A working face front and rear support roof multi-physical field optical fiber sensing monitoring method

Abstract

The application discloses a kind of working face frame front frame back roof multi-physical field optical fiber sensing monitoring method, comprising: collecting geological drilling data in and periphery of working face, analyzing lithology development condition of roof and periphery rock stratum;According to the analysis result, the layout scheme of monitoring borehole is designed, and monitoring borehole is constructed;Select multi-physical field optical fiber and sensor, install it in monitoring borehole, and protect optical fiber and sensor;Optimize grouting hole sealing technology, grouting hole sealing is carried out to monitoring borehole;Establish up and down linkage online monitoring system platform, realize the real-time transmission and acquisition of data;Dynamic analysis is carried out to monitoring data, and early warning and engineering application are carried out according to the analysis result.The application can realize multi-physical field coupling monitoring, provide continuous spatial distribution data, and overcome the limitations of traditional monitoring means.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine rock-soil engineering safety monitoring, and particularly relates to a working face front and rear roof multi-physical field optical fiber sensing monitoring method. BACKGROUND

[0002] In the process of coal mining, the stability of the roof in the front and rear areas of the hydraulic support (front and rear of the support) is crucial to the safety of the stope and production efficiency. Traditional monitoring methods mainly include point sensors such as resistance strain gauges, displacement sensors, and pressure pillows. These sensors can measure physical quantities such as roof stress and displacement, providing certain technical support for roof stability monitoring. In addition, optical fiber sensing technology has also been gradually applied in mine monitoring, mainly for roadway deformation or goaf settlement monitoring. These technologies have improved the efficiency and safety of coal mine roof monitoring to some extent.

[0003] However, the existing monitoring technology still has many shortcomings. Traditional point sensors measure a single physical quantity, making it difficult to simultaneously obtain multi-physical field coupling data and unable to achieve continuous spatial distribution monitoring. In the strong electromagnetic environment underground, these sensors have poor anti-interference ability and are easily disturbed, resulting in inaccurate monitoring data. In addition, most traditional monitoring methods require regular manual monitoring and cannot dynamically obtain monitoring parameter signal data in real time. Although optical fiber sensing technology has the advantages of intrinsic safety, anti-electromagnetic interference, and distributed measurement, existing optical fiber monitoring solutions are mostly applied to roadway deformation or goaf settlement monitoring, and the technical gap in multi-field coupling monitoring of the roof in front and rear of the hydraulic support has not been filled. SUMMARY

[0004] To solve the above technical problems, the application provides a working face front and rear roof multi-physical field optical fiber sensing monitoring method to solve the problems existing in the prior art.

[0005] To achieve the above purpose, in a first aspect, the application provides a working face front and rear roof multi-physical field optical fiber sensing monitoring method, comprising:

[0006] Collecting geological drilling data within and around the working face, analyzing the lithology development of the roof and surrounding rock layers;

[0007] According to the analysis results, designing a layout scheme for the monitoring drill holes, and constructing the monitoring drill holes;

[0008] Selecting a multi-physical field optical fiber and a sensor, installing them in the monitoring drill holes, and protecting the optical fiber and the sensor;

[0009] Optimizing the grouting and hole sealing process to grout and seal the monitoring drill holes;

[0010] Establishing the linkage of online monitoring system platform, realizing the real-time transmission and collection of data;

[0011] Making dynamic analysis on the monitoring data, and making early warning and engineering application according to the analysis results.

[0012] Preferably, the step of analyzing the lithology development of the roof and surrounding rock strata comprises:

[0013] Collecting the existing geological drilling data in the working face and surrounding area, and mastering the lithology development of the roof and surrounding rock strata of the working face;

[0014] Making interpolation processing on the drilling exposed stratum lithology thickness data, and determining the development position and range of the roof sand and mudstone in the monitoring area of the working face.

