Advanced water detection method based on combination of controllable microwave and optical fiber temperature measurement

Abstract

The invention discloses an advanced water detection method based on controllable microwave and optical fiber temperature measurement combination. The method comprises the following steps: arranging a controllable microwave and optical fiber temperature measurement system; then the microwave transmitter and the receiver are matched with each other to obtain microwave data; meanwhile, the distributed optical fiber sensor obtains temperature data; then the monitoring host performs attenuation analysis on each group of received microwave data in combination with microwave emission power, preliminarily judges whether a water-containing disaster-causing body exists or not, and performs inversion processing on the received temperature data through a heat conduction model if the water-containing disaster-causing body exists so as to obtain the position of a heat source; and finally, setting a water-containing disaster-causing body judgment condition, performing fusion processing on the obtained water-containing disaster-causing body position and the heat source position, and finally determining the position of the water-containing disaster-causing body. By combining controllable microwaves with optical fiber temperature measurement, on the premise of a large detection range, the position of a water-containing disaster-causing body can be rapidly and accurately detected, meanwhile, the device has the advantage of being convenient to arrange, and therefore advanced detection of mine water disasters is effectively achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced detection of mine water hazards, and in particular relates to an advanced water detection method based on the combination of controllable microwaves and optical fiber temperature measurement. Background Art

[0002] Mine water inrush is one of the five major disasters in coal mines, and preventing mine water disasters is a top priority for coal mine safety production. Therefore, continuing to optimize and develop advanced mine water hazard detection technology has great engineering and scientific significance.

[0003] Existing geophysical exploration technologies for advanced detection of underground coal mine tunnels primarily include Rayleigh wave, geological radar, and direct current electrical methods. Rayleigh wave geological radar can be used for detection in front of and to the sides of tunnels, but its range is short and its adaptability is poor. Typically, its detection range is only over 10 meters, and it cannot determine whether abnormal water content exists. Electrical advanced detection technology is primarily used to detect hidden structures directly ahead of the tunneling head. While simple and practical, it offers a wide range, is sensitive to water, and has a high anomaly detection rate. However, its drawbacks include a narrow control range, being able to only predict the presence of water-bearing structures directly ahead of the tunneling head, and requiring a high detection workload, significantly impacting the tunneling efficiency of high-yield and high-efficiency mines. Although mine transient electromagnetic detection has increased the detection distance to a certain extent, it has the following disadvantages because it is based on low-frequency electromagnetic induction (0.1Hz~10kHz) and uses conductivity differences (water has strong conductivity) to detect water-bearing structures: 1. Due to the use of low-frequency electromagnetic induction, its resolution is low and it is difficult to detect smaller water-bearing cracks; 2. Transient electromagnetic detection is sensitive to metal equipment in mines (such as coal mining machines and rails) and is prone to false anomalies.

[0004] Therefore, how to provide a new advanced water detection method that can quickly and accurately detect the location of water-containing fissures while having a large detection range, and at the same time has the advantage of easy deployment, thereby effectively realizing the advanced detection of mine water hazards, is the research direction required by the present invention. Summary of the Invention

[0005] In response to the problems existing in the above-mentioned prior art, the present invention provides an advanced water detection method based on the combination of controllable microwaves and optical fiber temperature measurement. By combining controllable microwaves with optical fiber temperature measurement, it can quickly and accurately detect the location of water-containing disaster-causing bodies while having a large detection range. At the same time, it also has the advantage of easy deployment, thereby effectively realizing the advanced detection of mine water hazards.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: an advanced water detection method based on the combination of controllable microwave and optical fiber temperature measurement, comprising the following steps: Step 1: Deploy a controllable microwave and fiber optic temperature measurement system: Distributed fiber optic sensors are laid along the coal seam to obtain temperature data; microwave transmitters and microwave receivers are symmetrically arranged in the tunnels on both sides of the coal seam to be measured, so that microwaves are transmitted from one side to the coal seam to be measured and then received by the other side after penetrating the coal seam; a monitoring host is connected to the distributed fiber optic sensors, microwave transmitters, and microwave receivers to control the transmission of the microwave transmitters and receive data fed back by the distributed fiber optic sensors and microwave transmitters; Step 2: Data Collection: The microwave transmitter transmits microwaves at a set power to the coal seam to be measured. The microwave receiver receives the microwave data after it penetrates the coal seam. Multiple transmission groups are set to continuously obtain multiple sets of microwave data. At the same time, the distributed fiber optic sensor monitors the temperature data of different locations in the coal seam to be measured in real time. Step 3: Data processing: The monitoring host performs attenuation analysis on each set of received microwave data in combination with the microwave transmission power, and then preliminarily determines whether there is a water-containing disaster-causing body. If there is a water-containing disaster-causing body, the location of the water-containing disaster-causing body is preliminarily determined and the process proceeds to step 1; otherwise, the process continues to process the next set of microwave data; The monitoring host performs inversion processing on the received temperature data through the heat conduction model to obtain the location of the heat source; Step 4: Determine the location of the water-bearing disaster-causing body: Based on the water-bearing disaster-causing body determination criteria, conduct a comprehensive analysis of the water-bearing disaster-causing body location and the heat source location obtained in step 3 to ultimately determine the location of the water-bearing disaster-causing body.

