Gas control method for short-distance coal seam group mining based on atmospheric pressure regulation and control

Abstract

The invention discloses a gas treatment method for short-distance coal seam group mining based on atmospheric pressure regulation and control, and relates to the technical field of coal mine safety, the treatment steps are as follows: S1, based on a laser scanning technology, a coal seam mining environment is scanned, point cloud data is acquired, a coal seam three-dimensional model is constructed, and in the three-dimensional model, based on aerodynamics, a coal seam group mining model is constructed; the air flow condition in the currently built coal seam is simulated, the gas control equipment is arranged at the required position based on the air flow condition, gas discharge results are obtained through continuous simulation, and the optimal discharge result is selected. Reasonable resource allocation is achieved, lower coal seam working face goaf gas is forced to enter an upper coal seam working face goaf along the gas circulation channel, and therefore the upper coal seam working face goaf gas and the lower coal seam working face goaf gas can be effectively prevented from rushing into a workplace, and gas accidents can be effectively reduced; and moreover, the cost is low, only two adjusting air windows need to be arranged, and the practical value is achieved.

Description

Technical Field

[0001] The present invention relates to the field of coal mine safety technology, and in particular to a gas control method for mining a group of coal seams at close range based on atmospheric pressure regulation. Background Art

[0002] In coal mining activities, the high-concentration gas in the goaf flowing into the workplace is an extremely serious safety hazard. Taking the common U-shaped ventilation working face as an example, fresh air flows in from the air inlet tunnel, part of it enters the return air tunnel through the workplace, and the other part enters the goaf, carrying the high-concentration gas in the goaf, and then flows out from the other side of the workplace and flows into the return air tunnel. When the gas content in the goaf is high, the workplace, especially the return air corner, is prone to excessive gas concentration, which can cause suffocation of personnel and even cause gas explosion accidents;

[0003] There are many existing control methods for the problem of gas outburst in goafs, including gas extraction from goafs, local ventilation to dilute gas, and changing the ventilation system. Although these methods can solve the problem of gas exceeding the limit to a certain extent, they each have their own disadvantages. Gas extraction requires a large amount of capital to build an extraction system, and changing the ventilation system often requires the addition of new tunnels, which is costly. As for the method of local ventilation to dilute gas, the air volume of small fans is limited, and wind barriers need to be frequently installed and disassembled as the workplace moves, resulting in poor reliability. In this regard, we proposed a gas control method for close-range coal seam mining based on atmospheric pressure control. Summary of the invention

[0004] In order to solve the above technical problems, a gas control method for close-range coal seam group mining based on atmospheric pressure regulation is provided. This technical solution solves the above problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a gas control method for close-range coal seam group mining based on atmospheric pressure regulation, and the control steps are:

[0006] S1. Scan the mining coal seam environment based on laser scanning technology, obtain point cloud data, and construct a three-dimensional model of the coal seam. In the three-dimensional model, simulate the air flow in the current coal seam based on aerodynamics, set the gas control equipment at the required position based on the air flow, continuously simulate the gas discharge results, and select the best discharge result;

[0007] S2. Preliminary preparation: After the mining of the upper coal seam working face is completed, according to the best simulation results, a sealing wall is built in the air intake tunnel and the return air tunnel, and a gas discharge pipe is reserved;

[0008] S3. Pressure control of the upper coal seam: Install an adjustable wind window in the air intake system of the goaf area of ​​the upper coal seam working face. Adjust the wind window to reduce the atmospheric pressure of the return air system of the mining area, thereby driving down the atmospheric pressure of the goaf area of ​​the upper coal seam working face and the adjacent areas;

[0009] S4, lower coal seam pressure control, set an adjustable wind window in the return air system of the lower coal seam working face to increase the atmospheric pressure of the lower coal seam working face and the goaf;

[0010] S5, gas drainage and discharge: under the pressure difference formed in the goaf of the upper and lower coal seams, the gas in the goaf of the lower coal seam working face flows into the goaf of the upper coal seam working face, and is discharged through the gas discharge pipe of the closed wall of the goaf of the upper coal seam working face;

[0011] S6. Gas dilution and discharge. The discharged gas is diluted by fresh air flow to a safe concentration. The gas concentration is monitored in real time. For gas that has not reached a safe concentration, the gas concentration is calculated and the dilution gas is intelligently selected to be injected to reduce the gas concentration. The gas enters the mine return air system and is discharged to the ground to complete the gas control.

