A method for pressure relief and rock burst prevention in a heading roadway of an acute-inclined super-thick coal seam

Abstract

This invention provides a method for stress relief and rockburst prevention at the face of a steeply inclined, extra-thick coal seam tunnel, belonging to the field of mining technology. The method includes: collecting stress data on the surrounding rock at the face of the steeply inclined, extra-thick coal seam tunnel and determining the main impact stresses; determining the peak stress zone and potential peak stress zone of the surrounding rock at the face of the steeply inclined, extra-thick coal seam tunnel; formulating a stress relief measure scheme for the facing of the steeply inclined, extra-thick coal seam tunnel; monitoring the energy released by rock failure; based on the energy released by rock failure, determining whether there is a risk of rockburst; if so, modifying the parameters of the stress relief measure scheme for the facing of the steeply inclined, extra-thick coal seam tunnel and repeating the determination; if not, the current stress relief measure scheme for the facing of the steeply inclined, extra-thick coal seam tunnel is effective. This method effectively reduces rockburst and improves mine production efficiency through scientific stress analysis and specific stress relief measures.

Description

Technical Field

[0001] This invention relates to the field of mining technology, and in particular to a method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunnel. Background Technology

[0002] During coal mine roadway excavation, especially when facing steeply inclined and extra-thick coal seams, the high stress and rockburst potential of the surrounding rock often pose a severe challenge, leading to increased safety hazards and decreased production efficiency. Because the stress on the underlying surrounding rock is more complex under steeply inclined and extra-thick coal seams, stress concentration and rockburst are more likely to occur. Therefore, the applicability of general coal seam roadway stress relief and rockburst prevention methods to steeply inclined and extra-thick coal seams is still unclear. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for relieving pressure and preventing rockburst at the face of steeply inclined, extra-thick coal seam tunnels. This method reduces the impact of rockburst on tunneling in steeply inclined, extra-thick coal seams, ensuring safe mine production and continuous mining operations. Specifically, it includes:

[0004] A method for relieving pressure and preventing rock shove at the face of a steeply inclined, extra-thick coal seam tunnel, comprising:

[0005] S1. Collect the stress of the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel and determine the main impact stress.

[0006] S2. Based on the main impact stress and the stress of the surrounding rock at the face, determine the peak stress zone and potential peak stress zone of the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel.

[0007] S3. Based on the peak stress zone and potential peak stress zone of the surrounding rock at the face, formulate a stress relief plan for the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel.

[0008] S4. Implement the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunneling roadway, and monitor the energy released by the rock failure.

[0009] S5. Based on the energy released by the surrounding rock failure, determine whether there is a risk of rockburst.

[0010] If present, change the parameters of the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunnel and repeat step S4;

[0011] If not, then the current rock pressure relief measures for the face of steeply inclined extra-thick coal seam tunnels are effective.

[0012] Optionally, the S3 step of formulating a stress relief measure scheme for the face rock of the steeply inclined extra-thick coal seam tunnel based on the peak stress zone and the potential peak stress zone includes:

[0013] Develop blasting and pressure relief measures for the main stress concentration areas in front of the working face, and carry out borehole blasting towards the solid coal face each time:

[0014] Two blasting holes are set with a diameter of Ф42mm, a height of 1.0m-1.5m from the roadway floor, and an azimuth angle of 0° with the roadway excavation direction. Water-filled mud is used to seal the blasting holes.

[0015] One of the blast holes is 11m long, the sealing length is greater than 5m, and the explosive charge weighs 1.8kg.

[0016] The other blast hole is 6m long, the sealing length is greater than 5m, and the charge weight is 1.2kg;

[0017] The explosive used is a Class III coal mine permitted emulsion explosive, and the detonator is a coal mine permitted millisecond delay electric detonator. It is charged in the forward direction and detonated in one step.

[0018] Develop pressure relief measures for large-diameter boreholes targeting the main stress concentration areas in front of the face:

[0019] The pressure relief hole has a diameter of Ф130mm, is located 1.5m-1.8m from the side of the roadway and 1.8m-2.0m from the bottom of the roadway, and has an azimuth angle of 0° with the roadway excavation direction.

