Goaf gas and coal spontaneous combustion composite disaster simulation system and prediction method

Abstract

The invention discloses a goaf gas and coal spontaneous combustion composite disaster simulation system and prediction method, and belongs to the technical field of coal mine thermodynamic disaster evolution process simulation tests. The simulation system comprises a transparent cover body, a simulation test bed, a mining working face similar simulation model, a gas supply unit, a monitoring unit, a camera device and a balancing weight. The inclination angle of the base is adjusted by adjusting the telescopic supporting legs, a water bag is used for simulating a coal seam, and a coal pillar serves as a methane release channel in the simulated mining process. A mining process is simulated, gas is conveyed, methane and oxygen concentration data evolution laws are monitored, a related contour map is drawn, interpolation is carried out to reconstruct a space dangerous area, finally, a phase space reconstruction method is adopted to carry out chaos prediction, and disaster space form changes are analyzed. The simulation test and visualization of the evolution process of the gas and coal spontaneous combustion composite disaster can be realized, a dangerous area is quantitatively represented, a theoretical basis is provided for disaster prevention and control, and the energy safety and the life safety of workers are guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of simulation test of coal mine thermal dynamic disaster evolution process, and in particular to a simulation system and prediction method for composite disaster of spontaneous combustion of gas and coal in goaf. Background Art

[0002] Gas and coal spontaneous combustion combined disasters are the most serious and most severe disasters in coal mine accidents, which seriously threaten the environment and the lives of workers. Air leakage can cause spontaneous combustion of coal in the goaf and affect the migration of gas in the goaf. When the combustion temperature of coal rises to the ignition temperature of gas, the gas can be ignited and develop into a gas explosion.

[0003] According to statistics, spontaneous combustion of coal residues has caused gas explosion accidents all over the world, causing huge casualties and economic losses. In recent years, as shallow coal resources have been exhausted, deep coal mining has become the new normal for China's coal resource mining. As the mining depth gradually extends to the depth, the observable ground stress, ground temperature, gas content, and gas pressure also increase, making the compound disasters represented by spontaneous combustion of gas and coal in the goaf more frequent and serious. At the same time, due to the complexity, concealment, dynamics, and coupling of the compound disaster of gas and coal spontaneous combustion, the study of the disaster mechanism and evolution process of such compound disasters is full of difficulties.

[0004] At present, relevant scholars mainly study the occurrence, evolution and expansion process of gas and coal spontaneous combustion compound disasters through theoretical analysis, numerical simulation and field experiments, lacking relevant theories on the evolution and disaster-causing mechanism of gas and coal spontaneous combustion compound disasters and research and analysis on the spatial characteristics of its dangerous areas. In addition, there is little research on the development law of the fracture field of the overlying rock strata and the distribution law of the flow field in the goaf during coal mining, making it difficult to clarify the diffusion characteristics of the disaster and the migration law of the compound dangerous area when the gas and coal spontaneous combustion compound disaster occurs.

[0005] The invention patent with application number CN201910928112.6 discloses a simulation test device and method for the thermal dynamic process of coal fire disasters at different scales, which can simulate the collapse process of the goaf and the evolution process of coalfield fire, so as to realize the real-time monitoring of the distribution of temperature field, the law of crack distribution and development, and the law of change of crack channels during the evolution of coalfield fire. However, this technology can only visualize the evolution process of coal spontaneous combustion, ignoring that coal spontaneous combustion in the actual mining process may cause gas explosion, causing greater disasters.

[0006] At present, there is no comprehensive and systematic test platform and test method for the evolution process of gas and coal spontaneous combustion combined disasters at home and abroad. Summary of the invention

[0007] The purpose of the present invention is to provide a simulation system and prediction method for composite disasters of spontaneous combustion of gas and coal in goaf, so as to solve the problems existing in the above-mentioned prior art and realize simulation test of the evolution process of composite disasters of spontaneous combustion of gas and coal.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides a goaf gas and coal spontaneous combustion compound disaster simulation system, which is characterized by comprising:

[0010] A transparent cover body, the transparent cover body is sealed, an exhaust port is provided on the transparent cover body, and an exhaust device is provided on the exhaust port;