[0012] Preferably, in step S1, the coal seam is scanned based on a laser scanning device, and the point cloud data includes coal seam terrain data and obstacle data. The acquired point cloud data is preprocessed and then a three-dimensional model is constructed. The specific steps of constructing the three-dimensional model from the point cloud data are:

[0013] Based on triangular meshing, the discrete point cloud is converted into a continuous triangular mesh model, and the object surface is estimated by Poisson surface reconstruction;

[0014] The model surface is smoothed based on bilateral filtering, and the hole filling algorithm is used to repair the holes;

[0015] The collected texture image is mapped to the surface of the 3D model to complete the 3D model construction.

[0016] Preferably, the basic formula for aerodynamic simulation in step S1 is:

[0017]

[0018] Where p is the air pressure, μ is the air dynamic viscosity, and f is the external force acting on the fluid. is the gradient operator, is the Laplace operator, v is the air velocity vector, t is the time, ρ is the air density, and the equations are solved based on the finite element method to obtain the velocity field v(x, t) and pressure field p(x, t) of the air in the coal seam, where x is the spatial coordinate;

[0019] The diffusion of gas in the air is described according to Fick's theorem, which is expressed as:

[0020]

[0021] Where C is the gas concentration, D is the diffusion coefficient of gas in the air, and combined with the velocity field v of the air flow, solving this equation can obtain the gas concentration field C(x, t).

[0022] Preferably, the gas discharge result evaluation step in step S1 is: defining an evaluation function J to measure the gas discharge effect, the expression is:

[0023] J = ∫ V w(x)[C0-C(x,t end )]dV

[0024] Where V is the volume of the simulation area, C0 is the initial gas concentration, and C(x,t end ) is the gas concentration at the end of the simulation, w(x) is the weight function used to highlight the gas discharge situation in the key area;

[0025] By traversing all possible combinations of equipment positions xi and working parameters pi, the evaluation function value J corresponding to each combination is calculated j , j = 1, 2, ..., m, m is the number of combinations, select the combination that maximizes J as the best solution:

[0026]

[0027] According to the simulation results, select the solution with the most recent output results, obtain the current solution, and actually build the gas treatment equipment.

[0028] Preferably, in step S2, qualified materials are selected according to the best results obtained from the simulation, a sealing wall is constructed according to the design requirements, and a position for a gas discharge pipe is reserved; debris and accumulated water are cleared before construction, the gas discharge pipe material is a high-strength corrosion-resistant material, and the diameter of the gas discharge pipe is determined according to the simulation results and the actual gas outflow.

[0029] Preferably, the step of adjusting the windshield installation in step S3 is:

[0030] Design and adjust fan specifications, prepare materials, conduct safety inspections on construction sites, and provide safety protection for personnel;

[0031] Based on the 3D simulation results, determine the installation position of the adjustable fan, clean the tunnel, fix the fan frame and seal it;

[0032] The installed regulating fans are subjected to quality inspection, including ventilation effect test and stability test. After the test is normal, they are put into use; thus, the atmospheric pressure in the goaf and adjacent areas of the upper coal seam working face is reduced.

[0033] Preferably, in step S4, the wind window is adjusted based on the ventilation resistance law, the ventilation resistance is increased in the return air system, the pressure is increased, dynamic regulation is performed based on sensors and controllers, and a pressure monitoring and early warning system is established for real-time monitoring and feedback.

