An advanced water detection method based on controllable microwave and optical fiber temperature measurement

Abstract

The application discloses an advanced water detection method based on controllable microwave and optical fiber temperature measurement combination, first, a controllable microwave and optical fiber temperature measurement system is laid; then, a microwave transmitter and a receiver cooperate to obtain microwave data; meanwhile, a distributed optical fiber sensor obtains temperature data; then, a monitoring host machine combines microwave transmitting power to perform attenuation analysis on each group of received microwave data, preliminarily judges whether a water-containing disaster body exists, if the water-containing disaster body exists, the monitoring host machine performs inversion processing on the received temperature data through a heat conduction model, so that a heat source position is obtained; finally, a water-containing disaster body judgment condition is set, the obtained water-containing disaster body position and the heat source position are fused, and finally, the position of the water-containing disaster body is determined. Through combination of the controllable microwave and the optical fiber temperature measurement, the position of the water-containing disaster body can be quickly and accurately detected under the premise of having a large detection range, and the method has the advantage of being convenient to lay, so that the advanced detection of the mine water disaster is effectively realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mine water disaster advanced detection, and particularly relates to an advanced water detection method based on controllable microwave and optical fiber temperature measurement. BACKGROUND

[0002] Mine water inrush is one of the five disasters in coal mines, and preventing mine water disaster accidents is the top priority in coal mine safety production work. Therefore, it is of great engineering and scientific significance to continue to optimize and develop the advanced detection technology of mine water disaster.

[0003] The existing advanced detection of underground roadway in coal mines mainly includes Rayleigh wave, geological radar, direct current method and other geophysical prospecting technologies. The Rayleigh wave geological radar technology can be used for front and side detection of the roadway, but the detection range is short and the adaptability is poor, and the detection distance is only more than 10 m in general, and it cannot be determined whether the abnormal water is present or not. The electrical method advanced detection technology is mainly used for hidden structure detection in front of the heading face, and is simple, practical, has a large detection range, is sensitive to water, and has a high abnormal detection rate, but the control range is small, and it can only predict whether there is water-bearing structure in front of the heading face, and the detection workload is large, which greatly affects the heading efficiency of high-yield and high-efficiency mines. Although the mine transient electromagnetic method increases the detection distance to a certain extent, the transient electromagnetic water detection is based on low-frequency electromagnetic induction (0.1 Hz~10 kHz), and uses the difference in conductivity (water has strong conductivity) to detect water-bearing structures, so it has the following shortcomings: 1. The low-frequency electromagnetic induction has low resolution, and it is difficult to detect small water-bearing fissures; 2. The transient electromagnetic method is sensitive to metal equipment (such as coal mining machines and steel rails) in the mine, and false anomalies are easily generated.

[0004] Therefore, how to provide a new advanced water detection method, which can quickly and accurately detect the position of the water-bearing fissure under the premise of having a large detection range, and also has the advantage of convenient layout, so as to effectively realize the advanced detection of mine water disaster, is the research direction of the present application. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides an advanced water detection method based on controllable microwave and optical fiber temperature measurement, which combines controllable microwave and optical fiber temperature measurement, and can quickly and accurately detect the position of the water-bearing disaster body under the premise of having a large detection range, and also has the advantage of convenient layout, so as to effectively realize the advanced detection of mine water disaster.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: an advanced water detection method based on controllable microwave and optical fiber temperature measurement, comprising the following steps:

[0007] Step one, layout controllable microwave and optical fiber temperature measurement system: along the measured coal seam to lay distributed optical fiber sensor, used to obtain temperature data; symmetrical layout microwave transmitter and microwave receiver on both sides of the measured coal seam roadway, used to transmit microwave from one side to the measured coal seam and be received by the other side after penetrating the coal seam; the monitoring host is connected with the distributed optical fiber sensor, microwave transmitter and microwave receiver, used to control the emission of microwave transmitter, and receive the data feedback by the distributed optical fiber sensor and microwave transmitter;

