A method for designing the depth of large-diameter drilling holes based on energy storage zoning of tunnel surrounding rock

Abstract

The present invention discloses a method for designing the depth of large-diameter drilling holes based on energy storage zoning of tunnel surrounding rocks, belonging to the technical field of rock burst disaster prevention and control in deep-buried tunnels. The method comprises the following steps: Step A. Collecting on-site data; Step B. Measuring the mechanical properties of coal and rock; Step C. Analyzing the energy storage theory of tunnel near-field surrounding rock zoning; Step D. Numerical simulation calculation; Step E. Performing energy monitoring; Step F. Constructing a dynamic energy zoning evolution model of tunnel surrounding rocks; Step G. Designing the depth of large-diameter pressure relief drilling holes based on the range of the tunnel surrounding rock energy storage zone; and Step H. Testing and optimization. In the present invention, numerical simulation is used to analyze the range of the energy storage zone by constructing a dynamic energy zoning evolution model of tunnel surrounding rocks, thereby determining the design depth of large-diameter drilling holes for coal body construction. The rationality of the large-diameter drilling hole design is determined by judging whether the range of the tunnel surrounding rock energy storage zone decreases or moves deeper, thereby more accurately evaluating the pressure relief effect of the tunnel surrounding rocks with energy storage zones.

Description

Technical Field

[0001] The present invention belongs to the technical field of prevention and control of rock burst disasters in deep-buried tunnels, and in particular relates to a method for designing the depth of large-diameter drilling holes based on energy storage zoning of tunnel surrounding rocks. Background Art

[0002] As coal mining depths increase year by year, the stress environment in the surrounding rock of roadways becomes more complex, and the frequency and intensity of rock bursts continue to increase, posing a serious threat to mine production and personnel safety. Currently, large-diameter drilling is one of the primary means of preventing and controlling rock bursts in China. Appropriate large-diameter drilling parameters can not only reduce damage to the surrounding rock of roadways, but also effectively prevent and control rock bursts.

[0003] Large-diameter drilling parameters primarily include diameter, spacing, and depth. Large-diameter borehole diameters are generally 150-200mm, with spacing typically ranging from 1-3m based on national standards and the degree of rock burst risk at the working face. Depths are generally determined based on coal seam thickness and practical experience at various mines, typically ranging from 15m, 20m, and 25m. However, the occurrence of rock burst is closely related to the mechanical properties of the coal and rock mass. Simply determining large-diameter drilling depth based on coal seam thickness lacks theoretical guidance. Rock burst is an energy-driven instability phenomenon in coal and rock. Before rock burst occurs, elastic energy accumulates in these areas, often referred to as energy storage zones. After rock burst occurs, this stored energy is converted into kinetic energy and released as coal and rock avalanches and spatter. Therefore, studying the energy storage zoning patterns in the surrounding rock of a roadway from an energy perspective and then using large-diameter drilling to disrupt the surrounding rock structure in these energy storage zones and reduce the rock's energy storage limit can effectively prevent rock burst.

[0004] For conventional fixed large-diameter drilling depth, under different roadway surrounding rock conditions, severe deformation and damage of the roadway surrounding rock and failure of the anchor support structure due to excessive unloading often occur, as well as rock burst caused by accumulation of elastic energy of the coal body due to insufficient unloading. It is very necessary to reasonably and appropriately unload the roadway surrounding rock. Therefore, a large-diameter drilling depth design method based on the energy storage zoning of the roadway surrounding rock is urgently needed. Summary of the Invention

[0005] The purpose of the present invention is to propose a large-diameter drilling depth design method based on the energy storage zoning of the tunnel surrounding rock in order to improve the large-diameter drilling unloading effect and avoid the problem of insufficient or excessive coal seam unloading caused by the empirical design of the large-diameter drilling depth in the tunnel.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for designing the depth of a large-diameter borehole based on energy storage zoning of surrounding rock in a roadway comprises the following steps:

[0008] Step A. Collect on-site data;

[0009] Step B. Determination of coal rock mechanical properties;

[0010] Step C. Energy storage theory of surrounding rock zones in the near-field of the roadway;

[0011] Step D. numerical simulation calculation;

[0012] Step E. Perform energy monitoring;

[0013] Step F. Constructing a dynamic energy partition evolution model of the tunnel surrounding rock;

[0014] Step G. Designing the depth of the large-diameter pressure relief drilling hole according to the range of the energy storage area of ​​the tunnel surrounding rock;

[0015] Step H. Inspection and optimization.

