A method for ground fracturing regulation and control of top coal of intelligent fully-mechanized top coal caving face with ten million tons

Abstract

The application discloses a kind of ten million tons intelligent fully mechanized working face top coal ground fracturing regulation methods, applied to coal mine well mining technical field. Including the following steps: analysis coal seam and the initial state of top coal, establish the relationship between coal seam pressure capacity and pressure;Coal seam and coal flow dynamic model, build the differential relationship of coal flow dynamics;Establish the optimization model of top coal rate, optimize intelligent top coal strategy;Implement ground fracturing technology, establish the model of ground fracturing pressure change;Real-time monitoring and adjusting top coal pressure, establish the coupling model of top coal stress and top coal rate;Intelligent regulation system feedback and adjustment, establish feedback regulation control model;In the process of coal flow and top coal pressure regulation, establish the coupling relationship of coal flow and top coal;The effectiveness of the model is verified by numerical simulation, and the parameters are adjusted according to the actual situation, finally realize the comprehensive regulation and optimization of coal flow and top coal.

Description

Technical Field

[0001] This invention relates to the field of coal mine mining technology, specifically to a method for controlling surface fracturing of top coal in a 10-million-ton intelligent fully mechanized longwall mining face. Background Technology

[0002] The mining of extra-thick coal seams is the main channel for ensuring coal supply. In extra-thick coal seam production bases, large-scale intelligent fully mechanized longwall mining has resulted in several mines with a capacity of tens of millions of tons. In these mines, the working face output can reach tens of millions of tons. However, due to incomplete coal flow balance and roof coal pressure, the recovery rate is low, resulting in significant coal resource losses. Therefore, in extra-thick coal seam production bases with a capacity of tens of millions of tons, coal flow balance and roof coal pressure are the main problems hindering working face production. Solving the problem of roof coal control and caving in intelligent fully mechanized longwall mining faces with a capacity of tens of millions of tons has become a key challenge in the mining of extra-thick coal seams.

[0003] Coal flow balance and top coal pressure regulation are key technical challenges in achieving efficient coal recovery in intelligent longwall mining faces with a capacity of tens of millions of tons. Surface fracturing to regulate coal flow balance and top coal pressure offers the advantage of being unrestricted by underground mining conditions, enabling real-time regulation of the top coal in intelligent longwall mining faces and optimizing the spatiotemporal system of top coal regulation. Based on the characteristics and stress distribution of the coal seam, surface fracturing forces intervene in the top coal descent, using intelligent decision-making to regulate top coal recovery through surface fracturing, increasing the top coal recovery rate, reducing coal loss, ensuring safe, efficient, and intelligent mining of the coal seam, and solving the key problem of top coal recovery in intelligent longwall mining faces with a capacity of tens of millions of tons. Therefore, providing a surface fracturing regulation method for the top coal in intelligent longwall mining faces with a capacity of tens of millions of tons is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a method for controlling the surface fracturing of top coal in a 10-million-ton intelligent fully mechanized longwall mining face, which solves the problem of intelligent control between coal flow balance and top coal pressure in the prior art, ensures coal extraction rate, and realizes safe, efficient and intelligent mining of coal seams.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for surface fracturing control of top coal in a 10-million-ton intelligent fully mechanized longwall mining face includes the following steps:

[0007] S1. Analyze the initial state of the coal seam and top coal, and establish the relationship between the coal seam's pressure-bearing capacity and pressure.

[0008] The pressure distribution within a coal seam varies with time and space; the spatiotemporal relationship of these pressure changes is as follows:

[0009]

[0010] In the formula, σ(x,t) is the pressure at position x, in MPa; α is the coal seam diffusion coefficient, in m³. 2 / s; t is time, in seconds; f is the external pressure source term, i.e., the pressure disturbance during the mining process, in MPa / s;

[0011] The initial conditions are:

[0012] σ(x,0)=σ0

[0013] The boundary conditions are:

[0014] σ(0,t)=σ boundary

[0015] In the formula, σ0 is the initial pressure of the coal seam, in MPa; σ boundary This represents the boundary pressure of the coal seam, in MPa.

