A goaf gas and coal spontaneous combustion combined disaster simulation system and prediction method

Abstract

The application discloses a goaf gas and coal spontaneous combustion composite disaster simulation system and a prediction method, and belongs to the technical field of coal mine thermal dynamic disaster evolution process simulation tests. The simulation system comprises a transparent cover body, a simulation test table, a similar simulation model of a mining working face, a gas supply unit, a monitoring unit, a camera device and a counterweight. The inclination angle of the base is adjusted by adjusting the telescopic supporting legs, the water bag is used to simulate the coal seam, and the coal pillar is used as a release channel of methane in the simulation mining process. The simulation mining process is carried out, the gas is conveyed, the evolution law of the methane and oxygen concentration data is monitored, the related contour maps are drawn, the space dangerous area is reconstructed by interpolation, finally, the chaos prediction is carried out by using the phase space reconstruction method, and the disaster space form change is analyzed. The application can realize the simulation test and visualization of the evolution process of the gas and coal spontaneous combustion composite disaster, quantitatively represents the dangerous area, provides a theoretical basis for disaster prevention, and guarantees the energy safety and the safety of workers.

Description

Technical Field

[0001] This invention relates to the field of simulation and testing technology for the evolution of thermal and dynamic disasters in coal mines, and in particular to a simulation system and prediction method for a combined disaster of gas and spontaneous combustion of coal in goaf areas. Background Technology

[0002] The combined disaster of gas and coal spontaneous combustion is the most prevalent and severe hazard among major coal mine accidents, seriously threatening the environment and workers' lives. Air leakage can cause spontaneous combustion of residual coal in the goaf and affect the movement of gas in the goaf. When the combustion temperature of the residual coal rises to the ignition temperature of the gas, the gas can be ignited and develop into a gas explosion.

[0003] Statistics show that gas explosions caused by spontaneous combustion of residual coal occur worldwide, resulting in significant casualties and economic losses. In recent years, with the depletion of shallow coal resources, deep coal mining has become the new normal in China's coal mining industry. As mining depth gradually extends, observable ground stress, ground temperature, gas content, and gas pressure also increase, making combined disasters such as gas and spontaneous combustion in goaf areas more frequent and severe. Furthermore, the complexity, concealment, dynamic nature, and coupling of these combined disasters make research into their causative mechanisms and evolution processes extremely difficult.

[0004] Currently, scholars mainly study the occurrence, evolution, and expansion of gas and coal spontaneous combustion combined disasters through theoretical analysis, numerical simulation, and field experiments. However, there is a lack of theoretical research on the evolution and hazard mechanism of gas and coal spontaneous combustion combined disasters, as well as research and analysis on the spatial characteristics of their hazardous areas. Furthermore, there is limited research on the development patterns of fracture fields in overlying strata and the distribution patterns of flow fields in goaf areas during coalfield mining, making it difficult to clarify the diffusion characteristics of gas and coal spontaneous combustion combined disasters and the migration patterns of the combined hazardous areas.

[0005] The invention patent application CN201910928112.6 discloses a simulation and testing device and method for the thermodynamic process of coal fire disasters at different scales. It can simulate the collapse process of goaf areas and the evolution process of coalfield fires, thereby achieving real-time monitoring of the temperature field distribution, fracture distribution and development patterns, and fracture channel changes during the evolution of coalfield fires. However, this technology can only visualize the evolution process of spontaneous combustion of coal, ignoring the possibility that spontaneous combustion of coal may trigger a gas explosion during actual mining, causing even greater disasters.

[0006] At present, there are no comprehensive and systematic test benches and test methods for the evolution of gas and coal spontaneous combustion combined disasters, both domestically and internationally. Summary of the Invention

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

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] This invention provides a simulation system for a combined disaster of gas and spontaneous combustion of coal in a goaf, characterized in that it comprises:

[0010] A transparent cover, the transparent cover being airtight, the transparent cover being provided with an exhaust port, and the exhaust port being provided with an exhaust device;

[0011] A simulation test bench is housed within the transparent enclosure. The simulation test bench includes a support unit, a base, and a frame. The frame is mounted on the base and is a cylindrical structure with a rectangular cross-section. Each sidewall of the frame is composed of multiple horizontally stacked channel steels. The support unit includes at least three retractable support legs, the top ends of which are hinged to the bottom end of the base via ball joints. The tilt angle of the base can be adjusted by adjusting each of the retractable support legs.

