A real-time measuring system and method for gas content in a sealed roadway in a coal mine underground

Abstract

The application discloses a kind of coal mine underground sealed roadway gas content real-time determination system and determination method, belong to coal mine gas content determination field;The method comprises: before roadway sealing, distribute distributed sensing optical fiber network and determine initial volume;After sealing, continuously monitor surrounding rock strain and internal gas pressure, temperature and gas concentration;Periodically inject known amount of inert gas into sealed space, use the change of gas concentration, pressure and temperature before and after injection, based on gas state equation to invert current absolute volume;Based on optical fiber strain data, calculate volume estimate through geometric and physical model, fuse the above two volume data, obtain continuous, high-precision optimal dynamic volume;Finally, fuse dynamic volume, concentration, pressure and temperature data, calculate gas total content and its change rate in standard state in real time, realize hierarchical early warning and gas resource, risk quantification management.

Description

Technical Field

[0001] This invention relates to the field of coal mine safety monitoring technology, specifically to a real-time measurement system and method for gas content in closed underground roadways of coal mines. Background Technology

[0002] In coal mining, it is often necessary to construct sealed walls to enclose roadways to prevent spontaneous combustion in goaf areas and isolate hazardous zones. According to the "Coal Mine Safety Regulations," effective monitoring of the gas situation within the sealed area is essential to prevent gas accumulation and abnormal outbursts, ensuring mine safety. Furthermore, the gas content within the roadway when the sealed wall is opened is a crucial basis for developing specific safety measures.

[0003] Currently, coal mines commonly monitor methane concentration by installing gas sensors in sealed walls or by relying on periodic manual checks. However, due to the continuous deformation of roadways under surrounding rock pressure, the internal volume of the roadway is in a dynamic state of change. Gas concentration data alone cannot accurately calculate the true total amount of methane, leaving the actual amount unknown. Existing technologies cannot achieve continuous and accurate measurement of total methane volume, failing to meet the safety regulations for real-time monitoring and early warning, and also hindering the effective extraction and utilization of methane resources. Discrete and lagging monitoring data turn sealed areas into a "black box" for safety management, making it impossible to quantitatively predict and provide tiered early warnings of methane changes, resulting in persistent safety hazards.

[0004] Therefore, there is an urgent need to develop a method and system that can measure the gas content in closed roadways in real time, continuously and accurately, in order to solve the calculation problem caused by the unknown dynamics of gas volume, realize the visual monitoring of the total amount and trend of gas, provide a basis for the utilization of gas resources, and improve the mine's safety early warning and risk management capabilities. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a real-time gas content measurement system and method for underground closed roadways in coal mines.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This application provides a real-time gas content measurement system for sealed underground roadways in coal mines, comprising:

[0008] The sensing layer includes a distributed sensing fiber optic network deployed in the surrounding rock of the tunnel, pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices installed in the observation holes of the sealed wall.

[0009] The data transmission and processing layer includes an optical fiber demodulator connected to the distributed sensing optical fiber network, a data acquisition instrument connected to each sensor and the optical fiber demodulator, and a ground monitoring center.

[0010] The application layer includes a dynamic volume fusion calculation module and a gas content calculation and early warning module running in the ground monitoring center;

[0011] The dynamic volume fusion calculation module is configured to periodically receive and fuse the absolute volume obtained by the quantitative gas injection device and the volume estimated by the monitoring data of the distributed sensing fiber optic network, so as to output a continuous optimal dynamic volume value V(t).

[0012] The gas content calculation and early warning module is configured to: calculate and warn based on the optimal dynamic volume value. and real-time monitoring of gas concentration Gas pressure and gas temperature Real-time calculation of total gas content under standard conditions and its rate of change And it provides tiered warnings based on preset thresholds.

[0013] Optionally, the quantitative gas injection device includes a high-pressure inert gas storage tank, a precision pressure reducing valve, a high-precision mass flow controller, and a solenoid valve connected in sequence via pipelines. The outlet end of the pipeline extends into the sealed space through an observation hole in the sealed wall. The inert gas is nitrogen or argon.

