A method for preventing and controlling outburst in working face based on mining mode

Abstract

The present invention provides a method for preventing and controlling working face outbursts based on mining modes, comprising the following steps: S1, defining the three-dimensional stress of the coal rock mass; S2, classifying and dividing the stress loading and unloading paths of the working face coal rock mass under the mining mode according to the loading and / or unloading modes of the coal rock mass under the three-dimensional stress; S3, during the coal mining process, setting the excavation rate and / or controlling the corresponding stress magnitude according to the type of stress loading and unloading path occurring in the coal rock mass of different working faces. The method for preventing and controlling working face outbursts described in the present invention classifies mining modes according to different stress loading and unloading paths, can accurately describe and predict the mechanical behavior of the coal body under different mining conditions, and accurately assess the destructive strength and gas outburst risk of the coal body; and adopts differentiated excavation rates for different mining modes, can adjust the excavation rate according to the actual mechanical state of the coal body, and significantly reduce the risk of coal and gas outbursts.

Description

Technical Field

[0001] The present invention relates to the technical field of coal and gas outburst prevention and control, and relates to a method for preventing and controlling the danger of outburst in an underground coal mine excavation working face, and in particular to a method for preventing and controlling outburst in a working face based on a mining mode. Background Art

[0002] Research has shown that the key to the incubation and initiation of a coal outburst lies in the timely exposure of the coal body. Due to mining disturbance, the coal body ahead of the working face is inevitably subjected to concentrated stress before being exposed. As stress progresses and transient equilibrium occurs, residual stress induces persistent damage and instability. Therefore, a coal and gas outburst accident occurs when, following artificial mining disturbance, the three-dimensional stresses in the stratum redistribute, causing deformation and damage to the coal body. This process is accompanied by the desorption and migration of gas within the coal seam, which, after being incubated under certain conditions, triggers an outburst. The initiation of coal damage and instability by ground stress under mining is a necessary condition for the occurrence of an outburst, and the degree of coal damage and instability plays a key role in the distribution of outburst intensity. Therefore, the key to outburst prevention and control is to implement measures to hinder the development of key stages of the outburst incubation process through human intervention, targeting the mechanical conditions met at different stages of the coal damage and instability process. Studies have also shown that whether a coal body under dynamic load will become unstable and fail is not only affected by the load size but also closely related to the stress change path. When carrying out outburst prevention work, the stress state of the coal seam, the mining rate and method should also be considered. Therefore, it is urgent to provide a method for preventing outbursts in the excavation working face to fill the gap in existing technology. Summary of the Invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for preventing and controlling a working face outburst based on a mining mode, which specifically includes the following technical solutions:

[0004] A method for preventing and controlling outbursts in a working face based on a mining mode comprises the following steps:

[0005] S1, defines the three-dimensional stress of coal rock mass, that is, the stress in the direction of coal seam strike is the minimum principal stress, the stress perpendicular to the coal seam strike in the horizontal plane is the intermediate principal stress, and the stress perpendicular to the coal seam strike in the vertical plane is the maximum principal stress;

[0006] S2, classify the stress loading and unloading paths of the coal and rock mass in the working face under the mining mode according to the loading and / or unloading mode of the coal and rock mass under three-dimensional stress;

[0007] S3, during the coal mining process, the excavation rate is set and / or the corresponding stress magnitude is controlled according to the stress loading and unloading path type occurring in the coal and rock masses at different working faces.

[0008] Furthermore, in step S2, the stress loading and unloading paths of the coal and rock mass of the working face under the mining mode are divided into the following four types:

[0009] Stress path I: unidirectional progressive unloading mode with constant pressure of the intermediate principal stress, that is, the minimum principal stress is progressively unloaded, the maximum principal stress is progressively loaded, and the intermediate principal stress remains constant;

[0010] Stress path II: bidirectional progressive unloading mode, i.e., progressive loading of the maximum principal stress and progressive unloading of the intermediate principal stress and the minimum principal stress;

[0011] Stress path III: Bidirectional progressive loading, minimum principal stress sudden unloading mode, that is, the maximum principal stress and intermediate principal stress are progressively loaded, and the minimum principal stress is suddenly unloaded;

[0012] Stress path IV: bidirectional loading with the minimum principal stress kept constant, and unidirectional servo mode, i.e., the maximum principal stress and the intermediate principal stress are progressively loaded, and the minimum principal stress is kept constant.