[0007] Furthermore, in step 1, the distributed optical fiber sensors are arranged in multiple rows, and each row of distributed optical fiber sensors is arranged parallel to each other along the direction of the coal seam in the coal seam to be measured, and the distance between two adjacent rows is ≤1m.

[0008] Furthermore, after the system deployment in step one is completed, system debugging is required, specifically: performing continuous wave or pulse modulation on the microwaves emitted by the microwave transmitter to achieve the required waveform, and adjusting the transmission power by adjusting the microwave transmission frequency until the required microwave transmission frequency and its corresponding power are obtained; and calibrating the temperature data collected by the distributed optical fiber sensor in a water-free environment.

[0009] Furthermore, the time periods of the emission groups in step 2 are the same, and the microwave transmitters in each emission group emit microwaves at the same time intervals, so that the total power of the microwaves emitted by each emission group is kept the same.

[0010] Furthermore, in step 2, when the monitoring host receives real-time microwave data fed back by the microwave receiver and real-time temperature data fed back by distributed optical fiber sensors at different locations, a timestamp is added to each received data to align the microwave data and temperature data within the same time period during subsequent data processing.

[0011] Furthermore, the steps are as follows: the monitoring host calculates the power difference between each group of received microwave data and each group of transmitted microwave data ,like If the signal persists for more than three groups, it is preliminarily determined that a water-containing disaster-causing body exists. Then, the distance d between the water-containing disaster-causing body and the microwave receiver is located through time domain reflectometry (TDR). The specific formula is: in is the speed of light, is the dielectric constant of the coal seam, Indicates the time difference between the microwave emission time and the microwave reception time.

[0012] Furthermore, the steps are specifically as follows: establishing a heat conduction model, performing inversion processing based on the received temperature data, and determining the location of the heat source. The specific formula is: in, is the density in units of ; is the specific heat capacity, in units of ; T is temperature, unit ; t is time, unit is s; is the thermal conductivity, in units of ; is the coordinate of the heat source position; is the heat source term, unit , which represents the heat generated inside the unit volume.

[0013] Furthermore, the conditions for determining the water-bearing disaster-causing body in step 4 are specifically as follows: Ⅰ. Microwave power per group And the temperature change at a certain position during each group of microwave emission ; II. The error between the location of the water-bearing disaster body and the location of the heat source obtained by each group is less than 30%; When the acquired microwave data and temperature data meet the above two conditions at the same time, the location of the water-bearing disaster-causing body is finally determined.

[0014] The core principle behind this invention's innovation is that microwaves, electromagnetic waves with frequencies between 300 MHz and 300 GHz, are easily focused into beams, are highly directional, and propagate in straight lines. A material's ability to absorb microwaves is primarily determined by its dielectric loss factor. Materials with high dielectric loss factors absorb microwaves more strongly, while materials with low dielectric loss factors absorb less. Generally speaking, the dielectric constant of a coal seam is usually less than 5, close to that of materials such as glass and plastic. Water, as a polar molecule, has a dielectric constant of 80. This difference causes microwaves to penetrate the coal seam. The inventors of the present invention further discovered that when a water-containing disaster-causing body exists in the coal seam, microwaves will cause water molecules in the disaster-causing body to vibrate 2.45 billion times per second. Friction between molecules will cause the temperature of the medium to rise, causing the inside and outside of the medium material to heat up almost simultaneously, forming a body heat source state. Therefore, after emitting microwaves to the coal seam, the position of the water-containing disaster-causing body can be located by monitoring the temperature changes at different positions in the coal seam. At the same time, because microwaves will cause the molecules of the water-containing disaster-causing body to heat up due to friction, thereby consuming more power, the power difference between the microwaves during transmission and reception can also be used to determine whether there is a water-containing disaster-causing body in the coal seam.