[0016] S2. Dynamic model of coal seam and coal flow, constructing differential relationship of coal flow dynamics;

[0017] The differential relationship of coal flow dynamics is:

[0018]

[0019] In the formula, ρ(x,t) is the coal flow density at position x, with units of kg / m³. 3 v(x,t) represents the coal flow velocity at position x, in m / s; S is the source term, representing the generation and consumption of coal flow, in kg / m³. 3 ·s; The divergence operator represents the spatial variation of the coal flow; t is time, in seconds; the differential relation describes the mass conservation of the coal flow and the change of the coal flow distribution on the working face over time.

[0020] Assume that the coal flow velocity v(x,t) is related to the coal seam thickness and fracturing conditions:

[0021]

[0022] In the formula, Q is the total flow rate of coal, in m³. 3 / s; A(x) is the cross-sectional area of ​​the coal flow channel at position x, in meters. 2 ;

[0023] S3. Establish a coal discharge rate optimization model and optimize the intelligent coal discharge strategy;

[0024] Coal discharge is affected by coal flow dynamics and gangue removal. To ensure a balance between coal flow and gangue, the coal flow is regulated by controlling the coal discharge rate Q. The regulation process can be described by the following differential relationship:

[0025]

[0026] In the formula, Q 放煤 (t) represents the coal discharge rate at time t, in meters per second (m). 3 / s;Q 矸 (t) represents the flow rate of coal gangue, in m³ / s. 3 / s;Q 矸，max Maximum coal gangue flow rate, in m³. 3 / s;σ 矸 (t) is the stress factor of coal gangue; Q 原煤 (t) represents the raw coal flow rate, in m³. 3 / s;Q 原煤，max Maximum raw coal flow rate, in m³. 3 / s;σ 原煤 (t) is the stress factor of raw coal; β is the coal discharge adjustment coefficient, with the unit being 1 / s;

[0027] S4. Implement surface fracturing technology and establish a model of surface fracturing pressure changes;

[0028] Pressure changes during surface fracturing are described by the following cumulative relationship:

[0029]

[0030] In the formula, P 压裂 (t) represents the fracturing pressure at time t, in MPa; F 压裂 (t) represents the fracturing force at time t, in units of MN; A 压裂 The area of ​​the fracturing zone is expressed in meters (m²). 2 Pressure accumulates over time, which causes cracks in the coal seam, providing external force for intelligent coal release strategy decisions.

[0031] S5. Real-time monitoring and adjustment of top coal pressure, and establishment of a coupling model between top coal stress and coal discharge rate;

[0032] The stress distribution in the top coal seam is affected by the combined effects of the coal discharge rate Q and surface fracturing, and the relationship between these effects is described by the following differential equation:

[0033]

[0034] In the formula, σ top (x,t) represents the stress at position x during coal release, in MPa; α1 is the diffusion coefficient of top coal stress, in 1 / s; α2 is the influence coefficient of coal release rate on top coal stress, in MPa·s / m. 3 Q 放煤 (t) represents the coal discharge rate at time t, in meters per second (m). 3 / s;ftop External interference term, unit is MPa / s; The Laplace operator represents the change in stress distribution. By adjusting the top coal stress in real time through changes in time and space, the release of top coal is not affected by changes in external stress.

[0035] S6. Intelligent control system feedback and adjustment, establishing a feedback regulation and control model;

[0036] The intelligent control system adjusts the coal discharge and fracturing strategies in real time through an integral feedback mechanism to maintain the balance between coal flow and top coal stress. The feedback regulation relationship is as follows:

[0037]

[0038] In the formula, ΔP adjust The adjusted pressure change is expressed in MPa; K feedback This is the feedback gain coefficient; This is the time derivative of the top coal pressure change, expressed in MPa / s. Through the system's feedback mechanism, the coal discharge rate and fracturing pressure are adjusted to ensure the balance of top coal stress.

[0039] S7. During the process of regulating coal flow and top coal pressure, establish the coupling relationship between coal flow and top coal.