[0013] Furthermore, for stress path I, the working face excavation rate is calculated using the following formula:

[0014]

[0015] Where, is the working face excavation rate of stress path I, mm / s; is the peak compressive strength of the stress path, MPa.

[0016] Furthermore, for stress path II, the working face excavation rate is calculated using the following formula:

[0017]

[0018] Where, is the working face excavation rate of stress path II, mm / s; is the peak compressive strength of stress path II, MPa.

[0019] Furthermore, for stress path III, the minimum stress to which the coal and rock mass at the working face can be unloaded is calculated using the following formula:

[0020]

[0021] Where, is the minimum stress to which the coal and rock mass at the working face can be unloaded, MPa; is the peak compressive strength of stress path III, MPa.

[0022] Furthermore, for stress path IV, the minimum servo stress of the coal and rock mass at the working face is calculated using the following formula:

[0023]

[0024] Where, is the minimum servo stress of coal and rock mass at the working face, MPa; is the peak compressive strength of stress path IV, MPa.

[0025] Furthermore, the peak compressive strength correction factor of the stress path is set to 0.8.

[0026] Furthermore, corresponding stress loading and unloading path types are set for different coal mining working faces, specifically:

[0027] The stress loading and unloading path type of the coal mining face is stress path I;

[0028] The stress loading and unloading path type of the coal roadway excavation working face is stress path II;

[0029] The stress loading and unloading path type of the Shimen coal uncovering working face is stress path III;

[0030] The stress loading and unloading path type for preventing coal wall disasters at the coal roadway excavation working face is stress path IV.

[0031] Based on the above technical solution, the present invention has the following beneficial effects:

[0032] 1. The method for preventing and controlling working face outbursts described in the present invention classifies mining modes according to four different stress loading and unloading paths. This scientific and refined classification method can accurately describe and predict the mechanical behavior of coal bodies under different mining conditions, thereby more accurately assessing the destructive strength of the coal bodies and the risk of gas outbursts.

[0033] 2. The method for preventing and controlling coal and gas outbursts in the working face described in the present invention adopts differentiated excavation rates for different mining modes, and can adjust the excavation rate according to the actual mechanical state of the coal body, significantly reducing the risk of coal and gas outbursts and improving the safety and efficiency of the excavation process.

[0034] 3. The method for preventing and controlling gas outbursts on working faces recorded in the present invention adopts differentiated gas control measures for different mining modes, effectively improving the effectiveness of gas outburst prevention measures and the efficiency of working face excavation. It is a precise control of disaster prevention and control based on source, intensity, time and space, and realizes the concept of source-based identification of gas outbursts. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : Schematic diagram of the working face protrusion prevention method described in the present invention;

[0036] Figure 2 : Schematic diagram of mechanical loading and unloading stress path I during coal-rock outburst process during mining;

[0037] Figure 3 : Schematic diagram of mechanical loading and unloading stress path II during coal and rock outburst process during mining;

[0038] Figure 4 :Schematic diagram of mechanical loading and unloading stress path III during coal and rock outburst process during mining;

[0039] Figure 5 : Schematic diagram of mechanical loading and unloading stress path IV during coal and rock outburst process during mining; DETAILED DESCRIPTION

[0040] It should be noted that:

[0041] 1. Certain terms are used in this specification and claims to refer to specific components. Those skilled in the art will understand that they may use different terms to refer to the same component. Therefore, this specification and claims do not distinguish components based on differences in terms, but rather on differences in their functions. Unless otherwise defined, technical or scientific terms used in this disclosure shall have the ordinary meanings understood by persons of ordinary skill in the art to which this disclosure pertains.

[0042] 2. Mining mode refers to the laws and patterns of stress changes, deformation and destruction of coal rock mass and strata caused by mining activities during the coal mining process.

[0043] 3. Three-dimensional stress refers to the principal stresses on the coal rock mass in the X-axis, Y-axis, and Z-axis directions. The X-axis direction refers to the direction of the coal seam, the Y-axis direction refers to the direction perpendicular to the direction of the coal seam in the horizontal plane, and the Z-axis direction refers to the direction perpendicular to the direction of the coal seam in the vertical plane. is the maximum principal stress, indicating the force on the coal rock mass in the Z-axis direction; is the intermediate principal stress, which represents the force on the coal rock mass in the Y-axis direction; is the minimum principal stress, which represents the force on the coal rock mass in the X-axis direction.

