An early warning method and system for coal and gas outburst in tunneling working face

Abstract

The present application relates to the technical field of coal and gas outburst early warning, and provides a method and system for early warning of coal and gas outburst at a tunneling working face. This method, based on the cross-sectional dimensions of the tunnel corresponding to the tunneling working face and the physical parameters of the coal body, lays strain optical fiber in the coal body of the tunneling working face through an embedded method to monitor the tunneling working face, and processes the obtained optical fiber monitoring data based on the cubic exponential smoothing method. Based on the processed optical fiber monitoring data, the stress concentration area of ​​the tunneling working face is delineated; the relationship between the stress peak value and stress change rate of the optical fiber monitoring data in the stress concentration area and the stress peak critical value and stress change critical value in the stress concentration area is established, and a step-by-step early warning of coal and gas outburst at the tunneling working face is provided. In this way, the problems of poor monitoring accuracy, small monitoring range, and discontinuity of existing stress monitoring technologies are overcome, and the timeliness of early warning of coal and gas outburst at the tunneling working 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 at a tunneling working face. Background Art

[0002] Coal and gas outbursts are a dynamic phenomenon in which the combined effects of ground stress, gas, and the physical and mechanical properties of coal cause a sudden and massive influx of coal and gas into the mining area. These outbursts primarily occur at the excavation face. They can cause suffocation, burial by flowing coal, and damage to tunneling facilities, posing a significant threat to underground workers. Therefore, they are a key 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 to break and deform. Stress (strain) is the earliest sensitive indicator of outburst. Monitoring of stress (strain) is the key to coal and gas outburst early warning.

[0004] At present, coal mines generally implement stress monitoring 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 existing technology. Summary of the Invention

[0006] The purpose of this application is to provide an early warning method and system for coal and gas outbursts in a tunneling working face, so as 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 a method for early warning of coal and gas outbursts at 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 based on the cross-sectional dimensions of the tunnel 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 delineate 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 and longest distances from the head of the excavation face;

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

[0011] Preferably, in step S101, based on the cross-sectional dimensions of the tunnel of the excavation working face, directional inclined drilling is performed in the coal body at a 30° inclination angle to the coal wall using a directional drilling rig 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 turns to be parallel to the tunnel coal wall at a vertical distance of 5 meters from the coal wall and drills 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 30 mm diameter splicable PVC pipe using 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 at 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 load, W (0) is the Brillouin shift in the unloaded state; 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] Delineate the stress concentration area J(d x ,d y ); where is the stress concentration area J(d x ,d y The distance between the stress peak point in 0 and the head of the tunneling working face, d x d y They are the stress concentration areas J(d x ,d y ) the shortest and longest distances from the head 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 ) The critical value of the stress peak σ of the excavation working face 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 And the coal seam gas storage parameters, geological structure distribution parameters, drilling test parameters, and step-by-step early warning of coal and gas outbursts in the excavation working face are carried out.

[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 early 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) within the tunneling working face, a Level 2 warning of coal and gas outburst will be 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 stuck drill (Z) or a blowhole (P) occurs during drilling at the tunneling working face, a level 3 warning of coal and gas outburst at the tunneling working face will be issued.

[0038] The present application also provides an early warning system for coal and gas outbursts at a tunneling working face, comprising: a data monitoring unit configured to, based on the cross-sectional dimensions of a tunnel corresponding to the tunneling working face and the physical parameters of the coal body, lay strain optical fibers in the coal body of the tunneling working face by an embedded method 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 delineate 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 and longest distances from the head of the excavation face;

[0040] The early warning unit is configured to 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 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 is used to provide step-by-step 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 at a tunneling working face provided in an embodiment of the present application, first, based on the cross-sectional dimensions of the tunnel corresponding to the tunneling working face and the physical parameters of the coal body, a strain optical fiber is laid in the coal body of the tunneling working face by an embedded method to monitor the tunneling working face and obtain optical fiber monitoring data; then, the optical fiber monitoring data is processed based on the cubic exponential smoothing method, and based on 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 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 of coal and gas outbursts at the tunneling working face. Distributed strain optical fiber is buried in the coal body of the entire tunneling working face through directional drilling. Focusing on monitoring stress, a key early factor in coal and gas outbursts at the tunneling working face, the stress peak value and stress changes in the stress concentration area are tracked, providing advanced early warning of coal and gas outbursts at the tunneling working face 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 coal and gas outburst warnings at the tunneling working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings and descriptions that constitute part of this application are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this 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 according to some embodiments of the present application;

[0045] Figure 2 A schematic diagram of a planar arrangement of distributed strain optical fibers on a tunneling working face 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 diagram of a step-by-step early warning system for coal and gas outbursts according to some embodiments of the present application;

[0048] Figure 5 This is a structural schematic diagram of an early warning system for coal and gas outbursts at a tunneling 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 can 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 part of one embodiment can 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 present invention should fall within the scope of protection of the embodiments of the present invention.