[0016] As a further description of the above technical solution: the field data mainly include: drill hole histograms, research reports on the distribution of ground stress, etc., which are used to determine the type and thickness of coal and rock layers, the stress environment of the tunnel surrounding rock, etc.; by collecting the above data, a preliminary understanding of the field conditions can be obtained, providing data support for the design of parameters such as numerical model size and boundary conditions.

[0017] As a further description of the above technical solution: In step B, drilling and sampling are carried out in the research target area, and the rock cores taken out on site are processed into standard specimens. By conducting indoor uniaxial compression tests, Brazilian splitting tests, triaxial tests, etc., the mechanical properties of the coal rock formation are obtained, which mainly include bulk modulus, cohesion, internal friction angle, tensile strength, etc., to provide data support for the design of numerical model parameters.

[0018] As a further description of the above technical solution: in step C, during the occurrence of rock burst, the shallow coal bodies on both sides of the tunnel belong to the energy release zone, and will eventually be destroyed due to stress overload or energy overlimit; the roof on both sides of the tunnel and the coal bodies in the deep elastic zone belong to the energy storage zone. At the moment of shallow coal body destruction, the lateral restraint force below the roof and the deep coal body suddenly decreases, the compressed roof recovers its deformation, and the constrained coal body expands laterally. Both will release strain energy to supply the shallow coal body, which is converted into dissipated energy for crack expansion in the shallow coal body and kinetic energy of coal blocks ejected; therefore, the "energy release zone + energy storage zone" jointly affect whether rock burst occurs and the severity of its occurrence.

[0019] As a further description of the above technical solution: in the step D, first, since there will be initial stress inside the rock mass in its natural state without being disturbed by artificial excavation, ground stress should be applied to the model to make the model stress conditions closer to the actual situation; secondly, the field data collected in the preliminary preparation step A and the parameters measured by the coal and rock mechanics test in step B are assigned to the model; finally, the working face mining activities are simulated.

[0020] As a further description of the above technical solution: In the step E, first, the energy calculation program is written using the relevant language in the numerical simulation software such as FLAC3D. The energy density U of the model unit i is calculated as follows:

[0021]

[0022] Where σ1, σ2, and σ3 are the maximum principal stress, intermediate principal stress, and minimum principal stress of unit i, respectively, in MPa; μ is the Poisson's ratio of the unit; and E is the elastic modulus of the unit body, in GPa. The energy density U of the surrounding rock of the roadway is calculated using numerical simulation software. If the numerical simulation software has this function, you can proceed directly to the next step without programming.

[0023] Secondly, energy measurement lines are arranged in the constructed numerical model. Considering that rock burst generally occurs 300m behind the tunnel excavation head and 500m in front of the stope, the measurement lines are generally arranged on both sides and the top and bottom plates of the tunnel. The specific number and spacing of measurement lines are determined according to the model and the complexity of the actual engineering stress, such as Figure 1 Finally, according to the numerical simulation results, the data on the energy measurement lines arranged at different positions in each tunnel are sorted and output, and the elastic energy density zoning curve of the tunnel surrounding rock is drawn using data analysis software such as Origin, as shown in Figure 2. Figure 2 As shown in the figure, the area with elastic energy density lower than E is defined as the energy release area, and the area with elastic energy density greater than 1.3E is defined as the energy storage area, thereby obtaining the distribution characteristics of the elastic energy density of the tunnel surrounding rock during the working face mining.

