through signal transformation, thereby calculating the displacement of the corresponding gauge length, thus realizing the measurement of multi-level geometric gauge length displacement of arbitrary combinations.

[0058] This application also provides a variable gauge length measurement method for use with a coaxial waveguide soil-rock multi-point deformation sensor as described above, the variable gauge length measurement method comprising:

[0059] The interference spectrum between any two of the metal support frames 2 is continuously acquired within a preset time period.

[0060] The deformation of the layer where the two metal support frames 2 are located is obtained by continuously acquiring the interference spectrum between any two of the metal support frames 2 within a preset time period.

[0061] See Figure 4The variable gauge length deformation measurement is based on the fact that any two reflection points in the coaxial waveguide soil-rock multi-point deformation sensor can form a sensing gauge length. The idea is to construct a time-domain gating function to select the signals of any two reflection points of the sensor, and then reconstruct the interference spectrum of the corresponding sensing gauge length through signal transformation, thereby calculating the deformation of the corresponding gauge length, thus realizing the measurement of multi-level geometric gauge length deformation of arbitrary combinations. The specific implementation process is as follows: 1) The signal demodulation and analysis device emits electromagnetic waves into the coaxial waveguide soil-rock multi-point deformation sensor and collects the time-domain response signal of the sensor. In the time-domain waveform, multiple reflection peaks can be observed. These reflection peaks correspond to the position of each reflection point on the sensor (e.g., ...). Figure 4 (as shown); 2) Construct a time-domain gating function by combining the time-domain waveform and the information of the two reflection points to be selected. The time-domain gating function can filter or isolate unwanted signals and leave only the signals of interest. The two reflection peaks of the time-domain gating function form a sensing gauge length at their corresponding positions; 3) After time-frequency transformation of the time-domain waveform after time-domain gating, the frequency domain interference spectrum of the sensing gauge length formed by the two selected reflection points is obtained. The deformation of the gauge length can be calculated from the frequency shift of the interference spectrum peaks; 4) According to the measurement requirements and the deformation evolution process of the rock strata, the sensing gauge length that matches the thickness of the rock strata to be measured can be flexibly selected. Repeating steps 1-3 can realize the variable gauge length fine measurement of the layered deformation of the rock and soil.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coaxial waveguide multi-point deformation sensor for the interior of rock and soil, characterized in that, The coaxial waveguide soil-rock multi-point deformation sensor includes: An outer conductor (1) is open at both ends and hollow inside; Metal support frame (2), there are multiple metal support frames (2) and they are arranged inside the outer conductor (1). Each metal support frame (2) is arranged at intervals along the axial direction of the outer conductor (1). Each metal support frame (2) is provided with a through hole. Inner conductor (3), the inner conductor (3) is disposed inside the outer conductor (1) and extends from one end of the outer conductor (1) to the other end, the inner conductor (3) passes through the through holes of each of the metal support frames (2) and contacts each of the through holes respectively; Magnetic rings (4), there are multiple magnetic rings (4), each magnetic ring (4) is sleeved on the outer conductor (1) and can move relative to the outer conductor (1). When a magnetic ring moves, the moving magnetic ring can drive the nearest metal support frame (2) to move; wherein, The central axis of the inner conductor (3), the central axis of the outer conductor (1), and the central axis of the through hole coincide; The coaxial waveguide soil-rock internal multi-point deformation sensor further includes: A first radio frequency coaxial connector (5) is mounted on one end of the outer conductor (1), and one end of the inner conductor (3) is in contact with the first radio frequency coaxial connector (5). The coaxial waveguide soil-rock internal multi-point deformation sensor further includes: The second radio frequency coaxial connector is installed at the other end of the outer conductor (1), and the other end of the inner conductor (3) is in contact with the second radio frequency coaxial connector; Radio frequency terminal load (6), the radio frequency terminal load (6) is connected to the second radio frequency coaxial connector; The coaxial waveguide soil-rock internal multi-point deformation sensor further includes: The signal demodulation and analysis device (7) is connected to the first radio frequency coaxial connector (5) via a coaxial signal transmission line; Each of the magnetic rings (4) has a groove on its inner wall; The outer conductor (1) has at least one groove guide rail (11) extending along the axial direction of the outer conductor (1), and the groove guide rail (11) is located in the groove where it contacts the magnetic ring (4).

2. The coaxial waveguide multi-point deformation sensor inside rock and soil as described in claim 1, characterized in that, The outer conductor (1) is filled with an insulator.

3. The coaxial waveguide multi-point deformation sensor inside rock and soil as described in claim 2, characterized in that, The center of one of the magnetic rings (4) coincides with the center of the metal support frame (2) that the magnetic ring (4) can drive.

4. The coaxial waveguide multi-point deformation sensor inside rock and soil as described in claim 3, characterized in that, Both the outer conductor (1) and the inner conductor (3) are made of copper.

5. A variable gauge length measurement method, used in a coaxial waveguide multi-point deformation sensor for soil and rock as described in any one of claims 1 to 4, characterized in that, The variable gauge length measurement method includes: The interference spectrum between any two of the metal support frames (2) is continuously acquired within a preset time period; The deformation of the layer where the two metal support frames (2) are located is obtained by continuously acquiring the interference spectrum between any two of the metal support frames (2) within a preset time period.

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