[0015] Preferably, the arrangement scheme of the monitoring drilling comprises:

[0016] The front support optical fiber sensor monitoring drilling is arranged in the return airway of the working face, and the bore diameter is Φ113mm;

[0017] The front support optical fiber strain monitoring drilling is arranged in the return airway of the working face, and the bore diameter is Φ113mm, and the angle of elevation is constructed;

[0018] The rear support optical fiber sensor monitoring drilling is arranged behind the support at the end of the transportation roadway of the working face, and the bore diameter is Φ113mm, and the angle of elevation is constructed.

[0019] Preferably, the step of selecting the multi-physical field optical fiber and sensor, installing them in the monitoring drilling, and protecting the optical fiber and sensor comprises:

[0020] Selecting the distributed strain optical fiber, soil pressure sensor, permeable water pressure sensor and humidity sensor;

[0021] Arranging the strain optical fiber in the whole hole section for monitoring the strain generated when the roof stratum is broken;

[0022] Installing the permeable water pressure sensor in the middle section of the sandstone layer in the drilling for monitoring the water pressure change of the sandstone aquifer;

[0023] Installing the humidity sensor in the middle section of the mudstone layer in the drilling for monitoring the water content change of the mudstone layer after absorbing water and mudifying;

[0024] Burying the rock-soil pressure sensor in the roof of the gob area behind the support for monitoring the overburden pressure of the caving zone rock;

[0025] Using the nylon cord to bind and fix the optical fiber and sensor on the PVC pipe, and protecting the surface of the sensor with the nylon gauze wrapped with coarse sand.

[0026] Preferably, the step of grouting and sealing the monitoring borehole in the optimized grouting and sealing process comprises:

[0027] A PVC pipe with a diameter of Φ50 mm and a length of 2 m is used to fix the optical fiber and sensor, and is sent to the final hole position together with the PVC pipe. A flower hole is drilled on the surface of the PVC pipe near the bottom of the hole, which serves as a channel for exhaust and back slurry during grouting and sealing;

[0028] The method of single / double bag sealing is used to grout and fill the sensors buried in the hole;

[0029] A flower hole is drilled on the PVC pipe at the bottom of the deep bag. After the space in the bag is filled with cement slurry, the slurry flows into the pipe wall from the PVC pipe flower hole, and the drilling is closed.

[0030] Preferably, the step of establishing an up-and-down linkage online monitoring system platform to realize real-time data transmission and collection comprises:

[0031] The lead wires of the strain optical fiber and sensor at the hole are connected by a communication cable, and the other end of the communication cable is connected to the optical fiber grating demodulator underground;

[0032] The demodulator is installed at the location of the underground local area network switch near the monitoring borehole;

[0033] The demodulator is connected to the underground local area network and is assigned an IP address to enable later acquisition of collected data on the ground.

[0034] Preferably, the step of dynamically analyzing the monitoring data and giving early warnings and engineering applications according to the analysis results comprises:

[0035] The monitoring data is dynamically analyzed to monitor the strain, pressure, seepage and humidity changes of the roof rock in real time;

[0036] According to the set early warning threshold, the system automatically triggers an early warning;

[0037] According to the real-time monitoring data, the timing of withdrawing the support is adjusted to prevent the roof caving in front of the support and the mudification of the rock after the support.

[0038] Preferably, the process of dynamically analyzing the monitoring data further comprises:

[0039] The tensile strain of the top coal, the water pressure change of the coarse sandstone layer and the pressure change of the caving zone in the goaf are analyzed;

[0040] According to the analysis results, the mining scheme of the working face is adjusted and the support arrangement and support parameters are optimized.

[0041] In a second aspect, the present application also discloses a computer device comprising a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method in the first aspect.

[0042] In a third aspect, the present application also discloses a computer readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the steps of the method in the first aspect.

[0043] Compared with the prior art, the present application has the following advantages and technical effects:

[0044] The present application provides a working face front and rear roof multi-physical field optical fiber sensing monitoring method, first, collecting the geological drilling data in and around the working face, analyzing the lithology development of the roof and surrounding rock; second, according to the analysis result, designing the layout scheme of the monitoring drill hole, and constructing the monitoring drill hole; then, selecting a multi-physical field optical fiber and a sensor, installing them in the monitoring drill hole, and protecting the optical fiber and the sensor; further, optimizing the grouting and sealing process of the monitoring drill hole; again, establishing an on-line monitoring system platform of the upper and lower wells, realizing real-time transmission and collection of data; finally, dynamically analyzing the monitoring data, and giving early warning and engineering application according to the analysis result.

