Early warning method and system for coal and gas outburst of driving face

Abstract

The invention relates to the technical field of coal and gas outburst early warning, and provides an early warning method and system for coal and gas outburst of a driving face. According to the method, strain optical fibers are laid in a coal body of a driving working face through an embedded method according to the size of a roadway section corresponding to the driving working face and physical parameters of the coal body so as to monitor the driving working face, obtained optical fiber monitoring data are processed based on a cubic exponential smoothing method, and the coal body of the driving working face is monitored according to the processed optical fiber monitoring data. Delimiting a stress concentration area of the driving working face; and establishing the relationship between the stress peak value and the stress change rate of the optical fiber monitoring data in the stress concentration area and the stress peak value critical value and the stress change quantity critical value in the stress concentration area, and carrying out step-by-step early warning on the coal and gas outburst of the driving working face. Therefore, the problems that an existing stress monitoring technology is poor in monitoring precision, small in monitoring range and discontinuous are solved, and the early warning timeliness of coal and gas outburst of the driving face is improved.

Description

Technical Field

[0001] The present application relates to the technical field of coal and gas outburst early warning, and in particular to an early warning method and system for coal and gas outburst in an excavation working face. Background Art

[0002] Coal and gas outburst refers to the dynamic phenomenon that coal and gas suddenly rush into the mining operation space in large quantities under the combined effects of ground stress, gas, and the physical and mechanical properties of coal. It mainly occurs at the excavation working face. When coal and gas outburst occurs, it will cause suffocation of personnel, burying of personnel by flowing coal, and destruction of shaft and tunnel facilities, posing a huge threat to underground workers. It is the focus of coal mine safety management.

[0003] According to the process mechanism of coal and gas outburst, in the outburst preparation stage, stress concentration mainly occurs inside the coal body, causing local coal body breakage and deformation. Stress (strain) is the earliest sensitive indicator of outburst. Monitoring of stress (strain) is the key to early warning of coal and gas outburst.

[0004] At present, coal mines generally monitor stress by drilling holes and burying stress sensors in the excavation working face. This monitoring method has the disadvantages of locality, large errors, discontinuity, large engineering workload, and occupying operation time and space. It cannot understand the temporal and spatial evolution of stress in front of the excavation working face in real time.

[0005] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the prior art. Summary of the invention

[0006] The purpose of this application is to provide an early warning method and system for coal and gas outburst in an excavation working face to solve or alleviate the problems existing in the above-mentioned prior art.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] The present application provides an early warning method for coal and gas outburst in a tunneling working face, comprising: step S101, laying a strain optical fiber in the coal body of the tunneling working face by an embedded method according to the tunnel cross-sectional dimensions corresponding to the tunneling working face and the physical parameters of the coal body, so as to monitor the tunneling working face and obtain optical fiber monitoring data;

[0009] Step S102: Process the optical fiber monitoring data based on the cubic exponential smoothing method, and define the stress concentration area J (d x ,d y ), where d x ,d y They are the stress concentration areas J(d x ,d y) the shortest distance and the longest distance from the head of the excavation working face;

[0010] Step S103: Establish the stress concentration area J(d x ,d y ) is the stress peak value σ of the optical fiber monitoring data max , stress change rate The stress concentration area J(d x ,d y ) is the critical value of the peak stress of the excavation working face σ 临 , critical value of stress change △σ 临 The relationship between them can be used to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

[0011] Preferably, in step S101, according to the cross-sectional size of the tunnel of the excavation working face, directional inclined drilling is performed in the coal body at an angle of 30° to the coal wall by a directional drilling machine at the middle of the upper wall and the lower wall 30 meters away from the front of the excavation working face, and at the end of the directional inclined drilling hole, the hole is turned to be parallel to the tunnel coal wall at a vertical distance of 5 meters from the coal wall and drilled for 200 meters; wherein the diameter of the directional inclined drilling hole is 60 mm;

[0012] After the strain optical fiber is adhered to the outer wall of the lower end of a splicable PVC pipe with a diameter of 30 mm by an adhesive and implanted into the directional inclined borehole, a filling slurry is filled into the directional inclined borehole; wherein the physical parameters of the filling slurry are the same as the physical parameters of the coal body of the excavation working face;

[0013] After the filling slurry reaches the coupling strength, the strain optical fiber is connected to the junction box, the single-ended optical fiber demodulator, and the monitoring host in sequence to monitor the excavation working face and obtain the optical fiber monitoring data.