[0034] Preferably, in step S6, the gas concentration is monitored in real time by a sensor, a gas sensor is installed at the gas discharge port and the dilution air flow mixing area, and the collected gas concentration data is processed and analyzed.

[0035] Preferably, in step S6, the intelligent selection of dilution gas is analyzed through an intelligent decision-making algorithm, and a multi-objective optimization algorithm is designed to comprehensively consider the dilution effect, cost and safety factors, and give priority to gases that can reduce the gas concentration to a safe range; compare the production and storage costs, and select low-cost gases while meeting safety requirements; evaluate the safety of the gas; and weigh the factors through an algorithm to determine the optimal dilution gas type and injection amount.

[0036] Preferably, the intelligent decision-making algorithm comprehensively considers dilution effect, cost and safety factors; gives priority to gases that can quickly reduce gas concentration to a safe range, evaluates different dilution gases, and determines the ability to dilute gas concentration;

[0037] Compare the production and storage costs of various gases, and select low-cost gases while meeting safety requirements; calculate the raw material costs, production process costs, and equipment and site costs required for the production of each dilution gas, and select low-cost gases;

[0038] The safety of each gas is analyzed, and the best type of dilution gas is determined by comprehensively weighing the dilution effect, cost and safety factors through a multi-objective optimization algorithm.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention constructs a three-dimensional model of the coal seam by utilizing laser scanning technology, intuitively presents the coal seam environment, simulates air flow and optimizes the layout of gas control equipment accordingly, thereby improving gas discharge efficiency, reducing control costs and time, avoiding blind installation of equipment, realizing reasonable allocation of resources, and ensuring that gas control work is carried out scientifically and efficiently. It will force the gas in the goaf of the lower coal seam working face to enter the goaf of the upper coal seam working face along the gas flow channel, thereby effectively preventing the gas in the goaf of the upper coal seam working face and the gas in the goaf of the lower coal seam working face from pouring into the workplace, and can effectively reduce gas accidents; moreover, it is low-cost, and only two adjusting wind windows need to be set, which is of practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram of the steps for gas mining and management of the present invention;

[0042] Figure 2 A flow chart of the steps of constructing a three-dimensional model from point cloud data of the present invention. DETAILED DESCRIPTION

[0043] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0044] Reference Figure 1 and Figure 2 As shown in the figure, the gas control method for close-range coal seam group mining based on atmospheric pressure control has the following control steps:

[0045] S1. Scan the mining coal seam environment based on laser scanning technology, obtain point cloud data, and construct a three-dimensional model of the coal seam. In the three-dimensional model, simulate the air flow in the current coal seam based on aerodynamics, set the gas control equipment at the required position based on the air flow, continuously simulate the gas discharge results, and select the best discharge result;

[0046] S2. Preliminary preparation: After the mining of the upper coal seam working face is completed, according to the best simulation results, a sealing wall is built in the air intake tunnel and the return air tunnel, and a gas discharge pipe is reserved;

[0047] S3. Pressure control of the upper coal seam: Install an adjustable wind window in the air intake system of the goaf area of ​​the upper coal seam working face. Adjust the wind window to reduce the atmospheric pressure of the return air system of the mining area, thereby driving down the atmospheric pressure of the goaf area of ​​the upper coal seam working face and the adjacent areas;

[0048] S4, lower coal seam pressure control, set an adjustable wind window in the return air system of the lower coal seam working face to increase the atmospheric pressure of the lower coal seam working face and the goaf;

[0049] S5, gas drainage and discharge: under the pressure difference formed in the goaf of the upper and lower coal seams, the gas in the goaf of the lower coal seam working face flows into the goaf of the upper coal seam working face, and is discharged through the gas discharge pipe of the closed wall of the goaf of the upper coal seam working face;

[0050] S6. Gas dilution and discharge. The discharged gas is diluted by fresh air flow to a safe concentration. The gas concentration is monitored in real time. For gas that has not reached a safe concentration, the gas concentration is calculated and the dilution gas is intelligently selected to be injected to reduce the gas concentration. The gas enters the mine return air system and is discharged to the ground to complete the gas control.