[0045] The present application can realize multi-physical field coupling monitoring, provide continuous spatial distribution data, and overcome the limitations of traditional monitoring methods. The present application can resist electromagnetic interference through optical fiber sensing technology, improve durability through sensor protection measures, and ensure stable and reliable monitoring data. The present application can realize real-time data transmission and dynamic analysis through an on-line monitoring system, reduce manual inspection, reduce safety risks, prevent and control roof caving and gob caving accidents caused by working face stop mining, and ensure the safety of mine recovery. In addition, real-time data of the present application support dynamic analysis and early warning, and provide a scientific basis for working face mining design and accident prevention. The present application has strong expansibility, reduces repeated construction, and reduces labor costs and maintenance workload.

[0046] The present application innovates the sensing network configuration, multi-physical field coupling analysis and engineering installation process, realizes the leap of roof rock multi-physical field monitoring from "single point static" to "global dynamic", significantly improves the timeliness and accuracy of coal mine working face roof disaster early warning, reduces manual maintenance cost, and has outstanding engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments illustrated in the drawings are presented to explain the present application and should not be considered as imposing on the present application any improper limitations. In the drawings:

[0048] Figure 1 Monitoring area geological drilling column chart for the embodiment of the application;

[0049] Figure 2 Front and rear frame monitoring drilling layout for the embodiment of the application;

[0050] Figure 3 Front and rear frame strain, sensor optical fiber monitoring drilling schematic diagram for the embodiment of the application;

[0051] Figure 4 Up and down well linkage monitoring system schematic diagram for the embodiment of the application;

[0052] Figure 5 Front frame multi-field optical fiber strain, sensor monitoring curve schematic diagram for the embodiment of the application;

[0053] Figure 6 Rear frame (goaf caving zone) optical fiber sensor monitoring curve schematic diagram for the embodiment of the application;

[0054] 1, MKS strain optical fiber; 2, PVC pipe; 3, pressure-resistant grouting rubber pipe; 4, woven cloth bag; 5, bag one-way grouting valve; 6, intermediate section one-way grouting valve; 7, orifice lead; 8, nylon strap; 9, PVC flower eye; 10, nylon gauze; 11, coarse sand; 12, osmotic pressure sensor; 13, humidity sensor; 14, pressure sensor; 15, rear frame (goaf caving zone) optical fiber sensor monitoring drilling; 16, front frame optical fiber sensor monitoring drilling; 17, front frame optical fiber strain monitoring drilling; 18, multi-core communication optical cable; 19, downhole demodulator; 20, downhole local area network switch; 21, downhole substation; 22, ground dispatching machine room switch; 23, ground monitoring server. DETAILED DESCRIPTION

[0055] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0056] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0057] Embodiment one

[0058] As shown in Figure 1 The present embodiment provides a working face front and rear frame roof multi-physical field optical fiber sensing monitoring method, comprising:

[0059] S1, collecting geological drilling data in and around the working face, analyzing the lithology development of the roof and surrounding rock;

[0060] Further, the step of analyzing the lithology development of the roof and surrounding rock includes:

[0061] Collecting existing geological drilling data in and around the working face to understand the lithology development of the roof and surrounding rock in the working face;

[0062] Interpolating the drilling exposed stratum lithology thickness data to determine the development position and range of the roof sand and mudstone in the working face monitoring area.

[0063] S2, according to the analysis result, design the layout scheme of the monitoring drill hole, and construct the monitoring drill hole;

[0064] Further, the layout scheme of the monitoring drill hole includes:

[0065] Front fiber sensor monitoring drill hole 16, the drill hole is arranged in the working face return airway, the hole diameter is Φ113mm;

[0066] Front fiber strain monitoring drill hole 17, the drill hole is arranged in the working face return airway, the hole diameter is Φ113mm, and the angle is constructed;

[0067] Rear (goaf caving zone) fiber sensor monitoring drill hole 15, the drill hole is arranged behind the support at the end of the working face transport roadway, the hole diameter is Φ113mm, and the angle is constructed.