[0014] Optionally, the dynamic volume fusion calculation module specifically includes:

[0015] The gas calibration volume calculation unit is configured to calculate the volume of gas injected each time a known number of moles are injected. Record stable methane concentrations before and after the introduction of inert gas. , gas pressure , and gas temperature , And calculate the absolute volume at the current moment according to the following formula. :

[0016]

[0017] in, It is the ideal gas constant;

[0018] The strain volume estimation unit is configured to calculate the volume estimate based on the distributed strain field data of the surrounding rock in the tunnel, obtained from the optical fiber demodulator, using a preset geometric and physical model. ;

[0019] The fusion correction unit is configured to calculate the volume estimate and the absolute volume during the same period. The deviation is used to dynamically correct the parameters of the geometric and physical model, thereby improving the subsequent estimation. Towards The system converges and ultimately outputs the optimal dynamic volume value after periodic calibration and correction. .

[0020] Optionally, the preset geometric and physical model in the strain volume estimation unit is:

[0021] Establish an initial three-dimensional geometric model of the tunnel and discretize it;

[0022] Based on the distributed strain field data, the three-dimensional displacement field on the tunnel surface is solved by introducing a regularization method. ;

[0023] Update the coordinates of the surface nodes of the tunnel, and perform three-dimensional Delaunay triangulation on the updated surface nodes to generate a closed volume mesh composed of tetrahedrons;

[0024] The estimated volume is obtained by summing the volumes of all tetrahedrons. :

[0025]

[0026] in, Representing the A tetrahedron This represents the total number of tetrahedrons.

[0027] Optionally, in the gas content calculation and early warning module, the total gas content... The calculation formula is:

[0028] .

[0029] in, and These represent temperature and pressure under standard conditions, respectively.

[0030] Optionally, the tiered early warning specifically refers to:

[0031] Set gas content threshold and rate of change threshold ;

[0032] when or When a level two warning is triggered, a red warning box pops up on the ground monitoring platform interface and the audible and visual alarm is activated.

[0033] when Within the preset yellow warning zone or When the rate of change exceeds the baseline, a Level 1 warning is triggered, and a yellow warning box pops up on the ground monitoring platform interface.

[0034] Secondly, this application provides a method for real-time determination of gas content in closed underground roadways of coal mines based on the above-mentioned system, comprising the following steps:

[0035] S1. Before the tunnel is sealed, a distributed sensing fiber optic network is pre-installed along the tunnel's axial and circumferential directions to determine the initial spatial volume of the tunnel. Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices are installed inside the observation holes of the sealed wall.

[0036] S2. After the tunnel is sealed, start the system to continuously collect distributed strain data of the surrounding rock of the tunnel, as well as gas pressure, gas temperature and gas concentration data inside the sealed space.

[0037] S3. Perform inert gas calibration periodically: Record the stable gas concentration in the confined space before injection. ,pressure and temperature Inject a known number of moles After the inert gas is mixed and stabilized, the gas concentration after stabilization is recorded. ,pressure and temperature The current absolute volume is calculated by inversion based on the ideal gas equation of state. ;

[0038] S4. Dynamic Volume Fusion: Based on the distributed strain data acquired in step S2, the volume estimate is calculated using geometric and physical models. ;Will The same period obtained in step S3 The model is compared and fused, and the model parameters are corrected through deviation feedback to output continuous optimal dynamic volume values. ;

[0039] S5. Gas content calculation: [The following is a partial translation of the original text and can be left as is:] With real-time monitoring , , Substitute the data into the following formula to calculate the total gas content under standard conditions. :

[0040]

[0041] S6. Early Warning and Output: Calculation rate of change ,Will and It compares the data with preset multi-level safety thresholds to achieve tiered early warning and displays the results in real time. and data.

[0042] Optionally, the inversion calculation of the current absolute volume in step S3... The formula is:

[0043]

[0044] Optionally, the dynamic volume fusion described in step S4 specifically includes:

[0045] Solving the three-dimensional displacement field on the tunnel surface based on fiber optic strain data;

[0046] Update the node coordinates of the tunnel geometry model, and obtain them through 3D Delaunay triangulation and volume summation. ;

[0047] by To achieve high-precision observations, establish and The deviation is the same as the equivalent elastic modulus of the geometric and physical model. The correction relationship between them, if This increases the equivalent elastic modulus. The assignment of values ​​reduces the displacement calculated by the model under the same strain, thereby reducing the displacement in the next iteration. Decrease and towards To move closer.