[0014] Preferably, in step S101, the optical fiber monitoring data includes: monitoring strain and monitoring stress; and according to the formula:

[0015]

[0016] Determining the monitoring strain ε and the monitoring stress σ;

[0017] Where W (ε) is the Brillouin shift under applied load, W (0) is the Brillouin shift when no load is applied; is a constant; E is the elastic modulus of the coal body at the excavation working face.

[0018] Preferably, in step S102, according to the formula:

[0019] σ t+L =a t +b t L+c t L 2

[0020] The optical fiber monitoring data is processed; wherein, according to the formula:

[0021]

[0022] Determine the smoothing parameter a t , b t 、c t ;

[0023] Where L is the smoothing step length of the optical fiber monitoring data, σ t+L is the processed optical fiber monitoring data, σ t is the optical fiber monitoring data before processing at time t; are the first smoothing index, second smoothing index and third smoothing index at time t respectively; α is the smoothing coefficient; They are the first smoothing index, second smoothing index and third smoothing index at time t-1 respectively.

[0024] Preferably, in step S102, according to the formula:

[0025]

[0026] Determine the stress concentration area J(d x ,d y );where, is the stress concentration area J(d x ,d y 0 is the distance from the peak stress point to the head of the excavation working face, d x d y are the stress concentration areas J(d x ,d y ) is the shortest distance and the longest distance from the front of the excavation working face.

[0027] Preferably, in step S103, according to the formula:

[0028]

[0029] Determine the stress concentration area J(d x ,d y ) The stress change rate of the optical fiber monitoring data

[0030] Among them, d x dy They are the stress concentration areas J(d x ,d y ) from the head of the excavation working face;

[0031] t i ,t i+1 For two adjacent moments, is the stress concentration area J(d x ,d y ) i+1 The stress value of each monitoring point at each moment; is the stress concentration area J(d x ,d y ) i The stress value of each monitoring point at each moment.

[0032] Preferably, in step S103, the stress concentration area J (d x ,d y ) is the critical value of the peak stress of the excavation working face σ 临 , critical value of stress change △σ 临 .

[0033] Preferably, in step S103, the stress concentration area J (d x ,d y ) coal seam gas storage parameters, geological structure distribution parameters, and drilling test parameters of the excavation working face,

[0034] According to σ max , σ 临 , △σ 临 According to the coal seam gas occurrence parameters, geological structure distribution parameters and drilling test parameters, a step-by-step early warning is provided for the coal and gas outburst at the excavation working face.

[0035] Preferably, in step S103, in response to σ max <σ 临 and There is no early warning of coal and gas outburst at the excavation working face; in response to σ max ≥σ 临 or A first-level warning of coal and gas outburst at the excavation working face is issued;

[0036] In response to σ max ≥σ 临 or And the stress concentration area J(d x,d y ) If there is a geological structure (G) or a high original gas content (M) in the tunneling working face, a secondary warning of coal and gas outburst at the tunneling working face is issued;

[0037] In response to σ max ≥σ 临 or And the stress concentration area J(d x ,d y ) If there is a geological structure (G) or a high original gas content (M) in the tunneling working face, and a top drill (D) or a clamped drill (Z) or a blowhole (P) occurs during drilling at the tunneling working face, a level 3 warning for coal and gas outburst at the tunneling working face will be issued.

