System and method for monitoring position and water conductivity of collapse column

Abstract

The invention discloses a collapse column position and water conductivity monitoring system and monitoring method. In the collapse column position and water conductivity monitoring system, a monitoring well is formed in a mine field stratum; the optical fiber part is at least partially arranged in a monitoring well, the DAS monitoring host is connected with the single-mode optical fiber, the single-mode optical fiber is used for continuously collecting sound wave signals generated by vibration of a vibration source and transmitting the sound wave signals to the DAS monitoring host, and the DAS monitoring host obtains the stratum strain rate by analyzing changes of the sound wave signals and defines the position of a collapse column through the stratum strain rate; the DTS monitoring host is connected with the multimode optical fiber, the multimode optical fiber is used for continuously collecting temperature signals and transmitting the temperature signals to the DTS monitoring host, and the DTS monitoring host judges the water conductivity of the collapse column by analyzing the temperature signals and combining the position of the collapse column. According to the collapse column position and water conductivity monitoring system and monitoring method provided by the invention, the safety of a coal mine is ensured, the construction is simplified, the cost is reduced, and the real-time monitoring of the position and water conductivity of the collapse column of the coal mine is realized.

Description

Technical Field

[0001] The present application relates to the field of distributed optical fiber sensing detection technology, and in particular to a system and method for monitoring the position and water conductivity of a subsidence column. Background Art

[0002] The collapse column is a common geological anomaly in coal mining. It is usually caused by the collapse of limestone caves under the long-term action of geological tectonic forces and the gravity of the overlying rock strata, resulting in the collapse of the overlying coal-bearing strata, forming a circular or irregular columnar structure. The collapse column causes the continuity of the coal seam to be destroyed, directly affecting the stability of the surrounding rock of the shaft and tunnel. The water diversion of the collapse column will cause water inrush from the roof and floor of the coal seam, seriously affecting the safety of the coal mine.

[0003] At present, the detection of water conductivity of subsidence columns mainly adopts a comprehensive geophysical method combining three-dimensional seismic exploration and electrical exploration. The spatial position of subsidence columns is detected by three-dimensional seismic exploration, and the water conductivity of subsidence columns is determined by electrical exploration. This method of detecting water-conducting subsidence columns combining seismic and electrical methods has been applied to coal mines to a certain extent, but due to the complex construction method and high cost, it is difficult to meet the real-time monitoring needs of coal mines for the water conductivity of subsidence columns. Summary of the invention

[0004] The purpose of the present application is to provide a system and method for monitoring the position and water conductivity of a subsidence column, so as to ensure the safety of a coal mine, simplify construction, reduce costs, and realize real-time monitoring of the position and water conductivity of a subsidence column in a coal mine.

[0005] The technical solution of the present application provides a system for monitoring the position and water conductivity of a collapse column, comprising: a monitoring well, which is opened in a mine formation; an optical fiber portion, which is at least partially arranged in the monitoring well, and the optical fiber portion comprises a single-mode optical fiber and a multi-mode optical fiber; a DAS monitoring host, which is connected to the single-mode optical fiber, and the portion of the single-mode optical fiber located in the monitoring well is used to continuously collect the acoustic wave signal generated by the vibration of the vibration source and transmit it to the DAS monitoring host, and the DAS monitoring host obtains the formation strain rate by analyzing the change of the acoustic wave signal, and defines the position of the collapse column by the formation strain rate; a DTS monitoring host, which is connected to the multi-mode optical fiber, and the portion of the multi-mode optical fiber located in the monitoring well is used to continuously collect the temperature signal and transmit the temperature signal to the DTS monitoring host, and the DTS monitoring host determines the water conductivity of the collapse column by analyzing the temperature signal and combining it with the position of the collapse column.

[0006] Optionally, the DAS monitoring host includes a DAS laser generator, a DAS pulse modulator, a DAS photoelectric detector and a DAS signal processor that are communicatively connected, and the single-mode optical fiber is connected to the DAS photoelectric detector; the DAS laser generator emits a laser, which is modulated into a DAS pulse light of the same frequency by the DAS pulse modulator, and the DAS pulse light generates back Rayleigh scattered light after entering the single-mode optical fiber, and the acoustic wave signal causes the phase of the back Rayleigh scattered light to change, and the DAS photoelectric detector collects the phase change value of the back Rayleigh scattered light along the length direction of the single-mode optical fiber, and obtains the formation strain rate through processing by the DAS signal processor, and the position of the collapse column is defined by the formation strain rate.