[0051] This application uses laser scanning technology to construct a three-dimensional model of the coal seam, which can intuitively present the coal seam environment, simulate air flow and optimize the layout of gas control equipment accordingly. This precise planning can improve the efficiency of gas discharge, reduce control costs and time, avoid blind installation of equipment, achieve reasonable allocation of resources, and ensure that gas control work is carried out scientifically and efficiently; by installing adjustable wind windows in the upper coal seam air intake system and the lower coal seam return air system, the pressure of the upper and lower coal seam goaf areas can be accurately controlled to form a stable pressure difference and guide the orderly flow of gas, which can effectively avoid gas accumulation, reduce the risk of gas explosions and suffocation accidents, and ensure the safety of underground workers and safe production in coal mines;

[0052] Gas is drained and discharged with the help of pressure difference and diluted with fresh air flow. Real-time monitoring and intelligent selection of dilution gas can ensure that the concentration of discharged gas is always within a safe range. Even if the gas outflow fluctuates, timely response can be made to prevent high-concentration gas leakage and reduce the probability of gas accidents. The entire process forms a complete gas management system. All links cooperate and operate in coordination. Preliminary preparations lay the foundation for subsequent work. Pressure regulation creates drainage conditions. Discharge and dilution ensure the safe discharge of gas. The system can adapt to different coal seam conditions and mining stages, achieve continuous and stable gas management, and ensure long-term safe production in coal mines.

[0053] In step S1, the coal seam is scanned based on the laser scanning equipment. The point cloud data includes the coal seam terrain data and obstacle data. The acquired point cloud data is preprocessed and then a three-dimensional model is constructed. The specific steps of constructing the three-dimensional model from the point cloud data are as follows:

[0054] Based on triangular meshing, the discrete point cloud is converted into a continuous triangular mesh model, and the object surface is estimated by Poisson surface reconstruction;

[0055] The model surface is smoothed based on bilateral filtering, and the hole filling algorithm is used to repair the holes;

[0056] The collected texture image is mapped to the surface of the 3D model to complete the 3D model construction.

[0057] This application uses laser scanning equipment to perform all-round scanning of coal seams, quickly and accurately obtains rich point cloud data, and performs preprocessing after obtaining the point cloud data. The preprocessing process aims to remove noise, outliers and redundant information in the data to improve data quality and lay a solid foundation for the subsequent construction of high-precision three-dimensional models. The discrete point cloud is converted into a continuous triangular mesh model based on triangular meshing technology, and the disordered point cloud data is organized into an ordered grid structure, so that the topological relationship between points can be clarified. In this way, the originally discrete point cloud data initially forms a model prototype with a certain shape and structure. On this basis, the Poisson surface reconstruction algorithm is used to further solve and estimate the object surface. The Poisson surface reconstruction algorithm is based on the Poisson equation. By analyzing and calculating the point cloud data, it can extract more accurate object surface information from the triangular mesh model, making the model closer to the real coal seam morphology and effectively improving the accuracy and completeness of the model. In order to make the constructed three-dimensional model smoother and more natural, the bilateral The filtering process performs a smoothing operation on the model surface. Bilateral filtering is a filtering algorithm that considers both spatial proximity and pixel value similarity. While smoothing the model surface, it can well preserve the edge and detail information of the model to avoid the loss of model features due to excessive smoothing. After the smoothing process is completed, there may still be some holes on the model surface due to data loss or other reasons. At this time, the hole filling algorithm is used to repair these holes. The hole filling algorithm analyzes the data information around the holes and uses a reasonable interpolation method to fill the holes, making the model surface more complete and continuous; the collected texture image is mapped to the three-dimensional model surface to complete the construction of the three-dimensional model. The texture image can add rich detail information to the three-dimensional model, such as the texture and color characteristics of the coal seam, making the constructed three-dimensional model more realistic and intuitive. By combining the texture image with the three-dimensional model, the staff can observe and analyze the actual situation of the coal seam more clearly and accurately, providing a more reliable basis for the subsequent layout planning of gas control equipment.