[0038] The embodiment of the present application also provides an early warning system for coal and gas outburst at a tunneling working face, comprising: a data monitoring unit, configured to lay strain optical fiber in the coal body of the tunneling working face by an embedded method according to the tunnel cross-sectional dimensions corresponding to the tunneling working face and the physical parameters of the coal body, so as to monitor the tunneling working face and obtain optical fiber monitoring data;

[0039] The data processing unit is configured to process the optical fiber monitoring data based on a cubic exponential smoothing method, and to define a stress concentration area J (d x ,d y ), where d x ,d y They are the stress concentration areas J(d x ,d y ) the shortest distance and the longest distance from the head of the excavation working face;

[0040] The early warning unit is configured to establish the stress concentration area J(d x ,d y ) is the stress peak value σ of the optical fiber monitoring data max , stress change rate and the predetermined critical value σ of the stress peak of the excavation working face in the stress concentration area 临 , critical value of stress change △σ 临 The relationship between them can be used to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

[0041] Beneficial effects:

[0042] In the early warning method for coal and gas outburst in the excavation working face provided in the embodiment of the present application, firstly, according to the tunnel cross-sectional dimensions corresponding to the excavation working face and the physical parameters of the coal body, a strain optical fiber is laid in the coal body of the excavation working face by an embedded method to monitor the excavation working face and obtain optical fiber monitoring data; then, based on the cubic exponential smoothing method, the optical fiber monitoring data is processed, and according to the processed optical fiber monitoring data, the stress concentration area J (d x ,d y ); Finally, establish the stress concentration area J(d x ,d y ) The stress peak value σ of the optical fiber monitoring data max , stress change rate With the predetermined stress concentration area J(d x ,d y ) The critical value of the stress peak value σ of the excavation working face 临 , critical value of stress change △σ 临 The relationship between the two is used to provide a step-by-step early warning for coal and gas outbursts at the excavation working face. Therefore, the distributed strain optical fiber is buried in the coal body of the entire excavation working face through directional drilling. Focusing on the monitoring of stress, which is an early key factor for coal and gas outbursts at the excavation working face, the stress peak value and stress changes in the stress concentration area are tracked, and advance warning of coal and gas outbursts at the excavation working face is provided in time and space. This effectively overcomes the problems of poor monitoring accuracy, small monitoring range, and discontinuity of existing stress monitoring technology, and improves the timeliness of early warning of coal and gas outbursts at the excavation working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. Among them:

[0044] Figure 1 A schematic flow chart of an early warning method for coal and gas outburst in a tunneling working face provided according to some embodiments of the present application;

[0045] Figure 2 A schematic diagram of a planar layout of distributed strain optical fibers on a tunneling working face provided according to some embodiments of the present application;

[0046] Figure 3 A schematic diagram of the arrangement of a distributed strain optical fiber in a borehole according to some embodiments of the present application;

[0047] Figure 4 A logical schematic diagram of a step-by-step early warning of coal and gas outburst provided according to some embodiments of the present application;

[0048] Figure 5 A schematic structural diagram of an early warning system for coal and gas outburst at an excavation working face provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0049] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the embodiments of the present invention should belong to the scope of protection of the embodiments of the present invention.

[0050] At present, in the monitoring of coal and gas outbursts in the excavation working face, stress monitoring is generally achieved by drilling holes and burying stress sensors in the excavation working face. Among them, the current coal mine drills a limited number of holes to test indicators according to the shift time, but some holes cannot fully cover the area in front of the coal body, there are blank zones, the drilling workload is large, and excavation production is not allowed during drilling, which takes up time and space. In addition, due to the strong heterogeneity of coal, the results obtained by drilling holes and burying stress sensors for testing have the disadvantages of locality, discontinuity, large workload, and occupying operation time and space, and cannot effectively represent the indicators of the entire front coal body. What is more serious is that the stress state of the coal has been destroyed by drilling and installing stress sensors, and the results obtained have large errors, which are difficult to fully reflect the actual state of coal and gas outbursts in the excavation working face.

[0051] Based on this, this application proposes an early warning method for coal and gas outburst in the excavation working face, such as Figures 1 to 4 As shown, the early warning method includes:

[0052] Step S101: According to the tunnel cross-sectional dimensions corresponding to the excavation working face and the physical parameters of the coal body, a strain optical fiber is laid in the coal body of the excavation working face by an embedded method to monitor the excavation working face and obtain optical fiber monitoring data.

[0053] In this application, by laying distributed strain optical fiber in the excavation working face, the problems of poor monitoring accuracy, small monitoring range, and discontinuous monitoring in the existing stress monitoring process are effectively overcome, and the timeliness of coal and gas outburst warning in the excavation working face is effectively improved.