[0068] Specifically, the monitoring drill hole is constructed in the front and rear areas of the working face: the drill hole is an upward hole, the hole diameter is Φ113mm, and the final hole layer position is in the working face roof caving zone, the caving zone height H = the mining height h x the caving mining ratio α; according to the coal seam roof lithology exposed by the geological drill hole in and around the working face, the roof rock lithology development in the monitoring area is predicted, and the fiber sensing design scheme is preliminarily determined.

[0069] S3, selecting a multi-physical field optical fiber and a sensor, installing the same in the monitoring drill hole, and protecting the optical fiber and the sensor;

[0070] Further, the step of selecting a multi-physical field optical fiber and a sensor, installing the same in the monitoring drill hole, and protecting the optical fiber and the sensor includes:

[0071] Selecting a distributed strain optical fiber, a soil pressure sensor, a permeable water pressure sensor, and a humidity sensor;

[0072] The strain optical fiber is arranged in the full hole section for monitoring the strain generated when the roof rock layer is broken;

[0073] The permeable water pressure sensor is installed in the middle section of the sandstone layer in the drill hole for monitoring the water pressure change of the sandstone aquifer;

[0074] The humidity sensor is installed in the middle section of the mudstone layer in the borehole for monitoring the change of water content of the mudstone layer after cementation;

[0075] The geotechnical pressure sensor is buried in the roof of the gob behind the hydraulic support for monitoring the overburden pressure of the rock in the caving zone;

[0076] The optical fiber and the sensor are fixed on the PVC pipe by nylon straps, and the surface of the sensor is protected by nylon gauze wrapped with coarse sand.

[0077] Specifically, the positions of the strain optical fiber, the earth pressure, the seepage water pressure and the humidity sensor are determined: during the drilling process, the real lithology of the whole section is recorded. On this basis, the preliminary design of the optical fiber sensing scheme is adjusted in time; according to different monitoring objects, the borehole is divided into a strain optical fiber monitoring hole in front of the support and a sensor optical fiber monitoring hole in front of and behind the support. The strain optical fiber is buried in the whole section to dynamically monitor the rock strain under the influence of mining; the water pressure and humidity sensors are buried in the coarse sandstone layer and the mudstone layer respectively in the optical fiber monitoring hole to monitor the water pressure of the sandstone aquifer and the change of the water content of the mudstone after absorbing water. The pressure sensor is buried in the borehole behind the hydraulic support in the working face to monitor the change law of the rock pressure behavior in the goaf.

[0078] S4, optimizing the grouting and sealing process of the monitoring borehole;

[0079] As an innovative implementation, the step of optimizing the grouting and sealing process of the monitoring borehole includes:

[0080] A PVC splicing pipe with a diameter of Φ50mm and a single length of 2m is used to fix the optical fiber and the sensor, and is sent to the final hole position together with the PVC pipe, and at the same time, it is used as a channel for exhaust and backfilling of slurry during grouting and sealing;

[0081] The single / double capsule bag plugging method is used to grout and fill the sensor buried in the hole;

[0082] A flower hole is opened at the PVC pipe part at the bottom of the deep capsule bag, and after the space in the middle of the capsule bag is filled with cement slurry, the slurry flows into the inner wall of the PVC pipe from the flower hole, and the drilling is closed.

[0083] Specifically, the grouting and backfilling process of the optical fiber monitoring borehole is optimized:

[0084] The strain optical fiber and various sensors are fixed on the PVC pipe (diameter Φ50mm, 2.0m / rod) by nylon straps, and the surface of the sensor is protected by nylon gauze wrapped with coarse sand, and is sent into the hole together with the casing pipe.