[0048] Thirdly, this application provides a method for pinpoint determination of gas content in sealed historical roadways, comprising:

[0049] Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices were installed in the observation holes of the sealed walls of the historical alleyways.

[0050] Perform a single or periodic inert gas injection calibration operation, and use the following formula to inversely calculate the absolute volume of the sealed tunnel at the calibration time. :

[0051]

[0052] This volume Gas concentration measured at the same time ,pressure and temperature Substitute into the following formula to calculate the standard state gas content at that moment. :

[0053] .

[0054] Compared with the prior art, this application has the following beneficial effects:

[0055] This application provides a real-time gas content measurement system and method for sealed underground roadways in coal mines. It integrates periodic inert gas injection calibration with distributed fiber optic strain monitoring to construct a dynamic volume inversion mechanism. This solves the problem of inaccurate calculation of total gas volume due to unknown volume caused by roadway deformation, and realizes non-contact, continuous, and accurate measurement of total gas volume in sealed roadways. It provides a reliable basis for gas resource extraction and utilization, conforms to green mining policies, and enables a shift from passive storage to proactive prevention and control in safety management through real-time content and rate of change early warning, thereby improving the mine's safety assurance capabilities. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the overall system architecture of the present invention.

[0057] Figure 2 This is a schematic diagram of the fiber optic sensor layout in the tunnel.

[0058] Figure 3 This is a schematic diagram of the sealed wall structure and sensor installation.

[0059] Figure 4 This is a schematic diagram of the gas injection device.

[0060] Figure 5 This is the overall flow chart of the real-time gas content determination method of the present invention.

[0061] Figure 6 This is a logic block diagram for calculating and warning of gas content.

[0062] In the attached diagram: 1-Sealed tunnel; 2-Circumferential sensing fiber optic cable; 3-Axial sensing fiber optic cable; 4-Measurement hole; 5-Observation hole; 6-Water outlet hole; 7-Fiber optic demodulator; 8-Pressure sensor; 9-Temperature sensor; 10-Gas concentration sensor; 11-Quantitative gas injection device; 12-Inert gas injection pipeline; 13-Data acquisition instrument; 14-Sealed wall; 15-Backfill loess; 16-Valve; 17-Control box; 18-High-pressure inert gas storage tank; 19-Precision pressure reducing valve; 20-High-precision mass flow controller; 21-Solenoid valve. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Furthermore, in this invention, an element referred to as fixed to or disposed on another element may be directly disposed on the other element, or there may be an intermediate element. When an element is considered to be connected to another element, it may be directly connected to the other element, or there may be an intermediate element present simultaneously. The terms vertical, horizontal, left, right, and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0065] See Figures 1-6 This application provides a real-time gas content measurement system for sealed underground roadways in coal mines, comprising:

[0066] The sensing layer includes a distributed sensing fiber optic network deployed in the surrounding rock of the tunnel, pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices installed in the observation holes of the sealed wall.

[0067] The data transmission and processing layer includes an optical fiber demodulator connected to the distributed sensing optical fiber network, a data acquisition instrument connected to each sensor and the optical fiber demodulator, and a ground monitoring center.

[0068] The application layer includes a dynamic volume fusion calculation module and a gas content calculation and early warning module running in the ground monitoring center;

[0069] The dynamic volume fusion calculation module is configured to periodically receive and fuse the absolute volume obtained by the quantitative gas injection device and the volume estimated by the monitoring data of the distributed sensing fiber optic network, so as to output a continuous optimal dynamic volume value V(t).

[0070] The gas content calculation and early warning module is configured to: calculate and warn based on the optimal dynamic volume value. and real-time monitoring of gas concentration Gas pressure and gas temperature Real-time calculation of total gas content under standard conditions and its rate of change And it provides tiered warnings based on preset thresholds.

[0071] In one specific embodiment, the quantitative gas injection device includes a high-pressure inert gas storage tank, a precision pressure reducing valve, a high-precision mass flow controller, and a solenoid valve connected in sequence via pipelines. The outlet end of the pipeline extends into the sealed space through an observation hole in the sealed wall. The inert gas is nitrogen or argon.

