Self-pressure-bearing sleeve drilling pressure relief method for deep coal body high stress area

Abstract

This invention discloses a method for stress relief through drilling with self-supporting sleeves in high-stress zones of deep coal seams. The method includes: 1. Obtaining the rock mechanics parameters of each stratum in the mining area; 2. Constructing an initial stress equilibrium model; 3. Dividing different areas in front of the working face into strong stress relief zones, medium stress relief zones, and weak stress relief zones; 4. Determining the basic parameters of the self-supporting sleeves; 5. Determining the number of self-supporting sleeve boreholes, the borehole length, and the borehole spacing; 6. Installing the self-supporting sleeves in the roadway sidewalls and relieving stress in the high-stress zones of the deep coal seams; 7. Calculating the stress relief interval and performing multiple drilling and stress relief operations on the deep coal seams within the self-supporting sleeves until the working face is mined back to a distance from the self-supporting sleeves that meets a set threshold. Through scientific numerical simulation and theoretical analysis, the optimal stress relief range and parameters are determined, enabling multiple drilling for stress relief. This effectively reduces stress concentration while improving the support strength and disturbance resistance of the surrounding rock in the roadway.

Description

Technical Field

[0001] This invention relates to a method for relieving pressure in the high-stress zone of deep coal seams by drilling with a self-supporting sleeve. Background Technology

[0002] In coal mining, high stress concentration in the deep surrounding rock of roadways is one of the main causes of rockburst disasters. When the static load and dynamic load on the coal body exceed its ultimate strength, the coal body will break down, and the elastic energy stored in the coal body and roof and floor will be rapidly released, leading to severe deformation of the roadway, damage to the support structure, and even casualties and equipment damage. Therefore, how to effectively reduce the high stress in the deep surrounding rock of roadways and ensure safe and efficient coal mine production has become an urgent technical problem to be solved in coal mining.

[0003] Drilling for stress relief is widely used in the prevention and control of rockbursts due to its simplicity, low construction cost, and strong applicability to geological conditions. By drilling into the coal seam, it can effectively reduce the static load on the coal. However, traditional drilling for stress relief technology has many problems in practical applications:

[0004] First, insufficient pressure relief in a single drilling operation: When implementing pressure relief in a single drilling operation in the surrounding rock of a roadway, the pressure relief is often insufficient, and the deep part of the surrounding rock in the roadway remains in a state of high stress, which poses a risk of impact pressure.

[0005] Second, repeated pressure relief damage: When multiple borehole pressure relief operations are carried out on the surrounding rock of the roadway, the integrity of the shallow surrounding rock is severely damaged, resulting in a decrease in roadway stability. When dynamic loads are applied to the surrounding rock of the roadway, it is easy to cause impact in the roadway, increasing the risk of accidents.

[0006] Therefore, there is an urgent need for a new type of stress relief method that can effectively reduce high stress while maintaining the structural integrity and stability of the surrounding rock in the roadway and enhancing its resistance to disturbance. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a self-supporting sleeve drilling method for stress relief in high-stress zones of deep coal seams. Through scientific numerical simulation and theoretical analysis, the optimal stress relief range and parameters are determined, enabling multiple drilling stress relief operations. This method effectively reduces stress concentration while improving the support strength and disturbance resistance of the surrounding rock in the roadway.

[0008] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0009] A method for relieving pressure in the high-stress zone of deep coal seams using a self-supporting sleeve drilling method includes the following steps:

[0010] Step 1: Obtain the rock mass mechanical parameters of each rock stratum in the mining area;

[0011] Step 2: Construct an initial geostress equilibrium model based on the coal seam strike and stratigraphic structure conditions;

[0012] Step 3: Based on the numerical simulation results, obtain the distribution characteristics of the advance support pressure of the working face. Along the advancing direction of the working face, divide the different areas in front of the working face into high, medium and low stress zones, which correspond to strong pressure relief zone, medium pressure relief zone and weak pressure relief zone, respectively.