[0024] As a further description of the above technical solution: In the step F, based on the data analysis results and the output elastic energy density partition curve, establish Figure 3 The energy storage model of the tunnel near-field surrounding rock is shown in the figure. According to this model, the tunnel surrounding rock can be divided into an energy release zone and an energy storage zone. Before tunnel excavation, the roof and floor plates close to the tunnel accumulate elastic energy under the action of initial ground stress. After tunnel excavation, the elastic energy stored in the roof and floor plates is released, forming an energy release zone. Since coal seams are easier to store elastic energy than rock strata, an energy storage zone appears in front of the tunnel. For the tunnel side coal body, the elastic energy stored in the coal body close to the tunnel is released, forming an energy release zone. The coal body within a certain range from the tunnel and the front of the tunnel form an energy storage zone, as shown in Figure 2. Figure 3shown.

[0025] As a further description of the above technical solution: In step G, first, the design of the depth of the large-diameter pressure relief drilling hole must conform to actual production. According to the thickness of the coal seam and the production practice experience of the mine, when the coal seam mining thickness is less than 3.5m, the drilling depth is generally not less than 15m; when the coal seam mining thickness is 3.5m to 8m, the drilling depth is generally not less than 20m; when the coal seam mining thickness is greater than 8m, the drilling depth is generally not less than 25m;

[0026] Table 1 Large diameter drilling depth based on coal seam thickness

[0027] Coal thickness / m ≤3.5 3.5～8 ≥8 Hole depth / m 15 20 25

[0028] Therefore, the drilling depth of the present invention is designed to be within the range of 10-20m when the coal seam mining thickness is less than 3.5m; the drilling depth is within the range of 15-25m when the coal seam mining thickness is 3.5m to 8m; and the drilling depth is within the range of 20-30m when the coal seam mining thickness is greater than 8m.

[0029] Secondly, the fundamental basis for drilling depth design is the range of the tunnel surrounding rock energy storage area. In principle, the design depth should exceed the range of the tunnel surrounding rock energy storage area. Figure 4 The design guidance of large diameter pressure relief drilling depth based on the energy storage zoning of tunnel surrounding rock is given, such as Figure 4 As shown in (a), during the tunnel excavation, the energy storage area is roughly distributed in a "U" shape on both sides and the front of the tunnel. Therefore, the arrangement of large-diameter boreholes should exceed the energy storage area; Figure 4 As shown in (b), during the mining period, the energy storage area is roughly distributed in a strip shape at a certain distance in front of the mining face, and large-diameter drill holes are arranged on both sides of the tunnel, and the depth exceeds the range of the energy storage area.

[0030] As a further description of the above technical solution: in the step H, first, the geological structure ahead is detected by advance drilling; if special geological structures such as faults and folds are encountered, whether they are normal faults or reverse faults, mining disturbance and the resulting stress superposition are one of the necessary conditions for the occurrence of fault impact ground pressure; therefore, when the borehole is close to geological structures such as coal seam faults, the borehole depth should be no less than 3.5 times the coal seam thickness, and the borehole depth needs to be appropriately increased on the basis of the original borehole depth; secondly, by using the numerical simulation method, combined with the actual situation on site, such as the influence of goafs and coal pillars, additional boreholes are added on the basis of the original model, and the designed large-diameter pressure relief borehole depth parameters are substituted into the tunnel surrounding rock energy zoning evolution model, and the data is output to observe whether its energy change conforms to the decrease in the energy storage area or the transfer to the deep part; finally, the on-site inspection method is adopted to observe the mine pressure manifestation in the tunnel and use a borehole stress meter or a drill cuttings method to verify whether the designed large-diameter borehole depth has an ideal pressure relief effect;

[0031] The above two methods are used to judge whether the design of the large-diameter pressure relief drilling depth is reasonable. If the range of the tunnel surrounding rock energy storage area decreases or moves to a deeper level, it is reasonable and large-diameter drilling can continue to be carried out on-site; if the range does not decrease or move, it is unreasonable and further optimization of the large-diameter drilling depth design is required and it must pass the inspection again before on-site construction can be carried out.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] 1. In the present invention, numerical simulation is used to construct a dynamic energy zoning evolution model of the tunnel surrounding rock to analyze the range of the energy storage zone, thereby determining the design depth of the large-diameter drilling hole for coal body construction. By judging whether the range of the tunnel surrounding rock energy storage zone decreases or moves deeper, it is determined whether the design depth of the large-diameter drilling hole is reasonable. Therefore, the evaluation of the unloading effect of the tunnel surrounding rock in the energy storage zone is more accurate.