[0072] In one specific embodiment, the dynamic volume fusion calculation module specifically includes:

[0073] The gas calibration volume calculation unit is configured to calculate the volume of gas injected each time a known number of moles are injected. Record stable methane concentrations before and after the introduction of inert gas. , gas pressure , and gas temperature , And calculate the absolute volume at the current moment according to the following formula. :

[0074]

[0075] in, It is the ideal gas constant;

[0076] The strain volume estimation unit is configured to calculate the volume estimate based on the distributed strain field data of the surrounding rock in the tunnel, obtained from the optical fiber demodulator, using a preset geometric and physical model. ;

[0077] The fusion correction unit is configured to calculate the volume estimate and the absolute volume during the same period. The deviation is used to dynamically correct the parameters of the geometric and physical model, thereby improving the subsequent estimation. Towards The system converges and ultimately outputs the optimal dynamic volume value after periodic calibration and correction. .

[0078] In one specific embodiment, the preset geometric and physical model in the strain volume estimation unit is:

[0079] Establish an initial three-dimensional geometric model of the tunnel and discretize it;

[0080] Based on the distributed strain field data, the three-dimensional displacement field on the tunnel surface is solved by introducing a regularization method. ;

[0081] Update the coordinates of the surface nodes of the tunnel, and perform three-dimensional Delaunay triangulation on the updated surface nodes to generate a closed volume mesh composed of tetrahedrons;

[0082] The estimated volume is obtained by summing the volumes of all tetrahedrons. :

[0083]

[0084] in, Representing the A tetrahedron This represents the total number of tetrahedrons.

[0085] In one specific implementation, the gas content calculation and early warning module calculates the total gas content. The calculation formula is:

[0086]

[0087] in, and These represent temperature and pressure under standard conditions, respectively.

[0088] In one specific implementation, the tiered early warning system specifically refers to:

[0089] Set gas content threshold and rate of change threshold ;

[0090] when or When a level two warning is triggered, a red warning box pops up on the ground monitoring platform interface and the audible and visual alarm is activated.

[0091] when Within the preset yellow warning zone or When the rate of change exceeds the baseline, a Level 1 warning is triggered, and a yellow warning box pops up on the ground monitoring platform interface.

[0092] In this embodiment, combined with the appendix Figure 2 To be continued Figure 4 A real-time gas content measurement system for sealed underground roadways in coal mines includes: a sealed roadway 1, a circumferential sensing fiber optic cable 2, an axial sensing fiber optic cable 3, a measurement hole 4, an observation hole 5, a water discharge hole 6, a fiber optic demodulator 7, a pressure sensor 8, a temperature sensor 9, a gas concentration sensor 10, a quantitative gas injection device 11, an inert gas injection pipeline 12, a data acquisition instrument 13, a sealed wall 14, a loess filling 15, a valve 16, a control box 17, a high-pressure inert gas storage tank 18, a precision pressure reducing valve 19, a high-precision mass flow controller 20, and a solenoid valve 21.

[0093] As attached Figure 1 and attached Figure 2As shown, the surrounding rock deformation monitoring module is responsible for acquiring direct physical quantities characterizing the spatial structural changes of the sealed roadway. Circumferential sensing fibers 2 and axial sensing fibers 3 are pre-embedded along the axial and circumferential (top, side, bottom) front of the sealed roadway to form a spatial grid-like monitoring network. All circumferential sensing fibers 2 and axial sensing fibers 3 are fused at nodes, and finally, the ends of all sensing fibers are converged at the designed sealed wall location, and led out through the reserved observation holes to the fiber optic demodulator 7 outside the sealed wall. The fiber optic demodulator 7 transmits the calculated strain information to the data acquisition instrument 13. The data acquisition instrument 13 receives the raw data from the fiber optic demodulator, performs secondary data processing, and transmits it to the ground monitoring center.