[0085] The two bags are connected by a high-pressure rubber tube to form a complete sealing material. The injection grouting valve I and II are arranged at the connection between the grouting rubber tube and the two bags, and the injection grouting valve III is arranged in the middle section, and the opening pressure of the injection grouting valve III in the middle section is greater than that of the injection grouting valves I and II. In the initial stage of grouting, the injection grouting valves I and II of the bags are opened first, and then the grouting liquid enters the bags through the high-pressure rubber tube, and the bags are inflated to effectively seal the two ends of the borehole. As the grouting pressure increases, the injection grouting valve III in the middle section is opened, and the two bags are filled with grouting liquid.

[0086] Notably, to reduce a grouting return pipe in the borehole, three flower eyes are threaded on the PVC pipe, and the flower eyes are located below the in-hole section bag.

[0087] The woven bag and the grouting rubber tube are fixed together on the PVC pipe, and the two bags are fixed below the orifice and the in-hole sensor.

[0088] S5, an up-down linkage online monitoring system platform is established to realize real-time transmission and collection of data;

[0089] As an innovative implementation, the step of establishing an up-down linkage online monitoring system platform to realize real-time transmission and collection of data includes:

[0090] The lead wires of the strain optical fiber and the sensor at the orifice are connected by a communication optical cable, and the other end of the communication optical cable is connected to the fiber grating demodulator underground;

[0091] The demodulator is installed at the position of the local area network switch near the monitoring borehole underground;

[0092] The demodulator is connected to the local area network underground, and is given an IP address to realize acquisition of collected data on the ground.

[0093] Specifically, the underground fiber demodulator is in communication with the fiber strain and sensor: the strain optical fiber and the sensor in the hole are led to the outside of the orifice by fiber lead wires, and the lead wires led out of the orifice are connected by a multi-core communication optical cable. After the connection is completed, test whether there is signal data output. The other end of the communication optical cable is connected to the fiber demodulator. The underground demodulator is installed near the local area network switch near the monitoring borehole, so as to shorten the length of the communication optical cable, reduce the optical loss, and ensure the accuracy of the data. The fiber demodulator equipment connected to the local area network switch underground is allocated an enterprise local area network IP address.

[0094] S6, dynamically analyzing the monitoring data, and giving a warning and engineering application according to the analysis result.

[0095] Further, the step of dynamically analyzing the monitoring data and giving a warning and engineering application according to the analysis result includes:

[0096] Dynamic analysis of monitoring data, real-time monitoring of roof strata strain, pressure, seepage and humidity changes;

[0097] According to the set early warning threshold, the system automatically triggers early warning;

[0098] According to the real-time monitoring data, adjust the timing of support withdrawal, prevent the arch from falling and the arch from mud outburst accident.

[0099] Further, the process of dynamic analysis of monitoring data also includes:

[0100] Analysis of the tensile strain of the top coal position, the water pressure change of the coarse sandstone layer and the pressure change of the goaf caving zone;

[0101] According to the analysis results, adjust the mining scheme of the working face, and optimize the support arrangement and support parameters.

[0102] Specifically, after the communication between the downhole demodulator and the monitoring drill hole strain and sensor is completed, a large storage server device is installed in the mine ground dispatching room machine room. Assign an IP address to the ground server, connect it to the switch in the machine room. Through the local connection of the server, configure the IP address, connect it to the same local area network with the downhole demodulator. At the same time, install the strain and sensor monitoring application program on the server, configure the program running parameters (monitoring period, light loss threshold, etc.), realize the data inquiry of the downhole demodulator on the ground server.

[0103] Example:

[0104] Taking No. 11702 working face of Xinjiang Hami Dananhu No. 7 coal mine as an example, the working face roadway height is 3.2 m, and the top coal caving mining method is adopted. The inner section (0-1000 m) is 310 m long, and the outer section (1000-2400 m) is 260 m long. When the width of the stope face changes, the working face needs to stop production and remove part of the fully mechanized support. In order to do a good job in the management of roof safety during the withdrawal of the support, the multi-physical field optical fiber sensing monitoring is carried out in the working face before and after the support.