[0020] There are two pressure relief holes, each 30m long, and the remaining length of the pressure relief holes after each excavation is no less than 25.2m.

[0021] Optionally, in step S4, the pressure relief measures for the facing rock of the steeply inclined, extra-thick coal seam tunnel are implemented, and the energy released by the failure of the surrounding rock is monitored, including:

[0022] The energy released by the failure of the surrounding rock is monitored through microseismic activity, ground sounds, and electromagnetic radiation.

[0023] Optionally, the determination of whether there is a risk of rockburst in S5 based on the energy released by the failure of the surrounding rock includes:

[0024] If the energy released by the failure of the surrounding rock is greater than a preset value, it is determined that there is a risk of rockburst.

[0025] Otherwise, there is no risk of rockburst.

[0026] Optionally, the measure parameters in S5 include:

[0027] The parameters for the measures include:

[0028] Number of pressure relief holes, length of pressure relief holes, diameter of pressure relief holes, number of blasting holes, and length of blasting holes.

[0029] Optionally, the parameters of the modified rock pressure relief measures for the face of a steeply inclined, extra-thick coal seam tunneling roadway in S5 include:

[0030] Each time, one or more parameters of the measure parameters can be changed;

[0031] The changes to the measure parameters shall follow the following rules:

[0032] Add one pressure relief hole at a time;

[0033] Add one blast hole at a time;

[0034] The increase in length of the single-stage pressure relief hole is 5m;

[0035] The increase in length of a single blast hole is 1m;

[0036] The increase in the diameter of the pressure relief orifice in a single expansion is 5 mm.

[0037] The above technical solution has at least the following advantages compared with the existing technology:

[0038] This method first identifies the main impact stresses, stress concentration zones, and potential concentration zones by collecting surrounding rock stress data. Next, it develops targeted stress relief measures, including techniques such as blasting and large-diameter drilling, to reduce the stress level in the surrounding rock. Finally, a monitoring system is used to verify the effectiveness of the stress relief measures, ensuring their effective control over rockbursts.

[0039] This method, through scientific stress analysis and specific pressure relief measures, can effectively reduce the rockburst of the surrounding rock, improve mine production efficiency, and ensure mining continuity. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the process of the present invention;

[0042] Figure 2 Numerical simulation model for the 400B3 tunnel;

[0043] Figure 3A cloud map showing the vertical stress distribution in the 400B3 tunneling roadway;

[0044] Figure 4 The horizontal stress distribution in the 400B3 tunneling roadway;

[0045] Figure 5 The curve showing the horizontal stress distribution at the face of the tunnel being excavated.

[0046] Figure 6 This is the horizontal stress distribution curve above the tunnel;

[0047] Figure 7 This is a side view of the borehole blasting hole;

[0048] Figure 8 A schematic diagram of the front view of the pressure relief hole;

[0049] Figure 9 This is a schematic diagram of the side cross-section of the pressure relief hole;

[0050] Figure 10 The effect of anti-scour measures on the face pressure relief of tunnel excavation. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0052] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0053] It should be noted that the terms "up", "down", "left", "right", "front" and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0054] like Figures 1 to 6 As shown, a method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunnel includes:

[0055] S1. Collect the stress of the surrounding rock at the face of the steeply inclined, extra-thick coal seam tunnel and determine the main impact stresses; specifically including:

[0056] The vertical and horizontal stresses at the face of the tunnel are collected, which can be done through computer simulation, numerical calculation, and field testing.

[0057] Determine the primary impact stress by comparing the collected vertical and horizontal stresses. If the vertical stress is significantly greater than the horizontal stress, then the vertical stress is the primary impact stress; if the horizontal stress is significantly greater than the vertical stress, then the horizontal stress is the primary impact stress.

[0058] S2. Based on the main impact stress and the surrounding rock stress at the face, determine the peak stress zone and potential peak stress zone of the facing rock in the steeply inclined extra-thick coal seam tunnel; specifically including:

[0059] Analyze the main stress concentration areas in front of the tunnel face where major impact stresses are formed;

[0060] Analyzing the main stress concentration areas behind the tunnel face and the distribution range of these stress concentration areas relative to the tunnel space reveals that the same distribution range relative to the area to be excavated is the potential stress concentration area.