[0094] As attached Figure 3 As shown, the pressure sensor 8, temperature sensor 9, gas concentration sensor 10, and quantitative gas injection device 11 are directly installed in the sealed wall 14, with their probes extending into the sealed space to collect the raw physical parameters required for calculation. Each set of sealed walls consists of two layers, with the sealed wall 14 being 0.5m thick and filled with 4m of loess in the middle (the wall thickness and loess filling thickness can be adjusted according to the actual site conditions underground). The sealed wall is equipped with a safety hole 4, an observation hole 5, and a water outlet 6. The safety hole 4 is mainly used for fire prevention and extinguishing, gas control, and sampling. The observation hole 5 is mainly used to monitor the temperature, gas concentration, and internal and external air quality within the sealed tunnel. Pressure differential, etc., the drain hole 6 is mainly used to release accumulated water in the sealed roadway, protect the sealed wall structure, and prevent water seepage; the pressure sensor 8, temperature sensor 9, gas concentration sensor 10, and quantitative gas injection device 11 are all installed in the observation hole 5 left in the sealed wall; the monitoring data of the pressure sensor 8 is used to perform volume inversion in the gas state equation and correct the gas volume to the standard state; the monitoring data of the temperature sensor 9 is used for gas state equation calculation and temperature compensation of the readings of gas concentration sensor 10 and pressure sensor 8 to eliminate errors; the monitoring data of the gas concentration sensor 10 is used to calculate the gas content.

[0095] As attached Figure 4 As shown, the quantitative gas injection device 11 includes a valve 16, a control box 17, a high-pressure inert gas storage tank 18, a precision pressure reducing valve 19, a high-precision mass flow controller 20, and a solenoid valve 21; the inert gas is a non-flammable, non-reactive gas such as nitrogen or argon; the inert gas injection pipeline 12 is connected to the sealed space through the observation hole 5; the quantitative gas injection device 11 will provide core data for the volume calculation of the sealed tunnel.

[0096] Secondly, this application provides a method for real-time determination of gas content in closed underground roadways of coal mines based on the above-mentioned system, comprising the following steps:

[0097] S1. Before the tunnel is sealed, a distributed sensing fiber optic network is pre-installed along the tunnel's axial and circumferential directions to determine the initial spatial volume of the tunnel. Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices are installed inside the observation holes of the sealed wall.

[0098] In this embodiment, before the tunnel is sealed, sensing optical fibers are laid along the critical path of the tunnel and initial calibration is performed to calculate the initial spatial volume of the tunnel. Pressure sensor 8, temperature sensor 9, gas concentration sensor 10, and quantitative gas injection device 11 are installed inside the observation hole of the sealed wall, and all sensors are connected to the data acquisition instrument 13 outside the wall.

[0099] S2. After the tunnel is sealed, start the system to continuously collect distributed strain data of the surrounding rock of the tunnel, as well as gas pressure, gas temperature and gas concentration data inside the sealed space.

[0100] In this embodiment, after the tunnel is sealed, the monitoring system is activated. The surrounding rock deformation monitoring uses the fiber optic demodulator 7 to periodically acquire the strain field data of the surrounding rock in the sealed tunnel. The gas content calculation uses the sensor group installed on the sealed wall to acquire the gas pressure, gas temperature and gas concentration inside the sealed tunnel. All data are synchronized and uploaded to the database of the ground monitoring center through the data acquisition instrument 7.

[0101] S3. Perform inert gas calibration periodically: Record the stable gas concentration in the confined space before injection. ,pressure and temperature Inject a known number of moles After the inert gas is mixed and stabilized, the gas concentration after stabilization is recorded. ,pressure and temperature The current absolute volume is calculated by inversion based on the ideal gas equation of state. ;

[0102] In this embodiment, when it is necessary to calculate the gas content in a closed roadway, the gas concentration before the injection of inert gas must be accurately recorded. tunnel pressure and temperature Then, the control box 17 of the metering gas injection device 11 instructs the valve 16 and the high-precision mass flow controller 20 to open, and then injects a known number of moles. After the inert gas is injected, wait 30 minutes (this can be adjusted according to the tunnel size) to allow the inert gas to mix thoroughly in the closed tunnel until the pressure and temperature stabilize (fluctuations less than 0.1 kPa and 0.1 K). Record the gas concentration after stabilization. tunnel pressure Given temperature T2, apply the ideal gas law to calculate the absolute volume of the current sealed tunnel. for:

[0103]

[0104] Based on the above calculation method, inert gas is periodically injected to perform volume inversion calculation;

[0105] absolute volume The derivation process is as follows:

[0106] Before calibration, the number of moles of gas in the sealed space was: At this point, we have:

[0107]

[0108] injection After adding molar inert gas, the total number of moles of gas in the closed tunnel becomes At this point, we have:

[0109]

[0110] From equations (2) and (3), we can obtain:

[0111]

[0112] Equation (4) is another way of writing equation (1).