[0040] During the regulation of coal flow and top coal pressure, the coupling relationship between coal flow and top coal is as follows:

[0041]

[0042] In the formula, F 煤流 F represents the force on the coal flow at time t, expressed in N. 顶煤 The force on the top coal at time t, in N; A 煤流 The area of ​​the coal flow subjected to force is expressed in m². 2 A 顶煤 The area of ​​the top coal under stress is expressed in m². 2 T represents the calculation time in seconds, which adjusts the balance between the coal flow and the stress on the top coal to optimize the coal flow and the top coal.

[0043] S8. Verify the effectiveness of the model through numerical simulation and adjust the parameters according to the actual situation.

[0044] As can be seen from the above technical solution, compared with the prior art, the present invention provides a method for surface fracturing control of top coal in a 10-million-ton intelligent fully mechanized longwall mining face, which has the following beneficial effects: The present invention establishes the differential relationship between the coal seam's pressure-bearing capacity and pressure distribution by analyzing the initial state of the coal seam and top coal; constructs a dynamic model of the coal seam and coal flow, and establishes the differential relationship of coal flow dynamics; optimizes the intelligent coal release strategy; constructs a surface fracturing technology to control the top coal pressure, and establishes a coupling model of top coal stress and coal release rate; adjusts the coal release and fracturing strategies according to the feedback mechanism of the intelligent control system; and finally achieves comprehensive control and optimization of coal flow and top coal, ensuring the coal recovery rate and realizing safe, efficient and intelligent mining of the coal seam. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0046] Figure 1 This is a flowchart of the top coal surface fracturing control method for a 10-million-ton intelligent fully mechanized longwall mining face according to the present invention. Detailed Implementation

[0047] 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.

[0048] This invention discloses a method for controlling surface fracturing of top coal in a 10-million-ton intelligent fully mechanized longwall mining face, such as... Figure 1 As shown, it includes the following steps:

[0049] S1. Analyze the initial state of the coal seam and top coal, and establish the relationship between the coal seam's pressure-bearing capacity and pressure.

[0050] The pressure distribution within a coal seam varies with time and space; the spatiotemporal relationship of these pressure changes is as follows:

[0051]

[0052] In the formula, σ(x,t) is the pressure at position x, in MPa; α is the coal seam diffusion coefficient, in m³. 2 / s; t is time, in seconds; f is the external pressure source term, i.e., the pressure disturbance during the mining process, in MPa / s;

[0053] The initial conditions are:

[0054] σ(x,0)=σ0

[0055] The boundary conditions are:

[0056] σ(0,t)=σ boundary

[0057] In the formula, σ0 is the initial pressure of the coal seam, in MPa; σ boundary This represents the boundary pressure of the coal seam, in MPa.

[0058] S2. Dynamic model of coal seam and coal flow, constructing differential relationship of coal flow dynamics;

[0059] The differential relationship of coal flow dynamics is:

[0060]

[0061] In the formula, ρ(x,t) is the coal flow density at position x, with units of kg / m³. 3 v(x,t) represents the coal flow velocity at position x, in m / s; S is the source term, representing the generation and consumption of coal flow, in kg / m³. 3 ·s; The divergence operator represents the spatial variation of the coal flow; t is time, in seconds; the differential relation describes the mass conservation of the coal flow and the change of the coal flow distribution on the working face over time.

[0062] Assume that the coal flow velocity v(x,t) is related to the coal seam thickness and fracturing conditions:

[0063]

[0064] In the formula, Q is the total flow rate of coal, in m³. 3 / s; A(x) is the cross-sectional area of ​​the coal flow channel at position x, in meters. 2 ;

[0065] S3. Establish a coal discharge rate optimization model and optimize the intelligent coal discharge strategy;

[0066] Coal discharge is affected by coal flow dynamics and gangue removal. To ensure a balance between coal flow and gangue, the coal flow is regulated by controlling the coal discharge rate Q. The regulation process can be described by the following differential relationship:

[0067]

[0068] In the formula, Q 放煤 (t) represents the coal discharge rate at time t, in meters per second (m). 3 / s;Q 矸(t) represents the flow rate of coal gangue, in m³ / s. 3 / s;Q 矸，max Maximum coal gangue flow rate, in m³. 3 / s;σ 矸 (t) is the stress factor of coal gangue; Q 原煤 (t) represents the raw coal flow rate, in m³. 3 / s;Q 原煤，max Maximum raw coal flow rate, in m³. 3 / s;σ 原煤 (t) is the stress factor of raw coal; β is the coal discharge adjustment coefficient, with the unit being 1 / s;