[0044] The following is combined with Figure 1 To the attached Figure 5 , the present invention is described in detail by way of embodiments.

[0045] A method for preventing and controlling outbursts in a working face based on a mining mode comprises the following steps:

[0046] During S1 coal mining, outbursts are accompanied by sudden or gradual loading and unloading of the coal and rock mass under triaxial forces. The loading and unloading directions and rates of the coal and rock mass during this process are complex and variable, and each one is completely different. To accurately describe and predict the mechanical behavior of coal and rock mass under different mining conditions, the stress loading and unloading paths of coal and rock mass under mining modes are classified as follows based on the loading and / or unloading patterns of the in-situ stress, i.e., the principal stresses to which the coal and rock mass is subjected in the X, Y, and Z directions:

[0047] Stress path I is a unidirectional progressive unloading mode in which the intermediate principal stress maintains a constant pressure. That is, in stress path I, Gradual uninstallation, progressive loading, Keep constant;

[0048] Stress path II is a bidirectional progressive unloading mode, that is, in stress path II, progressive loading, and Gradual uninstallation;

[0049] Stress path III is a bidirectional progressive loading and minimum principal stress sudden unloading mode, that is, in stress path III, and progressive loading, Uninstall suddenly;

[0050] Stress path IV is a bidirectional loading with a constant minimum principal stress and a unidirectional servo mode, that is, in stress path IV, and progressive loading, Keep it constant.

[0051] S2. To improve the safety and efficiency of the excavation process, different excavation rates and / or corresponding stress magnitudes are set according to the stress loading and unloading path types occurring in the coal and rock mass at the working face during the excavation process. This can effectively reduce the risk of coal and gas outbursts in the coal and rock mass, and improve the safety and efficiency of the excavation process. Specifically, the following calculation method is included:

[0052] S201, for stress path I, the working face advancement rate is calculated using the following formula:

[0053]

[0054] S202, for stress path II, calculate the working face advancement rate using the following formula:

[0055]

[0056] S203, for stress path III, calculate the minimum stress to which the coal and rock mass at the working face can be unloaded using the following formula:

[0057]

[0058] S204, for stress path IV, calculate the minimum servo stress of the coal and rock mass at the working face using the following formula:

[0059]

[0060] In the above formula:

[0061] are the working face advancement rates of stress path I and stress path II, mm / s;

[0062] is the minimum stress to which the coal and rock mass at the working face can be unloaded, MPa;

[0063] is the minimum servo stress of coal and rock mass at the working face, MPa;

[0064] - are the peak compressive strengths of stress path I to stress path IV, MPa.

[0065] The calculation method of peak compressive strength is briefly described as follows:

[0066] The original triaxial stresses of the coal body in front of the working face under different stress paths were measured. Based on the original triaxial stresses, triaxial compressive tests of coal samples were carried out in the laboratory in accordance with GB / T 23561.9-2009 “Methods for determination of physical and mechanical properties of coal and rock” to determine the peak compressive strength of the coal samples. The peak compressive strength of the coal samples measured in the experiment can be used to replace the peak compressive strength during the excavation process.

[0067] In step S3, in order to ensure that the coal and rock mass at the working face does not exceed its yield point during the excavation process and to avoid instability caused by the coal and rock mass entering a state of complete plastic yield, the peak compressive strength in step S2 is - To make corrections, use:

[0068] S301, in stress path I and stress path II, set the peak compressive strength and The safety factor is 0.8, that is, the maximum excavation rate of the working face is determined by 0.8 times the peak compressive strength in stress path I and stress path II;

[0069] S302, in stress path III, set the peak compressive strength The safety factor is 0.8, that is, the minimum stress to which the working surface can be suddenly unloaded is determined by 0.8 times the peak compressive strength;

[0070] S303, in stress path IV, set the peak compressive strength The safety factor is 0.8, that is, the minimum servo stress of the working surface is determined by 0.8 times the peak compressive strength.