[0061] S3. Based on the peak stress zone and potential peak stress zone of the surrounding rock at the face, formulate a stress relief plan for the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel.

[0062] Specifically, it includes:

[0063] Develop blasting and pressure relief measures for the main stress concentration areas in front of the working face, and carry out borehole blasting towards the solid coal face each time:

[0064] Two blasting holes are set with a diameter of Ф42mm, a height of 1.0m-1.5m from the roadway floor, and an azimuth angle of 0° with the roadway excavation direction. Water-filled mud is used to seal the blasting holes.

[0065] One of the blast holes is 11m long, the sealing length is greater than 5m, and the explosive charge weighs 1.8kg.

[0066] The other blast hole is 6m long, the sealing length is greater than 5m, and the charge weight is 1.2kg;

[0067] The explosive used is a Class III coal mine permitted emulsion explosive, and the detonator is a coal mine permitted millisecond delay electric detonator. It is charged in the forward direction and detonated in one step.

[0068] Develop pressure relief measures for large-diameter boreholes targeting the main stress concentration areas in front of the face:

[0069] The pressure relief hole has a diameter of Ф130mm, is located 1.5m-1.8m from the side of the roadway and 1.8m-2.0m from the bottom of the roadway, and has an azimuth angle of 0° with the roadway excavation direction.

[0070] There are two pressure relief holes, each 30m long, and the remaining length of the pressure relief holes after each excavation is no less than 25.2m.

[0071] like Figures 7 to 10 As shown, blasting pressure relief measures were formulated for the main stress concentration areas in front of the working face, and borehole blasting was carried out each time in front of the solid coal.

[0072] The blasting hole diameter is Ф42mm, the height from the roadway floor is 1.0-1.5m, and the azimuth angle is the same as the roadway excavation direction with an included angle of 0°.

[0073] Among them, No. 1 blasting hole was loaded with explosives using the drill cuttings hole after coal powder extraction, and the construction length of No. 2 hole was 6m.

[0074] The blasting holes were sealed with water-based mud. Hole #1 was charged with 1.8 kg of explosive (6 small sections) and the sealing length was greater than 5 m. Hole #2 was charged with 1.2 kg of explosive (4 small sections) and the sealing length was greater than 3 m.

[0075] The explosive used is a Class III coal mine permitted emulsion explosive, and the detonator is a coal mine permitted millisecond delay electric detonator. It is charged in the forward direction and detonated in one go.

[0076] Develop pressure relief measures for large-diameter boreholes targeting the main stress concentration areas in front of the face. Specific parameters for these measures are as follows:

[0077] The pressure relief hole has a diameter of Ф130mm, is located 1.5-1.8m from the sidewall of the roadway and 1.8-2.0m from the floor, and its azimuth angle is 0° with the roadway excavation direction.

[0078] There are two pressure relief holes, each 30m long, and the remaining length of the pressure relief holes after each excavation is no less than 25.2m.

[0079] S4. Implement the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunneling roadway, and monitor the energy released by the rock failure.

[0080] The energy released by the failure of the surrounding rock is monitored through microseismic activity, ground sounds, and electromagnetic radiation.

[0081] S5. Based on the energy released by the surrounding rock failure, determine whether there is a risk of rockburst.

[0082] If present, change the parameters of the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunnel and repeat step S4;

[0083] If not, then the current rock pressure relief measures for the face of steeply inclined extra-thick coal seam tunnels are effective.

[0084] Optionally, the determination of whether there is a risk of rockburst in S5 based on the energy released by the failure of the surrounding rock includes:

[0085] If the energy released by the failure of the surrounding rock is greater than a preset value, it is determined that there is a risk of rockburst.

[0086] Otherwise, there is no risk of rockburst.

[0087] Specifically, the parameters for the measures include:

[0088] Number of pressure relief holes, length of pressure relief holes, diameter of pressure relief holes, number of blasting holes, and length of blasting holes.

[0089] Each time, one or more parameters of the measure parameters can be changed;

[0090] The changes to the measure parameters shall follow the following rules:

[0091] Add one pressure relief hole at a time;

[0092] Add one blast hole at a time;

[0093] The increase in length of the single-stage pressure relief hole is 5m;

[0094] The increase in length of a single blast hole is 1m;

[0095] The increase in the diameter of the pressure relief orifice in a single expansion is 5 mm.