[0050] Currently, stress monitoring is commonly performed by drilling holes and embedding stress sensors in tunneling working faces. Currently, coal mines drill a limited number of holes to test indicators based on shift schedules. However, some holes fail to fully cover the area ahead of the coal body, leaving blank zones. The drilling effort is substantial, and drilling prohibits tunneling and production, which takes up time and space. Furthermore, due to the strong heterogeneity of coal, the results obtained from drilling holes and embedding stress sensors are localized, discontinuous, labor-intensive, and time-consuming, making them ineffective at effectively representing the entire coal body ahead. More seriously, the installation of stress sensors disrupts the stress state of the coal, resulting in significant errors and difficulty in fully reflecting the actual state of coal and gas outbursts in the tunneling working face.

[0051] Based on this, this application proposes an early warning method for coal and gas outburst in the tunneling 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 fibers 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 even 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 optical fiber with meter-level spatial resolution, and to use spontaneous Brühl optical time-domain reflectometry technology in conjunction with it.

[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 using a directional drilling rig in the middle of the upper and lower walls 30 meters away from the head of the excavation working face. At the end of the directional inclined drilling hole, the drill turned to be 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] The optical fiber is then packaged. The strain fiber is attached to the outer wall of the lower end of a 30 mm diameter splicable PVC pipe using an adhesive and then implanted into a directional inclined borehole. The directional inclined borehole is then filled with a filling slurry with the same physical parameters as the coal body at the excavation working face. The strain fiber is tightly wrapped and packaged with steel wire and laid inside the borehole, where it is 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 fiber is sequentially connected to a junction box, a single-ended optical fiber demodulator, and a monitoring host to monitor the excavation working face and obtain optical fiber monitoring data. The single-ended optical fiber demodulator is connected to the underground substation of the coal mine and transmits data to a monitoring host deployed on the ground (e.g., a data workstation) via an underground ring network. The monitoring host analyzes and displays the data.

[0057] After the optical fiber is laid, the overlying coal and rock layers will generate 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. 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 load, W (0) is the Brillouin shift in the unloaded state, 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 delineate the stress concentration area J (d x ,d y ).

[0061] After determining the stress and strain data of the tunneling working face through the laid distributed optical fiber, the obtained stress and strain data of the tunneling 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 is 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 stress data after processing of the tunneling 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 ). Where, is the stress concentration area J(d x ,d y ) Peak stress σ max The distance between the corresponding position and the head 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 σ of the excavation working face 临 , critical value of stress change △σ 临 The relationship between them is used to provide step-by-step early warning of 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 ) 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 (one 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. Based on 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 in 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 ) 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 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 its corresponding critical value in the stress concentration area. max <σ 临 and There is no risk of coal and gas outburst at the excavation working face, and no outburst warning is issued; if σ max ≥σ 临 or A level one warning of coal and gas outburst at the excavation working face will be issued.

[0075] Furthermore, by obtaining the stress concentration area J(d x ,d y ) in each layer of gas storage parameters, 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 occurrence 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 Provide early warning for coal and gas outbursts at the excavation working face; then, combine the coal seam gas occurrence parameters and geological structure distribution parameters to provide early warning for coal and gas outbursts at the excavation working face; finally, combine the drilling test parameters to provide early warning for 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 holes before coal seam mining) is high (M), that is, the original gas content is between 7 and 8m 3 / t, a second-level warning of coal and gas outburst at the tunneling 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 released to engineering personnel through the coal mine's underground local area network, and sent to relevant managers via satellite, text messages, etc.

[0078] In this application, distributed strain optical fiber is laid in the coal body of the entire tunneling working face in an embedded manner through directional drilling, focusing on the monitoring of stress, which is a key early factor of coal and gas outburst in the tunneling working face, the stress peak size and stress change in the stress concentration area are tracked and compared with the critical value, and the gas occurrence characteristics of each layer of the tunneling working face, the address structure distribution status and drilling test data are simultaneously combined to perform multi-level early warning of coal and gas outburst in the tunneling working face step by step, and provide advance warning of coal and gas outburst in the tunneling working face 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 coal and gas outburst warning in the tunneling working face; it is particularly suitable for the prevention and control of coal and gas outburst in the tunneling working face of coal and gas outburst mines, and especially suitable for the prevention and control of coal and gas outburst in the tunneling 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 fibers in the coal body of the excavation working face by an embedded method based on the cross-sectional dimensions of the tunnel 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 delineate 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 σ of the excavation working face in the predetermined stress concentration area 临 , critical value of stress change △σ 临 The relationship between them is used to provide step-by-step early warning of 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.

[0084] In the description of the present invention, the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" 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 appropriate manner in any one or more embodiments or examples.