[0008] Step two, data acquisition: the microwave transmitter transmits microwave to the measured coal seam according to the set power, the microwave receiver receives the microwave data after penetrating the coal seam, and sets multiple transmission groups to continuously obtain multiple groups of microwave data; at the same time, the distributed optical fiber sensor monitors the temperature data of different positions of the measured coal seam in real time;

[0009] Step three, data processing:

[0010] The monitoring host combines the microwave transmission power to analyze the received microwave data, and then preliminarily judges whether there is a water-containing disaster body, if there is a water-containing disaster body, the position of the water-containing disaster body is preliminarily determined, and the step is entered; otherwise, continue to process the next group of microwave data;

[0011] The monitoring host inverses the received temperature data through the heat conduction model to obtain the position of the heat source;

[0012] Step four, determine the position of the water-containing disaster body: according to the water-containing disaster body determination condition, the position of the water-containing disaster body obtained in step three and the position of the heat source are comprehensively analyzed to finally determine the position of the water-containing disaster body.

[0013] Further, the distributed optical fiber sensor in step one is multiple rows, each row of distributed optical fiber sensor is arranged parallel to each other along the strike of the measured coal seam, and the distance between the adjacent two rows is ≤1m.

[0014] Further, after the system of step one is laid out, system debugging is needed, specifically: the microwave transmitted by the microwave transmitter is modulated by continuous wave or pulse, the required waveform is achieved, 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 the water-free environment.

[0015] Further, the time period of each transmission group in step two is the same, and the microwave transmitters in each transmission group transmit microwave at the same time interval, keeping the total power of the microwave transmitted by each transmission group the same.

[0016] Further, the step two is specifically that the monitoring host receives the real-time microwave data fed back by the microwave receiver and the real-time temperature data fed back by the distributed optical fiber sensor at different positions, and a time stamp is added to each received data for aligning the microwave data and the temperature data in the same time period in subsequent data processing.

[0017] Further, the step is specifically that the monitoring host calculates the power difference between each group of received microwave data and each group of transmitted microwave data , if and lasts for more than 3 groups, it is preliminarily judged that there is a water-containing disaster body; then the distance d between the water-containing disaster body and the microwave receiver is located by time domain reflection analysis (TDR), and the specific formula is:

[0018]

[0019] wherein is the speed of light, is the dielectric constant of the coal seam, represents the time difference between the microwave transmission time and the microwave receiving time.

[0020] Further, the step is specifically that a heat conduction model is established, and the received temperature data is processed by inversion to determine the position of the heat source, and the specific formula is:

[0021]

[0022] wherein, is the density, the unit is ; is the specific heat capacity, the unit is ; T is the temperature, the unit ; t is the time, the unit s; is the thermal conductivity, the unit is ; is the coordinate of the heat source position; is the heat source term, the unit , which represents the heat generated inside per unit volume.

[0023] Further, the determination condition of the water-containing disaster body in the step four is specifically:

[0024] I. each group of microwave power and the temperature change of a position in each group of microwave transmission process ;

[0025] II. the error between the obtained position of the water-containing disaster body and the position of the heat source is less than 30%;

[0026] When the obtained microwave data and temperature data meet the above two conditions at the same time, the position of the water-containing disaster body is finally determined.

[0027] The core principle of the present application is that microwave refers to electromagnetic waves with a frequency between 300 MHz and 300 GHz, which has the characteristics of easy to gather into a beam, high directivity and straight-line propagation. The ability of a substance to absorb microwaves is mainly determined by its dielectric loss factor. The greater the dielectric loss factor of the substance, the stronger its ability to absorb microwaves, and vice versa. Generally speaking, the dielectric constant of the coal seam is usually less than 5, close to glass, plastic and other materials, while water as a polar molecule has a dielectric constant of 80. This difference leads to the penetration of microwaves in the coal seam. The present inventor has further found that when there is a water-containing disaster-causing body in the coal seam, the microwaves will cause the water molecules in the disaster-causing body to vibrate 2.4 billion and 50 million times per second, causing friction between the molecules, resulting in an increase in the temperature of the medium, which causes the internal and external heating of the medium material to almost simultaneously heat up, forming a body heat source state. Therefore, by monitoring the temperature changes at different positions in the coal seam after emitting microwaves into the coal seam, the position of the water-containing disaster-causing body can be located. At the same time, since the microwaves cause the water-containing disaster-causing body molecules to heat up and further consume more power, the power difference between the emitted and received microwaves can also be used to determine whether there is a water-containing disaster-causing body in the coal seam.