[0011] A simulation test bench, the simulation test bench is arranged in the transparent cover; the simulation test bench comprises a support unit, a base and a frame, the frame is arranged on the base, the frame is cylindrical with a rectangular cross section, and each side wall of the frame is formed by stacking a plurality of horizontally placed channel steels; the support unit comprises at least three retractable support legs, the top ends of the retractable support legs are hinged to the bottom end of the base through ball joints; the inclination angle of the base can be adjusted by adjusting each of the retractable support legs;

[0012] A similar simulation model of a mining working face, wherein the bottom end of the similar simulation model of the mining working face is in contact with the base, and the similar simulation model of the mining working face is located in the frame; the similar simulation model of the mining working face includes a ventilation tunnel, a coal transportation tunnel, a simulated coal seam and a simulated rock layer distributed from bottom to top, the simulated coal seam includes a plurality of water bags arranged in sequence in a horizontal direction, the water bags are filled with water, and adjacent water bags are in contact with each other, and a circle of coal pillars is also arranged outside the simulated coal seam, the coal pillars are located below the simulated rock layer and the The top of the coal pillar is in contact with the simulated coal seam; each of the water bags is connected to a water pipe at one end, and a flow meter and a valve are arranged on the water pipe; the ventilation lane and the coal transport lane are arranged side by side on the base, and the ventilation lane and the coal transport lane are connected to the same end of the simulated coal seam, and the ventilation lane includes an air inlet lane and a return air lane; a plurality of methane content monitors and a plurality of oxygen content monitors are fixedly arranged on the channel steel, and the probes of the methane content monitor and the oxygen content monitor are both extended into the simulated rock formation;

[0013] A gas supply unit, the gas supply unit comprising a methane storage tank and an oxygen storage tank, the oxygen storage tank being connected to the air inlet tunnel through a pipeline, and the methane storage tank being connected to the coal pillar through a pipeline;

[0014] A monitoring unit, the monitoring unit comprising a computer, the methane content monitor and the oxygen content monitor being respectively connected to the computer signals;

[0015] A camera device, which is used to photograph the interior of the transparent cover during the test;

[0016] A plurality of counterweight blocks are arranged above the similar simulation model of the mining working face, and the counterweight blocks are used to apply loads to the similar simulation model of the mining working face.

[0017] Preferably, two adjacent channel steels are connected by bolts.

[0018] Preferably, the coal transport roadway is located between the air intake roadway and the return air roadway.

[0019] Preferably, a first regulating valve is provided on the connecting pipeline between the methane storage tank and the coal pillar.

[0020] Preferably, a second regulating valve is provided on the connecting pipeline between the oxygen storage tank and the air inlet tunnel.

[0021] Preferably, the coal pillar is open on one side close to the coal transport tunnel.

[0022] Preferably, the methane content monitor and the oxygen content monitor are staggered in the horizontal direction.

[0023] Preferably, the air inlet tunnel is closed at one end away from the similar simulation model of the mining working face, and the return air tunnel is open at one end away from the similar simulation model of the mining working face.

[0024] Preferably, the mining face similarity simulation model and the counterweight block are both located inside the transparent cover.

[0025] The present invention also provides a method for predicting a composite disaster of spontaneous combustion of gas and coal in goaf, based on the above-mentioned composite disaster simulation system of spontaneous combustion of gas and coal in goaf, comprising the following steps:

[0026] (1) designing a similar simulation model of the mining working face that matches the goaf area to be simulated;

[0027] (2) According to the designed model, select the number of channel steels required for model construction, and build the framework of the simulation test bench on the base;

[0028] (3) setting up a similar simulation model of the mining face within the framework; and installing and connecting all components to form a composite disaster simulation system for spontaneous combustion of gas and coal in the goaf;

[0029] (4) From one end close to the coal transport tunnel to the end far from the coal transport tunnel, the amount of water in each water bag is reduced in sequence at a preset speed to realize simulated mining, and at the same time, oxygen and methane gases of set concentrations are delivered to the model through a methane storage tank and an oxygen storage tank;