[0015] Fiber optic sensing technology also enables the reception and transmission of temperature signals. Fiber optic sensing is a measurement and monitoring technology based on optical principles and fiber optic transmission. It uses optical fibers as sensing elements and measures and analyzes the propagation, interference, and scattering characteristics of light signals within the fiber, enabling precise detection and monitoring of environmental parameters and physical quantities. The advantages of fiber optic sensing technology are reflected in multiple aspects. First, fiber optic sensing technology boasts extremely high sensitivity. Even small external forces or temperature changes can cause significant changes in the transmission of light signals, enabling precise measurement of even small changes. Second, fiber optic sensors are highly resistant to electromagnetic interference. Light signals transmitted through optical fibers are unaffected by electromagnetic interference, allowing them to operate reliably in environments with strong electromagnetic interference. Furthermore, fiber optic sensors offer low transmission loss and high transmission capacity, enabling remote monitoring and multi-point distributed measurement. This makes fiber optic sensing technology a distinct advantage in applications requiring remote or distributed monitoring. Furthermore, fiber optic sensors are compact, lightweight, and offer flexible geometry. They are also corrosion-resistant, high-temperature-resistant, and high-voltage-resistant, enabling long-term, stable operation in harsh environments. Finally, fiber optic sensors offer high measurement speeds and high information capacity. The same optical fiber can transmit multiple signals, improving the system's integration and reliability. Therefore, the inventors applied distributed optical fiber temperature monitoring to coal seams, which can accurately obtain temperature changes at different locations in real time when the coal seams are affected by microwaves, providing data support for the subsequent determination of the location of water-containing disaster-causing bodies.

[0016] Compared with the existing technology, the present invention adopts a combination of controllable microwave and optical fiber temperature measurement, which has the following advantages: 1. The present invention uses controllable microwaves for detection. Since microwaves have short wavelengths and high resolution, they can increase the probability of detecting water-bearing fissures. In addition, the dielectric constant of microwaves to water ( ≈80) and coal seam ( ≈3~5) has significant differences, which can directly distinguish water from dry rock formations, effectively reducing false alarms, and thus achieving high-resolution detection of water-bearing fractures with good accuracy.

[0017] 2. The microwave detection of the present invention adopts directional emission and reception each time, and is less affected by electromagnetic interference from underground cables, motors, etc.; while the transient electromagnetic detection range is larger each time, and it is sensitive to metal equipment (such as coal mining machines and rails), and is prone to false anomalies. Therefore, the method of the present invention has better anti-interference performance.

[0018] 3. Multi-parameter fusion criterion. This invention combines microwave attenuation with fiber optic temperature inversion. When microwaves pass through water, they accelerate the movement of water molecules, generating heat energy. Since heat energy consumes microwave power, the microwave attenuation can be used to locate the water-bearing disaster-causing body. Distributed optical fiber monitoring of temperature rise at different locations can also locate the water-bearing disaster-causing body. Finally, the two are combined to determine the location of the water-bearing disaster-causing body. This dual-verification method for locating water-bearing disaster-causing bodies reduces reliance on a single piece of data. While maintaining a large detection range, it can also quickly and accurately detect the location of the water-bearing disaster-causing body. It also has the advantage of easy deployment, effectively achieving advanced detection of mine water hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall layout of the present invention.

[0020] In the figure: 1-transportation track, 2-distributed optical fiber sensor, 3-microwave transmitter, 4-microwave receiver, 5-water-containing disaster-causing body. DETAILED DESCRIPTION

[0021] The present invention will be further described below.