[0054] During the coal mining process, the excavation working face may reach hundreds or thousands of meters, and the construction environment is harsh and cumbersome. During the laying of strain optical fiber, it is advisable to use single-ended, metal-based, steel stranded wire, meter-level spatial resolution optical fiber, and use spontaneous Brühl's optical time-domain reflectometry technology in conjunction.

[0055] During the strain fiber construction, according to the cross-sectional size of the tunnel of the excavation working face, directional inclined drilling was carried out in the coal body at an angle of 30° to the coal wall by a directional drilling rig in the middle of the upper and lower walls 30 meters away from the excavation working face. At the end of the directional inclined drilling hole, the directional drilling rig turned to drill parallel to the tunnel coal wall at a vertical distance of 5 meters from the coal wall and drilled 200 meters. The diameter of the directional inclined drilling hole was 60 mm.

[0056] Then the optical fiber is packaged. After the strain optical fiber is attached to the outer wall of the lower end of the splicable PVC pipe with a diameter of 30 mm by an adhesive and implanted into the directional inclined borehole, the directional inclined borehole is filled with a filling slurry with the same physical parameters as the coal body of the excavation working face. Among them, the strain optical fiber is tightly wrapped and packaged by steel wire and laid inside the borehole, and then filled with a filling slurry with similar physical and mechanical parameters to the coal body. After the filling slurry reaches the coupling strength, the strain optical fiber is connected to the junction box, the single-ended optical fiber demodulator, and the monitoring host in sequence to monitor the excavation working face and obtain optical fiber monitoring data. Among them, the single-ended optical fiber demodulator is connected to the underground substation of the coal mine, and the data is transmitted to the monitoring host deployed on the ground (for example, a data workstation, etc.) through the underground ring network, and the monitoring host analyzes and displays the data.

[0057] After the optical fiber is laid, the overlying coal and rock layers will produce a certain load on the optical fiber (i.e., mechanical action), which will affect the light reflection in the optical fiber (i.e., Brillouin shift). The light waves propagating in the optical fiber interact with the sound waves, where the frequency of the backscattered light is lower than that of the incident light, and the frequency shift of the Brillouin scattered light is linearly related to the strain and temperature of the optical fiber axis. Therefore, the Brillouin shift of the optical fiber center wavelength is analyzed by a single-ended optical fiber demodulator to obtain the strain of the excavation working face under the load state, and then the stress of the excavation working face is obtained from the strain of the excavation working face. Specifically, according to the formula:

[0058]

[0059] Determine the monitoring strain ε and monitoring stress σ of the excavation working face. (ε) is the Brillouin shift under applied load, W (0) is the Brillouin shift when no load is applied, is a constant with a value of 490MHz, and E is the elastic modulus of the coal body at the excavation working face.

[0060] Step S102: Process the optical fiber monitoring data based on the cubic exponential smoothing method, and define the stress concentration area J (d x ,d y ).

[0061] After the stress and strain data of the excavation working face are determined by laying distributed optical fibers, the obtained stress and strain data of the excavation working face are processed based on the cubic exponential smoothing method. Specifically, according to the formula:

[0062] σ t+L =a t +b t L+c t L 2

[0063] Process the optical fiber monitoring data. According to the formula:

[0064]

[0065] Determine the smoothing parameter a t , b t 、c t Where L is the smoothing step length of the optical fiber monitoring data, σ t+L is the processed optical fiber monitoring data, σ t is the optical fiber monitoring data before processing at time t, are the first smoothing index, second smoothing index and third smoothing index at time t, respectively; α is the smoothing coefficient, which takes the value of 0.3 (when the data fluctuation is large) or 0.5 (when the data fluctuation is small); They are the first smoothing index, second smoothing index and third smoothing index at time t-1 respectively.

[0066] Then, according to the processed stress data of the excavation working face, based on the optical fiber stress at different positions at the same time (processed stress data), the stress concentration area range J (d x ,d y ), where d x d y They are stress concentration areas J(d x ,d y ) The shortest and longest distances from the front of the excavation working face. Specifically, according to the formula:

[0067]

[0068] Delineate the stress concentration area J(d x ,d y ). In the formula, is the stress concentration area J(d x ,d y ) The peak stress σ max The corresponding position is the distance from the front of the excavation working face.