[0034] 2. In the present invention, the actual coal seam thickness and on-site construction experience are taken into consideration, and the large-diameter drilling depth design can meet on-site construction conditions and is more in line with the actual on-site conditions, thus avoiding the situation where on-site construction cannot be carried out due to the deviation of theoretical calculation results from reality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for designing the depth of large-diameter drilling holes based on energy storage zoning of surrounding rock in tunnels proposed by the present invention;

[0036] Figure 2 This is a schematic diagram of the survey line layout of a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed by the present invention;

[0037] Figure 3This is a curve diagram of elastic energy density zoning for a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed by the present invention;

[0038] Figure 4 Schematic diagram of the dynamic energy zoning evolution model of tunnel surrounding rock based on the large-diameter drilling depth design method proposed in the present invention;

[0039] Figure 5 This is a large-diameter pressure relief drilling depth design diagram based on a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed by the present invention;

[0040] Figure 6 This is a numerical model of the 2307 excavation working face based on a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed in this invention;

[0041] Figure 7 This is a curve of elastic energy density zoning of the two sides of the tunnel based on the large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed by the present invention;

[0042] Figure 8 This is a schematic diagram of a dynamic energy zoning evolution model of a tunnel surrounding rock based on a large-diameter drilling depth design method for tunnel surrounding rock energy storage zoning proposed in the present invention;

[0043] Figure 9 This is a design diagram of the large-diameter pressure relief drilling depth in a certain tunnel, based on a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning proposed by the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] Combine Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 8 As shown, a specific implementation method of a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning provided by the present invention is described.

[0046] The existing large-diameter drilling depth is usually constructed at a uniform depth based on engineering experience, and the depth will be densely arranged in different impact hazard areas to reduce the possibility of rock burst. However, there is little research on the large-diameter drilling depth under different roadway surrounding rock conditions. To solve this problem, theoretical analysis and numerical simulation methods are used to study the dynamic evolution process of roadway surrounding rock energy, analyze the evolution law of roadway surrounding rock energy zoning, and then construct a dynamic energy zoning evolution model of roadway surrounding rock. Based on the roadway surrounding rock energy zoning, the large-diameter anti-bumping drilling depth is designed and the practicality of this design method is verified by combining numerical simulation and field testing. The results show that: (1) The pressure relief effect of the large-diameter drilling depth designed based on coal seam thickness and engineering experience varies greatly. In fact, rock burst is an energy-driven coal rock state instability phenomenon. Therefore, it is more universal to study the large-diameter drilling depth from the energy perspective and in combination with engineering practice. (2) As the large-diameter drilling effectively "destroys" the energy storage area, the range of the roadway surrounding rock energy storage area gradually decreases or moves deeper, resulting in a decrease in the release of elastic energy stored in the coal body energy storage area, achieving the expected pressure relief effect. (3) The rationality of the designed large-diameter drilling depth is tested by adopting numerical simulation and field testing methods to achieve better pressure relief effect.

[0047] Through field practice, under normal circumstances, the depth of large-diameter drilling in construction is mostly: when the coal seam mining thickness is less than 3.5m, the drilling depth is generally not less than 15m, and 15m is taken; when the coal seam mining thickness is 3.5m to 8m, the drilling depth is generally not less than 20m, and 20m is taken; when the coal seam mining thickness is greater than 8m, the drilling depth is generally not less than 25m, and 25m is taken. However, rock burst is an energy-driven coal rock state instability phenomenon. Before the rock burst occurs, it will inevitably be accompanied by the accumulation of elastic energy areas. When the elastic energy accumulation exceeds the energy storage limit of the surrounding rock, the stored energy is converted into kinetic energy and released in the form of coal rock collapse and splashing. In order to solve this problem, the present invention provides a large-diameter drilling depth design method based on tunnel surrounding rock energy storage zoning.