[0058] The basic formula for aerodynamic simulation in step S1 is:

[0059]

[0060] Where p is the air pressure, μ is the air dynamic viscosity, and f is the external force acting on the fluid. is the gradient operator, is the Laplace operator, v is the air velocity vector, t is the time, ρ is the air density, and the equations are solved based on the finite element method to obtain the velocity field v(x, t) and pressure field p(x, t) of the air in the coal seam, where x is the spatial coordinate;

[0061] The diffusion of gas in the air is described according to Fick's theorem, which is expressed as:

[0062]

[0063] Where C is the gas concentration, D is the diffusion coefficient of gas in the air, and combined with the velocity field v of the air flow, solving this equation can obtain the gas concentration field C(x, t).

[0064] The S1 step of this application utilizes the basic formulas of aerodynamic simulation and Fick's theorem, and uses the finite element method to solve the equations to obtain the velocity field, pressure field and gas concentration field of the air in the coal seam. This can not only accurately grasp the air flow characteristics, but also accurately predict the gas diffusion trend, providing a scientific basis for optimizing the gas control strategy, and ultimately ensuring the safe production of coal mines and reducing accident risks and losses.

[0065] The gas emission result evaluation step in step S1 is: define an evaluation function J to measure the gas emission effect, the expression is:

[0066] J = ∫ V w(x)[C0-C(x,t end )]dV

[0067] Where V is the volume of the simulation area, C0 is the initial gas concentration, and C(x,t end ) is the gas concentration at the end of the simulation, w(x) is the weight function used to highlight the gas discharge situation in the key area;

[0068] By traversing all possible combinations of equipment positions xi and working parameters pi, the evaluation function value J corresponding to each combination is calculated j , j = 1, 2, ..., m, m is the number of combinations, select the combination that maximizes J as the best solution:

[0069]

[0070] According to the simulation results, select the solution with the most recent output results, obtain the current solution, and actually build the gas treatment equipment.

[0071] This application measures the gas discharge effect by defining an evaluation function that includes the simulation area volume and gas concentration factors, traverses the equipment position and working parameter combinations to calculate the function value, selects the combination that maximizes the function value as the best solution, and selects the solution that is close to the effect based on the simulation results to guide the actual construction of gas control equipment.

[0072] In step S2, qualified materials are selected according to the best results obtained from the simulation, and the sealing wall is constructed according to the design requirements, and the location of the gas discharge pipe is reserved; debris and accumulated water are cleared in advance before construction, and the material of the gas discharge pipe is high-strength and corrosion-resistant material. The diameter of the gas discharge pipe is determined according to the simulation results and the actual gas outflow.

[0073] This application carries out construction based on the best simulation results, selects qualified materials to build sealing walls according to the design, reserves positions for gas discharge pipes, clears accumulated water before construction, and uses high-strength and corrosion-resistant materials for gas discharge pipes. The pipe diameter is determined based on the simulation results and actual gas outburst volume. These measures ensure the quality, efficiency, equipment life and cost control of gas control work from many aspects.

[0074] The steps for adjusting the windshield installation in step S3 are as follows:

[0075] Design and adjust fan specifications, prepare materials, conduct safety inspections on construction sites, and provide safety protection for personnel;

[0076] Based on the 3D simulation results, determine the installation position of the adjustable fan, clean the tunnel, fix the fan frame and seal it;

[0077] The installed regulating fans are subjected to quality inspection, including ventilation effect test and stability test. After the test is normal, they are put into use; thus, the atmospheric pressure in the goaf and adjacent areas of the upper coal seam working face is reduced.