[0012] A similar simulation model of a mining face is provided, wherein the bottom end of the similar simulation model contacts the base, and the similar simulation model is located within the frame; the similar simulation model includes ventilation roadways, coal conveying roadways, simulated coal seams and simulated rock strata distributed from bottom to top, the simulated coal seams include multiple water bags arranged sequentially in a horizontal direction, the water bags are filled with water, and adjacent water bags are in contact with each other, and a ring of coal pillars is also provided around the simulated coal seams, the coal pillars being located below the simulated rock strata and the... The top of the coal pillar abuts against the simulated coal seam; each water bag is connected to a water pipe at one end, and the water pipe is equipped with a flow meter and a valve; the ventilation roadway and the coal transportation roadway are arranged side by side on the base, and the ventilation roadway and the coal transportation roadway are connected to the same end of the simulated coal seam, the ventilation roadway including an intake roadway and a return air roadway; multiple methane content monitors and multiple oxygen content monitors are fixed on the channel steel, and the probes of the methane content monitors and the oxygen content monitors extend into the simulated rock strata;

[0013] A gas supply unit, comprising a methane storage tank and an oxygen storage tank, wherein the oxygen storage tank is connected to the intake roadway via a pipeline, and the methane storage tank is connected to the coal pillar via a pipeline;

[0014] The monitoring unit includes a computer, and the methane content monitor and the oxygen content monitor are respectively connected to the computer via signal connection.

[0015] A camera device for photographing the interior of the transparent enclosure during the experiment;

[0016] Several counterweights are disposed above the similar simulation model of the mining face, and the counterweights are used to apply loads to the similar simulation model of the mining face.

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

[0018] Preferably, the coal conveying roadway is located between the intake air 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 intake tunnel.

[0021] Preferably, the coal pillar has an opening on the side closest to the coal conveying roadway.

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

[0023] Preferably, the end of the intake airway away from the simulation model of the mining face is closed, and the end of the return airway away from the simulation model of the mining face is open.

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

[0025] This invention also provides a method for predicting combined hazards of gas and spontaneous combustion of coal in goaf areas, based on the aforementioned simulation system for combined hazards of gas and spontaneous combustion of coal in goaf areas, comprising the following steps:

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

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

[0028] (3) Set up a similar simulation model of the mining face within the framework; and install and connect all components to form the simulation system for the combined disaster of gas and spontaneous combustion of coal in the goaf.

[0029] (4) From one end close to the coal conveying roadway to the other end far from the coal conveying roadway, the water volume in each water bag is reduced sequentially at a preset speed to simulate mining. At the same time, oxygen and methane gas of a set concentration are supplied to the model through methane storage tank and oxygen storage tank.

[0030] (5) The evolution process is monitored by methane content monitors and oxygen content monitors, and the monitoring data of the methane content monitors and oxygen content monitors at different times are automatically recorded by computer, so as to obtain the oxygen concentration data and methane data at the positions corresponding to the methane content monitors and oxygen content monitors in the similar simulation model of the mining face; at the same time, the evolution law of the overlying rock starting to collapse and generate cracks is observed by 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 composite disasters, and using Origin software to draw contour maps and Matlab software to perform spatial interpolation, the dangerous area of ​​gas and coal composite disasters based on the coupling of the fracture field, oxygen concentration field and methane explosion concentration field of the overlying rock strata in the goaf is reconstructed.

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

[0033] The present invention achieves the following technical effects compared to the prior art:

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

[0035] Furthermore, this invention enables visualization of the evolution process of gas and coal spontaneous combustion combined disasters during mining, and quantitative characterization of the dangerous areas of gas and coal spontaneous combustion combined disasters at different stages. This not only provides a theoretical basis for the prevention and control of gas and coal spontaneous combustion disasters, but also ensures the energy security of coalfields and the safety of workers' lives.

[0036] Furthermore, the use of a transparent enclosure not only prevents methane gas from spreading and causing safety accidents, but also allows for easy observation of changes in the internal structure during the simulation test.

[0037] Furthermore, the retractable support legs of the simulation test bench allow for adjustment of the base tilt angle, increasing the flexibility and versatility of the simulation.

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

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

[0040] Furthermore, by using software to draw contour maps and perform spatial interpolation, the hazardous areas of gas and coal combined disasters were reconstructed, achieving quantitative characterization of the hazardous areas.