[0096] The method of this embodiment will be further explained below in conjunction with specific application scenarios:

[0097] This case study uses the +400m B3 tunneling roadway in a Wudong coal mine as an example. A simulation model of the mine's longwall face was established using FLAC3D numerical simulation software. Following the actual excavation steps, the tunneling process of the +400B3 roadway was simulated in FLAC3D software. The vertical and horizontal stress distributions at the tunnel face were collected during the tunneling process. The main impact stresses, stress concentration zones, and potential stress concentration points were identified. Pressure relief and anti-impact measures for the roadway face were formulated, and the effectiveness of these measures was verified. The specific steps are as follows:

[0098] A numerical simulation model covering the +400B3 tunneling roadway of the Wudong Coal Mine was established based on the mine's geological conditions. The model simulated the tunneling process of +400B3 and collected the vertical and horizontal stresses of the surrounding rock at the tunnel face during the tunneling process. Figure 2 It is a numerical simulation model. Figure 3 It refers to the vertical stress distribution of the surrounding rock after tunnel excavation. Figure 4 It refers to the distribution of horizontal stress in the surrounding rock after tunnel excavation.

[0099] Comparing the magnitudes of vertical and horizontal stresses, the peak horizontal stress near the tunnel face is approximately 33 MPa, while the peak vertical stress near the tunnel face is approximately 14 MPa. This indicates that the horizontal stress in the surrounding rock is significantly greater than the vertical stress, confirming that horizontal stress is the primary impact stress.

[0100] Analysis of the horizontal stress concentration zones in the surrounding rock of the tunnel and the potential stress concentration zones during excavation determined that the horizontal stress concentration zone is approximately 30m ahead of the face. Figure 5 Analysis revealed that the area approximately 4 meters from the upper and lower boundaries of the tunnel is a horizontal stress concentration zone. Therefore, the area approximately 4 meters from the upper and lower boundaries of the area to be excavated is a potential horizontal stress concentration zone. Figure 6 .

[0101] Develop blasting and large-diameter borehole pressure relief measures for tunneling roadways in steeply inclined, extra-thick coal seams, such as... Figure 7 As shown, the details are as follows:

[0102] The blasting hole diameter is Ф42mm, the height from the roadway floor is 1.0-1.5m, and the azimuth angle is the same as the roadway excavation direction with an included angle of 0°.

[0103] Among them, No. 1 blasting hole was loaded with explosives using the drill cuttings hole after coal powder extraction, and the construction length of No. 2 hole was 6m.

[0104] The blasting holes were sealed with water-based mud. Hole #1 was charged with 1.8 kg of explosive (6 small sections) and the sealing length was greater than 5 m. Hole #2 was charged with 1.2 kg of explosive (4 small sections) and the sealing length was greater than 3 m.

[0105] The explosive used is a Class III coal mine permitted emulsion explosive, and the detonator is a coal mine permitted millisecond delay electric detonator. It is charged in the forward direction and detonated in one go.

[0106] Develop pressure relief measures for large-diameter boreholes targeting the main stress concentration areas in front of the face, such as... Figure 8 and Figure 9 As shown, the specific parameters for the measures are:

[0107] The pressure relief hole has a diameter of Ф130mm, is located 1.5-1.8m from the roadway sidewall, and 1.8-2.0m from the roadway floor. Its azimuth angle is 0° to the roadway excavation direction. Figure 8 As shown.

[0108] There are two pressure relief holes, each 30m long. After each excavation, the remaining length of the pressure relief holes should be no less than 25.2m. Figure 9 As shown.

[0109] Field implementation revealed that after implementing this pressure relief and anti-impact method, the ground sound energy at the tunnel face was significantly reduced, such as... Figure 10 As shown, this indicates that the risk of rockburst has been reduced and effectively controlled.

[0110] In summary, this embodiment provides a method for stress relief and rockburst prevention at the face of a steeply inclined, extra-thick coal seam tunnel. Through scientific stress analysis and specific stress relief measures, the rockburst of the surrounding rock can be effectively reduced, mine production efficiency can be improved, and mining continuity can be ensured.