[0007] Optionally, the DTS monitoring host includes a DTS laser generator, a DTS demodulator, a DTS photoelectric detector and a DTS data processor that are communicatively connected, and the multimode optical fiber is connected to the DTS photoelectric detector; the DTS laser generator emits a laser, which is modulated into a DTS pulse light of the same frequency by the DTS demodulator, and the DTS pulse light produces a Raman scattering effect in the multimode optical fiber, decomposed into Stokes reflected light and anti-Stokes reflected light, which is received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the collapse column, and the water conductivity of the collapse column is judged by the temperature signal and combined with the position of the collapse column.

[0008] Optionally, the single-mode optical fiber and the multi-mode optical fiber are combined to define a composite optical cable, the first end of the composite optical cable is located outside the monitoring well, the second end of the composite optical cable extends to the bottom of the monitoring well and then turns around and extends out of the monitoring well; the composite optical cable is provided with a plurality of fixed points along the length direction, and the composite optical cable is limited on the drilling casing of the monitoring well by the plurality of fixed points.

[0009] Optionally, the monitoring well is filled with concrete or cement for sealing.

[0010] The present application also provides a method for monitoring the position and water conductivity of a collapse column, which is monitored by the collapse column position and water conductivity monitoring system described in any one of the above items, and includes the following steps: opening a monitoring well, determining the position of the monitoring well and opening a monitoring well in the mine formation; laying an optical fiber section in the monitoring well, lowering one end of the optical fiber section from the wellhead of the monitoring well to the bottom of the monitoring well and then turning back to extend to the wellhead of the monitoring well; configuring a monitoring system, wherein the optical fiber section includes a single-mode optical fiber and a multi-mode optical fiber, connecting the DAS monitoring host to the single-mode optical fiber of the optical fiber section, and connecting the DTS monitoring host to the multi-mode optical fiber of the optical fiber section; data acquisition, continuously collecting acoustic wave signals through the DAS monitoring host, and continuously collecting temperature signals through the DTS monitoring host; data processing, the DAS monitoring host analyzes changes in the acoustic wave signals to obtain formation strain rate, and defines the position of the collapse column through the formation strain rate; the DTS monitoring host determines the water content of the collapse column based on the temperature signal and the position of the collapse column.

[0011] Optionally, continuously collecting acoustic wave signals through the DAS monitoring host includes the following steps: communicating and connecting the DAS laser generator and the DAS pulse modulator in the DAS monitoring host, communicating and connecting the DAS photoelectric detector and the DAS signal processor, and connecting the single-mode optical fiber to the DAS photoelectric detector; controlling the DAS laser generator to emit laser, modulating it into DAS pulse light with the same frequency through the DAS pulse modulator, and generating back Rayleigh scattered light after the DAS pulse light enters the single-mode optical fiber, and the acoustic wave signal causes the phase of the back Rayleigh scattered light to change, and the DAS photoelectric detector collects the phase change value of the back Rayleigh scattered light along the length direction of the single-mode optical fiber, and obtains the formation strain rate through processing by the DAS signal processor, and defines the position of the collapse column by the formation strain rate.

[0012] Optionally, continuously collecting temperature signals through the DTS monitoring host includes the following steps: communicating the DTS laser generator and the DTS modem in the DTS monitoring host, communicating the DTS photoelectric detector and the DTS data processor, and connecting the multimode optical fiber with the DTS photoelectric detector; controlling the DTS laser generator to emit laser, modulating it into DTS pulse light with the same frequency through the DTS modem, the DTS pulse light generates a Raman scattering effect in the multimode optical fiber, decomposes into Stokes reflected light and anti-Stokes reflected light, which is received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the collapse column, and the water conductivity of the collapse column is judged by the temperature signal and combined with the position of the collapse column.