[0013] Step 4: Calculate the lateral support pressure distribution characteristics of the roadway based on the determined working face advance support pressure distribution characteristics, and determine the basic parameters of the self-supporting sleeve so that the critical pressure of the self-supporting sleeve meets the bearing capacity.

[0014] Step 5: Based on the pre-stress concentration level of the working face and the strength of the self-bearing sleeve, determine the number of self-bearing sleeve holes, the length of the self-bearing sleeve holes, and the spacing of the self-bearing sleeve holes.

[0015] Step 6: Based on the drilling layout plan of the self-pressure bearing sleeve obtained in Step 5, install the self-pressure bearing sleeve in the roadway side and relieve the pressure in the high stress zone of the deep coal body in the roadway side.

[0016] Step 7: Calculate the decompression interval based on the stress concentration factor corresponding to the borehole position in front of the working face, and perform multiple drilling and decompression operations on the deep coal body inside the self-supporting sleeve until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. .

[0017] Preferably, step 1 specifically includes the following steps:

[0018] Step 1.1: Obtain rock samples from various rock strata in the mining area, measure the elastic modulus of the rock samples, and calculate the volumetric model and shear modulus mechanical parameters of the rock mass.

[0019] Step 1.2: Establish a numerical model of the rock sample with uniform dimensions, and assign initial parameters to the mechanical parameters of the blocks and joints in the rock sample;

[0020] Step 1.3: Adjust the mechanical parameters of the block and joints until the elastic modulus of the rock sample in the numerical model is consistent with the actual rock sample result. Use the data at this time as the rock mass mechanical parameters in the numerical model.

[0021] Preferably, step 2 specifically includes the following steps:

[0022] Step 2.1: Construct a model of the working face advancing direction. The left and right sides of the model are fixed in the horizontal direction, and the bottom of the model is fixed in the vertical direction. Determine the lateral pressure coefficient of the model based on the measured geostress environment of the coal mine, and apply a uniformly distributed load to the top of the model to replace the static load of the overlying strata.

[0023] Step 2.2: Based on the actual geological columnar section of the mine, group the rock strata in the model;

[0024] Step 2.3: Apply gravitational acceleration to the model and assign the mechanical parameters of the block and joint obtained in Step 1.3 to the corresponding rock layers to obtain the model with initial geostress equilibrium.

[0025] Preferably, step 3 specifically includes the following steps:

[0026] Step 3.1: Excavate the coal seam in the initial stress balance model to the actual advancing position on site, solve the initial stress balance model to obtain the distribution characteristics of the advance support pressure of the working face, and find the value and location of the maximum vertical stress.

[0027] Step 3.2: Based on the calculation results, the different areas in front of the working face are divided into high, medium, and low stress zones, corresponding to the strong pressure relief zone, medium pressure relief zone, and weak pressure relief zone, respectively.

[0028] The area of ​​the strong pressure relief zone is: ;

[0029] The range of the intermediate depressurization zone is: ;

[0030] The range of the weak pressure relief zone is: ;

[0031] In the formula: Distance from the working surface Stress state at position 1 meter; The stress state of the original coal seam rock; This represents the peak value of the advance support pressure.

[0032] Preferably, step 4 specifically includes the following steps:

[0033] Step 4.1: Determine the peak value of the lateral support pressure. The calculation method is as follows: ;

[0034] Step 4.2: Determine the basic parameters of the self-supporting sleeve and calculate its critical pressure.

[0035] ;

[0036] Step 4.3: Determine if the self-supporting sleeve meets the load-bearing capacity requirements: Once the self-supporting sleeve meets the load-bearing capacity, proceed to the next step;

[0037] In the formula, This represents the peak value of the lateral support pressure. The lateral pressure coefficient, This represents the average unit weight of the rock mass. The depth of the coal seam; The critical pressure of the self-supporting sleeve. The elastic modulus of the self-supporting sleeve. The Poisson's ratio of the self-supporting sleeve. The thickness of the self-supporting sleeve, The outer diameter is the self-supporting sleeve.