[0028] In addition, the optical fiber sensing technology realizes the reception and transmission of temperature signals. Optical fiber sensing technology is a measurement and monitoring technology based on optical principles and optical fiber transmission. It uses optical fiber as a sensing element, measures and analyzes the propagation, interference, scattering and other characteristics of light signals in optical fiber, and realizes accurate detection and monitoring of environmental parameters and physical quantities. The advantages of optical fiber sensing technology are reflected in many aspects. First, optical fiber sensing technology has very high sensitivity. Small external forces or temperature changes will cause large changes in light signal transmission, thus achieving accurate measurement of small changes. Second, optical fiber sensors have strong anti-electromagnetic interference capability. Light signals are not affected by electromagnetic interference during transmission in optical fiber, so they can work reliably in strong electromagnetic interference environments. It cannot be ignored that optical fiber sensors have low transmission loss and large transmission capacity, and can realize remote monitoring and distributed measurement. This makes optical fiber sensing technology have obvious advantages in situations that require remote monitoring or distributed measurement. Then, optical fiber sensors are small in size, light in weight, and have a plastic geometry, and also have corrosion resistance, high temperature resistance, high pressure resistance and other characteristics, and can operate stably in harsh environments for a long time. Finally, optical fiber sensors have fast measurement speed and large information capacity. The same optical fiber can transmit multiple signals, improving the integration and reliability of the system. Therefore, the present inventor applies the distributed optical fiber temperature monitoring method to the coal seam, which can accurately obtain the temperature changes at different positions in real time when the coal seam is affected by microwaves, providing data support for subsequent determination of the position of the water-containing disaster-causing body.

[0029] Compared with the prior art, the present application combines controllable microwaves and optical fiber temperature measurement, which has the following advantages:

[0030] 1、The present application adopts controllable microwave for detection, because the wavelength of microwave is short, the resolution is high, it can improve the probability of detecting water fracture; and the dielectric constant of microwave to water ( ≈80) and coal seam ( ≈3~5) difference is significant, so it can directly distinguish water and dry rock layer, effectively reduce false alarm, so as to realize high resolution detection of water containing fracture and has good accuracy.

[0031] 2、The microwave detection of the present application adopts directional emission and reception each time, and the electromagnetic interference is small under the influence of downhole cable, motor and the like; while the transient electromagnetic detection range is larger each time, and it is sensitive to metal equipment (such as coal mining machine, steel rail), false anomaly is easy to produce, therefore, the mode of the present application has good anti-interference performance.

[0032] 3、Multi-parameter fusion criterion. The present application combines microwave attenuation + optical fiber temperature inversion, uses the fact that microwave can accelerate the movement of water molecules when passing through water body and then produce heat energy, at the same time, the power of microwave is consumed due to the generation of heat energy, the position of water containing disaster body can be located through the attenuation of microwave, at the same time, the position of water containing disaster body can also be located through the temperature rise of different positions monitored by distributed optical fiber, finally, the position of water containing disaster body is determined after the fusion of the two; this way of locating water containing disaster body through double verification reduces the dependence of single data, under the premise of having large detection range, it can also quickly and accurately detect the position of water containing disaster body, at the same time, it also has the advantage of convenient layout, so as to effectively realize the advanced detection of mine water disaster. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is the overall layout schematic diagram of the present application.

[0034] In the figure: 1-transportation track, 2-distributed optical fiber sensor, 3-microwave transmitter, 4-microwave receiver, 5-water containing disaster body. DETAILED DESCRIPTION

[0035] The present application will be further described below.