[0041] Furthermore, by employing a nonlinear modeling method based on phase space reconstruction for chaotic prediction, the dangerous areas of gas and coal composite disasters in the goaf can be predicted in advance, providing strong support for disaster prevention and control. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0044] Figure 2 This is a partial structural schematic diagram of the simulated system for combined gas and coal spontaneous combustion disasters in goaf areas according to the present invention;

[0045] Figure 3 This is a partial structural diagram of the similarity simulation model of the mining face in the goaf gas and coal spontaneous combustion combined disaster simulation system of the present invention. Figure 1 ;

[0046] Figure 4 This is a partial structural diagram of the similarity simulation model of the mining face in the goaf gas and coal spontaneous combustion combined disaster simulation system of the present invention. Figure 2 ;

[0047] Figure 5 This is a partial structural diagram of the similarity simulation model of the mining face in the goaf gas and coal spontaneous combustion combined disaster simulation system of the present invention. Figure 3 ;

[0048] Figure 6 This is a flowchart of the method for predicting combined disasters of gas and spontaneous combustion of coal in goaf areas according to the present invention;

[0049] Figure 7This is a flowchart illustrating the process of reconstructing the hazardous area of ​​the next stage of the combined gas and coal combustion disaster prediction method in the goaf area of ​​the present invention.

[0050] The components include: 1. Transparent enclosure; 2. Exhaust port; 3. Telescopic support legs; 4. Base; 5. Coal conveying roadway; 6. Air intake roadway; 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 roadway; 18. Water bag; 19. Coal pillar; 20. Water pipe; 21. Flow meter; 22. Valve. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

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

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Example 1

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

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

[0057] The simulation test bench is set inside the transparent enclosure 1. The simulation test bench includes a support unit, a base 4, and a frame. The frame is set on the base 4 and is a cylindrical shape with a rectangular cross-section. Each side wall of the frame is made of multiple horizontally placed channel steels 7 stacked together. The support unit includes at least three telescopic support legs 3. The top of the telescopic support legs 3 is hinged to the bottom of the base 4 through ball joints. The tilt angle of the base 4 can be adjusted by adjusting each telescopic support leg 3.

[0058] A similar simulation model of the mining face is provided, with its bottom end in contact with the base 4 and located within a frame. The simulation model includes ventilation roadways, coal conveying roadways 5, and simulated coal seams and simulated rock strata distributed from bottom to top. The simulated coal seam includes multiple water bags 18 arranged horizontally in sequence, each filled with water and in contact with adjacent bags. A ring of coal pillars 19 is also provided around the simulated coal seam, located below the simulated rock strata. 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 installed on the water pipe 20; the ventilation roadway and the coal transportation roadway are arranged side by side on the base 4, and the ventilation roadway and the coal transportation roadway are connected to the same end of the simulated coal seam; multiple methane content monitors 8 and multiple oxygen content monitors 9 are fixed on the channel steel 7, and the probes of the methane content monitors 8 and the oxygen content monitors 9 extend into the simulated rock strata; the ventilation roadway includes a return air roadway 17 and an intake air roadway 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 intake airway 6 through a pipeline. A second regulating valve 14 is installed on the connecting pipeline between the oxygen storage tank 13 and the intake airway 6. The methane storage tank 11 is connected to the coal pillar 19 through a pipeline. A first regulating valve 12 is installed on the connecting pipeline between the methane storage tank 11 and the coal pillar 19.

[0060] The monitoring unit includes a computer 15, a methane content monitor 8, and an oxygen content monitor 9, which are respectively connected to the computer 15 via signal connection cables.

[0061] Camera device 16 is used to photograph the inside of the transparent enclosure 1 during the test;

[0062] Several counterweights 10 are placed above the similar simulation model of the mining face. The counterweights 10 are used to apply loads to the similar simulation model of the mining face.

[0063] It is worth noting that the production of a similar simulation model of a mining face is a well-known existing technology in the field. The improvement of the similar simulation model of a mining face in this embodiment is that a row of water-filled bags 18 is used to simulate the coal seam, and a ring of coal pillars 19 is also set 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 ring of coal pillars 19 set outside the simulated coal seam also serves as a channel for methane gas to diffuse into the goaf and the simulated rock strata, and also serves as a channel for oxygen gas to diffuse into the simulated rock strata.

[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 schemes of this embodiment, it is more preferred that the coal conveying roadway 5 is located between the intake air roadway 6 and the return air roadway 17.

[0066] In the optional scheme of this embodiment, it is more preferred that the coal pillar 19 is opened on the side near the coal conveying roadway 5, so as to avoid the coal pillar 19 blocking the oxygen entering the goaf from the air intake roadway.

[0067] In the optional embodiments of this example, it is more preferred that the methane content monitor 8 and the oxygen content monitor 9 are staggered in the horizontal direction.

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

[0069] In the optional embodiments of this example, the camera device 16 is preferably a high-speed camera.

[0070] The probes of methane content monitor 8 and oxygen content monitor 9 extend into the simulated rock layer to measure the concentrations of methane and oxygen within the simulated rock layer.