[0030] (5) monitoring the evolution process by means of a methane content monitor and an oxygen content monitor, and automatically recording the monitoring data of the methane content monitor and the oxygen content monitor at different times by means of a computer, thereby obtaining oxygen concentration data and methane data at positions corresponding to the methane content monitor and the oxygen content monitor in a similar simulation model of the mining face; and simultaneously observing the evolution law of the overburden rock beginning to collapse and generate cracks by means of a high-speed camera;

[0031] (6) Based on the obtained oxygen concentration data and methane concentration data, based on the conditions for the occurrence of gas and coal compound disasters, the contour map was drawn using Origin software, and the spatial interpolation was performed using Matlab software to reconstruct the dangerous area of ​​gas and coal compound disasters based on the coupling of the overlying rock fracture field, oxygen concentration field, and methane explosion concentration field in the goaf;

[0032] (7) The nonlinear modeling method of phase space reconstruction is used to make chaotic predictions on the gas concentration data at the measuring point at the next moment; and then the dangerous area of ​​gas and coal combined disasters in the goaf in the next stage is reconstructed.

[0033] Compared with the prior art, the present invention has achieved the following technical effects:

[0034] The goaf gas and coal spontaneous combustion compound disaster simulation system and prediction method of the present invention realizes the simulation test of the evolution process of the gas and coal spontaneous combustion compound disaster, and provides an effective experimental means for studying such compound disasters.

[0035] Furthermore, the present invention can visualize the evolution process of the combined disaster of gas and coal spontaneous combustion during the mining process, and quantitatively characterize the dangerous areas of the combined disaster of gas and coal spontaneous combustion at different periods. It can not only provide a theoretical basis for the prevention and control of gas and coal spontaneous combustion disasters, but also ensure the energy security of coalfields and the life safety of workers.

[0036] Furthermore, a transparent cover is used to prevent the diffusion of methane gas and cause safety accidents, and to facilitate the observation of changes in the internal structure during the simulation test.

[0037] Furthermore, the retractable support legs of the simulation test bench can adjust the inclination angle of the base, increasing the flexibility and diversity of the simulation.

[0038] Furthermore, water bags filled with water were used to simulate coal seams and set up coal pillars, which more realistically simulated the actual situation in the coal mining process. At the same time, the coal pillars served as a diffusion path for methane gas, which improved the accuracy of the simulation.

[0039] Furthermore, it is possible to monitor the evolution process and automatically record data to obtain accurate oxygen concentration and methane data.

[0040] Furthermore, by drawing contour maps and performing spatial interpolation through software, the dangerous areas of gas and coal combined disasters were reconstructed, achieving quantitative characterization of the dangerous areas.

[0041] Furthermore, the nonlinear modeling method of phase space reconstruction is used for chaos prediction, which can predict in advance the dangerous areas of gas and coal combined disasters in the goaf in the next stage, providing strong support for disaster prevention and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0043] Figure 1 It is a schematic diagram of the structure of the goaf gas and coal spontaneous combustion composite disaster simulation system of the present invention;

[0044] Figure 2 It is a partial structural schematic diagram of the goaf gas and coal spontaneous combustion composite disaster simulation system of the present invention;

[0045] Figure 3 The schematic diagram of the partial structure of the simulation model similar to the mining working face in the goaf gas and coal spontaneous combustion compound disaster simulation system of the present invention Figure 1 ;

[0046] Figure 4 The schematic diagram of the partial structure of the simulation model similar to the mining working face in the goaf gas and coal spontaneous combustion compound disaster simulation system of the present invention Figure 2 ;

[0047] Figure 5 The schematic diagram of the partial structure of the simulation model similar to the mining working face in the goaf gas and coal spontaneous combustion compound disaster simulation system of the present invention Figure 3 ;

[0048] Figure 6 It is a flow chart of the method for predicting the composite disaster of spontaneous combustion of gas and coal in goaf of the present invention;

[0049] Figure 7It is a flow chart for reconstructing the dangerous area of ​​the next stage of the composite disaster of gas and coal in the goaf area in the method for predicting the composite disaster of spontaneous combustion of gas and coal in the goaf area of ​​the present invention;