[0036] As shown in Figure 1 , the present application comprises the following steps:

[0037] Step one, layout controllable microwave and optical fiber temperature measurement system: along the measured coal seam in the distribution of distributed optical fiber sensor 2, for obtaining temperature data; the distributed optical fiber sensor 2 is multiple rows, each row of distributed optical fiber sensor 2 is arranged in parallel in the measured coal seam along the coal seam trend by close to the coal wall or drilling implantation, and the spacing between the adjacent two rows is ≤1m. In the high and low position of the measured coal seam, the respective roadway is arranged along the roadway trend of the transport track 1, the microwave transmitter 3 is arranged on the transport track 1 in the high position, and the microwave receiver 4 is arranged on the transport track in the low position, which are symmetrically arranged on both sides of the measured coal seam and synchronously moved; for transmitting microwave from one side to the measured coal seam and being received by the other side after penetrating the coal seam, realizing microwave penetration in different positions of the measured coal seam; the monitoring host is connected with the distributed optical fiber sensor 2, the microwave transmitter 3 and the microwave receiver 4 through the underground industrial Ethernet or RS485 data line, for controlling the emission of the microwave transmitter 3, receiving the data feedback by the distributed optical fiber sensor 2 and the microwave transmitter 3; after the layout is completed, system debugging is carried out, specifically: the microwave emitted by the microwave transmitter 3 is continuously modulated or pulsed, the required waveform is reached, and the emission power is adjusted by adjusting the microwave emission frequency, until the required microwave emission frequency and the corresponding power are obtained; the temperature data collected by the distributed optical fiber sensor 2 is calibrated in the water-free environment.

[0038] Step two, data acquisition: the microwave transmitter 3 emits microwave to the measured coal seam according to the set power, the microwave receiver 4 receives the microwave data after penetrating the coal seam, and sets multiple emission groups to continuously obtain multiple groups of microwave data; the time period of each emission group is the same, and the microwave transmitter 3 in each emission group emits microwave at the same time interval, keeping the total power of microwave emitted by each emission group the same. At the same time, the distributed optical fiber sensor 2 monitors the temperature data of different positions of the measured coal seam in real time; when the monitoring host receives the real-time microwave data feedback by the microwave receiver 4 and the real-time temperature data feedback by the distributed optical fiber sensor 2 at different positions, a time stamp is added to each received data, which is used to align the microwave data and temperature data in the same time period for subsequent data processing.

[0039] Step three, data processing:

[0040] The monitoring host combines the microwave emission power to analyze the attenuation of each received microwave data, and then preliminarily judges whether there is water-containing disaster body 5, if there is water-containing disaster body 5, the position of the water-containing disaster body is preliminarily determined, and step is entered; otherwise, continue to process the next group of microwave data, specifically: the monitoring host calculates the power difference between each group of received microwave data and each group of emitted microwave data , if and lasts for more than 3 groups, it is preliminarily judged that there is a water-containing disaster body 5; then the distance d between the water-containing disaster body 5 and the microwave receiver 4 is located through time domain reflection analysis (TDR), and the specific formula is:

[0041]

[0042] wherein is the speed of light, is the dielectric constant of the coal seam, represents the time difference between the microwave emission time and the microwave receiving time.

[0043] A heat conduction model is established, and the received temperature data is combined for inversion processing to determine the heat source position, and the specific formula is:

[0044]

[0045] wherein, is the density, and the unit is ; is the specific heat capacity, and the unit is ; T is the temperature, and the unit is ; t is the time, and the unit is s; is the thermal conductivity, and the unit is ; is the coordinate of the heat source position; is the heat source term, and the unit is , which represents the heat generated inside per unit volume.

[0046] Step four, determine the position of the water-containing disaster body: according to the water-containing disaster body determination condition, specifically:

[0047] I. The microwave power of each group and the temperature change of a position in each microwave emission process ;

[0048] II. The error between the water-containing disaster body position obtained by each group and the heat source position is less than 30%;

[0049] The water-containing disaster body position and the heat source position obtained in step three are compared with the determination condition, and when the obtained microwave data and temperature data simultaneously satisfy the above two conditions, the position of the water-containing disaster body 5 is finally determined. If the microwave transmitter 3 completes all emission groups of a position, the microwave transmitter 3 and the microwave receiver 4 are controlled to move to the next position along the coal seam, and steps one to four are repeated, until the advance water detection process of the controllable microwave and optical fiber temperature measurement is completed for all positions of the coal seam to be measured, so as to accurately locate the positions of each water-containing disaster body in the coal seam to be measured.