[0071] It should be noted that the counterweight 10 only contacts the top of the simulation model of the mining face, and not the top of the frame, to avoid the frame supporting the counterweight 10 and thus affecting the load applied by the counterweight 10 to the simulation model of the mining face. The simulated rock strata are used to simulate the overlying rock strata of the coal seam.

[0072] The simulation test bench, the similar simulation model of the mining face, and the counterweight 10 are all located inside the transparent enclosure 1. The transparent enclosure 1 serves to prevent the diffusion of methane gas. Since the simulation system involves a methane storage tank 11 supplying methane gas to the model, the airtight transparent enclosure 1 effectively prevents the methane gas from diffusing into the surrounding environment, avoiding methane leaks and safety accidents, and ensuring the safety of the experimental environment and personnel. During the simulation test, the camera device 16 captures images of the interior of the transparent enclosure 1. The transparent enclosure 1 allows for unobstructed imaging, facilitating observation of changes in the internal structures of the simulation test bench, the similar simulation model of the mining face, etc., during the test, such as observing the evolution of cracks caused by the collapse of the overlying rock.

[0073] Example 2

[0074] like Figure 6 and Figure 7As shown, this embodiment provides a method for predicting combined hazards of gas and spontaneous combustion of coal in goaf areas. Based on the simulation system for combined hazards of gas and spontaneous combustion of coal in goaf areas in Embodiment 1, the method includes the following steps:

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

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

[0077] (3) Set up a similar simulation model of the mining face within the framework; and install and connect all components to form the above-mentioned simulation system for the combined disaster of gas and spontaneous combustion of coal in the goaf;

[0078] (4) Start the simulation. From the end closest to the coal transport roadway 5 to the end furthest from the coal transport roadway 5, reduce the water volume in each water bag 18 at a preset speed to realize simulated mining. At the same time, oxygen and methane gas of a set concentration are supplied 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 into the simulated coal seam, simulated rock strata and goaf through the coal pillar 19. After the oxygen gas is introduced into the air intake roadway 6, it enters the goaf and diffuses into the simulated rock strata through the goaf and the coal pillar 19.

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

[0080] (6) Based on the obtained oxygen concentration data and methane concentration data, based on the conditions for the occurrence of gas and coal composite disasters, and using Origin software to draw contour maps and Matlab software to perform spatial interpolation, the dangerous area of ​​gas and coal composite disasters based on the coupling of the fracture field, oxygen concentration field and methane explosion concentration field of the overlying rock strata in the goaf is reconstructed.

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

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

[0083] In the optional schemes of this embodiment, the preferred method is to assume that in step (7), a certain single variable information time series is collected as {w(t)Ⅰt=1,2,…,N}. First, the time series is standardized, and the time delay τ is calculated using the CC algorithm. Then, the original time series is reconstructed in phase space, and the correlation dimension D is calculated using the GP algorithm to obtain the embedding dimension m. Finally, the maximum Lyapunov exponent is calculated based on the small data volume method to determine the chaotic characteristics of the time series, and progressive chaotic prediction is performed according to the weighted first-order local method. Based on the judgment steps of the chaotic characteristics of the system, the gas concentration change in the next stage is predicted. This indicates that the gas change process is more complex and the changes are more unpredictable. The gas concentration change is affected by many factors, including the working environment and method, output, and advance speed, all of which have a significant impact on it. The degree of change in geological conditions is also greater. 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, their maximum predictable time scales are 45 min (predicted 9 steps in advance, with a time interval of 5 min) and 50 min (predicted 10 steps in advance, with a time interval of 5 min). Larger prediction step sizes will reduce the prediction accuracy. Phase space reconstruction is a method to transform a univariate time series into a trajectory in a high-dimensional phase space. By analyzing the evolution law of phase points in phase space, the intrinsic dynamic characteristics of the system can be extracted, thereby predicting the gas concentration change in the next stage, and then reconstructing the dangerous area of ​​gas and coal composite disaster in the goaf in the next stage. This method is based on chaos theory, which posits that seemingly random system behavior may actually contain inherent deterministic patterns. By analyzing the phase space, these patterns can be captured and predicted.