[0113] S4. Dynamic Volume Fusion: Based on the distributed strain data acquired in step S2, the volume estimate is calculated using geometric and physical models. ;Will The same period obtained in step S3 The model is compared and fused, and the model parameters are corrected through deviation feedback to output continuous optimal dynamic volume values. ;

[0114] In this embodiment, the initial three-dimensional geometric model is discretized into a shell element mesh. Assuming the surrounding rock is a linear elastic material, its equivalent elastic modulus is defined. Compared to Poisson For the parameters to be calibrated, for each fiber optic measurement point Its measured axial strain It is the strain component of the element at that point along the fiber direction, and the element strain { } and nodal displacements { The relationship between} is { }=[ ]{ },in[ ] is a geometric matrix;

[0115] Therefore, large systems of linear equations can be established: in[ ] is composed of each unit [ The system matrix is ​​assembled by projecting the matrix into the measurement directions. Since the number of measurement points is usually less than the model's degrees of freedom, the equation is an underdetermined problem. Therefore, the Tikhonov regularization method is introduced to solve for minimizing the objective function. in For regularization parameters, [ [This refers to the Laplace smoothing operator. By solving this optimization problem, a stable and smooth optimal displacement solution can be obtained.] }, that is, the three-dimensional displacement field on the surface of the tunnel. .

[0116] Update the coordinates of the roadway surface nodes: The updated surface nodes are subjected to 3D Delaunay triangulation to generate a closed volume mesh composed of tetrahedrons. The volume of each tetrahedron is calculated and summed to obtain the volume of the internal cavity of the tunnel based on the current strain estimate. : The formula for the volume of a tetrahedron is: ,in These are the coordinates of the four vertices of the tetrahedron.

[0117] calculate The volume value V obtained by inversion from the periodic gas law. q The deviation originates from the parameters of the finite element model ( The inaccuracy of ) will As an observation, the model parameters are adjusted in reverse. The correction logic is to feed back the deviation signal; if... > This indicates that the model's estimated volume is too large, potentially underestimating the surrounding rock stiffness. The algorithm will appropriately increase the equivalent elastic modulus E, thus reducing the displacement calculated by the model under the same strain input, and consequently improving the next calculation. Decrease, towards By approaching the target area, the system can output continuous optimal dynamic volume values ​​that have undergone periodic calibration and correction based on multiple tests. .

[0118] S5. Gas content calculation: [The following is a partial translation of the original text and can be left as is:] With real-time monitoring , , Substitute the data into the following formula to calculate the total gas content under standard conditions. :

[0119] .

[0120] In this embodiment, the system will dynamically adjust the volume. gas concentration ,pressure and temperature Substitute into the core algorithm:

[0121]

[0122] Real-time calculation of the total standard state gas content in a confined space This formula is based on the ideal gas law and Dalton's law of partial pressures;

[0123] The derivation process of equation (5) is as follows:

[0124] According to the ideal gas law The partial pressure of gas at that moment is:

[0125]

[0126] The actual volume of gas at time t is:

[0127]

[0128] Under standard conditions, the same amount of gas The volume is The following equation is satisfied:

[0129]

[0130] Equation (5) can be obtained by combining equations (6), (7) and (8).

[0131] S6. Early Warning and Output: Calculation rate of change ,Will and It compares the data with preset multi-level safety thresholds to achieve tiered early warning and displays the results in real time. and data.

[0132] In this embodiment, the system calculates the time in the past hour every 10 minutes. average rate of change According to the mine safety regulations and historical data of this roadway:

[0133] Level 1 Warning (Yellow): Standard cubic meters per hour, or Standard cubic meters; Level II warning (red): Standard cubic meters per hour, or Standard cubic meters.

[0134] When the threshold is triggered, the corresponding area on the monitoring platform interface changes color and flashes, a warning box pops up, and a warning SMS is automatically sent to the person in charge. The second-level warning also triggers the alarm in the dispatch room.