[0071] S4, in order to better control and prevent outburst accidents in mining working faces, the main corresponding stress loading and unloading path types are set for different working faces, specifically:

[0072] The stress loading and unloading path type of the coal mining face is stress path I;

[0073] The stress loading and unloading path type of the coal roadway excavation working face is stress path II;

[0074] The stress loading and unloading path type of the Shimen coal uncovering working face is stress path III;

[0075] The stress loading and unloading path type for preventing coal wall disasters at the coal roadway excavation working face is stress path IV.

[0076] S5: Coal strength is significantly affected by stress path. Whether a coal body experiences instability and failure under dynamic load is not only influenced by the load magnitude but also closely related to the stress path. Therefore, in addition to implementing the tunneling rate and / or controlling the corresponding stress magnitude in steps S2 or S3 to prevent and control outbursts in established stress paths, appropriate gas control measures can also be implemented in accordance with the provisions of the "Detailed Rules for Preventing and Controlling Coal and Gas Outbursts" to enhance gas extraction effectiveness and further reduce gas accumulation levels.

Claims

1. A method for preventing and controlling outbursts in a working face based on a mining mode, characterized in that: The following steps are involved: S1, defines the three-dimensional stress of coal rock mass, that is, the stress in the direction of coal seam strike is the minimum principal stress, the stress perpendicular to the coal seam strike in the horizontal plane is the intermediate principal stress, and the stress perpendicular to the coal seam strike in the vertical plane is the maximum principal stress; S2, based on the loading and / or unloading mode of the coal and rock mass under triaxial stress, the stress loading and unloading paths of the coal and rock mass in the working face under mining mode are divided into the following four types: Stress path I: Unidirectional progressive unloading mode with constant pressure of the intermediate principal stress, that is, the minimum principal stress is progressively unloaded, the maximum principal stress is progressively loaded, and the intermediate principal stress remains constant; Stress path II: bidirectional progressive unloading mode, i.e., progressive loading of the maximum principal stress and progressive unloading of the intermediate principal stress and the minimum principal stress; Stress path III: Bidirectional progressive loading, minimum principal stress sudden unloading mode, that is, the maximum principal stress and intermediate principal stress are progressively loaded, and the minimum principal stress is suddenly unloaded; Stress path IV: bidirectional loading with the minimum principal stress kept constant, and unidirectional servo mode, i.e., the maximum principal stress and the intermediate principal stress are progressively loaded, while the minimum principal stress is kept constant; S3, during the coal mining process, the excavation rate is set and / or the corresponding stress magnitude is controlled according to the stress loading and unloading path type occurring in the coal and rock masses at different working faces.

2. The method for preventing and controlling working face outburst based on mining mode according to claim 1 is characterized in that: For stress path I, the working face advancement rate is calculated using the following formula: ， Where, is the working face excavation rate of stress path I, mm / s; is the peak compressive strength of the stress path, MPa.

3. The method for preventing and controlling working face outburst based on mining mode according to claim 1 is characterized in that: For stress path II, the working face advancement rate is calculated using the following formula: ， Where, is the working face excavation rate of stress path II, mm / s; is the peak compressive strength of stress path II, MPa.

4. The method for preventing and controlling working face outburst based on mining mode according to claim 1 is characterized in that: For stress path III, the minimum stress to which the coal and rock mass at the working face can be unloaded is calculated using the following formula: ， Where, is the minimum stress to which the coal and rock mass at the working face can be unloaded, MPa; is the peak compressive strength of stress path III, MPa.

5. The method for preventing and controlling working face outburst based on mining mode according to claim 1 is characterized in that: For stress path IV, the minimum servo stress of the coal and rock mass at the working face is calculated using the following formula: ， Where, is the minimum servo stress of coal and rock mass at the working face, MPa; is the peak compressive strength of stress path IV, MPa.

6. A method for preventing and controlling working face outburst based on mining mode according to any one of claims 2 to 5, characterized in that: Set the peak compressive strength correction factor of the stress path to 0.

8.

7. A method for preventing and controlling working face outburst based on mining mode according to any one of claims 1 to 5, characterized in that: The corresponding stress loading and unloading path types are set for different coal mining faces, specifically: The stress loading and unloading path type of the coal mining face is stress path I; The stress loading and unloading path type of the coal roadway excavation working face is stress path II; The stress loading and unloading path type of the Shimen coal uncovering working face is stress path III; The stress loading and unloading path type for preventing coal wall disasters at the coal roadway excavation working face is stress path IV.

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