[0069] Step S103: Establish stress concentration area J(d x,d y ) The stress peak value σ of the optical fiber monitoring data max , stress change rate With the predetermined stress concentration area J(d x ,d y ) The critical value of the stress peak value σ of the excavation working face 临 , critical value of stress change △σ 临 The relationship between the two is to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

[0070] Specifically, according to the formula:

[0071]

[0072] Determine the stress concentration area J(d x ,d y ) The stress change rate of the optical fiber monitoring data Among them, d x d y They are stress concentration areas J(d x ,d y ) from the front of the excavation working face; t i ,t i+1 For two adjacent moments, is the stress concentration area J(d x ,d y ) i+1 The stress value at each monitoring point at any given moment (a monitoring point is set every 1 meter in the optical fiber); is the stress concentration area J(d x ,d y ) i The stress value of each monitoring point at each moment.

[0073] At the same time, numerical simulation of coal and gas outburst in the tunneling working face was carried out. According to the numerical simulation results and the historical data of coal and gas outburst in the tunneling working face, the critical value of the stress peak σ of the tunneling working face in the stress concentration area was determined. 临 , critical value of stress change △σ 临 .

[0074] Then, according to the stress concentration area J(d x ,d y ) The stress change rate of the optical fiber monitoring data And the stress concentration area J(d x ,d y ) The critical value of the stress peak value σ of the excavation working face 临 , critical value of stress change △σ 临, build a step-by-step early warning mechanism for coal and gas outbursts, and make real-time comparisons between the stress peak value, stress change rate and their corresponding critical value in the stress concentration area. max <σ 临 and There is no risk of coal and gas outburst in the excavation working face, and no outburst warning is issued; if σ max ≥σ 临 or A Level 1 warning for coal and gas outburst at the excavation face will be issued.

[0075] Furthermore, by obtaining the stress concentration area J(d x ,d y ) gas storage parameters of each layer, address structure distribution parameters, and drilling test parameters of the excavation working face, according to σ max , σ 临 , △σ 临 And coal seam gas storage parameters, geological structure distribution parameters, drilling test parameters, to carry out step-by-step early warning of coal and gas outbursts in the excavation working face. max , σ 临 , △σ 临 Early warning of coal and gas outbursts at the excavation working face; then, combined with coal seam gas occurrence parameters and geological structure distribution parameters, early warning of coal and gas outbursts at the excavation working face; finally, combined with drilling test parameters, early warning of coal and gas outbursts at the excavation working face.

[0076] That is, if σ max ≥σ 临 or And the stress concentration area J(d x ,d y ) There are geological structures (G) (i.e. faults) or the original gas content (i.e. the gas content tested by drilling before coal mining) is high (M), that is, the original gas content is between 7 and 8m 3 / t, a secondary warning of coal and gas outburst at the excavation working face will be issued; if σ max ≥σ 临 or And the stress concentration area J(d x ,d y ) If there are geological structures (G) or high original gas content (M) in the tunneling working face, and top drill (D) or drill clamping (Z) or blowhole (P) occurs during drilling at the tunneling working face, a Level 3 warning for coal and gas outburst at the tunneling working face will be issued.

[0077] Finally, the early warning signal will be issued to engineering personnel through the coal mine's underground local area network, and sent to relevant managers via satellite, text messages, etc.

[0078] In the present application, distributed strain optical fiber is laid in the coal body of the entire excavation working face in an buried manner through directional drilling, and the monitoring of stress, which is a key early factor of coal and gas outburst in the excavation working face, is carried out. The stress peak value and stress change in the stress concentration area are tracked and compared with the critical value. Simultaneously, the gas storage characteristics of each layer of the excavation working face, the address structure distribution status and the drilling test data are combined to carry out multi-level early warning of coal and gas outburst in the excavation working face step by step, and advance warning of coal and gas outburst in the excavation working face is carried out in time and space, so as to determine the risk of coal and gas outburst earlier, effectively overcoming the problems of poor monitoring accuracy, small monitoring range and discontinuity of existing stress monitoring technology, and improving the timeliness of early warning of coal and gas outburst in the excavation working face; it is particularly suitable for the prevention and control of coal and gas outburst in the excavation working face of coal and gas outburst mines, and is particularly suitable for the prevention and control of coal and gas outburst in the excavation working face of deep high-stress coal and gas outburst mines.