[0105] S1. Geological analysis of monitoring area and drilling design;

[0106] According to the stratum exposed by the drill hole in the 11702 working face and the surrounding area, as shown in Table 1;

[0107] Table 1

[0108]

[0109] The roof strata in this area are mainly weakly cemented siltstone and gravel-containing coarse sandstone. The lithology development of the roof strata is preliminarily mastered, and the monitoring drill hole layout position is determined as follows: Figure 2 ).

[0110] S101. The pre- and post-frame sensor monitoring holes (1#-6#): The drilling holes are arranged in the working face return airway, with a hole diameter of Φ113 mm. The 1#-3# holes end in the 7 coal roof rock layer, 12.3 m away from the side and 17.8 m away from the top; the 4#-6# holes are arranged in the 6 coal floor rock layer, 21.0 m away from the side and 17.8 m away from the top.

[0111] S102. The pre-frame strain monitoring holes (7#-9#): The 7#-9# holes are arranged in the working face return airway, with a hole diameter of Φ113 mm, and are constructed at an angle, ending in the 5 coal roof coarse sandstone layer, 26.3 m away from the side and 44.8 m away from the top.

[0112] S103. The goaf caving zone monitoring hole (10#): The drilling hole is arranged behind the support at the end of the working face haulage roadway, with a hole diameter of Φ113 mm, and is constructed at an angle, ending in the 7 coal immediate roof rock layer.

[0113] S2. Selection and installation of optical fibers and sensors;

[0114] S201. Selection of strain optical fiber: The distributed MKS strain optical fiber 1 has a spatial resolution of 1 m, a strain range of ±15000με, and is used to monitor the strain generated by the rock layer rupture in the whole hole section of the roof.

[0115] S202. Selection of sensors: The optical fiber grating osmotic pressure sensor 12 has a range of 0-0.5 MPa and an accuracy of ±0.5% FS, and is used to monitor the water pressure of the sandstone aquifer; the optical fiber grating humidity sensor 13 has a range of 0-100% RH and an accuracy of ±2% RH, and is used to monitor the moisture content of the mudstone layer; the optical fiber grating soil pressure sensor 14 has a range of 0-10 MPa and an accuracy of ±1% FS, and is buried in the immediate roof to monitor the overburden pressure of the caving zone rock and reflect its compaction degree.

[0116] S203. Fixing and protection of monitoring elements: The strain optical fiber 1 and the sensors are tied to the outer wall of the PVC pipe 2, and are fixed with nylon straps 8. The sensors are wrapped with eight-eye nylon gauze 10, and the inside is filled with coarse sand 11 with a particle size of 5-10 mm to prevent being affected by the grout. Three flower holes 9 are opened at the bottom of the PVC pipe as grouting and grout returning channels.

[0117] S3. Optimization of grouting and hole sealing process;

[0118] The "two plugging and one grouting" woven bag grouting process is adopted: Figure 3 The two woven bags 4 are fixed at the hole opening and below the sensors in the hole, respectively, and are connected through pressure-resistant grouting rubber pipes 3.

[0119] At the initial stage of grouting, open the one-way grouting valve 5 of the bag, inject the cement-water glass double liquid slurry (water-cement ratio 1:1, accelerator dosage 3%), and seal the two ends of the borehole after the bag expands. When the grouting pressure reaches 1.5 MPa, open the one-way grouting valve 6 of the middle section, fill the gap between the two bags, and close the borehole until the PVC pipe returns to the slurry.

[0120] S4. Network of monitoring system and data transmission;

[0121] By establishing an online monitoring system platform (up and down the well) Figure 4 , the data monitoring is intelligentized.

[0122] S401. Downhole networking: the borehole optical fiber and sensor port lead 7 are connected to the downhole demodulator 19 through the multi-core communication optical cable 18. The downhole demodulator 19 is installed near the downhole local area network switch 20 in the downhole substation 21 of the mining area, and the local area network IP address is distributed.

[0123] S402. Ground platform construction: connect the large-capacity ground monitoring server 23 (storage ≥10TB) to the ground dispatching room switch 22 in the ground dispatching room, configure the IP address, and connect to the same network segment with the downhole equipment. Install data acquisition software, set the sampling interval to 10 min, and receive monitoring data in real time.