[0135] In one specific implementation, the inversion calculation of the current absolute volume in step S3 The formula is:

[0136]

[0137] In one specific implementation, the dynamic volume fusion in step S4 specifically includes:

[0138] Solving the three-dimensional displacement field on the tunnel surface based on fiber optic strain data;

[0139] Update the node coordinates of the tunnel geometry model, and obtain them through 3D Delaunay triangulation and volume summation. ;

[0140] by To achieve high-precision observations, establish and The deviation is the same as the equivalent elastic modulus of the geometric and physical model. The correction relationship between them, if This increases the equivalent elastic modulus. The assignment of values ​​reduces the displacement calculated by the model under the same strain, thereby reducing the displacement in the next iteration. Decrease and towards To move closer.

[0141] Thirdly, this application provides a method for pinpoint determination of gas content in sealed historical roadways, comprising:

[0142] Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices were installed in the observation holes of the sealed walls of the historical alleyways.

[0143] Perform a single or periodic inert gas injection calibration operation, and use the following formula to inversely calculate the absolute volume of the sealed tunnel at the calibration time. :

[0144]

[0145] This volume Gas concentration measured at the same time ,pressure and temperature Substitute into the following formula to calculate the standard state gas content at that moment. :

[0146] .

[0147] In this embodiment, for such historically closed roadways, the core method of the present invention can still provide a discretized, fixed-point method for estimating gas content; in specific implementation:

[0148] Pressure, temperature, and gas concentration sensors, as well as a quantitative gas injection device, are installed in the observation hole of the sealed wall.

[0149] Referring to step 3, perform a single or periodic inert gas injection operation, and use formula (1) to calculate the absolute volume of the sealed tunnel at the current moment. ;

[0150] This volume Gas concentration measured at the same time Substituting into formula (5), the standard state gas content at the current moment can be calculated. .

[0151] It should be noted that this simplified scheme lacks continuous deformation monitoring provided by distributed optical fibers, and therefore cannot construct a dynamic volume V(t). Consequently, the measurement results are volume and content at discrete time points, not continuous real-time data. The continuous change in volume between two calibrations cannot be accurately known and can only be estimated through interpolation or simple trend extrapolation, which limits accuracy. This scheme is mainly used for fixed-point verification, risk assessment, or to provide a rough basis for sampling decisions, and its effectiveness is lower than the main scheme of this invention (pre-embedded optical fiber + dynamic fusion).

[0152] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0153] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A real-time gas content measurement system for sealed underground roadways in coal mines, characterized in that, include: The sensing layer includes a distributed sensing fiber optic network deployed in the surrounding rock of the tunnel, pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices installed in the observation holes of the sealed wall. The data transmission and processing layer includes an optical fiber demodulator connected to the distributed sensing optical fiber network, a data acquisition instrument connected to each sensor and the optical fiber demodulator, and a ground monitoring center. The application layer includes a dynamic volume fusion calculation module and a gas content calculation and early warning module running in the ground monitoring center; The dynamic volume fusion calculation module is configured to periodically receive and fuse the absolute volume obtained from the calibration of the quantitative gas injection device with the volume estimated from the monitoring data of the distributed sensor fiber optic network, so as to output a continuous optimal dynamic volume value. ; The gas content calculation and early warning module is configured to: calculate and warn based on the optimal dynamic volume value. and real-time monitoring of gas concentration Gas pressure and gas temperature Real-time calculation of total gas content under standard conditions and its rate of change And it provides tiered warnings based on preset thresholds.

2. The system according to claim 1, characterized in that, The quantitative gas injection device includes a high-pressure inert gas storage tank, a precision pressure reducing valve, a high-precision mass flow controller, and a solenoid valve connected in sequence by pipelines. The outlet end of the pipeline extends into the sealed space through the observation hole of the sealed wall. The inert gas is nitrogen or argon.

3. The system according to claim 1 or 2, characterized in that, The dynamic volume fusion calculation module specifically includes: The gas calibration volume calculation unit is configured to calculate the volume of gas injected each time a known number of moles are injected. Record stable methane concentrations before and after the introduction of inert gas. , gas pressure , and gas temperature , And calculate the absolute volume at the current moment according to the following formula. : ； in, It is the ideal gas constant; The strain volume estimation unit is configured to calculate the volume estimate based on the distributed strain field data of the surrounding rock in the tunnel, obtained from the optical fiber demodulator, using a preset geometric and physical model. ; The fusion correction unit is configured to calculate the volume estimate and the absolute volume during the same period. The deviation is used to dynamically correct the parameters of the geometric and physical model, thereby improving the subsequent estimation. Towards The system converges and ultimately outputs the optimal dynamic volume value after periodic calibration and correction. .