[0085] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection 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: Based on the cross-sectional dimensions of the tunnel corresponding to the tunneling working face and the physical parameters of the coal body, a strain optical fiber is laid in the coal body of the tunneling working face by an embedded method to monitor the tunneling working face and obtain optical fiber monitoring data. In this step, based on the cross-sectional dimensions of the tunnel at the tunneling working face, a directional drilling rig is used to drill a 30° inclination angle with the coal wall in the middle of the upper and lower walls, 30 meters from the front of the tunneling working face. At the end of the directional inclined drill hole, the drill turns parallel to the tunnel coal wall at a vertical distance of 5 meters from the coal wall and drills for 200 meters. The diameter of the directional inclined drill hole is 60 mm. After the strain optical fiber is adhered to the outer wall of the lower end of a 30 mm diameter splicable PVC pipe using an adhesive and implanted into the directional inclined borehole, a filling slurry is filled into the directional inclined borehole; the physical parameters of the filling slurry are the same as those of the coal body at 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; The optical fiber monitoring data includes: monitoring strain and monitoring stress; and according to the formula: Determine the monitoring strain and the monitoring stress ; Where, is the Brillouin shift under applied load, is the Brillouin shift in the unloaded state; is a constant; is the elastic modulus of the coal body at the excavation working face; Step S102: Based on the triple exponential smoothing method, according to the formula: The optical fiber monitoring data is processed; wherein, according to the formula: Determine the smoothing parameter ; Where, is the smoothing step length of the optical fiber monitoring data, is the processed optical fiber monitoring data, for Fiber optic monitoring data before processing; They are The first, second and third smoothed indices at the moment; is the smoothing coefficient; They are The first, second and third smoothed indices at the moment; Delineate the stress concentration area of ​​the tunneling working face based on the processed fiber optic monitoring data ; The stress concentration areas are The shortest and longest distances from the head of the excavation working face; Step S103: Establish the stress concentration area The stress peak value of the optical fiber monitoring data , stress change rate With the predetermined stress concentration area The critical value of the stress peak of the excavation working face , critical value of stress change The relationship between them is used to provide step-by-step warning for coal and gas outbursts in the excavation working face.

2. The method for early warning of coal and gas outburst in a tunneling working face according to claim 1, characterized in that: In step S102, according to the formula: Delineate the stress concentration area of ​​the excavation working face ; Where, The stress concentration area Medium stress peak The distance between the corresponding position and the head of the excavation working face, The stress concentration areas are The shortest and longest distances from the head of the excavation working face.

3. The method for early warning of coal and gas outburst in a tunneling working face according to claim 2, characterized in that: In step S103, according to the formula: Identify the stress concentration area The stress change rate of the optical fiber monitoring data ; in, The stress concentration areas are The shortest and longest distances from the head of the excavation working face; For two adjacent moments, The stress concentration area Inside The stress value of each monitoring point at each moment; The stress concentration area Inside The stress value of each monitoring point at each moment.

4. 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, Based on the numerical simulation results of coal and gas outburst at the tunneling working face and the historical data of coal and gas outburst at the tunneling working face, the stress concentration area is determined. The critical value of the stress peak of the excavation working face , critical value of stress change .

5. 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, Obtaining the stress concentration area of ​​the excavation working face Inner coal seam gas storage parameters, geological structure distribution parameters, and drilling test parameters of the excavation working face, according to 、 And the coal seam gas storage parameters, geological structure distribution parameters, drilling test parameters, and step-by-step early warning of coal and gas outbursts in the excavation working face are carried out.

6. The method for early warning of coal and gas outburst in a tunneling working face according to claim 5, characterized in that: In step S103, In response to and , then there is no early warning of coal and gas outburst at the excavation working face; In response to or , a Level 1 warning of coal and gas outburst at the tunneling working face is issued; In response to or , and the stress concentration area There are geological structures ( ) or the original gas content is high ( ), a Level 2 early warning of coal and gas outburst at the excavation working face is issued; In response to or , and the stress concentration area There are geological structures ( ) or the original gas content is high ( ), and top drilling occurs when drilling on the excavation working face ( ) or clamp drill ( ) or nozzle ( ), a Level 3 warning of coal and gas outburst at the excavation working face will be issued.

7. An early warning system for coal and gas outburst at a tunneling working face, characterized in that: The method for early warning of coal and gas outburst in a tunneling working face according to any one of claims 1 to 6 is used to provide step-by-step warning of coal and gas outburst in the tunneling working face, the system comprising: a data monitoring unit configured to lay strain optical fibers in the coal body of the excavation working face by an embedded method based on the cross-sectional dimensions of the tunnel 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; A data processing unit is configured to process the optical fiber monitoring data based on a cubic exponential smoothing method, and to delineate the stress concentration area of ​​the tunneling working face according to the processed optical fiber monitoring data ;in, The stress concentration areas are The shortest and longest distances from the head of the excavation working face; An early warning unit is configured to establish the stress concentration area The stress peak value of the optical fiber monitoring data , stress change rate and the predetermined critical value of the stress peak of the excavation working face in the stress concentration area. , critical value of stress change The relationship between them is used to provide step-by-step warning for coal and gas outbursts in the excavation working face.

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