[0013] Optionally, the laying of the optical fiber portion in the monitoring well includes the following steps: combining the single-mode optical fiber and the multi-mode optical fiber to define a composite optical cable, wherein the first end of the composite optical cable is located outside the monitoring well, and the second end of the composite optical cable extends to the bottom of the monitoring well and then rotates and extends out of the monitoring well in the opposite direction; and the composite optical cable is provided with a plurality of fixed points along the length direction, and the composite optical cable is limited on the drilling casing of the monitoring well through the plurality of fixed points.

[0014] Optionally, the method further includes the following steps: filling the monitoring well with concrete or cement to seal the monitoring well.

[0015] The above technical solution has the following beneficial effects:

[0016] The present application provides a system and method for monitoring the position and water conductivity of a collapse column. The DAS monitoring host continuously collects acoustic signals through a single-mode optical fiber and defines the position of the collapse column according to changes in the acoustic signals. The DTS monitoring host continuously collects temperature signals through a multi-mode optical fiber and determines the water conductivity of the collapse column according to changes in the temperature signals. Real-time dynamic monitoring of the position and water conductivity of collapse columns in coal mines is performed to ensure the safety of coal mines. The system and method have the advantages of low detection cost, long measurement distance, strong anti-electromagnetic interference, high temperature resistance, high pressure resistance and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a collapse column position and water conductivity monitoring system in one embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of the structure in which the optical fiber part is fixed in the monitoring well in one embodiment of the present application.

[0019] Figure 3 This is a flow chart of a method for monitoring the position and water conductivity of a collapse column in one embodiment of the present application.

[0020] Reference Numbers

[0021] 1- monitoring well, 10- bottom of well, 2- DAS monitoring host, 3- DTS monitoring host, 4- optical fiber part, 5- collapse column, 6- ground, 7- drilling casing, 8- fastener, 9- cement. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0023] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the invention.

[0024] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0025] The present application provides a system for monitoring the position and water conductivity of a collapse column 5 , comprising: a monitoring well 1 , an optical fiber unit 4 , a DAS monitoring host 2 and a DTS monitoring host 3 .

[0026] Please refer to Figure 1 to Figure 2 The monitoring well 1 is opened in the mine stratum; the optical fiber part 4 is at least partially arranged in the monitoring well 1, and the optical fiber part 4 includes a single-mode optical fiber and a multi-mode optical fiber.

[0027] On the basis of analyzing the existing geological exploration results of the coal mine, the stratum distribution, geological structure development characteristics and geological conditions revealed by the tunnel are comprehensively studied, and the distribution range of the collapse column 5 is inferred by combining the results of geophysical logging, seismic exploration and electrical exploration. The physical parameters such as stratum temperature, velocity, density and resistivity are preferably selected to determine the location of the monitoring well 1 and make construction deployment. Among them, the monitoring well 1 can be set above the tunnel where the coal mining operation is carried out.

[0028] The DAS monitoring host 2 is connected to the single-mode optical fiber. The portion of the single-mode optical fiber located in the monitoring well 1 is used to continuously collect the acoustic wave signal generated by the vibration of the vibration source and transmit it to the DAS monitoring host 2. The DAS monitoring host 2 obtains the formation strain rate by analyzing the changes in the acoustic wave signal, and defines the position of the collapse column 5 through the formation strain rate.

[0029] The DTS monitoring host 3 is connected to the multimode optical fiber. The part of the multimode optical fiber located in the monitoring well 1 is used to continuously collect temperature signals and transmit the temperature signals to the DTS monitoring host 3. The DTS monitoring host 3 analyzes the temperature signals and combines the position of the collapse column 5 to determine the water conductivity of the collapse column 5.

[0030] In the embodiment of the present application, the sink column 5 is divided into a water-conducting sink column 5 and a waterless sink column 5. The temperature of the water-conducting sink column 5 will decrease due to water conduction. After the spatial distribution position of the sink column 5 is determined by the DAS monitoring host 2, the temperature value in the sink column 5 is measured according to the DTS monitoring host 3. When the temperature drops, it indicates that the water content of the sink column 5 increases.