[0038] Preferably, step 5 specifically includes the following steps:

[0039] Step 5.1: Calculate the location of the peak lateral support pressure. :

[0040] ;

[0041] Step 5.2: Determine the range of the pressure relief drilling:

[0042] ;

[0043] Step 5.3: Determine the number of pressure relief boreholes. :

[0044] ;

[0045] Step 5.4: Determine the drilling length of the self-supporting sleeve. :

[0046] ;

[0047] Step 5.5: Determine the spacing of the self-supporting sleeve drilling arrangement. :

[0048] ;

[0049] Step 5.6: Determine the spacing between the self-supporting sleeves. :

[0050] ;

[0051] Among them, when it is in the strong pressure relief zone, take ;

[0052] When within the intermediate depressurization zone, take ;

[0053] When within the weak pressure relief zone, take ;

[0054] In the formula: The approximate radius of the tunnel is... This represents the average unit weight of the rock mass. To deepen the tunnel; This refers to the cohesive force at the coal seam interface; The internal friction angle at the coal seam interface; Coal seam thickness; This refers to the range corresponding to the pressure relief. The diameter of a single borehole.

[0055] Preferably, step 6 specifically includes the following steps:

[0056] Step 6.1, Drilling holes for the self-supporting sleeve: Drilling diameter = ;

[0057] Step 6.2, Drilling in the self-supporting sleeve: Sleeve outer diameter , inner diameter The sleeve extends deep into the coal face. Strengthen the support of the plastic zone of the surrounding rock in the roadway;

[0058] Step 6.3: Insert the drill pipe to relieve pressure: The drill pipe diameter is smaller than the inner diameter of the sleeve, and the drilling length is... It passes through the high stress peak zone to relieve the pressure in the high stress zone of the deep coal body in the roadway.

[0059] Preferably, step 7 specifically includes the following steps:

[0060] Step 7.1: Calculate the pressure relief interval based on the stress concentration factor corresponding to the drilling position in front of the working face. Repeated depressurization is performed on the high-stress zone of the coal seam until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. ;

[0061] The method for calculating the depressurization interval is as follows: ;

[0062] Step 7.2: Remove the pressure-bearing sleeve from the tunnel wall.

[0063] Preferably, in step 1, the UDEC discrete element method software is used to obtain the rock mechanics parameters of each rock layer in the mining area, and in step 7, a threshold is set. It is 2m.

[0064] The beneficial effects of this invention are:

[0065] 1. This invention utilizes UDEC discrete element method software to recreate the actual geostress environment conditions of rock strata. The simulation process is consistent with the actual field conditions. Through numerical simulation, the stress distribution characteristics along the working face advancement direction are obtained, and pressure relief zones are delineated accordingly, providing a scientific basis for the rational design of self-supporting sleeve borehole pressure relief. This invention can accurately predict the pressure relief effect under actual conditions in the deep high-stress zone of coal mine roadways, improving the reliability and scientific nature of the design.

[0066] 2. This invention, through theoretical analysis and calculation of the plastic zone range and lateral support pressure of the surrounding rock in the roadway, determines parameters such as the length of the self-supporting sleeve, the sleeve wall thickness, the borehole pressure relief spacing, the pressure relief depth, and the number of pressure relief cycles. Precise parameter determination ensures high efficiency and safety during the pressure relief process, maintaining the structural integrity of the surrounding rock in the roadway during multiple borehole pressure relief cycles, and improving its support strength and resistance to disturbance.

[0067] 3. This invention effectively reduces the stress concentration coefficient in the deep surrounding rock of the roadway through multiple drilling for pressure relief, releasing high stress and ensuring that the surrounding rock remains at a low stress level. Simultaneously, it monitors the stress concentration at the working face in real time and dynamically adjusts the pressure relief plan based on the monitoring results, ensuring the continuity and reliability of the pressure relief effect, reducing the probability and intensity of rockburst dynamic disasters, and guaranteeing safe and efficient coal mine production.