[0050] Among them, 1. transparent cover; 2. exhaust port; 3. retractable supporting legs; 4. base; 5. coal transport tunnel; 6. air intake tunnel; 7. channel steel; 8. methane content monitor; 9. oxygen content monitor; 10. counterweight; 11. methane storage tank; 12. first regulating valve; 13. oxygen storage tank; 14. second regulating valve; 15. computer; 16. camera device; 17. return air tunnel; 18. water bag; 19. coal pillar; 20. water pipe; 21. flow meter; 22. valve. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The purpose of the present invention is to provide a simulation system and prediction method for composite disasters of spontaneous combustion of gas and coal in goaf, so as to solve the problems existing in the above-mentioned prior art and realize simulation test of the evolution process of composite disasters of spontaneous combustion of gas and coal.

[0053] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Embodiment 1

[0055] like Figures 1 to 5 As shown, this embodiment provides a goaf gas and coal spontaneous combustion compound disaster simulation system, including:

[0056] A transparent cover body 1 is sealed, an exhaust port 2 is provided on the transparent cover body 1, and an exhaust device is provided on the exhaust port 2;

[0057] The simulation test bench is arranged in a transparent cover 1; the simulation test bench comprises a support unit, a base 4 and a frame, the frame is arranged on the base 4, the frame is cylindrical with a rectangular cross section, and each side wall of the frame is formed by stacking a plurality of horizontally placed channel steels 7; the support unit comprises at least three retractable support legs 3, the top of the retractable support legs 3 is hinged to the bottom of the base 4 through a ball joint; the inclination angle of the base 4 can be adjusted by adjusting each retractable support leg 3;

[0058] A similar simulation model of a mining working face, the bottom of which is in contact with a base 4, and the similar simulation model of a mining working face is located in a frame; the similar simulation model of a mining working face includes a ventilation tunnel, a coal transport tunnel 5, a simulated coal seam and a simulated rock layer distributed from bottom to top, the simulated coal seam includes a plurality of water bags 18 arranged in a horizontal direction, the water bags 18 are filled with water, and adjacent water bags 18 are in contact with each other, and a circle of coal pillars 19 is also provided outside the simulated coal seam, the coal pillars 19 are located below the simulated rock layer and the coal pillars The top of 19 is in contact with the simulated coal seam; each water bag 18 is connected to a water pipe 20 at one end, and a flow meter 21 and a valve 22 are provided on the water pipe 20; the ventilation lane and the coal transport lane are arranged side by side on the base 4, and the ventilation lane and the coal transport lane are connected to the same end of the simulated coal seam; a plurality of methane content monitors 8 and a plurality of oxygen content monitors 9 are fixedly provided on the channel steel 7, and the probe rods of the methane content monitor 8 and the oxygen content monitor 9 are extended into the simulated rock formation; the ventilation lane includes a return air lane 17 and an air inlet lane 6.

[0059] The gas supply unit includes a methane storage tank 11 and an oxygen storage tank 13. The oxygen storage tank 13 is connected to the air inlet tunnel 6 through a pipeline. A second regulating valve 14 is provided on the connecting pipeline between the oxygen storage tank 13 and the air inlet tunnel 6. The methane storage tank 11 is connected to the coal pillar 19 through a pipeline. A first regulating valve 12 is provided on the connecting pipeline between the methane storage tank 11 and the coal pillar 19.

[0060] Monitoring unit, the monitoring unit includes a computer 15, and a methane content monitor 8 and an oxygen content monitor 9 are respectively connected to the computer 15 by signal connection lines;

[0061] A camera device 16, which is used to photograph the interior of the transparent cover body 1 during the test;

[0062] A plurality of counterweight blocks 10 are arranged above the similar simulation model of the mining working face, and the counterweight blocks 10 are used to apply load to the similar simulation model of the mining working face.

[0063] It is worth noting that the preparation of a similar simulation model of a mining working face is an existing technology well known in the art. The improvement of the similar simulation model of a mining working face in this embodiment is that a row of water bags 18 filled with water are used to simulate the coal seam, and a circle of coal pillars 19 are arranged outside the simulated coal seam to simulate the coal pillars 19 left in the goaf during the mining process. At the same time, since the coal pillars 19 are breathable, the circle of coal pillars 19 arranged outside the simulated coal seam also serves as a channel for methane gas to diffuse into the goaf and the simulated rock formation, and also serves as a channel for oxygen gas to diffuse into the simulated rock formation.