[0048] Taking the actual working face of a mine as an example, the design method of large-diameter drilling depth based on the energy storage zoning of the tunnel surrounding rock is further explained. The specific steps include:

[0049] Step A. Collect field data. The 2307 working face at a certain mine is located in the 3rd coal seam, with an average coal thickness of 3.5 meters and an average working face depth of 815 meters. The working face utilizes a dual-lane layout: the track chute connects to the track lane on the west wing of the second mining area, with a total length of 538.3 meters. The belt chute connects to the belt lane on the west wing of the second mining area, with a total length of 503.9 meters. The working face cut length is 200.1 meters. The working face is flanked by solid coal areas to the northeast, the main lane on the west wing of the second mining area to the south, and the 1308 working face in the first mining area to the west. The immediate roof of the coal seam is mudstone, the basic roof is siltstone, the immediate bottom is mudstone, and the basic bottom is fine sandstone. Overall, the 2307 working face is buried at a considerable depth, creating the basic conditions for rock bursts. Furthermore, the track chute is close to the goaf, significantly impacted by the lateral bearing pressure of the goaf, posing a certain risk of rock bursts during tunneling. Collect the plan view, bar chart, and research report on the distribution law of ground stress of the 2307 working face, organize and summarize the required information such as rock layer type, rock layer thickness, and ground stress distribution law, and provide data support for the design of parameters such as numerical model size and boundary conditions.

[0050] Step B. Determination of coal and rock mechanical properties. Drilling and sampling were performed at the 2307 working face. The cores were processed into standard specimens. Mechanical testing of the cores was performed to determine the relevant coal and rock mechanical properties. Specific parameters are shown in the table below.

[0051] Table 2 Parameters of coal and rock layer model of 2307 working face

[0052]

[0053] Step C. Zoned energy storage theory for the roadway's near-field surrounding rock. Based on the theory that shallow coal on both sides of the roadway releases energy, while the roof and deep elastic zone coal on both sides of the roadway store energy, the relevant parameters obtained in Steps A and B are input into the numerical model for simulation.

[0054] Step D. Numerical simulation calculation. A FLAC3D numerical model was established based on the design of the 2307 working face. Ground stress was applied to the numerical model and parameters were assigned. The model size was X×Y×Z=600m×800m×62m. The model included the 2307 working face and part of the goaf of the adjacent 1306, 1308, and 1310 working faces. The model height extended from 15m below the coal seam to 47m above the coal seam, including the main rock layers of the coal seam and its roof and floor, such as Figure 5 Table 2 shows the mechanical parameters of the coal and rock formations in the model. Displacement boundary conditions are used for the front, back, left, right, and bottom surfaces of the model, and stress boundary conditions are used for the top surface of the model. The stress is converted to 19.2 MPa according to the buried depth of the coal and rock formation. First, the 1308 working face is excavated, and after 2000 time steps, the 2307 working face roadway is excavated.

[0055] Step E. Perform energy monitoring. First, use the fish language in FLAC3D to write an energy calculation program. The energy density U of the model unit i is calculated as follows:

[0056]

[0057] Where σ1, σ2, and σ3 are the maximum principal stress, intermediate principal stress, and minimum principal stress of unit i, respectively, in MPa; μ is the Poisson's ratio of the unit; and E is the elastic modulus of the unit body, in GPa. The energy density U of the tunnel surrounding rock is calculated using numerical simulation software.

[0058] Secondly, energy measurement lines were arranged 10m behind the head of the track chute of the 2307 working face and 10m behind the head of the belt chute of the 2307 working face. In order to quantitatively analyze the evolution of the elastic energy density of the surrounding rock during the excavation of the track chute and belt chute, the model energy density data was extracted. The elastic energy density zoning curve of the tunnel surrounding rock was drawn using the Origin data analysis software, as shown in the figure below. Figure 6 As shown, the trend of elastic energy density change of the energy measurement line is analyzed.