[0068] 4. This invention provides a new technical solution for multiple stress relief and support reinforcement in high-stress areas of coal seams. It enables numerical calculations to evaluate the stress relief effect under different geological structures and geostress conditions, and has significant theoretical and applied value for studying stress relief methods in high-stress areas of coal seams. The method of this invention provides a scientific reference and effective means to solve the stress relief problem in deep high-stress areas of coal mine roadways, and has broad engineering application prospects. Attached Figure Description

[0069] Figure 1 This is a flowchart of a method for relieving pressure in the high-stress zone of deep coal seams using a self-supporting sleeve for drilling;

[0070] Figure 2 This is a schematic diagram of numerical simulation rock mechanics parameter calibration according to an embodiment of the present invention;

[0071] Figure 3 This is a schematic diagram of a numerical model for determining the advance support pressure of the working face according to an embodiment of the present invention.

[0072] Figure 4 This is a schematic diagram of the working face advanced support pressure distribution characteristics according to an embodiment of the present invention;

[0073] Figure 5 This is a schematic diagram illustrating the division of the degree of pre-stress concentration on the working surface according to an embodiment of the present invention;

[0074] Figure 6 This is a diagram showing the distribution of the working face's advanced support pressure and lateral support pressure according to an embodiment of the present invention.

[0075] Figure 7 This is a schematic diagram of a self-supporting sleeve according to an embodiment of the present invention;

[0076] Figure 8This is a schematic plan view of the construction layout of a self-bearing sleeve according to an embodiment of the present invention;

[0077] Figure 9 This is a three-dimensional schematic diagram of the actual construction layout of a self-bearing sleeve according to an embodiment of the present invention;

[0078] Figure 10 This is a schematic diagram of a method for determining the pressure relief range and sleeve length of a self-supporting sleeve according to an embodiment of the present invention. Detailed Implementation

[0079] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0080] like Figure 1 As shown, a method for relieving pressure in the high-stress zone of deep coal seams using a self-supporting sleeve drilling method includes the following steps:

[0081] Step 1: Obtain the rock mass mechanical parameters of each rock stratum in the mining area. In this embodiment, Step 1 preferably includes the following steps:

[0082] Step 1.1: Obtain rock samples from various rock strata in the mining area. The elastic modulus of the rock samples can be measured by a press. After calculation using the RQD method (rock quality designation), mechanical parameters such as the volume model and shear modulus of the rock mass can be obtained.

[0083] Step 1.2: Establish a numerical model of the rock sample at an equal size in the numerical model of the UDEC discrete element software, such as... Figure 2 As shown, the mechanical parameters of the blocks and joints in the rock sample are initially assigned, where: the joint model is set as a surface contact model, the block model is set as a Mohr-Coulomb model, the joint mechanical parameters include shear stiffness, normal stiffness, cohesion, friction angle, and tensile strength, and the block mechanical parameters include elastic modulus, Poisson's ratio, and density.

[0084] Step 1.3: Continuously adjust the mechanical parameters of the block and joints until the elastic modulus of the rock sample in the numerical model matches the actual rock sample. Use this data as the rock mass mechanical parameters in the UDEC rock sample numerical model. The specific mechanical parameters obtained in this embodiment are shown in Table 1 below:

[0085] Table 1 Rock mechanical parameters in discrete element numerical analysis

[0086]

[0087] Step 2: Construct an initial geostress equilibrium model based on the coal seam strike and stratigraphic structure conditions. In this embodiment, for example... Figure 3As shown, preferred step 2 specifically includes the following steps:

[0088] Step 2.1: Construct a model of the working face advancing direction. The left and right sides of the model are fixed in the horizontal direction, and the bottom of the model is fixed in the vertical direction. Determine the lateral pressure coefficient of the model based on the measured geostress environment of the coal mine. Apply a uniformly distributed load to the top of the model to replace the static load of the overlying strata.

[0089] Step 2.2: Based on the actual geological columnar section of the mine, group the rock strata in the model. Among them, the joint contact model between the coal seam and the rock strata is a surface contact model.

[0090] Step 2.3: Apply gravitational acceleration to the model and assign the mechanical parameters of the block and joint obtained in Step 1.3 to the corresponding rock layers to obtain the model with initial geostress equilibrium.