[0064] In the optional scheme of this embodiment, it is more preferred that two adjacent channel steels 7 are connected by bolts, that is, the adjacent channel steels 7 are detachably connected.

[0065] In the optional scheme of this embodiment, it is more preferred that the coal transportation tunnel 5 is located between the air intake tunnel 6 and the return air tunnel 17 .

[0066] In the optional scheme of this embodiment, it is more preferred that the coal pillar 19 is opened on one side close to the coal transportation tunnel 5 to prevent the coal pillar 19 from blocking the oxygen entering from the air intake tunnel from entering the goaf.

[0067] In the optional solution of this embodiment, it is more preferred that the methane content monitor 8 and the oxygen content monitor 9 are staggeredly distributed in the horizontal direction.

[0068] In the optional scheme of this embodiment, it is more preferred that the end of the air inlet channel 6 away from the similar simulation model of the mining working face is closed, and the end of the return air channel 17 away from the similar simulation model of the mining working face is open, so that the oxygen in the oxygen storage tank 13 can fully enter the goaf after entering the air inlet channel 6, and then flow out through the return air channel 17.

[0069] In the optional solution of this embodiment, it is more preferred that the camera device 16 adopts a high-speed camera.

[0070] The probe rod of the methane content monitor 8 and the probe rod of the oxygen content monitor 9 extend into the simulated rock formation to measure the concentrations of methane and oxygen in the simulated rock formation.

[0071] It should be noted that the counterweight 10 only contacts the top of the simulation model similar to the mining face, but not the top of the frame, so as to avoid the frame supporting the counterweight 10 and affecting the application of the load of the simulation model similar to the mining face by the counterweight 10. The simulated rock layer is used to simulate the overlying rock layer of the simulated coal seam.

[0072] The simulation test bench, the similar simulation model of the mining working face and the counterweight 10 are all located in the transparent cover 1. The transparent cover 1 can prevent the diffusion of methane gas. Since the simulation system involves a methane storage tank 11 to transport methane gas to the model, the transparent cover 1 is sealed to effectively prevent the diffusion of methane gas into the surrounding environment, avoid methane leakage causing safety accidents, and ensure the safety of the experimental environment and personnel. During the simulation test, the camera device 16 shoots the inside of the transparent cover 1. The transparent cover 1 makes the shooting unobstructed, making it convenient to observe the changes in the internal structures of the simulation test bench, the similar simulation model of the mining working face, etc. during the test, such as observing the evolution law of the cracks generated by the collapse of the overburden rock.

[0073] Embodiment 2

[0074] like Figure 6 and Figure 7As shown, this embodiment provides a method for predicting a combined disaster of spontaneous combustion of gas and coal in goaf, based on the combined disaster simulation system of spontaneous combustion of gas and coal in goaf of embodiment 1, comprising the following steps:

[0075] (1) Design a similar simulation model of the mining face that matches the goaf to be simulated;

[0076] (2) According to the designed model, select the number of channel steels 7 required for model construction, and build the framework of the simulation test bench on the base 4;

[0077] (3) Setting up a similar simulation model of the mining face within the framework; and installing and connecting all components to form the above-mentioned gas and coal spontaneous combustion composite disaster simulation system in the goaf;

[0078] (4) Start the simulation, from one end close to the coal transport tunnel 5 to the end far from the coal transport tunnel 5, reduce the water volume in each water bag 18 in sequence at a preset speed to realize simulated mining, and at the same time, deliver oxygen and methane gas of set concentration to the model through the methane storage tank 11 and the oxygen storage tank 13; after the methane gas is introduced into the coal pillar 19, it diffuses to the simulated coal seam, simulated rock formation and goaf through the coal pillar 19; after the oxygen gas is introduced into the air inlet tunnel 6, it enters the goaf, and diffuses to the simulated rock formation through the goaf and the coal pillar 19;