[0031] The DAS (Distributed Fiber-optic Acoustic Sensing) monitoring host uses the interferometric effect of Rayleigh backscattering of optical fibers to achieve continuous distributed detection of acoustic signals. The DTS (Distributed Temperature Sensing) monitoring host uses optical time domain reflectometry to measure temperature.

[0032] In the embodiment of the present application, the DAS monitoring host 2 continuously collects acoustic signals through single-mode optical fiber and defines the position of the collapse column 5 according to the change of the acoustic signal. The DTS monitoring host 3 continuously collects temperature signals through multi-mode optical fiber and determines the water conductivity of the collapse column 5 according to the change of the temperature signal. Real-time dynamic monitoring of the position and water conductivity of the coal mine collapse column 5 is performed to ensure the safety of the coal mine. At the same time, it has the advantages of low detection cost, long measurement distance, strong anti-electromagnetic interference, high temperature resistance, high pressure resistance and high reliability.

[0033] As an optional embodiment, the DAS monitoring host 2 includes a DAS laser generator, a DAS pulse modulator, a DAS photoelectric detector, and a DAS signal processor that are communicatively connected, and the single-mode optical fiber is connected to the DAS photoelectric detector. The DAS laser generator emits a laser, which is modulated into a DAS pulse light with the same frequency by the DAS pulse modulator. After the DAS pulse light enters the single-mode optical fiber, it generates back-Rayleigh scattered light. The acoustic signal causes the phase of the back-Rayleigh scattered light to change. The DAS photoelectric detector collects the back-Rayleigh scattered light phase change value along the length direction of the single-mode optical fiber, and the formation strain rate is obtained by processing the DAS signal processor. The position of the collapse column 5 is defined by the formation strain rate. The DAS pulse monitors the change of the acoustic signal in the single-mode optical fiber and transmits the change of the acoustic signal. The DAS photoelectric detector receives the back-Rayleigh scattered light phase change value along the axis of the single-mode optical fiber, and obtains the formation strain rate by derivation of the back-Rayleigh scattered light phase change value within a specific time, and uses the change of the formation strain rate to locate the spatial position of the collapse column 5. The time axis of the DAS signal acquisition is the sampling time t, which is needed to define the distance information x along the optical fiber. x can be obtained based on the speed of light C and the effective refractive index neff: x = (C x t) / (2 x neff). The interval between the emitted laser pulses is Δt, and the corresponding length is the gauge length ΔL (for an optical fiber with a certain effective refractive index neff, the time interval Δt corresponds to the difference in the propagation distance of the two pulses in the optical fiber, which is called the gauge length ΔL (Gauge Length: ΔL = (C x t) / (2 x neff)). The time sampling interval dt (i.e. the time interval of the signal) acquired by DAS is smaller, and the corresponding sampling distance is dx (i.e. the track spacing of the signal). At each observation time t (i.e. the time of the signal), DAS measures the relative change in the strain of the optical fiber segment within the range of ±ΔL / 2 (i.e. the gauge length ΔL) of the distance x position (i.e. the track position of the signal) along the optical fiber, which is proportional to the average strain rate within the gauge length ΔL. The observed quantity of DAS is the strain rate.

[0034] As an optional embodiment, the DTS monitoring host 3 includes a DTS laser generator, a DTS modulator, a DTS photoelectric detector, and a DTS data processor that are communicatively connected, and the multimode optical fiber is connected to the DTS photoelectric detector. The DTS laser generator emits a laser, which is modulated into a DTS pulse light with the same frequency by the DTS modulator. The DTS pulse light generates a Raman scattering effect in the multimode optical fiber, decomposed into Stokes reflected light and anti-Stokes reflected light, which are received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the sink column 5. The water conductivity of the sink column 5 is determined by the temperature signal and the position of the sink column 5. When the temperature of the sink column 5 drops, it indicates that the water content of the sink column 5 increases.