[0091] Step 3: Based on the numerical simulation results, obtain the distribution characteristics of the advance support pressure on the working face. Along the advancing direction of the working face, divide the different areas in front of the working face into high, medium, and low stress zones, corresponding to the strong pressure relief zone, medium pressure relief zone, and weak pressure relief zone, respectively. In this embodiment, preferably, step 3 specifically includes the following steps:

[0092] Step 3.1: In the initial stress equilibrium model, the coal seam is excavated to the actual advancing position on site. The initial stress equilibrium model is then solved to obtain the distribution characteristics of the advance support pressure at the working face, and the value and location corresponding to the maximum vertical stress are identified, such as... Figure 4 As shown.

[0093] Step 3.2: Based on the calculation results, the different areas in front of the working face are divided into high, medium, and low stress zones, corresponding to the strong pressure relief zone, medium pressure relief zone, and weak pressure relief zone, respectively. The specific division method is as follows:

[0094] The area of ​​the strong pressure relief zone is: ;

[0095] The range of the intermediate depressurization zone is: ;

[0096] The range of the weak pressure relief zone is: ;

[0097] In the formula: Distance from the working surface Stress state at position 1 meter; The stress state of the original coal seam rock; This represents the peak value of the advance support pressure.

[0098] In this embodiment, as Figure 5As shown, calculations show that 13-14m and 37-91m in front of the working face are weak pressure relief zones, 14-16m and 27-37m in front of the working face are medium pressure relief zones, and 16-27m in front of the working face is a strong pressure relief zone.

[0099] Step 4: Calculate the lateral support pressure distribution characteristics of the roadway based on the determined pre-support pressure distribution characteristics of the working face, and determine the basic parameters of the self-supporting sleeve so that the critical pressure of the self-supporting sleeve meets the bearing capacity. Preferably, such as... Figure 6 and Figure 7 As shown, step 4 specifically includes the following steps:

[0100] Step 4.1: Determine the peak value of the lateral support pressure. The calculation method is as follows: ;

[0101] In the formula, This represents the peak value of the lateral support pressure. The lateral pressure coefficient, This represents the average unit weight of the rock mass. The depth is the coal seam depth. In this embodiment, based on field measurement data, the depth is taken as... It is 1.5. It is 25000 kg / m3. Taking 500m, the calculation is as follows It is 18.75 MPa.

[0102] Step 4.2: Determine the basic parameters of the self-bearing sleeve, including its outer diameter, thickness, yield strength, and elastic modulus. Calculate the critical pressure of the self-bearing sleeve.

[0103] ;

[0104] In the formula, The critical pressure of the self-supporting sleeve (unit: kPa). The elastic modulus of the self-supporting sleeve (unit: kPa). The Poisson's ratio of the self-supporting sleeve. The thickness of the self-supporting sleeve is shown in mm. The outer diameter of the self-supporting sleeve is in mm.

[0105] In this embodiment, the elastic modulus of the self-supporting sleeve is taken as 2e. 5 With a pressure of 0.15 kPa, a Poisson's ratio of 0.15, a t of 160 mm, and an outer diameter of 200 mm for the self-supporting sleeve, the critical pressure of the self-supporting sleeve is calculated to be 3.27 GPa.

[0106] Step 4.3: Determine if the self-supporting sleeve meets the load-bearing capacity requirements: Once the self-supporting sleeve meets the load-bearing capacity, proceed to the next step.

[0107] In this embodiment, the calculated value is 3270MPa > 18.75MPa + 26MPa, which meets the load-bearing capacity requirement.

[0108] Step 5: Based on the pre-stress concentration level of the working face and the strength of the self-bearing sleeve, determine the number of self-bearing sleeve boreholes, the borehole length, and the spacing of the boreholes. For example... Figure 8 As shown, preferably, step 5 specifically includes the following steps:

[0109] Step 5.1: Calculate the location of the peak lateral support pressure. :

[0110] ;

[0111] In the formula: The approximate radius of the tunnel is... This represents the average unit weight of the rock mass. To deepen the tunnel; This refers to the cohesive force at the coal seam interface; This is the internal friction angle at the coal seam interface. In this embodiment, the approximate radius of the roadway is... It is 2m. It is 25000 kg / m3. It is 500m. It is 1.2 MPa. The angle is 30°, calculated as follows: It is 10.2.