[0079] (5) The evolution process is monitored by a methane content monitor 8 and an oxygen content monitor 9, and the monitoring data of the methane content monitor 8 and the oxygen content monitor 9 at different times are automatically recorded by a computer 15, so as to obtain oxygen concentration data and methane data at positions corresponding to the methane content monitor 8 and the oxygen content monitor 9 in a similar simulation model of the mining working face; at the same time, a high-speed camera is used to observe the evolution law of the overburden rock starting to collapse and generate cracks;

[0080] (6) Based on the obtained oxygen concentration data and methane concentration data, based on the conditions for the occurrence of gas and coal compound disasters, the contour map was drawn using Origin software, and the spatial interpolation was performed using Matlab software to reconstruct the dangerous area of ​​gas and coal compound disasters based on the coupling of the overlying rock fracture field, oxygen concentration field, and methane explosion concentration field in the goaf;

[0081] (7) The nonlinear modeling method of phase space reconstruction is used to make chaotic predictions on the gas concentration data at the measuring point at the next moment; and then the dangerous area of ​​gas and coal combined disasters in the goaf in the next stage is reconstructed.

[0082] It is worth noting that the nonlinear modeling method of phase space reconstruction and chaos prediction are both existing methods in this field, while the reconstruction function is a built-in function of Matlab software.

[0083] In the optional scheme of this embodiment, it is more preferred that in step (7), it is assumed that a certain univariate information time series is collected as {w(t)Ⅰt=1,2,…,N}, first the time series is standardized, the time delay τ is calculated using the CC algorithm, then the original time series is reconstructed in phase space, the correlation dimension D is calculated using the GP algorithm, and then the embedding dimension m is obtained, and finally the maximum Lyapunov exponent is calculated based on the small data method, the chaotic characteristics of the time series are judged, and progressive chaos prediction is performed according to the weighted first-order local method. According to the judgment steps of the chaotic characteristics of the system, the concentration change of the gas in the next stage is predicted, which shows that the change process of gas is more complex and the change is more irregular. The concentration change is also affected by many factors, such as the working environment and mode, production, and advancement speed. The geological conditions change more greatly. When the gas time delay is 3 and the oxygen time delay is 5, the embedding dimension of gas and oxygen is 3, and the average period is 19.5172 and 6.3973 respectively. At this time, their maximum Lyapunov exponents are 0.106 and 0.0911 respectively. Therefore, the maximum predictable time scale is 45min (prediction 9 steps ahead, time interval is 5min) and 50min (prediction 10 steps ahead, time interval is 5min). A larger prediction step will reduce the prediction accuracy. Phase space reconstruction is a method of converting a single variable time series into a trajectory in a high-dimensional phase space. By analyzing the evolution law of the phase point in the phase space, the intrinsic dynamic characteristics of the system can be excavated, so as to predict the concentration change of gas in the next stage, and then reconstruct the dangerous area of ​​gas and coal compound disaster in the next stage of the goaf. This method is based on chaos theory, which holds that seemingly random system behaviors may actually have inherent deterministic laws, and captures these laws and makes predictions through the analysis of phase space.