[0035] Distributed temperature sensors use optical time-domain backscattering (ODTR) technology to achieve distributed measurement. When a light pulse is injected into an optical fiber from point O and propagates in the optical fiber, scattering occurs. After a period of time, the backscattered light returns to point O. Assuming that the moment of light pulse injection is the origin of time, the relationship between the distance L between the scattering point and point O in the optical fiber and the return time t of the scattered light at that point is:

[0036]

[0037] In the formula: c is the speed of light in a vacuum; n is the refractive index of the optical fiber; t is the time taken for the signal to be transmitted and received.

[0038] It can be seen from formula (1) that the echoes at different times correspond to the scattering generated by points at different distances. The location of the temperature measurement point is achieved by measuring the echoes at different times.

[0039] The perception and measurement of temperature is based on the principle of optical fiber backscattering. When a laser with a wavelength of λ0 is injected into a multimode optical fiber, it continuously generates backscattered light while transmitting forward in the multimode optical fiber. In addition to the central spectrum line with the same wavelength λ0 as the incident light, there are two spectrum lines on both sides of the backscattered light, namely λ0-Δλ and λ0+Δλ. The central spectrum line is the Rayleigh scattering spectrum line. The spectrum line with a wavelength of λs=λ0+Δλ on the low-frequency side is called Stokes reflected light (Stokes); the spectrum line with a wavelength of λa=λ0-Δλ on the high-frequency side is called anti-Stokes reflected light (Anti-Stokes). Anti-Stokes scattered light is sensitive to temperature, and its intensity is modulated by temperature, while Stokes scattered light is basically independent of temperature. The ratio of the light intensities of the two is only related to the temperature of the scattered light, that is:

[0040]

[0041] In the formula: h is Planck's constant; c is the speed of light in vacuum; k is the Boltzmann constant; T is the absolute temperature; Δγ is the offset wave number.

[0042] Therefore, by using anti-Stokes light as the signal channel and Stokes light as the reference channel, and detecting the ratio of the two light intensities, the temperature information of the scattering area can be demodulated. Combining the measurement of back Raman scattering signals with OT-DR technology, a distributed optical fiber temperature measurement system based on back Raman scattering can be realized.

[0043] For formula (2), taking logarithmic functions on both sides, we have:

[0044]

[0045] By transformation we can get:

[0046]

[0047] In the actual test process, the optical fiber sensor is placed at a temperature of T 0 Calibration is performed in a constant temperature box, and the following can be learned through calibration:

[0048]

[0049] Substituting (Formula 5) into (Formula 4) yields:

[0050]

[0051] It can be seen from the above formula that after calibration, the temperature value of each point of the distributed optical fiber can be derived by measuring the ratio of light intensity R(T).

[0052] As an optional embodiment, the single-mode optical fiber and the multi-mode optical fiber are combined to define a composite optical cable, the first end of the composite optical cable is located outside the monitoring well 1, and the second end of the composite optical cable extends to the bottom 10 of the monitoring well 1 and then turns around and extends out of the monitoring well 1. Figure 1 to Figure 2 As shown, the composite optical cable is first lowered along the wall of the monitoring well 1 to the bottom of the monitoring well 1, and then returns upward to the wellhead of the monitoring well 1 to form a U-shaped loop to achieve the laying of the composite optical cable in the monitoring well 1.

[0053] The composite optical cable is provided with a plurality of fixing points along the length direction, and the composite optical cable is limited on the drilling casing 7 of the monitoring well 1 through the plurality of fixing points. The drilling casing 7 is arranged in the drilling well to support the monitoring well 1, and a fixing structure such as a centralizer or a clamp is arranged on the drilling casing 7 to fix the composite optical cable in the monitoring well 1 stably and reliably. The embodiment of the present application can realize the temporary installation of the composite optical cable.

[0054] As an optional embodiment, the monitoring well 1 is filled with concrete or cement 9 for sealing. By filling the monitoring well 1 with concrete or cement 9, the monitoring well 1 can be permanently laid, avoiding interference from the external environment, and being stable and reliable.

[0055] The present application also provides a method for monitoring the position and water conductivity of a collapse column 5, which is monitored by the collapse column 5 position and water conductivity monitoring system described in any of the above embodiments, and includes the following steps:

[0056] S1: Open monitoring well 1, determine the location of monitoring well 1 and open monitoring well 1 in the mine stratum.