[0112] Step 5.2: Determine the range of the pressure relief drilling:

[0113] ;

[0114] In the formula: Coal seam thickness; This refers to the range corresponding to pressure relief. In this embodiment, the coal seam thickness... Take 6m, Take 24MPa, Taking 21 MPa, the calculated borehole range is 0.86 m.

[0115] Step 5.3: Determine the number of pressure relief boreholes. :

[0116] ;

[0117] In the formula: This is the diameter of a single drill hole. In this embodiment, we take... The value is 200mm, calculated as follows =4.3, then the number of boreholes The value is 4.

[0118] Step 5.4: Determine the drilling length of the self-supporting sleeve. :

[0119] ;

[0120] Step 5.5: Determine the spacing of the self-supporting sleeve drilling arrangement. :

[0121] ;

[0122] In this embodiment, the coal seam thickness is 6m and the number of boreholes is 4, so the borehole spacing is 1.5m.

[0123] Step 5.6: Determine the spacing between the self-supporting sleeves. :

[0124] ;

[0125] Among them, when it is in the strong pressure relief zone, take ;

[0126] When within the intermediate depressurization zone, take ;

[0127] When within the weak pressure relief zone, take .

[0128] In this embodiment, take For 21 MPa, when When the pressure is 24 MPa, the spacing between boreholes is 0.875 m.

[0129] Step 6: Based on the drilling layout scheme of the self-supporting sleeve obtained in Step 5, install the self-supporting sleeve in the roadway sidewall and relieve pressure in the high-stress zone of the deep coal seam in the roadway sidewall. Preferably, as follows... Figure 9 and Figure 10 As shown, step 6 specifically includes the following steps:

[0130] Step 6.1, Drilling holes for the self-supporting sleeve: Drilling diameter = In this embodiment, the borehole diameter is 200mm.

[0131] Step 6.2, Drilling in the self-supporting sleeve: Sleeve outer diameter (Unit: mm), Inner Diameter (Unit: mm), divided into multiple sections, each 1m long, assembled by threads, with the sleeve extending deep into the coal face. Strengthen the support of the plastic zone of the surrounding rock in the tunnel.

[0132] Step 6.3: Insert the drill pipe to relieve pressure: The drill pipe diameter is smaller than the inner diameter of the sleeve, and the drilling length is... It passes through the high-stress peak zone to relieve pressure on the high-stress zone of the deep coal seam in the roadway. In this embodiment, the drill pipe diameter is taken as ( -50mm), The calculated value is 10.2, so the borehole pressure relief depth should be 20.4m.

[0133] Step 7: Calculate the decompression interval based on the stress concentration factor corresponding to the borehole position in front of the working face, and perform multiple drilling and decompression operations on the deep coal body inside the self-supporting sleeve until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. .

[0134] Preferably, step 7 specifically includes the following steps:

[0135] Step 7.1: Calculate the pressure relief interval based on the stress concentration factor corresponding to the drilling position in front of the working face. Repeated depressurization is performed on the high-stress zone of the coal seam until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. For example, setting a threshold It is 2m.

[0136] The method for calculating the depressurization interval is as follows: ;

[0137] In this embodiment, take The value is 21 MPa. If the pressure is 24 MPa, then the borehole pressure relief interval is 0.875 days.

[0138] Step 7.2: Remove the pressure-bearing sleeve from the tunnel wall.

[0139] 1. This invention utilizes UDEC discrete element method software to recreate the actual geostress environment conditions of rock strata. The simulation process is consistent with the actual field conditions. Through numerical simulation, the stress distribution characteristics along the working face advancement direction are obtained, and pressure relief zones are delineated accordingly, providing a scientific basis for the rational design of self-supporting sleeve borehole pressure relief. This invention can accurately predict the pressure relief effect under actual conditions in the deep high-stress zone of coal mine roadways, improving the reliability and scientific nature of the design.