[0124] S5. Dynamic analysis and application of monitoring data;

[0125] S501. Multi-field monitoring of the front roof: the #11 strain cable opening position is located about 7 m in front of the working face, similar to the other two optical fiber monitoring holes. A large tensile strain concentration area appears near the top coal position, indicating that the top coal position is fractured, and the top coal and the fine sandstone above it are in compressive strain. As the working face advances, the compressive strain gradually increases, and further in, the coarse sandstone and the overlying siltstone are separated, the optical fiber strain gradually changes to tensile strain, and the upper siltstone layer is in tensile strain. With the advancement of the working face, the water pressure in the coarse sandstone layer gradually increases, the internal part of the local delamination gradually fills with water, and the osmotic pressure sensor data gradually increases, with a peak value of about 0.1 MPa, as shown in Figure 5 .

[0126] S502. Monitoring behind the frame (goaf caving zone): the overburden pressure of the caving zone shows a trend of first increasing temporarily and then increasing slowly. The main reason is that the pressure suddenly increases due to the pressure of the crushed stone block in the goaf roof pressing the sensor at the initial stage of monitoring, and then decreases and remains stable. With the passage of time, the rock in the goaf caving zone collapses continuously, and the pressure gradually increases to 1.4 MPa. The osmotic water pressure fluctuates to some extent, but the overall change is small, and the osmotic pressure stabilizes at about 0.12 MPa, as shown in Figure 6 .

[0127] S6. Early warning and engineering effect.

[0128] Through real-time analysis of data by the ground server, when the sandstone aquifer permeation water pressure is greater than 0.2 MPa or the top coal tensile strain is greater than 1000με, the system triggers early warning. According to this, the 11702 working face adjusts the support retreat timing, successfully avoids the arch front draw and the arch rear argillization outburst accident, and verifies the engineering effectiveness of the method.

[0129] The embodiment has the following beneficial effects:

[0130] The application realizes synchronous acquisition and fusion analysis of stress field, seepage field, humidity field and other multi-physical field data by integrating strain optical fiber, earth pressure sensor, permeation water pressure sensor and humidity sensor. The application overcomes the limitation that the traditional point sensor (such as resistance strain gauge) can only obtain a single physical quantity; the optical fiber sensing technology has no electric signal transmission, has strong anti-underground electromagnetic interference ability, and avoids signal distortion caused by electromagnetic noise; the sensor is protected by the nylon gauze wrapped with coarse sand, combined with the "two plugging and one injection" grouting process (cloth bag plugging, high-pressure hose grouting), the durability of the sensor in the complex geological environment is improved; based on enterprise local area network IP address configuration, the ground dispatching room can directly call monitoring data, reduces the manual inspection frequency, and reduces the safety risk. The monitoring system platform supports parallel access of multiple sensors, and is convenient for later expansion of monitoring parameters or coverage range.

[0131] The application realizes the leap of the roof rock multi-physical field monitoring from "single point static" to "global dynamic" by innovating the sensing network configuration, multi-physical field coupling analysis and engineering installation process, significantly improves the timeliness and accuracy of the roof disaster early warning of the coal mine working face, reduces the manual maintenance cost, and has outstanding engineering application value.

[0132] Embodiment two

[0133] The embodiment also discloses a computer device, including a memory, a processor and a computer program stored on the memory, and the processor executes the computer program to realize the steps of the method in embodiment one.

[0134] Embodiment three

[0135] The embodiment also discloses a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method in embodiment one.