[0057] On the basis of analyzing the existing geological exploration results of the coal mine, the stratum distribution, geological structure development characteristics and geological conditions revealed by the tunnel are comprehensively studied, and the distribution range of the collapse column 5 is inferred by combining the results of geophysical logging, seismic exploration and electrical exploration. The physical parameters such as stratum temperature, velocity, density and resistivity are preferably selected to determine the location of the monitoring well 1 and make construction deployment. Among them, the monitoring well 1 can be set above the tunnel where the coal mining operation is carried out.

[0058] S2: Laying the optical fiber part 4 in the monitoring well 1, lowering one end of the optical fiber part 4 from the wellhead of the monitoring well 1 to the bottom of the monitoring well 1, and then turning back to extend to the wellhead of the monitoring well 1.

[0059] S3: Configure the monitoring system, the optical fiber part 4 includes a single-mode optical fiber and a multi-mode optical fiber, connect the DAS monitoring host 2 with the single-mode optical fiber of the optical fiber part 4, and connect the DTS monitoring host 3 with the multi-mode optical fiber of the optical fiber part 4.

[0060] S4: Data acquisition, continuously acquiring sound wave signals through the DAS monitoring host 2, and continuously acquiring temperature signals through the DTS monitoring host 3.

[0061] S5: Data processing, the DAS monitoring host 2 analyzes the change of the acoustic wave signal to obtain the formation strain rate, and defines the position of the collapse column 5 by the formation strain rate; the DTS monitoring host 3 determines the water content of the collapse column 5 according to the temperature signal and the position of the collapse column 5.

[0062] In the embodiment of the present application, the sink column 5 is divided into a water-conducting sink column 5 and a waterless sink column 5. The temperature of the water-conducting sink column 5 will decrease due to water conduction. After the spatial distribution position of the sink column 5 is determined by the DAS monitoring host 2, the temperature value in the sink column 5 is measured according to the DTS monitoring host 3. When the temperature drops, it indicates that the water content of the sink column 5 increases.

[0063] As an optional embodiment, continuously collecting the sound wave signal through the DAS monitoring host 2 includes the following steps:

[0064] Connect the DAS laser generator and DAS pulse modulator in the DAS monitoring host 2 in communication, connect the DAS photoelectric detector and DAS signal processor in communication, and connect the single-mode optical fiber to the DAS photoelectric detector;

[0065] The DAS laser generator is controlled to emit laser light, which is modulated into DAS pulse light of the same frequency by the DAS pulse modulator. After the DAS pulse light enters the single-mode optical fiber, back-Rayleigh scattered light is generated. The acoustic signal causes the phase of the back-Rayleigh scattered light to change. The DAS photoelectric detector collects the phase change value of the back-Rayleigh scattered light along the length direction of the single-mode optical fiber, and the formation strain rate is obtained after being processed by the DAS signal processor. The position of the collapse column 5 is defined by the formation strain rate. The DAS pulse monitors the change of the acoustic signal in the single-mode optical fiber and transmits the change of the acoustic signal. The DAS photoelectric detector receives the phase change value of the back-Rayleigh scattered light along the axis of the single-mode optical fiber, and derives the phase change value of the back-Rayleigh scattered light within a specific time to obtain the formation strain rate, and uses the change of the formation strain rate to locate the spatial position of the collapse column 5. As an optional embodiment, continuously collecting temperature signals through the DTS monitoring host 3 includes the following steps:

[0066] The DTS laser generator and the DTS modem in the DTS monitoring host 3 are communicatively connected, the DTS photoelectric detector and the DTS data processor are communicatively connected, and the multimode optical fiber is connected to the DTS photoelectric detector.

[0067] The DTS laser generator is controlled to emit laser light, which is modulated into DTS pulse light of the same frequency by the DTS modulator. The DTS pulse light generates Raman scattering effect in the multimode optical fiber, decomposes into Stokes reflected light and anti-Stokes reflected light, which are received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the sink column 5. The water conductivity of the sink column 5 is determined by the temperature signal and the position of the sink column 5. When the temperature of the sink column 5 decreases, it indicates that the water content of the sink column 5 increases.