[0069] S4. Implement surface fracturing technology and establish a model of surface fracturing pressure changes;

[0070] Pressure changes during surface fracturing are described by the following cumulative relationship:

[0071]

[0072] In the formula, P 压裂 (t) represents the fracturing pressure at time t, in MPa; F 压裂 (t) represents the fracturing force at time t, in units of MN; A 压裂 The area of ​​the fracturing zone is expressed in meters (m²). 2 Pressure accumulates over time, which causes cracks in the coal seam, providing external force for intelligent coal release strategy decisions.

[0073] S5. Real-time monitoring and adjustment of top coal pressure, and establishment of a coupling model between top coal stress and coal discharge rate;

[0074] The stress distribution in the top coal seam is affected by the combined effects of the coal discharge rate Q and surface fracturing, and the relationship between these effects is described by the following differential equation:

[0075]

[0076] In the formula, σ top (x,t) represents the stress at position x during coal release, in MPa; α1 is the diffusion coefficient of top coal stress, in 1 / s; α2 is the influence coefficient of coal release rate on top coal stress, in MPa·s / m. 3 Q 放煤 (t) represents the coal discharge rate at time t, in meters per second (m). 3 / s;f top External interference term, unit is MPa / s; The Laplace operator represents the change in stress distribution. By adjusting the top coal stress in real time through changes in time and space, the release of top coal is not affected by changes in external stress.

[0077] S6. Intelligent control system feedback and adjustment, establishing a feedback regulation and control model;

[0078] The intelligent control system adjusts the coal discharge and fracturing strategies in real time through an integral feedback mechanism to maintain the balance between coal flow and top coal stress. The feedback regulation relationship is as follows:

[0079]

[0080] In the formula, ΔP adjust The adjusted pressure change is expressed in MPa; K feedback This is the feedback gain coefficient; This is the time derivative of the top coal pressure change, expressed in MPa / s. Through the system's feedback mechanism, the coal discharge rate and fracturing pressure are adjusted to ensure the balance of top coal stress.

[0081] S7. During the process of regulating coal flow and top coal pressure, establish the coupling relationship between coal flow and top coal.

[0082] During the regulation of coal flow and top coal pressure, the coupling relationship between coal flow and top coal is as follows:

[0083]

[0084] In the formula, F 煤流 F represents the force on the coal flow at time t, expressed in N. 顶煤 The force on the top coal at time t, in N; A 煤流 The area of ​​the coal flow subjected to force is expressed in m². 2 A 顶煤 The area of ​​the top coal under stress is expressed in m². 2 T represents the calculation time in seconds, which adjusts the balance between the coal flow and the stress on the top coal to optimize the coal flow and the top coal.

[0085] S8. Verify the effectiveness of the model through numerical simulation and adjust the parameters according to the actual situation.

[0086] Furthermore, in one embodiment of the present invention, a 10-million-ton intelligent fully mechanized longwall face in a certain mining area is taken as an example. The main coal seam of this mine is an extra-thick coal seam with a thickness of 10m, a hardness of 0.7, and a coal gangue density of 1800kg / m³. 3 To improve coal mining efficiency and increase coal recovery rate, intelligent coal discharge and surface fracturing technology are used to regulate coal flow and top coal pressure. The steps are as follows:

[0087] S1. Analyze the initial state of the coal seam and top coal to establish the relationship between the coal seam's bearing capacity and pressure. In this embodiment, the coal seam thickness H = 10m, the coal seam hardness μ = 0.7, and the coal gangue density ρ... c=1800kg / m 3 The initial pressure of the coal seam is σ0 = 5 MPa, and the boundary pressure of the coal seam is σ boundary =5MPa; Coal seam diffusion coefficient α = 0.5m 2 / s; External pressure source term f = 1000MPa / s.