[0136] The above merely provides the preferred embodiments of the present application, and the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-physics fiber optic sensing monitoring method for the rear top plate of a work surface frame, characterized in that, Includes the following steps: Collect geological borehole data within and around the working face, and analyze the lithological development of the roof and surrounding rock strata; Based on the analysis results, a layout plan for the monitoring boreholes was designed, and the monitoring boreholes were constructed. The arrangement scheme of the monitoring boreholes includes: The fiber optic sensor in front of the frame monitors the borehole, which is located in the return airway of the working face and has a diameter of Φ113mm. Fiber optic strain monitoring boreholes were drilled in front of the frame. The boreholes were located in the return airway of the working face, with a diameter of Φ113mm and were drilled at an elevation angle. The fiber optic sensor monitors the borehole behind the support. The borehole is located behind the support at the end of the transport roadway of the working face. The borehole diameter is Φ113mm and the drilling is carried out at an elevation angle. Select multiphysics fiber optic cables and sensors, install them inside the monitoring borehole, and protect the fiber optic cables and sensors. The steps of selecting multiphysics fiber optic cables and sensors, installing them inside the monitoring borehole, and protecting the fiber optic cables and sensors include: Select distributed strain fiber optic cable, soil pressure sensor, seepage water pressure sensor and humidity sensor; Strain-sensitive optical fibers are deployed throughout the entire borehole section to monitor the strain generated when the top rock strata fracture. A permeable water pressure sensor was installed in the middle section of the sandstone layer inside the borehole to monitor changes in water pressure in the sandstone aquifer. A humidity sensor was installed in the middle section of the mudstone layer inside the borehole to monitor the change in water content after the mudstone layer was cemented. The soil and rock pressure sensor was buried in the roof of the goaf behind the frame to monitor the overlying pressure of the rock in the collapse zone. The optical fiber and sensor were secured to the PVC pipe using nylon cable ties, and the sensor surface was protected with a nylon mesh wrapped with coarse sand. Optimize the grouting and sealing process, and perform grouting and sealing on the monitoring boreholes; The optimized grouting and sealing process includes the following steps for grouting and sealing the monitoring borehole: A PVC connector with a diameter of Φ50mm and a single length of 2m is used to bind and fix the optical fiber and sensor. It is sent to the final hole position along with the PVC pipe. At the same time, perforated holes are drilled on the surface of the PVC pipe near the bottom of the hole to serve as channels for air release and grout return during grouting and sealing. The sensor already embedded in the borehole was filled with grout using a single / double bag sealing method. Drill holes are made in the PVC pipe at the bottom of the deep bladder. After the space between the two bladders is filled with cement grout, the grout flows from the holes in the PVC pipe into the inner wall of the pipe and returns to the inside, thus sealing the hole. Establish an online monitoring system platform that links the surface and underground operations to achieve real-time data transmission and acquisition; Dynamically analyze monitoring data, and use the analysis results for early warning and engineering applications.

2. The method according to claim 1, characterized in that, The steps for analyzing the lithological development of the top strata and surrounding rock layers include: Collect existing geological borehole data within and around the working face to understand the lithological development of the roof and surrounding rock strata of the working face; Interpolation processing was performed on the lithological thickness data of the strata exposed by the borehole to determine the location and extent of the development of sandstone and mudstone in the roof within the monitoring area of ​​the working face.

3. The method according to claim 1, characterized in that, The steps for establishing a surface-to-ground online monitoring system platform to achieve real-time data transmission and acquisition include: Connect the strain fiber and sensor lead at the orifice with a communication optical cable, and connect the other end of the communication optical cable to the fiber optic demodulator down in the well. Install the demodulator at a location near the downhole LAN switch, close to the monitoring borehole. Connect the demodulator to the downhole local area network and assign it an IP address so that it can acquire data on the surface later.

4. The method according to claim 1, characterized in that, The steps of dynamically analyzing monitoring data and issuing early warnings and applying the analysis results in engineering applications include: Dynamic analysis of monitoring data is performed to monitor changes in strain, pressure, seepage, and humidity in the roof strata in real time. The system automatically triggers an alert based on the set alert threshold. Based on real-time monitoring data, the timing of support retraction is adjusted to prevent accidents such as pre-support leakage and post-support mud outburst.

5. The method according to claim 4, characterized in that, The process of dynamically analyzing monitoring data also includes: The tensile strain at the top coal location, the water pressure changes in the coarse sandstone layer, and the pressure changes in the caving zone of the goaf were analyzed. Based on the analysis results, the mining plan for the working face was adjusted, and the support layout and support parameters were optimized.

6. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1-5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-5.

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