[0078] This application designs and adjusts the specifications of the wind window, prepares materials, conducts safety inspections on the construction site, and provides safety protection for personnel before installation, which can effectively avoid safety hazards during the construction process. Standardized preparation work can ensure that the construction is carried out in an orderly manner, prevent delays and accidents caused by insufficient materials, inconsistent specifications, or inadequate safety measures, protect the lives of construction personnel, and improve construction efficiency; determining the installation position of the wind window according to the three-dimensional simulation results can make the wind window play the best role, and accurately positioning ensures that the wind window is installed in the most effective position for pressure regulation, and by changing the ventilation resistance, it can drive the upper coal seam working face goaf area As the atmospheric pressure in the adjacent area drops, precise regulation of the pressure in the goaf can be achieved, the ventilation system can be optimized, favorable conditions for gas drainage can be created, the risk of gas accumulation can be reduced, and safe production in coal mines can be ensured. Quality inspections are carried out on the installed regulating wind windows, including ventilation effect tests and stability tests. They are put into use only if the tests are normal. This link can promptly discover and solve problems that arise during the installation process, such as poor ventilation and unstable wind windows, to ensure that the regulating wind windows can operate normally and give full play to their due pressure regulation function, thereby extending the service life of the equipment, reducing the subsequent maintenance costs, and providing strong support for long-term and stable gas management work.

[0079] In step S4, the wind window is adjusted based on the ventilation resistance law, the ventilation resistance is increased in the return air system, the pressure is increased, dynamic regulation is performed based on sensors and controllers, and a pressure monitoring and early warning system is established for real-time monitoring and feedback.

[0080] This application adjusts the wind window based on the law of ventilation resistance. By increasing the ventilation resistance in the return air system, the atmospheric pressure of the lower coal seam working face and the goaf is increased. Dynamic regulation is achieved using sensors and controllers, and a pressure monitoring and early warning system is established to monitor and feedback the pressure in real time, so as to stabilize the pressure, accurately control, and issue early warnings in time to ensure safe production in coal mines.

[0081] In step S6, the gas concentration is monitored in real time by sensors, gas sensors are installed at the gas discharge port and the dilution air flow mixing area, and the collected gas concentration data are processed and analyzed.

[0082] This application installs gas sensors at the gas discharge port and the dilution airflow mixing area, which is a key measure to achieve accurate monitoring. The gas discharge port is a direct channel for gas discharge, and its gas concentration change directly reflects the gas outflow situation; the dilution airflow mixing area is the area where gas and fresh airflow are mixed. Monitoring the gas concentration here can determine whether the gas dilution effect meets the safety standard. The gas concentration data at these two locations are crucial for evaluating the gas control effect and ensuring safe production; the selected gas sensors have the characteristics of high sensitivity and high precision, and can quickly and accurately sense subtle changes in gas concentration. These sensors are carefully installed at the best monitoring points between the gas discharge port and the dilution airflow mixing area to ensure that representative gas concentration data can be collected comprehensively and timely. In order to ensure the stable operation of the sensors, they are also equipped with special protective devices to prevent them from being interfered with by the complex underground environment, such as dust, humid air, and mechanical collisions, thereby ensuring the reliability of the monitoring data.

[0083] In step S6, the intelligent selection of dilution gas is analyzed through an intelligent decision-making algorithm, and a multi-objective optimization algorithm is designed to comprehensively consider the dilution effect, cost and safety factors, and give priority to gases that can reduce the gas concentration to a safe range; compare the production and storage costs, and select low-cost gases while meeting safety requirements; evaluate the safety of the gas; and weigh factors through an algorithm to determine the optimal dilution gas type and injection amount.