[0068] As an optional embodiment, the laying of the optical fiber section 4 in the monitoring well 1 includes the following steps:

[0069] The single-mode optical fiber and the multi-mode optical fiber are combined to define a composite optical cable, the first end of the composite optical cable is located outside the monitoring well 1, and the second end of the composite optical cable extends to the bottom of the monitoring well 1 and then rotates and extends out of the monitoring well 1 in the opposite direction. The composite optical cable is provided with multiple fixing points along the length direction, and the composite optical cable is limited on the drilling casing 7 of the monitoring well 1 through the multiple fixing points. The drilling casing 7 is arranged in the drilling well to support the monitoring well 1, and a fixing structure such as a centralizer or a clamp is provided on the drilling casing 7 to fix the composite optical cable in the monitoring well 1 stably and reliably. The embodiment of the present application can realize the temporary installation of the composite optical cable.

[0070] The monitoring method for the position of the collapse column 5 and the water conductivity is to fill the monitoring well 1 with concrete or cement 9 to seal the monitoring well 1. By filling the monitoring well 1 with concrete or cement 9, the monitoring well 1 can be permanently laid, avoiding interference from the external environment, and being stable and reliable.

[0071] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0072] The above are only the principles and preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several other modifications can be made based on the principles of the present invention, which should also be considered as the protection scope of the present invention.

Claims

1. A system for monitoring the position and water conductivity of a subsidence column, characterized in that: include: A monitoring well, wherein the monitoring well is opened in the mine stratum; an optical fiber section, the optical fiber section being at least partially disposed in the monitoring well, the optical fiber section comprising a single-mode optical fiber and a multi-mode optical fiber; A DAS monitoring host, wherein the DAS monitoring host is connected to the single-mode optical fiber, and the portion of the single-mode optical fiber located in the monitoring well is used to continuously collect the acoustic wave signal generated by the vibration of the vibration source and transmit it to the DAS monitoring host, and the DAS monitoring host obtains the formation strain rate by analyzing the change of the acoustic wave signal, and defines the position of the collapse column by the formation strain rate; DTS monitoring host, the DTS monitoring host is connected to the multimode optical fiber, the portion of the multimode optical fiber located in the monitoring well is used to continuously collect temperature signals and transmit the temperature signals to the DTS monitoring host, and the DTS monitoring host determines the water conductivity of the collapse column by analyzing the temperature signal and combining it with the position of the collapse column.

2. The system for monitoring the position and water conductivity of a subsidence column according to claim 1, characterized in that: The DAS monitoring host comprises a DAS laser generator, a DAS pulse modulator, a DAS photoelectric detector and a DAS signal processor which are communicatively connected, and the single-mode optical fiber is connected to the DAS photoelectric detector; The DAS laser generator emits a laser, which is modulated into a DAS pulse light of the same frequency by the DAS pulse modulator. The DAS pulse light generates backscattered Rayleigh light after entering the single-mode optical fiber. The acoustic wave signal causes the phase of the backscattered Rayleigh light to change. The DAS photoelectric detector collects the phase change value of the backscattered Rayleigh light along the length direction of the single-mode optical fiber. The formation strain rate is obtained through processing by the DAS signal processor, and the position of the collapse column is defined by the formation strain rate.

3. The system for monitoring the location and water conductivity of a subsidence column according to claim 1, characterized in that: The DTS monitoring host comprises a DTS laser generator, a DTS modem, a DTS photoelectric detector and a DTS data processor which are communicatively connected, and the multimode optical fiber is connected to the DTS photoelectric detector; The DTS laser generator emits laser, which is modulated into DTS pulse light of the same frequency by the DTS modulator. The DTS pulse light produces Raman scattering effect in the multimode optical fiber, decomposed into Stokes reflected light and anti-Stokes reflected light, which are received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the sinkhole column. The water conductivity of the sinkhole column is determined by the temperature signal and the position of the sinkhole column.

4. A system for monitoring the position and water conductivity of a subsidence column according to any one of claims 1 to 3, characterized in that: The single-mode optical fiber and the multi-mode optical fiber are combined to define a composite optical cable, the first end of the composite optical cable is located outside the monitoring well, and the second end of the composite optical cable extends to the bottom of the monitoring well and then turns around and extends out of the monitoring well in the opposite direction; The composite optical cable is provided with a plurality of fixing points along the length direction, and the composite optical cable is limited on the drilling casing of the monitoring well through the plurality of fixing points.