[0111] This method first identifies the main impact stresses, stress concentration zones, and potential concentration zones by collecting surrounding rock stress data. Next, it develops targeted stress relief measures, including techniques such as blasting and large-diameter drilling, to reduce the stress level in the surrounding rock. Finally, a monitoring system is used to verify the effectiveness of the stress relief measures, ensuring their effective control over rockbursts.

[0112] This method, through scientific stress analysis and specific pressure relief measures, can effectively reduce the rockburst of the surrounding rock, improve mine production efficiency, and ensure mining continuity.

[0113] The following points need to be explained:

[0114] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0115] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the invention, i.e., these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0116] (3) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0117] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunnel, characterized in that, include: S1. Collect the stress of the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel and determine the main impact stress. S2. Based on the main impact stress and the stress of the surrounding rock at the face, determine the peak stress zone and potential peak stress zone of the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel. S3. Based on the peak stress zone and potential peak stress zone of the surrounding rock at the face, formulate a stress relief plan for the surrounding rock at the face of the steeply inclined extra-thick coal seam tunnel, including: Develop blasting and pressure relief measures for the main stress concentration areas in front of the working face, and carry out borehole blasting towards the solid coal face each time: Two blasting holes are set with a diameter of Ф42mm, a height of 1.0m-1.5m from the roadway floor, and an azimuth angle of 0° with the roadway excavation direction. Water-filled mud is used to seal the blasting holes. One of the blast holes is 11m long, the sealing length is greater than 5m, and the explosive charge weighs 1.8kg. The other blasting hole is 6m long, the sealing length is greater than 5m, and the explosive charge weight is 1.2kg; The explosive used is a Class III coal mine permitted emulsion explosive, and the detonator is a coal mine permitted millisecond delay electric detonator. It is charged in the forward direction and detonated in one step. Develop pressure relief measures for large-diameter boreholes targeting the main stress concentration areas in front of the face: The pressure relief hole has a diameter of Ф130mm, is located 1.5m-1.8m from the side of the roadway and 1.8m-2.0m from the bottom of the roadway, and has an azimuth angle of 0° with the roadway excavation direction. There are two pressure relief holes, each 30m long, and the remaining length of the pressure relief holes after each excavation is no less than 25.2m. S4. Implement the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunneling roadway, and monitor the energy released by the rock failure. S5. Based on the energy released by the surrounding rock failure, determine whether there is a risk of rockburst. If present, change the parameters of the rock pressure relief measures for the face of the steeply inclined extra-thick coal seam tunnel and repeat step S4; If not, then the current rock pressure relief measures for the face of steeply inclined extra-thick coal seam tunnels are effective.

2. The method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunneling roadway according to claim 1, characterized in that, The implementation of S4, based on the rock pressure relief measures for the face of the steeply inclined, extra-thick coal seam tunnel, includes monitoring the energy released by rock failure, including: The energy released by the failure of the surrounding rock is monitored through microseismic activity, ground sounds, and electromagnetic radiation.

3. The method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunneling roadway according to claim 2, characterized in that, The determination of whether there is a risk of rockburst based on the energy released by the surrounding rock failure in S5 includes: If the energy released by the failure of the surrounding rock is greater than a preset value, it is determined that there is a risk of rockburst. Otherwise, there is no risk of rockburst.

4. The method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunneling roadway according to claim 3, characterized in that, The measure parameters in S5 include: The parameters for the measures include: Number of pressure relief holes, length of pressure relief holes, diameter of pressure relief holes, number of blasting holes, and length of blasting holes.

5. The method for relieving pressure and preventing scour at the face of a steeply inclined, extra-thick coal seam tunneling roadway according to claim 4, characterized in that, The parameters of the modified rock pressure relief measures for the face of steeply inclined, extra-thick coal seam tunneling roadways in S5 include: Each time, one or more parameters of the measure parameters can be changed; The changes to the measure parameters follow these rules: Add one pressure relief hole at a time; Add one blast hole at a time; The increase in length of the single-stage pressure relief hole is 5m; The increase in length of a single blast hole is 1m; The increase in the diameter of the pressure relief orifice in a single expansion is 5 mm.

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