[0088] S2. A dynamic model of the coal seam and coal flow is established to construct the differential relationship of coal flow dynamics. In this embodiment, the source term S = 0; the coal flow rate Q = 30 m³ / s. 3 / s; Cross-sectional area of ​​coal flow channel A(x) = 20m 2 Therefore, the coal flow velocity is calculated as follows:

[0089]

[0090] S3. Establish a coal discharge rate optimization model and optimize the intelligent coal discharge strategy. In this embodiment, the coal gangue flow rate Q 矸 (t)=5m 3 / s; Maximum coal gangue flow rate Q 矸，max =8m 3 / s; Stress factor σ of coal gangue 矸 (t) = 0.1; Raw coal flow rate Q 原煤 (t)=25m 3 / s; Maximum raw coal flow rate Q 原煤，max =35m 3 / s; Stress factor σ of raw coal 原煤 (t) = 0.05; Coal discharge adjustment coefficient β = 0.21 / s; Substituting the above parameters into the equations, we obtain the change in coal discharge rate:

[0091]

[0092] The change in coal discharge rate was found to be 0.04 m. 3 / s 2 Therefore, it is necessary to gradually increase the coal discharge rate to balance the flow difference between coal gangue and raw coal.

[0093] S4. Implement surface fracturing technology and establish a model of surface fracturing pressure changes; in this embodiment, the fracturing force F 压裂 (t) = 50MN; fracturing zone area A 压裂 =100m 2 Therefore, the fracturing pressure at time t is:

[0094]

[0095] The fracturing pressure is then:

[0096]

[0097] Therefore, the fracturing pressure for top coal control was determined.

[0098] S5. Real-time monitoring and adjustment of top coal pressure, establishing a coupled model of top coal stress and coal release rate; in this embodiment, the top coal stress σ top (x,t)=4MPa, the diffusion coefficient of top coal stress α1=0.51 / s, and the influence coefficient of coal release rate on top coal stress α2=0.1MPa·s / m 3 External interference term f top =0 MPa / s, thus obtaining the change in top coal stress.

[0099] S6. Intelligent control system feedback and adjustment, establishing a feedback regulation and control model; in this embodiment, the feedback gain coefficient K feedback =1.5, the time derivative of the top coal pressure change The adjusted pressure change is as follows:

[0100] ΔP adjust =1.5 × 0.2 = 0.3 MPa

[0101] By adjusting the system feedback, the stress of the top coal increases by 0.3 MPa, which can ensure the control of the top coal.

[0102] S7. During the process of regulating coal flow and top coal pressure, a coupling relationship between coal flow and top coal is established. In this embodiment, at time T = 10s, the coal flow is subjected to force F. 煤流 =3000N, coal flow area A 煤流 =20m 2 The top coal is subjected to force F 顶煤 =3750N, top coal bearing area A 顶煤 =25m 2 This aligns with the coupling relationship between coal flow and top coal:

[0103]

[0104] S8. Verify the effectiveness of the model through numerical simulation and adjust the parameters according to the actual situation. The numerical model yields the distribution of coal flow. Differential relationships are used to simulate the coal flow at the working face. Given the known coal flow velocity and density, the spatial distribution of the coal flow is obtained.

[0105]

[0106] Simulation results show that the coal flow is relatively uniformly distributed at the working face, and the coal flow density and velocity remain within a certain range.

[0107] The fracturing process on the ground was simulated using cumulative relationships, and the change of fracturing pressure over time was obtained:

[0108]