[0140] 2. This invention, through theoretical analysis and calculation of the plastic zone range and lateral support pressure of the surrounding rock in the roadway, determines parameters such as the length of the self-supporting sleeve, the sleeve wall thickness, the borehole pressure relief spacing, the pressure relief depth, and the number of pressure relief cycles. Precise parameter determination ensures high efficiency and safety during the pressure relief process, maintaining the structural integrity of the surrounding rock in the roadway during multiple borehole pressure relief cycles, and improving its support strength and resistance to disturbance.

[0141] 3. This invention effectively reduces the stress concentration coefficient in the deep surrounding rock of the roadway through multiple drilling for pressure relief, releasing high stress and ensuring that the surrounding rock remains at a low stress level. Simultaneously, it monitors the stress concentration at the working face in real time and dynamically adjusts the pressure relief plan based on the monitoring results, ensuring the continuity and reliability of the pressure relief effect, reducing the probability and intensity of rockburst dynamic disasters, and guaranteeing safe and efficient coal mine production.

[0142] 4. This invention provides a new technical solution for multiple stress relief and support reinforcement in high-stress areas of coal seams. It enables numerical calculations to evaluate the stress relief effect under different geological structures and geostress conditions, and has significant theoretical and applied value for studying stress relief methods in high-stress areas of coal seams. The method of this invention provides a scientific reference and effective means to solve the stress relief problem in deep high-stress areas of coal mine roadways, and has broad engineering application prospects.

[0143] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for relieving pressure in the high-stress zone of deep coal seams by drilling with a self-supporting sleeve, characterized in that, Includes the following steps: Step 1: Obtain the rock mass mechanical parameters of each rock stratum in the mining area; Step 2: Construct an initial geostress equilibrium model based on the coal seam strike and stratigraphic structure conditions; Step 3: Based on the numerical simulation results, obtain the distribution characteristics of the advance support pressure on the working face. Along the advancing direction of the working face, divide the different areas in front of the working face into high, medium, and low stress zones, corresponding to the strong pressure relief zone, medium pressure relief zone, and weak pressure relief zone, respectively; where: The area of ​​the strong pressure relief zone is: ; The range of the intermediate depressurization zone is: ; The range of the weak pressure relief zone is: ; In the formula: Distance from the working surface Stress state at position 1 meter; The stress state of the original coal seam rock; This represents the peak value of the advance support pressure; Step 4: Calculate the lateral support pressure distribution characteristics of the roadway based on the determined working face advance support pressure distribution characteristics, and determine the basic parameters of the self-supporting sleeve so that the critical pressure of the self-supporting sleeve meets the bearing capacity. Step 5: Based on the pre-stress concentration level of the working face and the strength of the self-bearing sleeve, determine the number of self-bearing sleeve holes, the length of the self-bearing sleeve holes, and the spacing of the self-bearing sleeve holes. Step 6: Based on the drilling layout plan of the self-pressure bearing sleeve obtained in Step 5, install the self-pressure bearing sleeve in the roadway side and relieve the pressure in the high stress zone of the deep coal body in the roadway side. Step 7: Calculate the decompression interval based on the stress concentration factor corresponding to the borehole position in front of the working face, and perform multiple drilling and decompression operations on the deep coal body inside the self-supporting sleeve until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. ; Step 5 specifically includes the following steps: Step 5.1: Calculate the location of the peak lateral support pressure. : ； Step 5.2: Determine the range of the pressure relief drilling: ； Step 5.3: Determine the number of pressure relief boreholes. : ； Step 5.4: Determine the drilling length of the self-supporting sleeve. : ； Step 5.5: Determine the spacing of the self-supporting sleeve drilling arrangement. : ； Step 5.6: Determine the spacing between the self-supporting sleeves. : ； Among them, when it is in the strong pressure relief zone, take ; When within the intermediate depressurization zone, take ; When within the weak pressure relief zone, take ; In the formula: The approximate radius of the tunnel is... This represents the average unit weight of the rock mass. To deepen the tunnel; This refers to the cohesive force at the coal seam interface; The internal friction angle at the coal seam interface; Coal seam thickness; This refers to the range corresponding to the pressure relief. The diameter of a single borehole.

2. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 1, characterized in that, Step 1 specifically includes the following steps: Step 1.1: Obtain rock samples from various rock strata in the mining area, measure the elastic modulus of the rock samples, and calculate the volumetric model and shear modulus mechanical parameters of the rock mass. Step 1.2: Establish a numerical model of the rock sample with uniform dimensions, and assign initial parameters to the mechanical parameters of the blocks and joints in the rock sample; Step 1.3: Adjust the mechanical parameters of the block and joints until the elastic modulus of the rock sample in the numerical model is consistent with the actual rock sample result. Use the data at this time as the rock mass mechanical parameters in the numerical model.

3. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 2, characterized in that, Step 2 specifically includes the following steps: Step 2.1: Construct a model of the working face advancing direction. The left and right sides of the model are fixed in the horizontal direction, and the bottom of the model is fixed in the vertical direction. Determine the lateral pressure coefficient of the model based on the measured geostress environment of the coal mine. Apply a uniformly distributed load to the top of the model to replace the static load of the overlying strata. Step 2.2: Based on the actual geological columnar section of the mine, group the rock strata in the model; Step 2.3: Apply gravitational acceleration to the model and assign the mechanical parameters of the block and joint obtained in Step 1.3 to the corresponding rock layers to obtain the model with initial geostress equilibrium.

4. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 3, characterized in that, Step 3 specifically includes the following steps: Step 3.1: Excavate the coal seam in the initial stress balance model to the actual advancing position on site, solve the initial stress balance model to obtain the distribution characteristics of the advance support pressure of the working face, and find the value and location of the maximum vertical stress. Step 3.2: Based on the calculation results, the different areas in front of the working face are divided into high, medium and low stress zones, which correspond to strong pressure relief zone, medium pressure relief zone and weak pressure relief zone, respectively.

5. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 4, characterized in that, Step 4 specifically includes the following steps: Step 4.1: Determine the peak value of the lateral support pressure. The calculation method is as follows: ; Step 4.2: Determine the basic parameters of the self-supporting sleeve and calculate its critical pressure. ； Step 4.3: Determine if the self-supporting sleeve meets the load-bearing capacity requirements: Once the self-supporting sleeve meets the load-bearing capacity, proceed to the next step; In the formula, This represents the peak value of the lateral support pressure. The lateral pressure coefficient, This represents the average unit weight of the rock mass. The depth of the coal seam; The critical pressure of the self-supporting sleeve. The elastic modulus of the self-supporting sleeve. The Poisson's ratio of the self-supporting sleeve. The thickness of the self-supporting sleeve, The outer diameter is the self-supporting sleeve.

6. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 1, characterized in that, Step 6 specifically includes the following steps: Step 6.1, Drilling holes for the self-supporting sleeve: Drilling diameter = ; Step 6.2, Drilling in the self-supporting sleeve: Sleeve outer diameter , inner diameter The sleeve extends deep into the coal face. Strengthen the support of the plastic zone of the surrounding rock in the roadway; Step 6.3: Insert the drill pipe to relieve pressure: The drill pipe diameter is smaller than the inner diameter of the sleeve, and the drilling length is... It passes through the high stress peak zone to relieve the pressure in the high stress zone of the deep coal body in the roadway.

7. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 6, characterized in that, Step 7 specifically includes the following steps: Step 7.1: Calculate the pressure relief interval based on the stress concentration factor corresponding to the drilling position in front of the working face. Repeated depressurization is performed on the high-stress zone of the coal seam until the working face is mined back to a distance from the self-supporting sleeve that meets the set threshold. ; The method for calculating the depressurization interval is as follows: ; Step 7.2: Remove the pressure-bearing sleeve from the tunnel wall.

8. The method for relieving pressure in the high-stress zone of deep coal seam by drilling with a self-supporting sleeve according to claim 7, characterized in that, In step 1, the UDEC discrete element method software is used to obtain the rock mechanics parameters of each rock layer in the mining area. In step 7, a threshold value is set. It is 2m.

Images