[0084] In the description of this invention, it should be noted that the terms "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0085] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for simulating the combined disaster of goaf gas and coal spontaneous combustion, characterized in that, The goaf gas and coal spontaneous combustion combined disaster simulation system comprises: A transparent cover body is closed, and an exhaust port is arranged on the transparent cover body, and an exhaust device is arranged on the exhaust port; A simulation test bench is arranged in the transparent cover body; the simulation test bench comprises a support unit, a base and a frame, the frame is arranged on the base, the frame is in a cylindrical shape with a rectangular cross section, and each side wall of the frame is stacked by a plurality of horizontally arranged channel steels; the support unit comprises at least three telescopic support legs, the top end of the telescopic support leg is hinged to the bottom end of the base through a ball hinge; the inclination angle of the base can be adjusted by adjusting each telescopic support leg; A mining working face similar simulation model is in contact with the base, and is located in the frame; the mining working face similar simulation model comprises a ventilation roadway, a coal conveying roadway, a simulation coal seam and a simulation rock layer distributed from bottom to top, the simulation coal seam comprises a plurality of water bags arranged in a horizontal direction, the water bags are filled with water, and adjacent water bags are in contact with each other, a row of water-filled water bags is used to simulate a coal seam, a coal pillar is further sleeved outside the simulation coal seam, the coal pillar is located below the simulation rock layer, and the top end of the coal pillar is in abutment with the simulation coal seam, the coal pillar has the function of a channel for methane gas to diffuse into the goaf and the simulation rock layer, and also has the function of a channel for oxygen gas to diffuse into the simulation rock layer; each water bag is connected with a water pipe at one end, and the water pipe is provided with a flow meter and a valve; the ventilation roadway and the coal conveying roadway are arranged side by side on the base, and the ventilation roadway and the coal conveying roadway are in communication with the same end of the simulation coal seam, the ventilation roadway comprises an air inlet roadway and an air return roadway; a plurality of methane content monitors and a plurality of oxygen content monitors are fixed on the channel steel, and the probe rods of the methane content monitors and the oxygen content monitors all extend into the simulation rock layer; A gas supply unit comprises a methane storage tank and an oxygen storage tank, the oxygen storage tank is in communication with the air inlet roadway through a pipeline, and the methane storage tank is in communication with the coal pillar through a pipeline; A monitoring unit comprises a computer, the methane content monitor and the oxygen content monitor are respectively signal connected with the computer; A camera is used to take pictures inside the transparent cover body during the test; A plurality of counterweights are arranged above the mining working face similar simulation model, and the counterweights are used to apply a load to the mining working face similar simulation model; The goaf gas and coal spontaneous combustion combined disaster prediction method comprises the following steps: (1) designing a mining working face similar simulation model matched with the goaf to be simulated; (2) according to the designed model, selecting the number of channel steels required for building the model, and building the frame of the simulation test bench on the base; (3) setting the mining face similar simulation model in the frame; and installing connecting all components to form the goaf gas and coal spontaneous combustion composite disaster simulation system; (4) from one end close to the coal conveying roadway to the end far from the coal conveying roadway, sequentially reducing the water amount in each water bag at a preset speed to realize simulation mining, and at the same time, the methane tank and the oxygen tank deliver methane and oxygen gas with a set concentration to the model; (5) monitoring the evolution process through the methane content monitor and the oxygen content monitor, and automatically recording the monitoring data of the methane content monitor and the oxygen content monitor at different times through the computer, so as to obtain the oxygen concentration data and the methane data at the positions corresponding to the methane content monitor and the oxygen content monitor in the mining face similar simulation model; at the same time, a high-speed camera is used to observe the evolution law of the cracks generated by the overlying rock collapse; (6) according to the obtained oxygen concentration data and methane concentration data, based on the conditions of gas and coal composite disaster, and using Origin software to draw the contour map, using Matlab software for spatial interpolation, reconstructing the dangerous area of gas and coal composite disaster based on the coupling of goaf overlying rock fracture field, oxygen concentration field and methane explosion concentration field; (7) using the phase space reconstruction nonlinear modeling method to predict the gas concentration data at the measuring point at the next time; and then reconstructing the dangerous area of goaf gas and coal composite disaster at the next stage.

2. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: Two adjacent channel steels are connected by bolts.

3. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: The coal conveying roadway is located between the air inlet roadway and the air return roadway.

4. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: A first regulating valve is arranged on the connecting pipeline between the methane tank and the coal pillar.

5. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: A second regulating valve is arranged on the connecting pipeline between the oxygen tank and the air inlet roadway.

6. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: The coal pillar is opened on one side close to the coal conveying roadway.

7. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: The methane content monitor and the oxygen content monitor are staggered in the horizontal direction.

8. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: The end of the air inlet roadway far from the mining face similar simulation model is closed, and the end of the air return roadway far from the mining face similar simulation model is opened.

9. The goaf gas and coal spontaneous combustion combined disaster simulation method according to claim 1, characterized in that: The mining face similar simulation model and the counterweight are both located in the transparent cover body.

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