[0084] In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0085] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A composite disaster simulation system for spontaneous combustion of gas and coal in goaf, characterized in that: include: A transparent cover body, the transparent cover body is sealed, an exhaust port is provided on the transparent cover body, and an exhaust device is provided on the exhaust port; A simulation test bench, the simulation test bench is arranged in the transparent cover; the simulation test bench comprises a support unit, a base and a frame, the frame is arranged on the base, the frame is cylindrical with a rectangular cross section, and each side wall of the frame is formed by stacking a plurality of horizontally placed channel steels; the support unit comprises at least three retractable support legs, the top ends of the retractable support legs are hinged to the bottom end of the base through ball joints; the inclination angle of the base can be adjusted by adjusting each of the retractable support legs; A similar simulation model of a mining working face, wherein the bottom end of the similar simulation model of the mining working face is in contact with the base, and the similar simulation model of the mining working face is located in the frame; the similar simulation model of the mining working face includes a ventilation tunnel, a coal transportation tunnel, a simulated coal seam and a simulated rock layer distributed from bottom to top, the simulated coal seam includes a plurality of water bags arranged in sequence in a horizontal direction, the water bags are filled with water, and adjacent water bags are in contact with each other, and a circle of coal pillars is also arranged outside the simulated coal seam, the coal pillars are located below the simulated rock layer and the The top of the coal pillar is in contact with the simulated coal seam; each of the water bags is connected to a water pipe at one end, and a flow meter and a valve are arranged on the water pipe; the ventilation lane and the coal transport lane are arranged side by side on the base, and the ventilation lane and the coal transport lane are connected to the same end of the simulated coal seam, and the ventilation lane includes an air inlet lane and a return air lane; a plurality of methane content monitors and a plurality of oxygen content monitors are fixedly arranged on the channel steel, and the probes of the methane content monitor and the oxygen content monitor are both extended into the simulated rock formation; A gas supply unit, the gas supply unit comprising a methane storage tank and an oxygen storage tank, the oxygen storage tank being connected to the air inlet tunnel through a pipeline, and the methane storage tank being connected to the coal pillar through a pipeline; A monitoring unit, the monitoring unit comprising a computer, the methane content monitor and the oxygen content monitor being respectively connected to the computer signals; A camera device, which is used to photograph the interior of the transparent cover during the test; A plurality of counterweight blocks are arranged above the similar simulation model of the mining working face, and the counterweight blocks are used to apply loads to the similar simulation model of the mining working face.

2. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: Two adjacent channel steels are connected by bolts.

3. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: The coal transport lane is located between the air intake lane and the return air lane.

4. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: A first regulating valve is arranged on the connecting pipeline between the methane storage tank and the coal pillar.

5. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: A second regulating valve is arranged on the connecting pipeline between the oxygen storage tank and the air inlet tunnel.

6. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: The coal pillar is open on one side close to the coal transport tunnel.

7. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: The methane content monitor and the oxygen content monitor are staggeredly distributed in a horizontal direction.

8. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: The air inlet tunnel is closed at one end away from the similar simulation model of the mining working face, and the return air tunnel is open at one end away from the similar simulation model of the mining working face.

9. The goaf gas and coal spontaneous combustion composite disaster simulation system according to claim 1 is characterized by: The mining face similarity simulation model and the counterweight block are both located in the transparent cover.

10. A method for predicting composite disasters of spontaneous combustion of gas and coal in goaf, characterized in that: The goaf gas and coal spontaneous combustion composite disaster simulation system based on claims 1-9 comprises the following steps: (1) designing a similar simulation model of the mining working face that matches the goaf area to be simulated; (2) According to the designed model, select the number of channel steels required for model construction, and build the framework of the simulation test bench on the base; (3) setting up a similar simulation model of the mining face within the framework; and installing and connecting all components to form a composite disaster simulation system for spontaneous combustion of gas and coal in the goaf; (4) From one end close to the coal transport tunnel to the end far from the coal transport tunnel, the amount of water in each water bag is reduced in sequence at a preset speed to realize simulated mining, and at the same time, methane and oxygen gases of set concentrations are delivered to the model through a methane storage tank and an oxygen storage tank; (5) monitoring the evolution process by means of a methane content monitor and an oxygen content monitor, and automatically recording the monitoring data of the methane content monitor and the oxygen content monitor at different times by means of a computer, thereby obtaining oxygen concentration data and methane data at positions corresponding to the methane content monitor and the oxygen content monitor in a similar simulation model of the mining face; and simultaneously observing the evolution law of the overburden rock beginning to collapse and generate cracks by means of a high-speed camera; (6) Based on the obtained oxygen concentration data and methane concentration data, based on the conditions for the occurrence of gas and coal compound disasters, the contour map was drawn using Origin software, and the spatial interpolation was performed using Matlab software to reconstruct the dangerous area of ​​gas and coal compound disasters based on the coupling of the overlying rock fracture field, oxygen concentration field, and methane explosion concentration field in the goaf; (7) The nonlinear modeling method of phase space reconstruction is used to make chaotic predictions on the gas concentration data at the measuring point at the next moment; and then the dangerous area of ​​gas and coal combined disasters in the goaf in the next stage is reconstructed.

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