[0079] like Figure 5 As shown, the embodiment of the present application also provides an early warning system for coal and gas outburst in a tunneling working face, comprising:

[0080] The data monitoring unit 501 is configured to lay strain optical fiber in the coal body of the excavation working face by an embedded method according to the tunnel cross-sectional dimensions corresponding to the excavation working face and the physical parameters of the coal body, so as to monitor the excavation working face and obtain optical fiber monitoring data;

[0081] The data processing unit 502 is configured to process the optical fiber monitoring data based on the cubic exponential smoothing method, and to define the stress concentration area J (d x ,d y ), where f x ,d y They are stress concentration areas J(d x ,d y ) from the head of the excavation face;

[0082] The early warning unit 503 is configured to establish a stress concentration area J(d x ,d y ) The stress peak value σ of the optical fiber monitoring data max , stress change rate The critical value of the stress peak value σ of the excavation working face in the predetermined stress concentration area 临 , critical value of stress change △σ 临 The relationship between the two is to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

[0083] The early warning system for coal and gas outburst in the tunneling working face provided in the embodiment of the present application can implement the steps and processes of any of the above-mentioned early warning methods for coal and gas outburst in the tunneling working face, and achieve the same technical effects, which will not be repeated here one by one.

[0084] In the description of the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0085] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An early warning method for coal and gas outburst in a tunneling working face, characterized in that: include: Step S101: according to the tunnel cross-sectional dimensions corresponding to the excavation working face and the physical parameters of the coal body, a strain optical fiber is laid in the coal body of the excavation working face by an embedded method to monitor the excavation working face and obtain optical fiber monitoring data; Step S102: Process the optical fiber monitoring data based on the cubic exponential smoothing method, and define the stress concentration area J (d x , d y ), where d x d y are the stress concentration areas J(d x , d y ) the shortest distance and the longest distance from the head of the excavation working face; Step S103: Establish the stress concentration area J(d x , d y ) is the stress peak value σ of the optical fiber monitoring data max , stress change rate The stress concentration area J(d x , d y ) is the critical value of the peak stress of the excavation working face σ 临 , critical value of stress change Δσ 临 The relationship between them can be used to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

2. The method for early warning of coal and gas outburst in the excavation working face according to claim 1 is characterized in that: In step S101, According to the cross-sectional dimensions of the tunnel of the excavation working face, directional inclined drilling is performed in the coal body at an angle of 30° to the coal wall by a directional drilling machine at the middle of the upper wall and the lower wall 30 meters away from the front of the excavation working face, and at the end of the directional inclined drilling hole, the hole is turned to be parallel to the tunnel coal wall at a vertical distance of 5 meters from the coal wall and drilled for 200 meters; wherein the diameter of the directional inclined drilling hole is 60 mm; After the strain optical fiber is adhered to the outer wall of the lower end of a splicable PVC pipe with a diameter of 30 mm by an adhesive and implanted into the directional inclined borehole, a filling slurry is filled into the directional inclined borehole; wherein the physical parameters of the filling slurry are the same as the physical parameters of the coal body of the excavation working face; After the filling slurry reaches the coupling strength, the strain optical fiber is connected to the junction box, the single-ended optical fiber demodulator, and the monitoring host in sequence to monitor the excavation working face and obtain the optical fiber monitoring data.

3. The coal and gas outburst early warning method according to claim 1, characterized in that: In step S101, the optical fiber monitoring data includes: monitoring strain and monitoring stress; and according to the formula: Determining the monitoring strain ε and the monitoring stress σ; Where W (ε) is the Brillouin shift under applied load, W (0) is the Brillouin shift when no load is applied; is a constant; E is the elastic modulus of the coal body at the excavation working face.