5. The system for monitoring the location and water conductivity of a subsidence column according to claim 1, characterized in that: The monitoring well is filled with concrete or cement for sealing.

6. A method for monitoring the position and water conductivity of a subsidence column, characterized in that: Monitoring is performed by the collapse column position and water conductivity monitoring system described in any one of claims 1 to 5, comprising the following steps: Open monitoring wells, determine the location of monitoring wells and open monitoring wells in the mine strata; Laying an optical fiber section in a monitoring well, lowering one end of the optical fiber section from the wellhead of the monitoring well to the bottom of the monitoring well and then rotating it back to extend to the wellhead of the monitoring well; Configure a monitoring system, wherein the optical fiber unit includes a single-mode optical fiber and a multi-mode optical fiber, connect the DAS monitoring host to the single-mode optical fiber of the optical fiber unit, and connect the DTS monitoring host to the multi-mode optical fiber of the optical fiber unit; Data acquisition, continuously acquiring sound wave signals through the DAS monitoring host, and continuously acquiring temperature signals through the DTS monitoring host; Data processing: the DAS monitoring host analyzes the change of the acoustic wave signal to obtain the formation strain rate, and defines the position of the collapse column by the formation strain rate; the DTS monitoring host determines the water content of the collapse column according to the temperature signal and the position of the collapse column.

7. The method for monitoring the position and water conductivity of a collapse column according to claim 6, characterized in that: Continuously collecting acoustic wave signals through the DAS monitoring host includes the following steps: Connecting the DAS laser generator and the DAS pulse modulator in the DAS monitoring host to each other, connecting the DAS photoelectric detector and the DAS signal processor to each other, and connecting the single-mode optical fiber to the DAS photoelectric detector; The DAS laser generator is controlled to emit laser, which is modulated into DAS pulse light of the same frequency by the DAS pulse modulator. The DAS pulse light generates back-Rayleigh scattered light after entering the single-mode optical fiber. The acoustic wave signal causes the phase of the back-Rayleigh scattered light to change. The DAS photoelectric detector collects the phase change value of the back-Rayleigh scattered light along the length direction of the single-mode optical fiber. The formation strain rate is obtained through processing by the DAS signal processor, and the position of the collapse column is defined by the formation strain rate.

8. The method for monitoring the position and water conductivity of a collapse column according to claim 6, characterized in that: The continuous acquisition of temperature signals by the DTS monitoring host includes the following steps: Connect the DTS laser generator and the DTS modem in the DTS monitoring host, connect the DTS photoelectric detector and the DTS data processor, and connect the multimode optical fiber to the DTS photoelectric detector; The DTS laser generator is controlled to emit laser, which is modulated into DTS pulse light of the same frequency by the DTS modulator. The DTS pulse light produces Raman scattering effect in the multimode optical fiber, and is decomposed into Stokes reflected light and anti-Stokes reflected light, which are received by the DTS photoelectric detector and processed by the DTS data processor to obtain the temperature signal of the sinkhole column. The water conductivity of the sinkhole column can be determined by the temperature signal and the position of the sinkhole column.

9. The method for monitoring the position and water conductivity of a collapse column according to any one of claims 6 to 8, characterized in that: The method of laying the optical fiber section in the monitoring well comprises the following steps: The single-mode optical fiber and the multi-mode optical fiber are combined to define a composite optical cable, wherein a first end of the composite optical cable is located outside the monitoring well, and a second end of the composite optical cable extends to the bottom of the monitoring well and then turns around and extends out of the monitoring well in the opposite direction; The composite optical cable is provided with a plurality of fixing points along the length direction, and the composite optical cable is limited on the drilling casing of the monitoring well through the plurality of fixing points.

10. The method for monitoring the position and water conductivity of a collapse column according to claim 6, characterized in that: The following steps are also included: The monitoring well is filled with concrete or cement to seal the monitoring well.

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