[0084] This application intelligently selects dilution gas using an intelligent decision-making algorithm. By designing a multi-objective optimization algorithm, the dilution effect, cost and safety are comprehensively considered, and priority is given to gases that can reduce gas concentration to a safe range. Low-cost gases that meet safety requirements are selected by comparing costs, and gas safety is evaluated. The optimal dilution gas type and injection amount are determined through algorithmic weighing. This can ensure governance effects, optimize resource utilization, enhance safety, and achieve precise governance.

[0085] The intelligent decision-making algorithm comprehensively considers dilution effect, cost and safety factors; it gives priority to gases that can quickly reduce gas concentration to a safe range, evaluates different dilution gases, and determines the ability to dilute gas concentration;

[0086] Compare the production and storage costs of various gases, and select low-cost gases while meeting safety requirements; calculate the raw material costs, production process costs, and equipment and site costs required for the production of each dilution gas, and select low-cost gases;

[0087] The safety of each gas is analyzed, and the best type of dilution gas is determined by comprehensively weighing the dilution effect, cost and safety factors through a multi-objective optimization algorithm.

[0088] The intelligent decision-making algorithm of this application comprehensively considers the dilution effect, cost and safety, gives priority to gases that can quickly reduce gas concentration to a safe range, and evaluates their dilution capacity; compares the gas production and storage costs, calculates various expenses, and selects low-cost gases under the premise of safety; analyzes gas safety, weighs various factors through a multi-objective optimization algorithm, and determines the best type of dilution gas, which can ensure safety, reduce gas risks, save costs, improve efficiency, and achieve scientific trade-offs and optimal choices.

[0089] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A gas control method for close-range coal seam group mining based on atmospheric pressure control, characterized in that: The governance steps are: S1. Scan the mining coal seam environment based on laser scanning technology, obtain point cloud data, and construct a three-dimensional model of the coal seam. In the three-dimensional model, simulate the air flow in the current coal seam based on aerodynamics, set the gas control equipment at the required position based on the air flow, continuously simulate the gas discharge results, and select the best discharge result; S2. Preliminary preparation: After the mining of the upper coal seam working face is completed, according to the best simulation results, a sealing wall is built in the air intake tunnel and the return air tunnel, and a gas discharge pipe is reserved; S3. Pressure control of the upper coal seam: Install an adjustable wind window in the air intake system of the goaf area of ​​the upper coal seam working face. Adjust the wind window to reduce the atmospheric pressure of the return air system of the mining area, thereby driving down the atmospheric pressure of the goaf area of ​​the upper coal seam working face and the adjacent areas; S4, lower coal seam pressure control, set an adjustable wind window in the return air system of the lower coal seam working face to increase the atmospheric pressure of the lower coal seam working face and the goaf; S5, gas drainage and discharge: under the pressure difference formed in the goaf of the upper and lower coal seams, the gas in the goaf of the lower coal seam working face flows into the goaf of the upper coal seam working face, and is discharged through the gas discharge pipe of the closed wall of the goaf of the upper coal seam working face; S6. Gas dilution and discharge. The discharged gas is diluted by fresh air flow to a safe concentration. The gas concentration is monitored in real time. For gas that has not reached a safe concentration, the gas concentration is calculated and the dilution gas is intelligently selected to be injected to reduce the gas concentration. The gas enters the mine return air system and is discharged to the ground to complete the gas control.

2. The gas control method for close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: In step S1, the coal seam is scanned based on the laser scanning equipment. The point cloud data includes the coal seam terrain data and obstacle data. The acquired point cloud data is preprocessed and then a three-dimensional model is constructed. The specific steps of constructing the three-dimensional model from the point cloud data are as follows: Based on triangular meshing, the discrete point cloud is converted into a continuous triangular mesh model, and the object surface is estimated by Poisson surface reconstruction; The model surface is smoothed based on bilateral filtering, and the hole filling algorithm is used to repair the holes; The collected texture image is mapped to the surface of the 3D model to complete the 3D model construction.