[0059] Step F. Construct the dynamic energy partition evolution model of the tunnel surrounding rock. Based on the numerical simulation results, establish Figure 7 The following figure shows a zoning energy storage model for the roadway's surrounding rock near the roadway. Based on this model, the roadway's surrounding rock can be divided into an energy release zone and an energy storage zone. The roadway has a height of 4 m and a width of 5 m. Before roadway excavation, the roof and floor plates closer to the roadway accumulate elastic energy under the action of initial geostress. After roadway excavation, this stored elastic energy is released, forming an energy release zone (0-5H) (0-20 m) between the roadway's roof and floor plates and the coal bodies on both sides. The rock layers farther from the roadway (>20 m) are less affected by excavation disturbances, resulting in less significant energy changes. Because coal seams are more susceptible to elastic energy than rock strata, an energy storage zone appears approximately 15-20 m in front of the roadway's face. For the coal bodies on the roadway's sides, the elastic energy stored within the coal bodies closer to the roadway is released, forming an energy release zone (0-5 m). Energy storage zones form in the coal bodies approximately 10-15 m from the coal bodies on both sides and 15-20 m from the face.

[0060] Step G. Design the large-diameter pressure relief borehole depth based on the tunnel surrounding rock energy storage area. First, the design of the large-diameter pressure relief borehole depth must conform to actual production conditions. Since the average coal thickness at the 2307 working face is 3.5 meters, the design range of the large-diameter pressure relief borehole depth should be between 10-25 meters.

[0061] Secondly, the design basis of large diameter drilling depth is that the design depth should exceed the range of the tunnel surrounding rock energy storage area. Therefore, considering the range of the energy storage area and the coal seam thickness of 3.5m, in order to prevent the drilling construction from reaching the rock layer, the drilling depth of the two sides of the solid coal is determined to be 15m, and the head drilling depth is 20m. Figure 8 shown.

[0062] Step H. Verification and Optimization. Field verification confirmed that, after implementing the large-diameter borehole depth decompression mitigation measures designed in Step F, no microseismic warning events occurred during track tunneling. Overall, the use of this large-diameter borehole depth for decompression effectively "destroyed" the surrounding rock energy storage zone, allowing safe excavation and breakthrough of the 2307 working face. No significant dynamic events were observed during excavation, confirming the rationality of the large-diameter decompression borehole depth design. Therefore, on-site construction can continue.

[0063] A large-diameter borehole depth design method based on the energy storage zoning of the roadway surrounding rock was developed through theoretical calculations, numerical simulations, and subsequent graphical rendering and data calculations. This method, while fully considering the influence of coal seam thickness, determined a reasonable and effective large-diameter pressure relief borehole depth. This method avoids the problem of insufficient pressure relief caused by large-diameter borehole parameters designed based on engineering experience. This method provides guidance for the prevention and control of rock bursts, further ensuring safe production in coal mines.