[0022] like Figure 1 As shown, the present invention includes the following steps: Step 1: Lay out a controllable microwave and optical fiber temperature measurement system: Lay distributed optical fiber sensors 2 along the coal seam to be measured to obtain temperature data; the distributed optical fiber sensors 2 are arranged in multiple rows, and each row of distributed optical fiber sensors 2 is laid parallel to each other along the direction of the coal seam in the coal seam to be measured by being closely attached to the coal wall or implanted through drilling, and the spacing between two adjacent rows is ≤1m. A transport track 1 is arranged in the high-level and low-level lanes of the coal seam to be measured in their respective lane directions. A microwave transmitter 3 is provided on the transport track 1 of the high-level lane, and a microwave receiver 4 is provided on the transport track of the low-level lane. The two are symmetrically arranged on both sides of the coal seam to be measured and move synchronously. The microwave is used to transmit microwaves from one side to the coal seam to be measured, and the microwaves penetrate the coal seam and are received by the other side, thereby realizing microwave penetration of different positions of the coal seam to be measured. The monitoring host is connected to the distributed optical fiber sensor 2, the microwave transmitter 3 and the microwave receiver 4 through an underground industrial Ethernet or RS485 data cable, which is used to control the emission of the microwave transmitter 3 and receive data fed back by the distributed optical fiber sensor 2 and the microwave transmitter 3. After the arrangement is completed, the system is debugged, specifically: the microwaves emitted by the microwave transmitter 3 are continuously wave or pulse modulated to achieve the required waveform, and the emission power is adjusted by adjusting the microwave emission frequency until the required microwave emission frequency and its corresponding power are obtained; the temperature data collected by the distributed optical fiber sensor 2 is calibrated in a water-free environment.

[0023] Step 2: Data Collection: Microwave transmitter 3 transmits microwaves at a set power into the coal seam to be measured. Microwave receiver 4 receives microwave data after penetrating the coal seam. Multiple transmission groups are set to continuously obtain multiple sets of microwave data. Each transmission group has the same time period, and microwave transmitters 3 within each transmission group transmit microwaves at the same time interval, maintaining the same total power for each transmission group. Simultaneously, distributed fiber optic sensors 2 monitor temperature data at different locations in the coal seam to be measured in real time. When the monitoring host receives real-time microwave data from microwave receiver 4 and real-time temperature data from distributed fiber optic sensors 2 at different locations, it adds a timestamp to each received data set. This is used to align microwave data and temperature data within the same time period during subsequent data processing.

[0024] Step 3: Data processing: The monitoring host performs attenuation analysis on each set of received microwave data in combination with the microwave transmission power, and then preliminarily determines whether there is a water-containing disaster-causing body 5. If there is a water-containing disaster-causing body 5, the location of the water-containing disaster-causing body is preliminarily determined and the process proceeds to step 5; otherwise, the next set of microwave data is processed. Specifically, the monitoring host calculates the power difference between each set of received microwave data and each set of transmitted microwave data. ,like If the signal persists for more than three groups, it is preliminarily determined that a water-containing disaster-causing body 5 exists. Then, the distance d between the water-containing disaster-causing body 5 and the microwave receiver 4 is located by time domain reflectometry (TDR). The specific formula is: in is the speed of light, is the dielectric constant of the coal seam, Indicates the time difference between the microwave emission time and the microwave reception time.

[0025] A heat conduction model is established and inversion processing is performed on the received temperature data to determine the location of the heat source. The specific formula is: in, is the density in units of ; is the specific heat capacity, in units of ; T is temperature, unit ; t is time, unit is s; is the thermal conductivity, in units of ; is the coordinate of the heat source position; is the heat source term, unit , which represents the heat generated inside the unit volume.