[0109] By accumulating numerical data, the change in fracturing pressure over time is obtained, ensuring that the fracturing pressure is not too high and avoiding excessive impact on the top coal.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0111] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for surface fracturing control of top coal in a 10-million-ton intelligent fully mechanized longwall mining face, characterized in that, Includes the following steps: S1. Analyze the initial state of the coal seam and top coal, and establish the relationship between the coal seam's pressure-bearing capacity and pressure. The pressure distribution within a coal seam varies with time and space, and the spatiotemporal relationship of these pressure changes is as follows: In the formula, For position x The pressure at the point is expressed in MPa. This is the coal seam diffusion coefficient, in meters. 2 / s; t Time, in seconds; f This refers to external pressure sources, i.e., pressure disturbances during the mining process, expressed in MPa / s. The initial conditions are: The boundary conditions are: In the formula, This represents the initial pressure of the coal seam, in MPa. This represents the boundary pressure of the coal seam, in MPa. S2. Dynamic model of coal seam and coal flow, constructing differential relationship of coal flow dynamics; The differential relationship of coal flow dynamics is: In the formula, For position x The coal flow density at the location is expressed in kg / m³. 3 ; For position x The coal flow velocity at the location, expressed in m / s; The source term represents the generation and consumption of coal flow, with units of kg / m³. 3 ·s; The divergence operator represents the spatial variation of the coal flow; t Time, in seconds; Differential relations describe the mass conservation of coal flow and the change of coal flow distribution on the working face over time; Assuming coal flow velocity It is related to the thickness of the coal seam and the fracturing conditions: In the formula, The total flow rate of coal is expressed in cubic meters (m³). 3 / s; For position x The cross-sectional area of ​​the coal flow channel at the location is expressed in m². 2 ; S3. Establish a coal discharge rate optimization model and optimize the intelligent coal discharge strategy; Coal discharge is affected by coal flow dynamics and gangue removal. To ensure a balance between coal flow and gangue, the coal discharge rate is controlled. To regulate coal flow, the regulation process is described by the following differential relationship: In the formula, For time t The coal feeding rate at that time, in meters. 3 / s; This refers to the flow rate of coal gangue, in cubic meters per second (m³). 3 / s; Maximum coal gangue flow rate, in m³. 3 / s; The stress factor of coal gangue; This represents the flow rate of raw coal, in meters (m³). 3 / s; Maximum raw coal flow rate, in m³. 3 / s; The stress factor of raw coal; β This is the coal discharge adjustment coefficient, with units of 1 / s; S4. Implement surface fracturing technology and establish a model of surface fracturing pressure changes; Pressure changes during surface fracturing are described by the following cumulative relationship: In the formula, For time t The fracturing pressure at that time, expressed in MPa; For time t The fracturing force at that time, expressed in MN; The area of ​​the fracturing zone is expressed in meters (m²). 2 Pressure accumulates over time, which causes cracks in the coal seam, providing external force for intelligent coal release strategy decisions. S5. Real-time monitoring and adjustment of top coal pressure, and establishment of a coupling model between top coal stress and coal discharge rate; The stress distribution of top coal is affected by the coal release rate. The combined action of fracturing and surface fracturing is described by the following differential relationship: In the formula, To place coal in position x The stress at the point is expressed in MPa. is the diffusion coefficient of top coal stress, with units of 1 / s; The coefficient representing the influence of coal discharge rate on top coal stress is expressed in MPa·s / m. 3 ; For time t The coal feeding rate at that time, in meters. 3 / s; External interference term, unit is MPa / s; The Laplace operator represents the change in stress distribution. By adjusting the top coal stress in real time through changes in time and space, the release of top coal is not affected by changes in external stress. S6. Intelligent control system feedback and adjustment, establishing a feedback regulation and control model; The intelligent control system adjusts the coal discharge and fracturing strategies in real time through an integral feedback mechanism to maintain the balance between coal flow and top coal stress. The feedback regulation relationship is as follows: In the formula, The adjusted pressure change is expressed in MPa. This is the feedback gain coefficient; This is the time derivative of the top coal pressure change, expressed in MPa / s. Through the system's feedback mechanism, the coal discharge rate and fracturing pressure are adjusted to ensure the balance of top coal stress. S7. During the process of regulating coal flow and top coal pressure, establish the coupling relationship between coal flow and top coal. During the regulation of coal flow and top coal pressure, the coupling relationship between coal flow and top coal is as follows: In the formula, For time t The force on the coal flow at that time is expressed in N; For time t The stress on the top coal at that time, expressed in N; The area of ​​the coal flow subjected to force is expressed in m². 2 ; The area of ​​the top coal under stress is expressed in m². 2 ; T The calculation time is expressed in seconds, and the balance between the coal flow and the stress on the top coal is adjusted to optimize the coal flow and the top coal. S8. Verify the effectiveness of the model through numerical simulation and adjust the parameters according to the actual situation.

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