[0064] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for designing the depth of large-diameter drilling holes based on the energy storage zoning of tunnel surrounding rocks, characterized in that: The following steps are involved: Step A. Collect on-site data; Step B. Determination of coal rock mechanical properties; Step C. Energy storage theory of surrounding rock zones in the near-field of the roadway; Step D. numerical simulation calculation; Step E. Perform energy monitoring; Step F. Constructing a dynamic energy partition evolution model of the tunnel surrounding rock; Step G. Designing the depth of the large-diameter pressure relief drilling hole according to the range of the energy storage area of ​​the tunnel surrounding rock; Step H. Inspection and optimization; In step C, during rock burst, the shallow coal on both sides of the roadway is in the energy release zone and will eventually fail due to stress overload or energy overrun. The roof on both sides of the roadway and the coal in the deep elastic zone are in the energy storage zone. At the moment of shallow coal failure, the lateral restraining force below the roof and in the deep coal suddenly decreases, causing the compressed roof to recover its deformation and the restrained coal to expand laterally. Both release strain energy to the shallow coal, which is converted into dissipated energy for crack propagation in the shallow coal and kinetic energy of coal blocks ejected. Therefore, the "energy release zone + energy storage zone" jointly influence whether rock burst occurs and its severity. In step E, first, an energy calculation program is written using the relevant language in FLAC3D numerical simulation software. The energy density U of the model unit i is calculated as follows: （1）； Where, 、 、 are the maximum principal stress, intermediate principal stress, and minimum principal stress of unit i, in MPa; μ is the Poisson's ratio of the unit; E is the elastic modulus of the unit, in GPa. The energy density U of the surrounding rock of the roadway is calculated using numerical simulation software. If the numerical simulation software has this function, you can proceed directly to the next step without programming. Secondly, energy measurement lines were arranged in the constructed numerical model. Considering that rock burst occurs 300m behind the tunnel excavation head and 500m in front of the stope, the measurement lines were arranged on both sides and the roof and floor of the tunnel. The specific number and spacing of the measurement lines were determined according to the model and the complexity of the actual engineering stress. Finally, based on the numerical simulation results, the data from the energy measurement lines arranged at different positions in each tunnel were sorted and output. The elastic energy density zoning curve of the tunnel surrounding rock was drawn using Origin data analysis software. The area with elastic energy density below E was defined as the energy release zone, and the area with elastic energy density greater than 1.3E was defined as the energy storage zone. The distribution characteristics of the elastic energy density of the tunnel surrounding rock during the working face mining period were obtained. In step F, a roadway near-field surrounding rock zoning energy storage model is established based on the data analysis results and the output elastic energy density zoning curve. According to this model, the roadway surrounding rock is divided into an energy release zone and an energy storage zone. Before roadway excavation, the roof and floor plates closer to the roadway accumulate elastic energy under the action of initial ground stress. After roadway excavation, the elastic energy stored in the roof and floor plates is released, forming an energy release zone. Since coal seams are more likely to store elastic energy than rock strata, an energy storage zone appears in front of the roadway head. For the coal body on the roadway side, the elastic energy stored in the coal body closer to the roadway is released, forming an energy release zone. The coal body within a certain range from the roadway and in front of the roadway head form an energy storage zone. In step G, first, the depth of the large-diameter pressure relief drilling hole must be designed to conform to actual production; Secondly, the fundamental basis for drilling depth design is the range of the roadway surrounding rock energy storage area, and the design depth must exceed the range of the roadway surrounding rock energy storage area; In the step H, first, the geological structure ahead is detected by advance drilling; if a special geological structure such as a fault or fold is encountered, whether it is a normal fault or a reverse fault, the mining disturbance and the stress superposition generated by it are one of the necessary conditions for the occurrence of fault impact ground pressure; therefore, when the borehole is close to the coal seam fault geological structure, the borehole depth must be no less than 3.5 times the coal seam thickness, and the borehole depth needs to be appropriately increased on the basis of the original borehole depth; secondly, by using the numerical simulation method, combined with the actual situation on site, such as the influence of goaf and coal pillars, additional boreholes are added on the basis of the original model, and the designed large-diameter pressure relief borehole depth parameters are substituted into the tunnel surrounding rock energy zoning evolution model, and the data is output to observe whether its energy change conforms to the decrease in the energy storage area or the transfer to the deep part; finally, the on-site inspection method is adopted to observe the mine pressure manifestation in the tunnel and use a borehole stress meter or a drill cuttings method to check whether the designed large-diameter borehole depth has an ideal pressure relief effect.

2. A method for designing the depth of large-diameter drilling holes based on tunnel surrounding rock energy storage zoning according to claim 1, characterized in that: The field data mainly include: drill hole histograms, and research reports on the distribution of ground stress, which are used to determine the type and thickness of coal and rock layers, and the stress environment of the surrounding rock of the roadway. By collecting the above data, a preliminary understanding of the field conditions is obtained, providing data support for the design of numerical model dimensions and boundary condition parameters.

3. The method for designing the depth of large-diameter drilling holes based on the energy storage zoning of tunnel surrounding rocks according to claim 1 is characterized in that: In step B, drilling and sampling are carried out in the target area, and the cores taken out on site are processed into standard specimens. By conducting indoor uniaxial compression tests, Brazilian splitting tests, and triaxial tests, the mechanical properties of the coal strata are obtained, which mainly include bulk modulus, cohesion, internal friction angle, and tensile strength, providing data support for the design of numerical model parameters.

4. The method for designing the depth of large-diameter drilling holes based on the energy storage zoning of surrounding rock of tunnels according to claim 1 is characterized in that: In step D, first, because initial stress exists inside the rock mass in its natural state without being disturbed by artificial excavation, geostress is applied to the model to make the model stress conditions closer to the actual situation; Secondly, the field data collected in the preliminary preparation step A and the parameters measured by the coal and rock mechanics test in step B are assigned to the model; finally, the working face mining activities are simulated.

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