[0026] Step 4: Determine the location of the water-bearing disaster-causing body: Based on the water-bearing disaster-causing body identification criteria, specifically: Ⅰ. Microwave power per group And the temperature change at a certain position during each group of microwave emission ; II. The error between the location of the water-bearing disaster body and the location of the heat source obtained by each group is less than 30%; The locations of the water-bearing disaster-causing body and heat source obtained in step 3 are compared with the determination criteria. When the acquired microwave data and temperature data meet both of these criteria, the location of the water-bearing disaster-causing body 5 is finally determined. Once microwave transmitter 3 completes all transmission groups at a location, microwave transmitter 3 and microwave receiver 4 are controlled to move synchronously along the coal seam to the next location. Steps 1 to 4 are repeated until the advanced water detection process, combining controllable microwave and fiber optic temperature measurement, is completed at all locations in the coal seam to be measured. This allows the precise location of each water-bearing disaster-causing body within the coal seam to be determined.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for advanced water exploration based on controllable microwave and optical fiber temperature measurement, characterized in that: The following steps are involved: Step 1: Deploy a controllable microwave and fiber optic temperature measurement system: Distributed fiber optic sensors are laid along the coal seam to obtain temperature data; microwave transmitters and microwave receivers are symmetrically arranged in the tunnels on both sides of the coal seam to be measured, so that microwaves are transmitted from one side to the coal seam to be measured and then received by the other side after penetrating the coal seam; a monitoring host is connected to the distributed fiber optic sensors, microwave transmitters, and microwave receivers to control the transmission of the microwave transmitters and receive data fed back by the distributed fiber optic sensors and microwave transmitters; Step 2: Data Collection: The microwave transmitter transmits microwaves at a set power to the coal seam to be measured. The microwave receiver receives the microwave data after it penetrates the coal seam. Multiple transmission groups are set to continuously obtain multiple sets of microwave data. At the same time, the distributed fiber optic sensor monitors the temperature data of different locations in the coal seam to be measured in real time. Step 3: Data processing: The monitoring host performs attenuation analysis on each set of received microwave data in combination with the microwave transmission power, and then preliminarily determines whether there is a water-containing disaster-causing body. If there is a water-containing disaster-causing body, the location of the water-containing disaster-causing body is preliminarily determined, and the process proceeds to step; Otherwise, continue to process the next set of microwave data; The monitoring host performs inversion processing on the received temperature data through the heat conduction model to obtain the location of the heat source; Step 4: Determine the location of the water-bearing disaster-causing body: Based on the water-bearing disaster-causing body determination criteria, conduct a comprehensive analysis of the water-bearing disaster-causing body location and the heat source location obtained in step 3 to ultimately determine the location of the water-bearing disaster-causing body.

2. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: In step 1, there are multiple rows of distributed optical fiber sensors, and each row of distributed optical fiber sensors is arranged parallel to each other along the direction of the coal seam in the coal seam to be measured, and the distance between two adjacent rows is ≤1m.

3. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: After the system deployment in step 1 is completed, system debugging is required, specifically: the microwaves emitted by the microwave transmitter are modulated into continuous waves or pulses to achieve the required waveform, and the transmission power is adjusted by adjusting the microwave transmission frequency until the required microwave transmission frequency and its corresponding power are obtained; the temperature data collected by the distributed optical fiber sensor is calibrated in a water-free environment.

4. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: In step 2, the time periods of the various emission groups are the same, and the microwave emitters in each emission group emit microwaves at the same time intervals, so that the total power of the microwaves emitted by each emission group is kept the same.

5. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: In step 2, when the monitoring host receives real-time microwave data fed back by the microwave receiver and real-time temperature data fed back by distributed optical fiber sensors at different locations, a timestamp is added to each received data to align the microwave data and temperature data within the same time period during subsequent data processing.

6. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: The steps are specifically as follows: the monitoring host calculates the power difference between each group of received microwave data and each group of transmitted microwave data ,like If the signal persists for more than three groups, it is preliminarily determined that a water-bearing disaster-causing body exists. Then, time domain reflection analysis is used to locate the distance d between the water-bearing disaster-causing body and the microwave receiver. The specific formula is: in is the speed of light, is the dielectric constant of the coal seam, Indicates the time difference between the microwave emission time and the microwave reception time.

7. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 6 is characterized in that: The steps are as follows: establishing a heat conduction model, performing inversion processing based on the received temperature data, and determining the location of the heat source. The specific formula is: in, is the density in units of ; is the specific heat capacity, in units of ; T is temperature, unit ; t is time, unit is s; is the thermal conductivity, in units of ; is the coordinate of the heat source position; is the heat source term, unit , which represents the heat generated inside the unit volume.

8. The advanced water exploration method based on controllable microwave and optical fiber temperature measurement according to claim 1 is characterized in that: The specific conditions for determining the water-bearing disaster-causing body in step 4 are: Ⅰ. Microwave power per group And the temperature change at a certain position during each group of microwave emission ; II. The error between the location of the water-bearing disaster body and the location of the heat source obtained by each group is less than 30%; When the acquired microwave data and temperature data meet the above two conditions at the same time, the location of the water-bearing disaster-causing body is finally determined.

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