3. The gas control method for close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: The basic formula for aerodynamic simulation in step S1 is: Where p is the air pressure, μ is the air dynamic viscosity, and f is the external force acting on the fluid. is the gradient operator, is the Laplace operator, v is the air velocity vector, t is the time, ρ is the air density, and the equations are solved based on the finite element method to obtain the velocity field v(x, t) and pressure field p(x, t) of the air in the coal seam, where x is the spatial coordinate; The diffusion of gas in the air is described according to Fick's theorem, which is expressed as: Where C is the gas concentration, D is the diffusion coefficient of gas in the air, and combined with the velocity field v of the air flow, solving this equation can obtain the gas concentration field C(x, t).

4. The gas control method for close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: The gas emission result evaluation step in step S1 is: define an evaluation function J to measure the gas emission effect, the expression is: Where V is the volume of the simulation area, C0 is the initial gas concentration, and C(x,t end ) is the gas concentration at the end of the simulation, w(x) is the weight function used to highlight the gas discharge situation in the key area; By traversing all possible combinations of equipment positions xi and working parameters pi, the evaluation function value J corresponding to each combination is calculated j , j = 1, 2, ..., m, m is the number of combinations, select the combination that maximizes J as the best solution: According to the simulation results, select the solution with the most recent output results, obtain the current solution, and actually build the gas treatment equipment.

5. The gas control method for close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: In step S2, qualified materials are selected according to the best results obtained from the simulation, and the sealing wall is constructed according to the design requirements, and the location of the gas discharge pipe is reserved; debris and accumulated water are cleared in advance before construction, and the material of the gas discharge pipe is high-strength and corrosion-resistant material. The diameter of the gas discharge pipe is determined according to the simulation results and the actual gas outflow.

6. The method for gas control in close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: The steps for adjusting the windshield installation in step S3 are as follows: Design and adjust fan specifications, prepare materials, conduct safety inspections on construction sites, and provide safety protection for personnel; Based on the 3D simulation results, determine the installation position of the adjustable fan, clean the tunnel, fix the fan frame and seal it; The installed regulating fans are subjected to quality inspection, including ventilation effect test and stability test. After the test is normal, they are put into use; thus, the atmospheric pressure in the goaf and adjacent areas of the upper coal seam working face is reduced.

7. The method for gas control in close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: In step S4, the wind window is adjusted based on the ventilation resistance law, the ventilation resistance is increased in the return air system, the pressure is increased, dynamic regulation is performed based on sensors and controllers, and a pressure monitoring and early warning system is established for real-time monitoring and feedback.

8. The method for gas control in close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: In step S6, the gas concentration is monitored in real time by sensors, gas sensors are installed at the gas discharge port and the dilution air flow mixing area, and the collected gas concentration data are processed and analyzed.

9. The method for gas control in close-range coal seam group mining based on atmospheric pressure control according to claim 1 is characterized in that: In step S6, the intelligent selection of dilution gas is analyzed through an intelligent decision-making algorithm, and a multi-objective optimization algorithm is designed to comprehensively consider the dilution effect, cost and safety factors, and give priority to gases that can reduce the gas concentration to a safe range; compare the production and storage costs, and select low-cost gases while meeting safety requirements; evaluate the safety of the gas; and weigh factors through an algorithm to determine the optimal dilution gas type and injection amount.

10. The method for gas control in close-range coal seam group mining based on atmospheric pressure control according to claim 9, characterized in that: The intelligent decision-making algorithm comprehensively considers dilution effect, cost and safety factors; it gives priority to gases that can quickly reduce gas concentration to a safe range, evaluates different dilution gases, and determines the ability to dilute gas concentration; Compare the production and storage costs of various gases, and select low-cost gases while meeting safety requirements; calculate the raw material costs, production process costs, and equipment and site costs required for the production of each dilution gas, and select low-cost gases; The safety of each gas is analyzed, and the best type of dilution gas is determined by comprehensively weighing the dilution effect, cost and safety factors through a multi-objective optimization algorithm.

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