4. The method for early warning of coal and gas outburst in a tunneling working face according to claim 1 is characterized in that: In step S102, according to the formula: s t+L =a t +b t L+c t L 2 The optical fiber monitoring data is processed; wherein, according to the formula: Determine the smoothing parameter a t , b t 、c t ; Where L is the smoothing step length of the optical fiber monitoring data, σ t+L is the processed optical fiber monitoring data, σ t is the optical fiber monitoring data before processing at time t; are the first smoothing index, second smoothing index and third smoothing index at time t respectively; α is the smoothing coefficient; They are the first smoothing index, second smoothing index and third smoothing index at time t-1 respectively.

5. The method for early warning of coal and gas outburst in a tunneling working face according to claim 1 is characterized in that: In step S102, according to the formula: Determine the stress concentration area J(d x , d y ); In the formula, is the stress concentration area J(d x , d y ) The peak stress σ max The distance between the corresponding position and the front of the excavation working face, d x d y are the stress concentration areas J(d x , d y ) is the shortest distance and the longest distance from the front of the excavation working face.

6. The method for early warning of coal and gas outburst in the excavation working face according to claim 5 is characterized in that: In step S103, according to the formula: Determine the stress concentration area J(d x , d y ) The stress change rate of the optical fiber monitoring data Among them, d x d y are the stress concentration areas J(d x , d y ) the shortest distance and the longest distance from the head of the excavation working face; t i ,t i+1 For two adjacent moments, is the stress concentration area J(d x , d y ) i+1 The stress value of each monitoring point at each moment; is the stress concentration area J(d x , d y ) i The stress value of each monitoring point at each moment.

7. The method for early warning of coal and gas outburst in a tunneling working face according to claim 1 is characterized in that: In step S103, Based on the numerical simulation results of coal and gas outburst in the tunneling working face and the historical data of coal and gas outburst in the tunneling working face, the stress concentration area J (d x , d y ) is the critical value of the peak stress of the excavation working face σ 临 , critical value of stress change Δσ 临 .

8. The method for early warning of coal and gas outburst in a tunneling working face according to claim 1, characterized in that: In step S103, Obtain the stress concentration area J(d x , d y ) coal seam gas storage parameters, geological structure distribution parameters, and drilling test parameters of the excavation working face, According to σ max , σ 临 , Δσ 临 According to the coal seam gas occurrence parameters, geological structure distribution parameters and drilling test parameters, a step-by-step early warning is provided for the coal and gas outburst at the excavation working face.

9. The method for early warning of coal and gas outburst in a tunneling working face according to claim 8, characterized in that: In step S103, In response to σ max <σ 临 and Then there is no early warning of coal and gas outburst at the excavation working face; In response to σ max ≥σ 临 or A first-level warning of coal and gas outburst at the excavation working face is issued; In response to σ max ≥σ 临 or And the stress concentration area J(d x , d y ) If there is a geological structure (G) or a high original gas content (M) in the tunneling working face, a secondary warning of coal and gas outburst at the tunneling working face is issued; In response to σ max ≥σ 临 or And the stress concentration area J(d x , d y ) If there is a geological structure (G) or a high original gas content (M) in the tunneling working face, and a top drill (D) or a clamped drill (Z) or a blowhole (P) occurs during drilling at the tunneling working face, a level 3 warning for coal and gas outburst at the tunneling working face will be issued.

10. An early warning system for coal and gas outburst in a tunneling working face, characterized in that: include: A data monitoring unit is configured to lay strain optical fiber in the coal body of the excavation working face by an embedded method according to the tunnel cross-sectional dimensions corresponding to the excavation working face and the physical parameters of the coal body, so as to monitor the excavation working face and obtain optical fiber monitoring data; The data processing unit is configured to process the optical fiber monitoring data based on a cubic exponential smoothing method, and to define a stress concentration area J (d x , d y ), where d x d y are the stress concentration areas J(d x , d y ) the shortest distance and the longest distance from the head of the excavation working face; The early warning unit is configured to establish the stress concentration area J(d x , d y ) is the stress peak value σ of the optical fiber monitoring data max , stress change rate and the predetermined critical value σ of the stress peak of the excavation working face in the stress concentration area 临 , critical value of stress change △σ 临 The relationship between them can be used to provide step-by-step early warning for coal and gas outbursts in the excavation working face.

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