[0050] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for advanced water detection based on a combination of controllable microwave and fiber optic temperature measurement, characterized in that, Includes the following steps: Step 1: Deploy a controllable microwave and fiber optic temperature measurement system: Lay distributed fiber optic sensors along the coal seam to be measured to acquire temperature data; symmetrically deploy microwave transmitters and receivers on both sides of the coal seam to transmit microwaves from one side to the coal seam, which then penetrate the coal seam and are received on the other side; the monitoring host is connected to the distributed fiber optic sensors, microwave transmitters, and microwave receivers to control the transmission of microwave transmitters and receive data from the distributed fiber optic sensors and microwave transmitters. Step 2, Data Acquisition: The microwave transmitter emits microwaves into the coal seam to be tested at a set power, and the microwave receiver receives the microwave data after penetrating the coal seam. Multiple transmission groups are set to continuously acquire multiple sets of microwave data. At the same time, distributed fiber optic sensors monitor the temperature data at different locations in the coal seam to be tested in real time. Step 3: Data Processing The monitoring host analyzes the attenuation of each group of received microwave data by combining the microwave transmission power, and then makes a preliminary judgment on whether there is a water-bearing disaster-causing body. If there is a water-bearing disaster-causing body, the location of the water-bearing disaster-causing body is preliminarily determined and the process proceeds to the next step. Otherwise, continue processing the next set of microwave data; The monitoring host uses a heat conduction model to invert the received temperature data to obtain the location of the heat source; Step 4: Determine the location of the water-bearing disaster-causing body: Based on the criteria for determining the water-bearing disaster-causing body, the location of the water-bearing disaster-causing body and the location of the heat source obtained in Step 3 are comprehensively analyzed to finally determine the location of the water-bearing disaster-causing body.

2. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, In step one, the distributed optical fiber sensors are arranged in multiple rows. Each row of distributed optical fiber sensors is arranged parallel to each other along the coal seam direction within the coal seam to be tested, and the distance between two adjacent rows is ≤1m.

3. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, After the system deployment in step one is completed, system debugging is required. Specifically, the microwaves emitted by the microwave transmitter are modulated by continuous wave or pulse 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 waterless environment.

4. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, In step two, the time period of each transmission group is the same, and the microwave transmitter in each transmission group emits microwaves at the same time interval, so as to keep the total power of microwaves emitted by each transmission group the same.

5. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, In step two, when the monitoring host receives real-time microwave data from the microwave receiver and real-time temperature data from distributed fiber optic sensors at different locations, a timestamp is added to each received data to align microwave and temperature data within the same time period during subsequent data processing.

6. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, The specific 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 three or more consecutive water-bearing hazardous materials are detected, it is preliminarily determined that a water-bearing hazardous material exists. Then, time-domain reflectometry is used to determine the distance d between the water-bearing hazardous material and the microwave receiver. The specific formula is: in At the speed of light, The dielectric constant of the coal seam is... It represents the time difference between the microwave transmission time and the microwave reception time.

7. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 6, characterized in that, The specific steps are as follows: Establish a heat conduction model, perform inversion processing based on the received temperature data, and determine the location of the heat source. The specific formula is: in, It is density, the unit is... ; It is specific heat capacity, and the unit is 1. T represents temperature, in units of... t represents time, in seconds (s). It is the thermal conductivity, with units of 1000 ppm. ; These are the coordinates of the heat source location; For heat source item, unit , which represents the heat generated per unit volume.

8. The advanced water detection method based on controllable microwave and fiber optic temperature measurement as described in claim 1, characterized in that, The specific criteria for determining water-containing disaster-causing bodies in step four are as follows: I. Microwave power of each group Furthermore, the temperature change at a certain location during each microwave transmission process ; II. The error between the location of the water-bearing disaster-causing body and the location of the heat source obtained in each group is less than 30%; When the acquired microwave data and temperature data simultaneously meet the above two conditions, the location of the water-bearing disaster-causing body can be finally determined.

Images