4. The system according to claim 3, characterized in that, The preset geometric and physical model in the strain volume estimation unit is as follows: Establish an initial three-dimensional geometric model of the tunnel and discretize it; Based on the distributed strain field data, the three-dimensional displacement field on the tunnel surface is solved by introducing a regularization method. ; Update the coordinates of the surface nodes of the tunnel, and perform three-dimensional Delaunay triangulation on the updated surface nodes to generate a closed volume mesh composed of tetrahedrons; The estimated volume is obtained by summing the volumes of all tetrahedrons. : ； in, Representing the A tetrahedron This represents the total number of tetrahedrons.

5. The system according to claim 1, characterized in that, In the gas content calculation and early warning module, the total gas content The calculation formula is: ； in, and These represent temperature and pressure under standard conditions, respectively.

6. The system according to claim 5, characterized in that, The tiered early warning system specifically refers to: Set gas content threshold and rate of change threshold ; when or When a level two warning is triggered, a red warning box pops up on the ground monitoring platform interface and the audible and visual alarm is activated. when Within the preset yellow warning zone or When the rate of change exceeds the baseline, a Level 1 warning is triggered, and a yellow warning box pops up on the ground monitoring platform interface.

7. A method for real-time determination of gas content in sealed underground roadways of coal mines based on the system described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Before the tunnel is sealed, a distributed sensing fiber optic network is pre-installed along the tunnel's axial and circumferential directions to determine the initial spatial volume of the tunnel. Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices are installed inside the observation holes of the sealed wall. S2. After the tunnel is sealed, start the system to continuously collect distributed strain data of the surrounding rock of the tunnel, as well as gas pressure, gas temperature and gas concentration data inside the sealed space. S3. Perform inert gas calibration periodically: Record the stable gas concentration in the confined space before injection. ,pressure and temperature Inject a known number of moles After the inert gas is mixed and stabilized, the gas concentration after stabilization is recorded. ,pressure and temperature The current absolute volume is calculated by inversion based on the ideal gas equation of state. ; S4. Dynamic Volume Fusion: Based on the distributed strain data acquired in step S2, the volume estimate is calculated using geometric and physical models. ;Will The same period obtained in step S3 The model is compared and fused, and the model parameters are corrected through deviation feedback to output continuous optimal dynamic volume values. ; S5. Gas content calculation: [The following is a partial translation of the original text and can be left as is:] With real-time monitoring , , Substitute the data into the following formula to calculate the total gas content under standard conditions. : ； S6. Early Warning and Output: Calculation rate of change ,Will and It compares the data with preset multi-level safety thresholds to achieve tiered early warning and displays the results in real time. and data.

8. The method according to claim 7, characterized in that, The inversion calculation of the current absolute volume in step S3 The formula is: 。 9. The method according to claim 7, characterized in that, The dynamic volume fusion described in step S4 specifically includes: Solving the three-dimensional displacement field on the tunnel surface based on fiber optic strain data; Update the node coordinates of the tunnel geometry model, and obtain them through 3D Delaunay triangulation and volume summation. ; by To achieve high-precision observations, establish and The deviation is the same as the equivalent elastic modulus of the geometric and physical model. The correction relationship between them, if This increases the equivalent elastic modulus. The assignment of values ​​reduces the displacement calculated by the model under the same strain, thereby reducing the displacement in the next iteration. Decrease and towards To move closer.

10. A method for pinpoint determination of gas content in sealed historical roadways, characterized in that, include: Pressure sensors, temperature sensors, gas concentration sensors, and quantitative gas injection devices were installed in the observation holes of the sealed walls of the historical tunnels. Perform a single or periodic inert gas injection calibration operation, and use the following formula to inversely calculate the absolute volume of the sealed tunnel at the calibration time. : ； This volume Gas concentration measured at the same time ,pressure and temperature Substitute into the following formula to calculate the standard state gas content at that moment. : 。

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